Molar Pregnancy

You are the junior resident on your ultrasound rotation, and you are scanning the board for pregnant females to examine. You finally find a 20-year-old female with a chief complaint of vaginal bleeding and vomiting. Her vitals are notable for tachycardia to 110 and hypertension to 186/98. The triage note states that she is pregnant, but the urine pregnancy test from the stat lab has already come back negative. At this point, you don’t know what to believe, but you pick up the patient and get ready to see her.

Upon entering the exam room, you find a young woman in no acute distress with an obviously gravid abdomen. As you take her history, she tells you that she is pregnant and about 10 weeks gestation by date of her last menstrual period. She has not had any prenatal care. This is her third pregnancy, and she admits that this pregnancy has been tough on her. The nausea and vomiting has been persistent and unbearable. She endorses a severe headache. For the last 3 days, she’s been spotting, but now she’s also passing clots and tissue. She also doesn’t understand why this baby has been growing so fast because she feels more like 20 weeks instead of 10 weeks!

As you take this history, you are perplexed because you agree that she looks more like 20 weeks, but you just assume she is a poor historian or her dates may not be reliable. Additionally, the negative urine pregnancy test doesn’t make sense, so there must have been a mix-up. You start your workup with an exam. Aside from her gravid abdomen, the pelvic is notable for moderate blood in the vaginal vault but no active bleeding from the cervix, and the os is closed. You perform a bedside endocavitary ultrasound and find the following:

Endocavitary Ultrasound

You don’t know what you are looking at, but you send off labs including Beta-hCG. You show your attending the ultrasound who makes this face:

He immediately recognizes the classic “snowstorm” appearance on ultrasound. Later, the Beta-hCG returns at 180,000 mIU/mL.

What is a molar pregnancy?

Molar pregnancies are part of the spectrum of gestational trophoblastic disease which include pathologies originating from the placenta. Gestational trophoblastic disease includes complete and partial hydatidiform moles, invasive moles, gestational choriocarcinomas, and placental site trophoblastic tumors.

Molar pregnancies are neoplasms of placental hCG-producing trophoblast cells and can be characterized as complete or partial. It is not necessary to make this distinction in the initial management of molar pregnancy. In either case, a non-viable fertilized egg implants in the uterus. Complete moles consist of chorionic villi in clusters of vesicles (i.e. “bunch of grapes”) and an absence of fetal parts.

Complete Mole

Partial moles have decreased proliferation of villi compared to complete moles and usually have fetal parts.

In the United States, molar pregnancies are observed in approximately 1 in 600 therapeutic abortions and 1 in 1500 pregnancies. Risk factors include extremes of child bearing age (less than 20 or greater than 40 years old). There is also a 10 to 15 times higher risk of molar pregnancy in patients with a previous history of such.

What are clinical features of a molar pregnancy?

Patients typically present during the first trimester of pregnancy. The most common presenting symptom is vaginal bleeding. They will have a uterine size that is larger than the estimated gestational age based on last menstrual period. Many patients will endorse severe nausea and vomiting, which is likely due to very high Beta-hCG levels. Patients may also exhibit signs of preeclampsia as well, so hypertension and proteinuria or signs of end organ dysfunction in the 1st trimester should make you suspicious for molar pregnancy. Since Beta-hCG is a glycoprotein hormone that is structurally similar to TSH, patients can also present with clinical hyperthyroidism.

What is the initial workup and management?

Initial imaging will often show a snowstorm appearance on ultrasound. A quantitative Beta-hCG will often exceed 100,000 mIU/mL. A qualitative urine pregnancy may give a false negative due to a phenomenon known as “hook effect.” Extremely high levels of circulating Beta-hCG can cause an oversaturation of the assay system leading to a false negative result.

It is important to assess the patient’s volume status, because they can have severe hyperemesis gravidarum and require aggressive antiemetics, fluid resuscitation, and electrolyte supplementation. Additionally, they may develop anemia from the vaginal bleeding.

Other complications of molar pregnancy such as pregnancy-induced hypertension and hyperthyroidism should be explored and treated accordingly. Although hypertensive emergency and thyrotoxicosis should be addressed prior to definitive treatment of the molar pregnancy, these complications usually abate after evacuation and may not require further therapy.

What is the disposition?

All patients with molar pregnancy require immediate gynecological consultation and admission for dilatation and curettage. After discharge, they are monitored with serial Beta-hCGs to ensure that there is no further progression of disease.

Beta-hCG levels that fail to decrease after evaluation are evidence of persistent or invasive disease which would then necessitate chemotherapy. Metastasis to lung, liver, and brain may occur, but the prognosis for most patients is very good.

Sources:

Dooley-Hash S, Lisse SA, Knoop KJ. Gynecologic and Obstetric Conditions. In: Knoop KJ, Stack LB, Storrow AB, Thurman R. eds. The Atlas of Emergency Medicine, 4e New York, NY: McGraw-Hill. http://accessmedicine.mhmedical.com.newproxy.downstate.edu/content.aspx?bookid=1763&sectionid=125434657. Accessed September 11, 2017.

Hoffman BL, Schorge JO, Bradshaw KD, Halvorson LM, Schaffer JI, Corton MM. Williams Gynecology, 3e; 2016 Available at: http://accessmedicine.mhmedical.com/content.aspx?sectionid=118173613&bookid=1758&jumpsectionID=118173624&Resultclick=2 Accessed: September 11, 2017.

Masterson, Lori, Shu B. Chan, and Bryan Bluhm. “Molar pregnancy in the emergency department.” Western Journal of Emergency Medicine 10.4 (2009): 295.

Pang, Y. P., H. Rajesh, and L. K. Tan. “Molar pregnancy with false negative urine hCG: the hook effect.” Singapore Med J 51.3 (2010): e58-e61.

Soper, John T., et al. “Diagnosis and treatment of gestational trophoblastic disease: ACOG Practice Bulletin No. 53.” Gynecologic oncology 93.3 (2004): 575-585.