Basic Obstetric POCUS

Chapter 7. First Trimester Complications

In this chapter we will review the most common variations and complications you will be encounter in early pregnancy. These include: early pregnancy loss, multiple gestation, and ectopic pregnancy.

Sonographic signs suggesting an abnormal pregnancy in early 1^st trimester:

Sac too small for contents
Poor decidual reaction (<2mm)
Irregular decidua appearance
Low implantation
Irregular gestational sac/yolk sac shape
Duplication or absence of yolk sac

Some major fetal anatomic anomalies may be seen in late first trimester, and detection of these is within the scope of a POCUS exam. However, diagnosis of the anomaly requires timely referral for more advanced imaging.

EARLY PREGNANCY LOSS - EPL

EPL Objectives:

By the completion of this chapter the participant will be able to:

Define Early Pregnancy Loss, and describe other terms used for this condition

List both suspicious and certain findings for EPL.

Recognize sonographic sign of subchorionic hemorrhage

Recognize sonographic sign of anembryonic pregnancy

Describe use of M-mode and/or color flow to confirm embryonic demise

Definition

The definition of EPL is:

“a nonviable, intrauterine pregnancy within the first trimester (up to 12wks 6 days from LMP)” Women prefer the terms “early pregnancy loss” or “miscarriage” over “early pregnancy failure” “or spontaneous abortion”

Figure 1. Definition of early pregnancy loss

This is likely the most common abnormal condition you will see in first trimester, since the overall incidence of early pregnancy loss can be as high as 20% to 25%, or 1 in 4-5 pregnancies.

NOTE: Although ultrasound is indispensable to detect early pregnancy failure, it can lead to inconclusive results or incorrect diagnosis if performed too early without adherence to guidelines.

Early Pregnancy Loss (EPL) Risk Factors

EPL risk factors include:

--Increasing age

Age 25-29 – incidence is 10%

Age >45 – incidence is 57%, likely due to the increase in chromosomal abnormalities

Prior pregnancy loss is also associated with a higher risk of loss in the current pregnancy

OR (adjusted odds ratio) of miscarriage after:

1 prior loss is 1.54

2 prior losses is 2.21

3 prior losses is 3.97

Figure 2. Risk factors for EPL

Early Preg Loss (EPL)

Common causes of EPL include:

--Chromosomal abnormalities

(These abnormalities are present in 70% of pregnancy losses before 20 wks.)

Figure 3. Common causes of EPL

--Maternal anatomic anomalies can also cause a problem with implantation. Some of the more common maternal causes are:

--Uterine fibroids (more likely to cause complications if they are large, or if they impinge on the endometrial cavity)

--Polyps

--Adhesions

--Uterine septa

--Other uterine malformation

--Trauma, such as a motor vehicle accident or direct abdominal trauma. There are mixed data on the significance of intimate partner violence contributing to an EPL.

Clinical signs

The two most common clinical signs of EPL are vaginal bleeding and cramping. Although bleeding or spotting is very common in early pregnancy (up to 20-30% of all pregnancies), about 12% of these will be in the process of losing a pregnancy.

EPL is more likely if the bleeding is heavy.

Figure 4. Clinical signs of EPL

Many providers attempt to reassure women with any spotting or bleeding during the first trimester that she is experiencing “implantation” or “nidation” bleeding. However, this type of bleeding occurs during the first 2 weeks of gestation.

Women commonly say that they suspected a problem when they suddenly noticed an absence of pregnancy symptoms they had previously been having.

Some women are totally asymptomatic and are unaware there is a problem. Women who have limited access to health care (such as remote areas) may have already passed the fetal tissue prior to being seen by a provider. The longer a woman waits with incomplete expulsion of products of conception, the greater the risk of hemorrhage and uterine infection.

Categories of EPL

The categories of EPL are described as

--Threatened (with early signs)

--Inevitable (failure of the GS to grow, or embryonic demise)

--Incomplete (retained tissue within the uterus, either fetal or placental)

--Complete: complete passage of pregnancy tissue (with or without intervention)

The categories may also be subdivided into:

--Asymptomatic: without bleeding, cramping, or passage of tissue

--Symptomatic. with bleeding and often cramping

Figure 5. Categories of EPL

It has been reported that neither bleeding or cramping alone are independent risk factors for EPL; however, the combination of the two makes the suspicion much greater.

There has been recent discussion about the validity of using so many different terms describing EPL. However, the above terms are still commonly used.

The order in which pregnancy structures can be seen by ultrasound (from earliest to latest) is:

1. Gestational sac

2. Yolk sac

3. Fetal (embryonic) pole

4. Embryonic cardiac activity

5. Amnion

Findings suspicious for EPL

-- Mean sac diameter of >16 mm without YS, or 20-24 mm and no embryo

--Crown-rump length (CRL) > 7 mm and no heartbeat seen with transvaginal ultrasound

-- Absence of embryo with a heartbeat 7 to 13 days after a scan showing a GS

-- Absence of embryo > 6wks after LMP

-- Empty amnion seen adjacent to YS, but no embryo

--Small GS in relationship to embryo (<5mm difference between mean sac diameter and CRL)

Figure 6. Findings suspious for EPL

Diagnosis of EPL – Certain Criteria

Once an IUP (intrauterine pregnancy) is identified on ultrasound, EPL is diagnosed if any subsequent ultrasound shows no IUP, or if there is no longer cardiac activity that was previously seen.

Other certain diagnostic criteria by ultrasound:

--Gestational sac >25 mm, with no yolk sac or embryo

--Embryo with CRL >7, without cardiac activity

-- Absence of embryo with heartbeat >2wks after a scan showing GS without a YS

--Absence of embryo with heartbeat >11 days after a scan that showed a GS WITH a YS

Figure 7. Certain criteria diagnostic of EPL

NOTE: Once an ultrasound between 6-12 weeks establishes a pregnancy with a normal heart rate, the risk of EPL decreases to about 1.6%

If a woman has bleeding in first trimester, her risk of pregnancy loss (compared to not having bleeding):

Gest Age	Heartbeat with bleeding	Heartbeat without bleeding
<6 wks	33%	16%
7-9 wks	10%	5%
10-11 wks	4%	1-2%

So the further into first trimester, the risk of pregnancy loss decreases even if she has bleeding.

Diagnosis of EPL

Figure 8. Diagnostic steps for EPL

The diagnosis of EPL is made by several findings, including:

History:

--Vaginal bleeding and pelvic pain

-- LMP and certainty of LMP

Physical exam:

--Visible bleeding from the cervical os, and possible appearance of an open or softened os.

--Absence of fetal heartbeat using doppler if gestation is greater than 11-12 weeks (depending on body habitus)

Lab evaluation:

There are no set diagnostic ranges of BhCG levels that are diagnostic for EPL, but some indicators are:

This is mentioned here so you will know what tests are typically done in areas with access to laboratory evaluations, or if a woman presents to you having had lab tests done elsewhere.

1. Drop of >25% in BhCG (serum pregnancy hormone) levels 48 hours from the prior level

2. Low or decreasing progesterone levels.

Differential Diagnosis

When a woman knows or suspects she is pregnant, and comes for care due to bleeding, cramping, or pelvic pain in the first trimester, these are the differential diagnoses (all the possible diagnoses) to consider:

--Normal pregnancy – Some normal pregnancies have bleeding/spotting without sequelae.

