Master the board step 3

Master the Boards: USMLE Step 3
Etiology
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Chromosomal abnormalities of the embryo or fetus are the most common
cause of spontaneous abortion. Risk factors are strongly related to advanced
maternal age, previous spontaneous abortion, and maternal smoking.
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Fetal demise is most commonly idiopathic. Risk factors include antiphospholipid
syndrome, overt maternal diabetes, maternal trauma, severe maternal
isoimmunization, and fetal infection.
Diagnostic Testing
1. Speculum exam to evaluate for cervical/vaginal sources of bleeding and
presence of vaginal dilation. Speculum exam is never the first step in management
of late trimester bleeding because of the risk of bleeding in a low
implanted placenta.
2. Ultrasound to evaluate fetal cardiac activity and ± of products of conception.
Complications
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When the case describes prolonged fetal demise (> 2 weeks), the most serious
complication to look out for is disseminated intravascular coagulation
(DIC), resulting from release of tissue thromboplastin from deteriorating
fetal organs.
CCS Tip: Always rule out coagulopathy by ordering platelet count, D-dimer,
fibrinogen, PT, and PTT in patients presenting with fetal demise. If DIC is identified,
immediate delivery is needed.
A 24-year-old woman visits the clinic with left-sided abdominal and flank pain and
vaginal spotting. Her last menstrual period was 7 weeks ago. She denies fevers,
nausea, or vomiting. She has one prior pregnancy with spontaneous vaginal delivery.
She has used OCPs in the past but currently uses an intrauterine device for
contraception. Pelvic examination, reveals a slightly enlarged uterus, closed cervix.
No palpable adnexal mass is identified however there is tenderness on bimanual
exam. A quantitative serum ß-hCG value is 2,650 mIU. What is the diagnosis?
a. Ectopic pregnancy
b. Hydatidiform mole
c. Incomplete abortion
d. Missed abortion
e. Threatened abortion
Answer: A. The classic presentation of ectopic pregnancy is 1) amenorrhea, 2) vaginal
bleeding, and 3) unilateral pelvic-abdominal pain. When the case also describes abdominal
guarding or rigidity, hypotension and tachycardia, ruptured ectopic pregnancy is the
diagnosis.
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