NBME OBGYN Form 3 - Answers & Explanations

Updated: Feb 25, 2020

1) Ectopic pregnancy

• ↑ β-hCH + abdominal pain + no gestational sac = ectopic pregnancy

• Ectopic pregnancies have a lower β-hCG than expected and don’t double every 24 hours

• This patient has a pseudo-gestational sac (present in ~10% of ectopic pregnancies)

2) Antenatal testing • Antenatal testing will explain why there is polyhydramnios

• Amniocentesis → ↑ risk of PROM

3) No longer indicated • Total abdominal hysterectomy (TAH) in a patient with no prior history of cervical dysplasia (further pap testing not needed because the TAH was due to a benign cause)

• Total abdominal hysterectomy includes removal of the cervix → stop pap testing (no cervix, no cancer) • A partial/supracervical hysterectomy would entail removal of the uterus with preservation fo the cervix

4) Placement of a copper IUD • Hormonal contraception should be avoided in women with current or past history of breast cancer

5) Insulin

• Maternal hyperglycemia → ↑ fetal insulin production → ↓ surfactant synthesis → ARDS (hyaline membranes)

• Cortisol & thyroxine → ↑ surfactant synthesis

6) Granulosa cell tumor

• Granulosa cells convert testosterone to estradiol via aromatase

• Malignant proliferation → ↑ estradiol levels → postmenopausal thickened endometrium

7) Injury to the fifth and sixth cervical roots • Erb-Duchenne palsy → pronated forearm, adducted, internally rotated shoulder • Klumpke palsy (injury to lower trunk, C8-T1) → total claw hand, Horner syndrome

• Spontaneously resolves within 3 months

8) Secretory endometrium • Progesterone, which is normally secreted by the corpus lute during ovulatory cycles, causes differentiation of the proliferative endometrium into secretory endometrium; withdrawal causes menstruation

9) Clomiphene

• Clomiphene treats infertility due to anovulation

• Clomiphene blocks estrogen receptors at the hypothalamus, inhibiting negative feedback mechanism and restoring pulsatile release of GnRH

• Clomiphene is associated with twins and ovarian hyper-stimulation

10) Parvovirus B19 infection • Polyhydramnios, ascites, and skin thickening are consistent with hydrops fetalis

(cardiac inability to keep up with the anemia induced by Parvo)

• Work in a preschool → obtain infection from children

11) Cocaine use • Cocaine → placental abruption

• Cocaine is a more significant risk factor than amphetamine or tobacco use

12) Estrogen deficiency • This patient has urge incontinence, a urinary sxs of atrophic vaginitis (menopause)

13) Normal development • Weight and height is normal, amenorrhea < 6 months

14) Intrahepatic cholestasis • Typically presents in the 3rd trimester with pruritis that is worse on hands/feet

• Dx: ↑ total bile acids (> 10) • Tx: Ursodeoxycholic acid + delivery at 37 weeks gestation

15) Incompetent cervix • Breech position “in the vagina” (not uterus) = fetus is descending, likely due to an incompetent cervix • No contractions rule out all labor options

16) Voiding immediately after coitus • Early postcoital voiding reduces risk of UTI

17) Karyotype analysis • Absent thelarche + ↑ FSH = primary hypogonadism, likely due to Turner syndrome

18) Cervical stenosis

• 2° dysmenorrhea or amenorrhea s/p cervical procedure = development of surgical stenosis (eg, this patients “small, scarred cervical os”)

• Unable to expel sloughed off layer → build up & possible retrograde menstruation → ↑ risk of endometriosis

19) Uterine rupture • Previous cesarean section + fetal parts above the fundus

20) Cyclic progesterone therapy • This adolescent has irregular menstrual bleeding due to anovulatory cycles • Progesterone, which is normally secreted by the corpus lute during ovulatory cycles, causes differentiation of the proliferative endometrium into secretory endometrium; withdrawal causes menstruation

21) Galactocele • Mobile, well-circumscribed, non-tender mass with no fever

• Mastitis = tenderness + erythema + fever • Abscess = tenderness + erythema + fever + fluctuant mass

22) Ultrasonography of the pelvis

• With 6cm dilation, presenting fetal part should be palpable

• U/S should be used to check for CPD (cephalopelvic disproportion), transverse fetal lie, etc.

• Performing an amniotomy prior to head engagement can cause cord prolapse

23) Premature labor • ~60% of twin are delivered preterm; ~90% of triplets are delivered preterm

24) Bartholin duct abscess

• Common in women age ≤ 30

• Bartholin ducts are located B/L at the posterior vaginal introitus and have ducts that drain into the vulvar vestibule at the 4 and 8 o’clock positions to provide vulvuvaginal lubrication

• Tx (symptomatic): I&D followed by a Word catheter placement

• Tx (asymptomatic): observation - spontaneous drainage and resolution may occur

25) Maternal fever • Fetal tachycardia (>160/min) is commonly associated with maternal fever • Cardiotocography (CTG) shows fetal tachycardia with minimal to moderate variability

26) Herpes simplex virus 1 • HSV and H. ducreyi are the two most common causes of tender genital lesions • Clusters of small round lesions and remnants of vesicle clusters are visible • This patient has had “increasing stress during the past month” = herpes outbreak

27) Measurement of urinary ketones

• Hyperemesis gravidarum (HG) is differentiated from typical vomiting of pregnancy by the presence of ketones on urinalysis or lab abnormalities (eg, hypokalemia, hypochloremic metabolic alkalosis)

• Tx: admission to hospital, antiemetics + IVF

28) Squamous cell carcinoma • Squamous cell carcinoma is the most common type of cervical carcinoma (~80%)

• Smoking and HPV 16, 18, 31, and 33 are the most significant risk factors • Usually presents in women > 60

29) Fibrocystic changes of the breast • Fibrocystic change = multiple, tender • Fibroadenoma = single, non-tender mass

30) Endometrial biopsy

• This obese patient (BMI 37) is having heavy menstrual flow, likely from ↑ estrogen (aromatase conversion in excess adipose tissue)

• Any woman ≥ 45 with abnormal uterine bleeding (AUB) → endometrial biopsy

• Any woman ≥ 35 with atypical glandular cells on Pap → endometrial biopsy

31) Parvovirus B19 • Polyhydramnios, ascites, and skin thickening are consistent with hydrops fetalis (cardiac inability to keep up with the anemia induced by Parvo)

32) Amniotic fluid embolism • Present with rapid onset of hypoxemic respiratory failure, severe hypotension, and DIC during labor or the immediate postpartum period • Tissue factor in amniotic fluid activates the coagulation cascade

33) Folic acid deficiency • No prenatal care in an alcoholic with macrocytic anemia • B12 deficiency would have neurological sxs • Pregnancy → ↑ plasma volume → dilution of WBC and platelet concentrations

34) Polymicrobial infection

• Fetal tachycardia + maternal fever + prolonged rupture of membranes = Chorioamnionitis

• Ampicillin & gentamicin are the correct antibiotics, but they were only given 8 hours ago and have not had enough time to impact maternal fever

• Septic pelvic thrombophlebitis is a diagnosis of exclusion which requires persistent fever unresponsive to antibiotics and a ⊖ infectivity workup

35) Alendronate now

• Bisphosphonates are the drug of choice for prevention and treatment of steroid induced osteoporosis

• SLE is a relative contraindication for estrogen use due to ↑ risk of VTE/stroke