-- Subchorionic hematoma (sometimes termed ‘hemorrhage’, or “bleed”). An SCH (subchorionic hemorrhage) is a collection of fluid or blood beneath the chorionic plate, sometimes with elevation of the membrane from the chorion. It appears as an irregularly shaped, mixed echogenic region without color flow.

--Ectopic pregnancy – Until imaging demonstrates a gestational sac, yolk sac, and embryo inside the uterine cavity, there is a possibility that a pregnancy could be an ectopic or PUL (pregnancy of undetermined location). Ectopic pregnancy is described in more detail later in this chapter.

--Hydatidiform mole (trophoblastic disease)– This is a complication causing abnormal gestational tissue to grow inside the uterus, usually without a normal embryo present. This is reviewed at the end of this chapter.

Figure 9. Differential diagnoses for EPL

Sonographic signs of abnormal pregnancy

GENERAL RULE:

Ultrasound is the imaging modality of choice to determine the presence and/or viability of an early gestation.

In a normally developing viable pregnancy, an embryo with cardiac activity should be seen

1) > 11 days after a gestational sac (GS) with a yolk sac (YS)

2) >14 days after a GS is noted.

The sonographic signs to look for when suspecting an EPL or even early pregnancy complication include:

--GS is too large or empty

--GS too small for contents (risk of SAB is 94% for a small GS even cardiac activity is seen)

--Poor decidual reaction

-- Low implantation of GS

--Irregular size/shape of YS (YS should measure less than 7 mm)

--Duplication or absence of YS

-- Subchorionic bleed

Figure 10. Sonographic signs of abnormal early pregnancy

Sonographic findings in early pregnancy loss: Threatened ab

A “threatened ab” is defined as the presence of clinical signs of a potential miscarriage, with a pregnancy that is still viable.

Many women experience spotting or pink discharge during the first trimester, and this can be from several causes such as implantation bleeding (usually within the first couple of weeks after conception), vaginitis, or cervical changes resulting in capillary breakage.

Figure 11. Indications for early pregnancy ultrasound for detecting threatened abortion

When vaginal bleeding is present it is important to:

1. Look for hypoechoic region outside the GS, between the chorion or placenta and the myometrium in late first trimester, suggestive of subchorionic bleed. It can be associated with spontaneous abortion (SAB), but in many cases it is insignificant if small.

2. Calculate GS volume to compare to the volume of the subchorionic hemorrhage (SCH). If the area of bleed is less than 25% of GS volume, the pregnancy has a good chance of progressing

3. Look for debris or contents in the cervical os, indicating an imminent spontaneous abortion (SAB).

4. Refer for full diagnostic scan even if reassured

Figure 12. Sonographic findings in EPL: Vaginal bleeding

ANEMBRYONIC PREGNANCY(no embryo seen)

Other signs of pregnancy loss are an empty gestational sac, when by size or dates there should easily be a viable embryo. This is termed “anembryonic gestation” meaning without a visible embryo. Some have termed this condition as a “chemical pregnancy” or “blighted ovum”, indicating that there was never an embryo. However, it is more likely an embryo lost viability early and was absorbed before it could be detected on ultrasound.

The earliest sonographic detection of an anembryonic gestation using a transabdominal transducer (such as the Lumify)

GS size

>20 mm MSD with NO YS

>25 mm MSD with NO embryo

Figure 13. Summary of anembryonic gestation

First Trimester Problems – Subchorionic hemorrhage (SCH)

Subchorionic bleeding or hemorrhage is a finding that can be associated with EPL.

Figure 14. Image of subchorionic hemorrhage

A SCH (subchorionic hemorrhage) is a collection of fluid or blood beneath the chorionic plate, sometimes with elevation of the membrane from the chorion. The red arrows point to the irregularly shaped, hypoechoic areas that represent subchorionic hematoma. Finding a subchorionic bleed is not always a predictor of pregnancy loss. The risk of SAB increases with size of the SCH. SCH is seen often in a viable pregnancy, typically with complete resolution as the pregnancy advances.

The red arrows point to the irregularly shaped, hypoechoic areas representing subchorionic hematoma.

A subchorionic hemorrhage can often be seen in a normally progressing pregnancy. It may be important to describe to the woman the presence of an SCH, and to reassure her that it is likely to resolve. She may or may not have had any spotting or bleeding associated with it. Bleeding is more likely to be experienced if the SCH is low in the uterus or near the cervix. Tell the woman that the word “hemorrhage” does not indicate a large amount of blood, as the term is commonly used, but rather a very small area of blood.

Figure 15. Image of anembryonic GS with SCH

In Figure 15 there is a small section of a hematoma; however, the most concerning feature is the irregularity to the shape of the sac itself and the absence of an embryonic pole or YS. The shape of the GS is also irregular, suggesting early collapse of the sac. Another concern is the lack of a YS or fetal pole, both of which should be easily noted in a sac that size.

Sometimes an EPL is signaled by an abnormal size of the YS. An abnormal YS would be one that is small (2mm or less) or large (greater than 5-6mm). This is an example of a large YS. There is no visible embryo either, so this image is non-reassuring.

Figure 16. Image of large YS and no embryo

In Figure 17 there are empty gestational sacs. The one on the right has the additional concern of an irregular shape. We do not see any obvious sign of subchorionic hemorrhage, except for some tiny spaces in the right Image toward the top of the gestational cavity.

Figure 17. Images of empty GS

When determining if a gestational sac is empty, it is IMPERATIVE that you scan through the entire sac/uterus in both transverse and sagittal views so that a small embryo or fetus is not missed.

Figure 18. Images of empty GS

Figure 18 (above) shows additional images of empty gestational sacs. The image on the left is a transabdominal view, showing that the sac measured 3.55 cm in one diameter (well exceeding the 2.5 CM limit for when you should be able to see an embryo easily). The same is true for the image on the right. Color flow was even applied to this to try to detect a possible tiny fetal heart activity, but no color flow was seen in the embryo.

Figure 19. Sonographic find In EPL

The gestation in Figure 20 (below) is not normal. First of all, the gestational sac is very irregular, and it certainly does not meet the size criteria (by observation) of a 7 week gestation. We should see a well-developed embryo at this stage if the pregnancy is truly 7 weeks by LMP. Inside the sac there is irregular tissue – and a fetal pole is not easily identified. Using color flow, there is a small amount of blood flow evident at the top of the gestational sac. It is possible that this is post-miscarriage debris or an incomplete abortion/miscarriage.

Figure 20. Image of gestation at 7 wks by LMP, showing abnormal GS

Figure 21 is an image of a pregnancy dating 9 weeks by LMP. This image demonstrates several things. The view is in a transverse plane (because it says TRV UT in the upper left of the image (as annotated by the sonographer). There is a definite YS on a vitelline stalk, but the embryo has an irregular shape. Also note that the inside contour of the gestational sac is not smooth, but irregular, and a small area of subchorionic hemorrhage is indicated by the blue arrow. All of these are indicative of a pregnancy loss.

Figure 21. Image of irregular GS and no fetal cardiac activity

Small gestational sacs

The other indicator of a failing pregnancy is the presence of abnormally small sacs. However, not all small sacs mean that there will be a pregnancy loss. It is important to measure them over time, and continue to observe, especially if there is a good fetal heart rate. In this image a fetal pole and a YS are seen, although the YS in the right image appears a bit irregular in shape.

Figure 22. Images of small gestational sacs

Figure 23 is an image of a fetus measuring 7w 2d demonstrates a true embryonic demise. The embryo at 7+ weeks should have a clearly identified fetal heartbeat. However, even with color flow, no activity is seen. So this is considered a “missed” ab or “missed miscarriage”. The correct term for this is “embryonic demise”. There are no symptoms of miscarriage yet, but the embryo is no longer viable, and miscarriage will eventually happen.

This is a definite embryonic demise. At this gestation, with an accurate CRL measurement, the fetal heartbeat should be seen but is not, even with color application.

Figure 23. Image of gestation at 7wks 2 days by LMP with small GS and no cardiac activity using color flow

Figure 24. Image of small gestational sac at 7.5 weeks, and no cardiac activity

Figure 25 is an embryo in a woman who had a known and certain LMP, with a history of regular menses. The embryo is clearly identified, but there is no heartbeat. Given the true size of the embryo (6 wk. 3 d), a fetal heartbeat might be seen, especially using color flow. However, since this is very close to the 6-week gestation, if there is any doubt about viability, one should wait another week and rescan, to be certain and to “give the fetus a chance”.

Figure 25. Embryo at 6 wks 3 days; possibly too early to detect cardiac activity

One risk factor for EPL, mentioned in a previous slide, was the presence of fibroids. Not all fibroids represent a problem for pregnancy. Their impact on pregnancy has more to do with location and size, and the most problematic seem to be those that are in:

--uterine cavity (submucosal)

--intramural and large

-- cornual region

-- lower uterine segment and impinging on the cervix (with a potential for disrupting cervical integrity or causing obstruction during labor)

In Figure 26, we see a first trimester gestation, and a small well-defined fibroid that is partly pedunculated to the right of the uterus (on the left side of the image). Since this fibroid is outside the uterus, and it is relatively small (3.4 X 2.9 X 2.5 cm) it should not present problems for the pregnancy.

Figure 26. Fundal fibroid with intrauterine pregnancy

Figure 27 an image of a 12w 5d fetus that has some anterior impingement. At first sight, it could appear to be a possible fibroid. But there is not a clearly defined border. To determine whether this is a contraction or fibroid, waiting about 10-15 minutes to rescan in this same plane, would show the contraction to have resolved.

Contractions are commonly seen while scanning, especially during first trimester when they appear “large” in comparison to the uterine or fetal size. However, they are benign and do not indicate impending labor, nor do they predict preterm labor.

Figure 27. Image of uterine contraction in first trimester

Reporting the early pregnancy loss

A report should be worded, “findings consistent with miscarriage or early fetal demise”, and the report should have an image documenting the findings.

Some facilities require a second sonographer to confirm the diagnosis.

Retained products of conception after SAB

There can sometimes be remaining tissue after a miscarriage or elective abortion, causing persistent bleeding. If the bleeding has persisted over 7-10 days, an pelvic ultrasound is beneficial to look for retained products of conception (RPOC) in the uterine cavity. These contents can appear to have mixed echogenicity and will distend the endometrium irregularly. Color doppler is helpful in determining if this tissue is still receiving blood supply from the endometrium, demonstrating that the POCs have not been completely expelled. If this is seen, it is important to refer the woman for medical or surgical management. When documenting this finding, the report should include the following:

--absence of a gestational sac

--description of the endometrial cavity with measurements

--documenting (image) the presence or absence of color flow into the tissue

Endometrial evaluation after EPL - determining retained products of conception

After expulsion of the products of conception the endometrium should be thin and smooth. The image in Figure 28 illustrates this.

Figure 28. Image of post-EPL endometrium

Figure 29. Image of post-sab (EPL) debris that has not been passed

Figure 30. Post EPL image with retained products, demonstrated by color flow

Figure 31. Positive color flow in endometrium demonstrating retained products of conception after EPL

CLINICAL MANAGEMENT

Document suspected findings

Refer for detailed sonogram to confirm

Follow pregnancy per local treatment protocols

—expectant management

—medical management with uterotonics like misoprostel (cytotec). If a prostaglandin medication such as misoprostel is used, the woman should return for a follow up POCUS to be sure that the POCs are completely expelled.

—referral for surgical evacuation (D&C) when recommended by protocol or consultation

Figure 32. Summary of EPL

MULTIPLE GESTATION

This section will review common types of multiples, more specifically twins. The importance of early detection of the chorionicity and amnionicity of twins is presented for the purpose of determining risks for later in gestation.

Objectives

By the completion of this section the learner will be able to:

Describe the difference between dizygotic and monozygotic twins

Recognize a multiple gestation on an image, and determine chorionicity and amnionicity

Describe the common complications encountered with multiple gestation, and the severity associated with chorionicity and amnionicity

Know the risks of preterm birth associated with twins and triplets

Multiple gestation

The importance of identifying multiple gestation is to mediate the inherent risks. The information in this course will describe these risks and how to identify those multiple gestations at highest risk.

Figure 33. Importance of early detection of multiple gestation

Incidence of twins:

The global incidence of twins varies by region, but overall is around 18 per1,000 gestations. Japan has the lowest incidence of twinning (4.3 per 1,000 pregnancies), and Western Nigeria has the highest (54 per 1,000 pregnancies). Twinning rates in different areas also differ in the type of twinning, whether monozygotic or dizygotic.( ACOG reported slightly different numbers in their 2018 practice bulletin, citing the twin birth rate was 32.6 twins per 1,000 total births in 2018. Another statistic was that 25.5% (25.5 per 100) of women using ART (artificial reproductive technology) had multiple gestation.

Figure 34. Factors associated with multiple gestation

Factors associated with having a multiple gestation include:

--Heredity

--Older age (older than 30)

--Assisted reproduction

--Ovulation stimulation/induction with medication

--In-vitro fertilization

--Past pregnancy with multiples

--Race*

Highest rate of twinning: African descent – more likely than any other race

Sub-Saharan Africa – highest rates of natural twinning: 6-9 per 1000 births, can be up to 18 per 1000

A grim statistic is that one-fifth of twins in this region dies before age 5

Lowest rate of twinning: Asian and Native Americans

Implications of twin gestation

Most of the risks for multiple gestation seem less to do with zygosity than with chorionicity (whether the fetuses share placental circulation). Sonographic assessment of chorionicity is most accurate in the first trimester.

RISKS:

--Monozygotic twins (derived from the same zygote) have higher incidence of structural abnormalities; and all twin gestations have increased risk of chromosomal abnormalities.

NOTE: if prenatal genetics screening is done, there is a greater risk of inaccuracy of the results. This technology is expanding rapidly, however, and some companies are able to obtain more accurate information by separating out the twin DNA.

--Monochorionic twins (sharing the same placenta) have a greater risk of TTS (Twin to Twin Transfusion Syndrome)

--Risk of fetal growth restriction (FGR) is 10 times higher in twin pregnancies than in singletons

--Low birth weight of at least one of the twin occurs in up to 35% of twin gestations

--Perinatal mortality in twin pregnancies is 6 times higher than the singleton rate.

--Risk of preterm labor (birth <37 wks gestation) is approximately 60%

--Increased risk of cord and placenta-related problems: velamentous cord insertion, marginal cord insertion, and higher incidence of placenta previa spectrum

--Higher risk of pre-eclampsia

Another important reason for detecting multiple pregnancy during the first trimester is to increase surveillance for those pregnancies at risk for preterm delivery.

It is well known that twin pregnancy is associated with a high risk of perinatal mortality and morbidity

--Multiple births account for 3% of births but 14% of infant deaths

--Higher incidence of growth abnormalities

--Multiple pregnancies are at increased risk of iatrogenic preterm delivery, which is significantly higher in monochorionic twin gestations. Triplets have a much greater likelihood of delivering VERY prematurely.

Figure 35. List of increased risks of multiple gestation

Other risks

Figure 36. Other risks associated with multiple gestation

Other risks for pregnancies with multiples include:

--Anemia

--Malpresentation of one or both

--Intrauterine growth restriction

--Postpartum hemorrhage

--Hypertensive disorders

--Increased maternal mortality

Statistics on multiples risk of preterm birth

Figure 37. Risks of preterm birth in multiple gestations

RISK OF STILLBIRTH IN MULTIPLE GESTATION

Risk of stillbirth increases with advancing gestational age.

Dichorionic twins have a fivefold increased risk compared to singleton gestations.

Monochorionic twins have a thirteen-fold increased risk for stillbirth.

Figure 38. Risk of still birth in multiple gestation

For these reasons, it is critical to learn early in the pregnancy of the presence of multiple gestation so risks can be mitigated when possible.

In some settings, practitioners may only be providing point-of-care ultrasound. They may or may not refer pregnant women for a routine or standard first trimester scan. This makes it even more important to confirm multiple gestation in early pregnancy by the POCUS provider.

Ultrasound evaluation of multiple gestation in early pregnancy

Figure 39. Determining chorionicity and amnionicity in multiple gestation

TYPES OF TWINNING

Before scanning, one must be aware of the types of twin implantation and understand the sonographic signs of these types. The two types of twins: dizygotic (arising from 2 separate eggs and 2 sperm), and monozygotic (one egg is united with one sperm, and the fertilized egg divides into two after fertilization).

When evaluating twins with ultrasound, we are looking for the number of gestational sacs (chorionicity) and the number of amniotic sacs (amnionicity).

The amniotic sac is a sac separate from and within the chorionic sac. and is the compartment where the fetus lies. It is possible to have a combination of numbers of gestational sacs and amniotic sacs. The following illustrations and images will illustrate these differences.

Figure 40. Types of multiple gestation

Types of twins are described by whether the fetuses are monozygotic (1 egg that splits) or dizygotic (2 separate eggs). This is a factor that determines whether twins are identical (same egg), which has implication for shared genetic concerns. This is also a factor for adequacy of placentation and fetal circulation.

Figure 41. types of twinning and placentation

This can be determined by looking for the presence or absence of a membrane separating the embryos/fetuses, as well as the configuration of the placenta. Demonstrating chorionicity is a critical assessment, because it can predict risk of potential complications related to shared circulation and or potential for cord entanglement if the fetuses are in the same amniotic sac.

DETECTING MULTIPLE GESTATION

Suspicion of Twins

There should be suspicion of twins in the following circumstances:

Uterine size greater than dates

Strong family history of fraternal twins

Severe hyperemesis gravidarum

Elevated Serum b-HCG

Pregnancy achieved by use of reproductive technology or ovulation stimulation

Figure 42. Signs of suspicion of twins

Steps for imaging

Identify number of sacs and note significant size differences
Identify number of fetal poles
Identify presence and thickness of membrane (>2mm suggests dichoronicity)
Identify site of membrane attaching to the placenta and look for lambda or T-sign

Figure 43. Early detection of multiple gestation

The earliest that a multiple gestation can be detected is around the same time that a singleton gestational sac can be identified – around 5 to 5.5 weeks’ menstrual age.

Because the early sac is so small, it could be overlooked or noted to be a tiny cystic area in the endometrium, rather than a sac. So it is very important to look through the entire uterus to be certain you have seen every possible area that a sac or sacs could be located.

Fetal number

Once you have determined the number of gestational sacs, it is important to identify if there is a viable embryo or fetus in each sac. There is a condition known as “vanishing” twin, where one twin succumbs early in the pregnancy and is reabsorbed, while the other one continues as normal. In this case you can easily see that the sac sizes are very different, as well as the size of the fetal pole. In addition to identifying sacs, also be sure that in each sac you identify either a yolk sac or fetal pole.

Figure 44. Detection of fetal number

Figure 44.b Another image of a ‘vanishing’ twin sac above the sac with a fetal pole

It is equally important to measure each gestational sac separately. Care must be taken to be sure the same sac is being measured when changing scanning angles and not mistakenly include a measurement of the other sac. It is common for the 2 sacs to be slightly different in size, so the computer will assess this in its computations.

Figure 45. Measuring each GS separately

One important thing to remember is that a pregnancy in a retroverted or retroflexed uterus may be much harder to see. So be certain that the uterine position is assessed as you are scanning to optimize your view of a gestational sac. Use of a transabdominal probe is limited in this case and filling the bladder will only push the uterus further back. Sometimes emptying the woman’s bladder will allow the uterus to rise forward, but this is not always helpful. If a transvaginal probe is not available, the woman may need to be referred to a provider with a TV probe.

Dichorionic diamniotic DCDA

Figure 46. Illustration of Dichorionic Diamniotic gestation

In this type of twinning, each twin has its own chorion and amniotic sac. Most often the twins are dizygotic (derived from 2 eggs) but can occur with monozygotic (split egg).

DCDA accounts for 76% of all twin pregnancies

2 ova are independently fertilized by two sperm, leading to 2 zygotes

Sonographic findings:

2 gestational sacs with thick echogenic chorion surrounding each embryo

Thick inter-twin membrane (often >2mm)

Twin peak (lambda) sign

When there is no placental fusion, 2 separate placental sites may be seen.

DCDA carries the lowest rate of complications among twin pregnancies

Lambda sign

In Dichorionic twinning, you can see that there is a wing-like curve where the 2 separate placentas meet. This is called the lambda sign. In dichorionic twins, look for the thickness of the membranes, already mentioned.

Figures 47 and 48 each show definite lambda sign (wing-like curve where the two separate placentas merge), as well as a thick membrane between the two gestational sacs

Figures 47-48. Images demonstrating the Lambda sign

Monchorionic diamniotic DCDA

A Monochorionic Diamniotic gestation results from division of a single zygote at 4-8 days (blastocyst).

The embryos share a single gestational sac, each with their own separate amniotic sac and yolk sac; but they share a single placenta.

This type of twinning accounts for 70-75% of monozygotic twin pregnancies, but only 30% of all twin pregnancies

The Incidence of MCDA is about 1 in 400 pregnancies

Figure 49. Illustration of Monochorionic Diamniotic twins

A thin inter-twin chorionic ridge is seen; thinner than with DCDA twins. It is important to see this in early gestation because it becomes more difficult to detect later in pregnancy

There is what is called the T-sign, indicating that the two amnions are equally adjacent to the placenta.

These twins are most always the same gender.

Complications of this twinning result from placental/circulation sharing, and include:

--Twin to twin transfusion syndrome (occurs in 15-30% of MCDA pregnancies)

--Demise of one twin often associated with adverse outcome to the other twin

--Placental cord insertion irregularities

Figure 51 is an image of a twin pregnancy showing 2 separate amniotic sacs but a single shared placenta. The membrane between the fetuses is thinner than than with dichorionic diamniotic twins. The curved line where the amnion approaches the uterine wall is not wave-shaped, but T-shaped instead.

Figure 50. Image showing the “T” sign.

Figure 51 is another example of a MONO chorionic early gestation with a T shaped attachment of the amnion.

Figure 51. Image of monochorionic twin gestation and the “T” sign

Monochorionic twins pose a risk for twin-to-twin transfusion syndrome (acronym TTTS)

Figure 52. Monochorionic twin complications

Other complications include

--Selective fetal growth restriction

-- Twin anemia polycythemia sequence (TAPS)

--Twin reverse arterial perfusion sequence (TRAP)

--Monoamniotic twinning

NOTE: It is not the role of the POCUS provider to diagnose these complications, but instead to be aware of the potential problems that can occur if twin zygosity and chorionicity are not identified early in the pregnancy.

The last type of twinning we will look at is much rarer. This is where there are 2 embryos or fetuses in a single amniotic sac within a single gestational sac. This type of pregnancy carries a much higher rate of potential complications, so these women need increased surveillance during the pregnancy, and if possible, a high-risk provider to care for them.

Figure 53. Illustration of monochorionic monoamniotic twins

Monochorionic Monoamniotic pregnancies account for 1-2% of all twin pregnancies, with an overall incidence of 1 in 10,000.

The findings in this type of twinning are: a single chorionic sac, single amniotic sac and generally a single YS. There is no inter-twin membrane

This results from separation of a single ovum after the trophoblast has formed, so this results in a single placenta. These are always identical and of the same gender.

MCMA is associated with a higher incidence of congenital anomalies.

Figure 54. Image of early monochorionic monoamniotic twin gestation

Figure 55. Image of mono-mono twin gestation

In second trimester there can be cord entanglement and cord fusion, as well as cord knots and cord thrombosis. There is an increased risk of abnormal placental cord insertion. In addition, there is greater risk of twin-to-twin transfusion syndrome (TTS or TTTS), and twin embolization syndrome.

The primary risk for twins in a single gestational sac or single amniotic sac is the risk of one twin shunting blood to another due to shared circulation in the placenta. The outcomes for both twins are poor if this happens. If one fetus succumbs, there is a great likelihood that the other will also, shortly after.

Figure 56. Illustration of twin to twin transfusion

There is a condition known as twin-to-twin transfusion, or TTTS. This is a chronic condition where one fetus receives less maternal blood flow through the placenta. This is a high-risk situation for the fetus who is not growing. The donor twin is at risk for hypovolemia, oliguria, and oligohydramnios. The recipient twin is at risk of hypervolemia, polyuria, and therefore polyhydramnios.

This is not as likely to happen in DCDA pregnancies, since each fetus typically has its own placental circulation.

Figure 57. 3-D image of triplets demonstrating risk of cord and limb entanglement

There is a greater risk of twisting cords and entanglement with multiples in the same amniotic sac. The obvious risk is accidental cord tension and compression or prolapse, both of which require rapid intervention. Another concern is for providers who only perform vaginal deliveries. With mono-mono twins, there could be limb entanglement creating a compound presentation that is not deliverable vaginally. These risks necessitate early consultation and referral of mono-mono twins for high-risk maternity care.

TRIPLETS

When evaluating for triplets, it is even more important to establish very early in the pregnancy the number of chorions or gestational sacs, and the number and location of the fetuses and amniotic sacs. Figure 58 shows what appears to be 3 separate chorions and 3 separate amnions. This would be the best scenario of all the possible configurations of triplet gestations since each fetus has its own placenta.

Figure 58. Image of triplets: trichorionic (3 GS) and Triamniotic (3 amnions)

Figure 59. Image of Dichorionic (2 chorions) and triamniotic (3 amnions)gestation

Once again, it is important to carefully look through each gestational sac to be sure you do not miss a second embryo within the same sac. In Figure 59 there is a Dichorionic, and TRIamntiotic pregnancy. This image shows there are 2 gestations sacs, but one of them has 2 amniotic sacs each with a fetus inside.

This last triplet image (Figure 60) is of a pregnancy with one chorion and 3 amniotic sacs. This represents a very high risk pregnancy.

Figure 60. Image of monochorionic (single chorion) triamniotic (3 sacs) gestation

This is an image of a monochorionic (single gestational sac) and triamniotic amnion gestation. This pregnancy is at very high risk since all 3 fetuses will share the same placenta, and there is very high risk of one or more of the fetuses succumbing.

Of course, any time a higher risk twin gestation or triplet pregnancy is diagnosed, a consultation or a referral to an obstetric specialist is indicated.

FETAL DEMISE OF ONE TWIN

At times there is a demise of one twin while the other remains viable. If this occurs very early in pregnancy, often the GS of the deceased embryo will decrease in size and eventually be absorbed.

Figure 61. Image of vanishing twin

First trimester demise of one twin is not associated with adverse pregnancy outcomes.

When the demise occurs late in first trimester (or later), the deceased fetus may remain in the uterus, compressed up against the uterine wall. The fetus does not decompose but is preserved in a distorted shape. This is a condition known as fetus papyraceus.

DOCUMENTATION:

Labeling of the twin fetuses is an important process for the POCUS provider. ISUOG). Considered a good practice point by ISUOG, this identification should follow a reliable and consistent strategy and should be recorded accurately in the woman’s medical record. It should begin with identifying the gestational sacs in either a longitudinal or transverse orientation.

First trimester documentation should include: dating, labeling, chorionicity, and genetic screening (where available). ISUOG

Once the fetuses have been identified, it is important to label the fetus closest to the cervix as Twin A, and the other Twin B. Most ultrasound machines will have a preset when entering the patient information to identify how many gestations will be measured. Once you select that number, the computer will always start with Twin A (that you have identified). Then you will measure all the parameters associated with Twin A. Once that is completed, then the computer will allow you to switch to Twin B to measure those parameters as separate from the Twin A measurements. It is important to measure each twin one at a time, correctly identifying the structures of that twin as separate from the other. Often it is easier to distinguish between the two if they are in different positions, or if the amnion is clearly seen between the two.

CLINICAL MANAGEMENT

Document suspected findings

Refer for detailed sonogram to confirm chorionicity and amnionicity

Follow pregnancy per local standards and guidelines

Figure 62. Summary of first trimester multiple gestation

PREGNANCY OF UNKNOWN LOCATION (PUL), and ECTOPIC

This section will review steps to evaluate pregnancy of unknown location (also called PUL) and etopic pregnancy (also called EP). This is one of the most critical conditions for a woman’s health provider to either detect or rule out, since the early detection of an ectopic has the potential to save a woman’s life.

Objectives

By the completion of this Section the participant will be able to:

Describe the clinical significance of early detection of a PUL or confirmed ectopic

Describe typical locations of ectopic pregnancy

Scan through a uterus to identify a gestational sac

Recognize a “ring of fire” on an ultrasound, and discriminate between a “ring of fire” associated with a corpus luteum cyst versus an ectopic pregnancy

Clinical significance of PUL and ectopic

Ectopic pregnancy (EP) is any pregnancy that is detected and seen to be outside of the normal uterine location (the endometrium). A PUL (pregnancy of unknown location) is a pregnancy not seen either in or outside the uterus, and yet to be confirmed as an ectopic.

Figure 63. Clinical significance of PUL and ectopic pregnancy

Incidence: approximately 2% of all pregnancies

Ectopic pregnancy is a medical emergency and is the leading cause of maternal death, second to hemorrhage. Complications of EP account for 3- 6% of all maternity-related deaths in the United States.

EP also significantly impacts future fertility in women; 50% fail to achieve pregnancy again.

Accurate diagnosis is crucial because:

Failure to diagnose could lead to rupture and possible maternal death.
Incorrect diagnosis (where there is NOT an ectopic) can lead to inappropriate evacuation of a desired pregnancy

Figure 64. Clinical importance of detection of PUL or ectopic pregnancy

The table in Figure 65 lists the various risk factors for ectopic pregnancy

Figure 65. Table of risk factors for PUL/ectopic

--Previous Ectopic Pregnancy –the highest risk of all is a history of having 2 or more prior ectopics

--Prior tubal surgery

--History of infertility

--History of pelvic inflammatory disease

--Endometriosis

--Smoking (risk increases with the number of cigarettes smoked per day)

--Maternal age – increases after age 35

--Prior pelvic/abdominal surgery

--Prior termination of pregnancy

--Previous early pregnancy loss

--Assisted conception – IVF or Clomid

--NOTE: Conception with IUD in place has been implicated in the past as a risk factor, but Schultheis, et al, reported in a study of 9,256 women) that those who used progesterone contraception had a significantly lower risk of ectopic pregnancy compared with women using no contraception or barrier method of contraception.

However, keep in mind that almost 50% of women with an EP do NOT have any risk factors.

Figure 66. Clinical signs of PUL/EP

Positive pregnancy test, and/or pregnancy symptoms

Pain (unilateral pelvic, abdominal)
Bleeding

Adnexal mass on bimanual pelvic exam

Other possible symptoms:

--hypotension (due to blood loss)

--shoulder pain (due to hemoperitoneum – blood or fluid accumulation in the peritoneum impinging on the diaphragm)

Lab findings (where lab is available):

Slower than expected rise in serial serum B-hCG levels, or plateauing levels

Detection of EP/PUL:

The 3 rule out diagnoses for PUL are:

Incorrect dates - pregnancy is too early to see in the uterus
Missed ab - early loss and gestation has already shed
Ectopic

Due to the urgency of early detection of EP, relying on risk factors (history) and clinical symptoms is insufficient. Although these provide suspicion, PELVIC ULTRASOUND is the most reliable diagnostic tool for confirming an intrauterine pregnancy (IUP) versus an EP/PUL . Transvaginal ultrasound is the MINIMUM diagnostic evaluation step in confirming location of a pregnancy.

Sensitivity of transvaginal ultrasound for diagnosing EP ranges from 73% to 93%, depending on gestational age and experience of sonographer.

Figure 67. Classic ectopic sonographic findings

It is considered to be within the scope of a POCUS to be able to use ultrasound to assess for this complication. Even if a POCUS provider is uncertain about locating the extrauterine pregnancy, he/she can at the very least confirm absence of an IUP, necessitating direct referral or further imaging.

Figure 68. Summary of findings for ectopic

Clinical importance

Detecting a PUL compels the provider to investigate with either serial B-hCGs (pregnancy levels) and repeat ultrasound until the location is found. If these measures are not available to the provider, then the woman should immediately be referred to a higher level of imaging and or care. For providers performing POCUS who also have credentials for managing ectopic pregnancy, outside referral may not be needed. Any time there is uncertainty about the location of the pregnancy, it is imperative to have a second opinion or more advanced assessment, since missing an ectopic pregnancy can be a life-and-death situation for the mother.

Once the pregnancy has been identified, and is NOT in the uterus or endometrium, it can be termed “Ectopic”

The appropriate terms used to describe findings of early pregnancy of unknown location are:

Definite Extrauterine Pregnancy (EP) – this means that a pregnancy is confirmed songraphically to be outside the uterus or endometrial cavity

Probable EP – this means that the pregnancy is most likely to be outside the uterus or endometrial cavity. In other words, there is no evidence that the gestation is in the uterus, but presence outside the uterus has not yet been confirmed.

PUL: no signs of either EP or IUP – this means that it is perhaps too early to establish where the pregnancy is implanted

Probable IUP – this means that there are signs of an intrauterine implantation, such as a small gestational sac, but no real confirmation of a YS or embryo.

Definite IUP – this means that there is either a yolk sac or embryo seen within the uterus/endometrial cavity

The differences between these definitions seem subtle, but using these categories might help with clinical decision-making, such as next level imaging or immediate referral.

Do not get overly concerned about these terms - in essence, if you do not see a pregnancy clearly in the endometrium when it is expected, consider the pregnancy a possible ectopic and refer for further imaging right away, especially if the woman has symptoms like pelvic pain.

Figure 69. Locations of ectopic pregnancy

This is a diagram of where ectopic pregnancies are commonly seen, and the incidence for each location.

Interstitial pregnancy is located in the fallopian tube at the junction of the uterus and fallopian tube. This can often be mistaken for a cornual pregnancy, described later in this chapter.

An isthmic pregnancy is located in the isthmus of the fallopian tube.

The most common place for an ectopic to implant is in the ampulla, or mid-section of the tube, with about 80% of ectopics landing there.

A fimbrial pregnancy occurs in about 5% of ectopics.

The rarer ectopic locations are ovarian, cervical and even abdominal pregnancy.

C/Section scar pregnancy will be discussed in more detail later in this chapter. The incidence of prior C/Section is variable in different regions – some as high as 30-40% of births. This creates increased potential for scar defects where pregnancies might implant.

Figure 70. Ectopic/PUL primary clue

For establishing that a pregnancy has an unknown location, first note if a BhCG level was done. If the BhG level is where a YS or fetal pole should be seen in the uterus, but is NOT seen, it raises suspicion that the pregnancy might be elsewhere.

If you see a YS in the uterus or endometrial cavity, this virtually excludes the presence of an ectopic pregnancy. There is always a possibility for a heterotopic pregnancy (one gestation inside and one outside the uterus). Although this is rare, it validates the need to survey the entire pelvis, even when an IUP is seen in the uterus.

Ultrasound Findings Consistent with EP/PUL

Endometrium – thickened, possibly a small amount of fluid without a decidual sign (pseudosac*)

no evidence of a gestational sac or decidual sign at 6 weeks’ gestation by certain LMP

Cervical Canal – absent of fluid or tissue

Posterior culdesac (Pouch of Douglas)- moderate to large amount of fluid

Slide – Describing amount of FF in pelvis

Adnexa - Complex mass in the adnexa with mixed echogenicty, sometimes cystic, and color flow encircling it (“Ring of Fire”). The mass needs to be seen as separate from the ovary.

Seeing a mass separate from the ovary has a predictive value of 80%, which means 20% of the time there may be other adnexal structures labeled as an ectopic and misdiagnosed. These structures could be: paratubal cyst, corpus luteum cyst, hydrosalpinx, endometrioma, or bowel. For this reason, a POCUS exam that suspects EP MUST be confirmed by a higher level of assessment such as imaging/sonography.

NOTE: A pseudosac used to be considered a reliable indicator of an ectopic gestation. However,

To confirm that a pregnancy is ectopic, the following ultrasound findings seen OUTSIDE of the endometrial cavity are evident:

--Double decidual sign (usually within the mass)

-- GS with YS, or fetal pole (usually within the mass)

*A pseudo sac is a small collection of fluid within the endometrium which used to be used as an indicator of an ectopic. This is no longer a valid sign of ectopic. f you hear that term mentioned, understand that it is not a reliable indicator of an ectopic. Recent literature review indicates that most of the time this actually represents a very early pregnancy.

Figure 72. Image of fluid in culdesac and small echogenic area in endometrium

RULE OUTS

Figure 73. Images demonstrating sonographic appearance of ectopic pregnancy

The most common appearance of an ectopic gestation is that its shape is less well-defined than an intrauterine gestation. It is a non-simple cystic adnexal mass separate from the ovary. It could be described as an irregular structure, or inhomogeneous adnexal mass. Because of its thickened walls, it can appear like a ‘bagel’ or ‘donut’; the EP walls are thicker than a normal intrauterine chorion, and thicker than the walls of a CL cyst.

--Retention of products of conception post-ab

-- Trophoblastic disease. BhCG levels greater than 100,000 mIU/ml occur in 50% of patients with an early molar pregnancy (levels can be lower with partial molar pregnancy)

--Intrauterine ‘ectopic’ (in the uterus but not in the endometrium) – typically an intramural pregnancy (located in the uterine musculature)

Cornual

The cornual region describes the area in the upper corners of the uterus at the junction of the fallopian tube. The sonographic criteria for this type of pregnancy are 1) empty uterine cavity, 2) GS located eccentrically (1 cm from lateral wall of the uterine cavity, and 3) a thin myometrial layer (less than 5mm of myometrium surrounding the GS). Regardless of the precise definition, this implantation is abnormal, requiring an advanced sonographer to discriminate. A POCUS provider would simply identify a pregnancy in the upper/outer region of the junction of tube and uterus as abnormal and seek additional imaging.

This image shows a gestational sac with a tiny embryo in a transverse view of the uterus. Although it might appear that the gestation is off to the patient’s left side of the uterus, it is still within the endometrium – so it is NOT a cornual pregnancy.

Figure 74. Image of a cornual pregnancy

A pregnancy is sometimes located in a uterine cornual region. Some consider a true cornual pregnancy to only be found in a bicornuate or unicornate uterus, with the pregnancy located in one of the horns. But many still use the term “cornual” to describe the general location, even in a normal uterus. The term is also used to describe the region of the tube adjacent to the uterus.

Sonographic criteria for cornual pregnancy are 1) empty uterine cavity, 2) GS located eccentrically (1 cm from lateral wall of the uterine cavity, with a thin myometrial layer (<5mm surrounding the GS). This measurement is the determining factor for labeling an ectopic as cornual – the amount of myometrium between the GS and the outer margin of the uterus.

Regardless of the precise definition, this implantation is abnormal, requiring an advanced sonographer to discriminate. A POCUS provider would simply identify a pregnancy in the upper/outer region of the junction of tube and uterus as abnormal and seek additional imaging.

Extrauterine ectopic

This image is of a confirmed ectopic outside the uterus altogether. Using color doppler, definite blood flow to the embryo is noted. The uterus is identified toward the right of the image, and the right adnexa is identified in the far left of the image. The fetal pole and yolk sac are located in a space between the uterus and the right ovary.

Figure 75. Image of ectopic in adnexa

There are pitfalls in identifying an ectopic pregnancy.

Figure 76 Pitfalls in ultrasound diagnosis of EP

Structures that could mimic an ectopic pregnancy include a corpus luteum cyst, or other adnexal cysts. Color or spectral doppler can show vascularity with any of these – so it can be difficult to determine with just the use of color flow imaging.

For differentiating between an ectopic and a corpus luteum cyst, a transvaginal probe can be used to gently push the ovary to demonstrate sliding. A corpus luteum will move along with the ovary, since it is located on it. The echogenicity of the CL is also quite similar to the ovary itself, and one can see ovarian tissue surrounding the CL in most cases.

An ectopic, however, is in the adnexa separate from the ovary, and would not slide with the ovary. Probing of an ectopic typically elicits a marked pain response so scanning the region should be performed as gently as possible. Also, the tubal ring in a tubal ectopic is more echogenic than the stroma of an ovary.

As previously described, simple ovarian cysts do not have sonographic characteristics of an ectopic. Their walls are thin and smooth, and internally there are few or no echoes.

Figure 77. Image of Ring of fire surrounding a corpus luteum

This is what a “ring of fire” looks like. Remember that a “ring of fire” indicates increased vascularity that encircles an active structure requiring additional circulation to grow. This image happens to be a corpus luteum (CL) cyst on an ovary since this is in a non-pregnant woman. However, if there was a confirmed pregnancy, with an empty endometrium, you should be suspicious if you saw this in the adnexa as separate from the ovary itself. This is how you would identify whether this is a “ring of fire” with an ectopic. You would likely also see other signs like free fluid in the cul-de-sac.

NOTE: Identification of the CL can sometimes be helpful in locating the ectopic, since it is most likely implanted on the same side of the pelvis as the CL.

The image below (Figure 78) demonstrates an ectopic in a woman who has a positive pregnancy test and no evidence of an intrauterine gestation.

Figure 78. Image of Ring of fire surrounding ectopic pregnancy slide

CL vs Ectopic

To review, comparing an ectopic with normal corpus luteum cyst, the ectopic is:

Separate from the ovary – if the ovary is probed, the ectopic will not move with it
Thicker-walled and more echogenic (brighter) than the CL
Shape often has a “donut” or “bagel” appearance
More likely to have a heterogeneous texture, while the CL is more likely to have an anechoic texture

Figure 79. Comparison of corpus luteum versus ectopic pregnancy

NON-tubal Ectopic pregnancies

Ectopic pregnancies NOT in the fallopian tubes include:

C-section scar

Cervix

Intramural

Ovary

Cervical, Lower Uterine Segment and Cesarean Scar pregnancy

Signs:

These may be mistaken for an abortion in progress.

Color doppler may reveal flow in ectopic implantation.

Cardiac activity confirms EP

Rounded shape causing bulging of uterus/cervix suggests ectopic

Figure 80. Description of Non-tubal ectopic pregnancy

C-Section Scar pregnancy

Globally, C-Section scar pregnancy rates have doubled since the year 2000, caused by an increase in the C-Section rates in some regions. Some have considered it to be an ectopic pregnancy, since it is not located in the usual endometrial space. However, It is now considered to be a type of ectopic and is known as a Cesarean Scar Pregnancy.

We discussed in the GYN course the importance of looking for a C-Section scar defect when scanning a non pregnant woman to determine whether a C/S scar with significant defect could potentially cause a problem. If a simple notch is seen, it is not as likely to be a problem if the pregnancy does implant low and anteriorly near the scar.

Figure 81. Image of C-section scar in non-pregnant uterus

This is described in more detail in the Second/Third Trimester Course describing the placenta.

Figure 82. Image of early pregnancy inside C-section scar

This image demonstrates what an early C/Section scar pregnancy looks like. As previously stated, this pregnancy has the potential to advance outward toward the anterior surface of the uterus, causing a possible rupture, or a placental invasion of the anterior myometrium (placenta accreta). This finding would necessitate a referral to an advanced provider for follow up and management.

The image below demonstrates early pregnancy detection of a thin myometrium at the base of a C/Section scar notch or defect. This could indicate a problem later in the pregnancy and lead to a potential uterine rupture during labor if the woman labors instead of having a repeat C/section.

Figure 83. Image of early pregnancy inside uterus with a C-section scar notch (thin myometrium)

Cervical Ectopic

A cervical ectopic is very rare, but it presents a potential for massive hemorrhage if it ruptures. Treatment with methotrexate (to halt growth of the gestation) or aspiration are the recommended treatments. If hemorrhage cannot be stopped, emergency hysterectomy becomes necessary, associated with a high mortality rate. The sign of a cervical pregnancy is a heterogeneous mass in the cervical canal with a Ring of Fire. If the mass is probed with the transvaginal probe, there is a negative sliding sign; in other words, the mass does not slide or compress with pressure.

Ovarian Pregnancy

Tips:

An ovarian pregnancy is RARE and can easily appear like a corpus luteum or ovarian cyst. However, with an ovarian pregnancy, the sac rim is thicker and more echogenic.

And the VERY RARE abdominal pregnancy may occur anywhere on a peritoneal or visceral organ

Heterotopic

Heterotopic pregnancy is what we call a pregnancy where there is an intrauterine pregnancy AND an ectopic simultaneously. It used to be quite rare (1 in 4,000 to 1 in 30,000) but now the incidence has increased in populations where artificial reproductive technology (ART) is0 used for infertile couples; this incidence is now estimated to be up to 1 in 100. So if you are seeing a woman who has had this performed, it is critical to observe the adnexa carefully, even if you see a definite intrauterine pregnancy.

Figre 84. Incidence of heterotopic pregnancy

Figure 85. Image of heterotopic pregnancy

Figure 85 is an example of a true heterotopic – one gestation is in the uterus (appropriately) and the other is in the C-Section scar (the ectopic). Management of this pregnancy will be difficult to spare the intrauterine pregnancy, so expedited referral for advanced care is imperative.

CLINICAL MANAGEMENT

Refer for higher level management

TREATMENT

Treatment options are overed only generally in this course. Treatment and follow up may be beyond the scope of the POCUS provider. There are a number of decision trees that delineate courses of action for the suspected ectopic pregnancy.

The options are to treat with methotrexate if the B-hCG is less than 5,000.

The most important information is the list of indications for urgent surgical referral. These include: (ACOG,Hendricks)

Hemodynamic instability
Peritoneal signs
Ultrasound showing ectopic pregnancy with fetal cardiac activity
Ultrasound showing substantial fluid in the culdesac (significant or extensive)

TROPHOBLASTIC DISEASE (HYDATIDIFORM MOLE)

The next few paragraphs discuss trophoblastic disease, which is also referred to as a hydatidiform mole or “molar pregnancy”. This occurs when there is an abnormal combination of genetic material that forms within the uterus as a result of pregnancy implantation. The occurrence is about 1 in 3000, although it is more common in Asian women (about 1 in 250). The cause is unknown, but one theory is that an early embryo succumbs, while the chorionic villi continue to proliferate as the maternal circulation continues. Another theory of causation is that duplicated chromosomes within the sperm (or fertilization of one egg by 2 sperm) causes genetic aberration of the ovum. This leads to a buildup of abnormal placental tissue and fluid, causing the cystic appearance seen on ultrasound.

As this placental tissue develops there is an accelerated production of BhCG levels above what is expected for the gestational age by LMP. This accelerated increase in BhCG levels often causes women to have hyperemesis.

Most often it is complete, in that there is only abnormal placental tissue, without embryonic tissue.

In some cases, a partial molar gestation is seen. In this situation, an embryo forms along with the molar tissue. The embryo is typically a product of a triploidy genetic abnormality and will not likely be viable.

A major concern about molar pregnancy is its ability to become an invasive mole which grows through the decidua and into the myometrium, becoming a malignancy known as choriocarcinoma. This is not always diagnosed until after the uterine contents are evacuated. If left untreated, it can cause hemorrhage. It can also metastasize to the lung, vagina, pelvis, brain, and liver. Because of this, women with a molar pregnancy must be referred for treatment and surveillance for this condition, even after the pregnancy is evacuated.

A reassuring note for counseling women is that the trophoblastic (molar) pregnancy is not likely to recur.

Figure 86. Description of trophoblastic disease (hydatidiform mole)

The sonographic appearance is fairly easy to see. In the absence of the usual landmarks there is amorphous, cystic like material in the uterus. Serum pregnancy levels will seem abnormally high, and the woman may have higher levels of pregnancy symptoms such as nausea and vomiting.

The image on the left in Figure 87 (below) is an example of what trophoblastic tissue would look like in early pregnancy. It appears cystic, and without borders. Enlarged ovarian theca lutein cysts are sometimes seen with a molar pregnancy. The image on the left demonstrates these.

Figure 87. Images demonstrating characteristics of trophoblastic pregnancy

A molar pregnancy can occur in conjunction with an embryo/fetus. Typically the fetus has chromosomal abnormalities.

Figure 88. Image of a partial molar pregnancy

--The tissue in the endometrium will have poorly delineated borders,

--Molar tissue may have increased vascularity, with possible invasion of this tissue into the myometrium

--If a molar pregnancy is suspected, referral is indicated for confirmation. Thyroid testing should also be done. The reason for this is that high levels of B-hCG can mimic thyroid stimulating hormone (TSH) and subsequent hyperthyroidism. Excessive levels of B-hCG can cause thyroid toxicity and thyroid storm.

--Treatment is evacuation of the uterus as quickly as possible to avoid the potential for malignancy

CLINICAL MANAGEMENT

Consult and or refer if this is suspected.

Figure 89. Summary of PUL/Ectopic and Molar pregnancy

YOU MAY NOW TAKE THE QUIZ AND MOVE TO THE NEXT CHAPTER. YOU WILL NOT BE ABLE TO OPEN THE NEXT CHAPTER UNTIL YOU COMPLETE AND PASS THE QUIZ. YOU WILL HAVE AS MANY TRIES AS YOU NEED TO GET ALL THE ANSWERS CORRECT!

GULU Midwives Basic Obstetric POCUS

Chapter 8. First Trimester Complications