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NBME OBGYN Form 2 - Answers & Explanations

Updated: Feb 25, 2020

1) Enterocele

• Enterocele = descent of small intestines into lower pelvic cavity → pushes on top part of vagina (ie, origin is high in vaginal vault) → bulge

• Hysterectomy → ↑ risk of enterocele (removal of uterus → space available for intestines to descend)

• Rectocele → bowel movement problems (not seen in enterocele since it is the small intestines that descends)

• Cystocele → urinary tract sxs. Cystocele would involve the anterior vaginal wall, not posterior wall

2) Fetal parvovirus B19 infection

• Patient works in a daycare (contact with children); Parvovirus B19 is most common infection associated with hydrops

• CMV and Toxo are less common causes of hydrops

• ‘Antibody screening is negative’ = Rh sensitization has not occurred

3) Iron deficiency • ↓ MCV (microcytic)

• Physiologic dilution of pregnancy and sickle cell would both be normocytic

• Folic acid or B12 deficiency would be macrocytic

• Hb electrophoresis excludes sickle cell

4) Vulvar carcinoma • Clinical features: vulvar pruritis, vulvar plaque/ulcer, abnormal bleeding • Patients often have a unifocal friable mass, commonly located on the labia majora

5) Cesarean delivery • Leopold’s Maneuvers help determine position of fetus

• If transverse lie is recognized during active labor → C-section • Can’t perform external cephalic version (ECV) or internal podalic version if in active labor

6) Condyloma acuminata • HPV 6, 11 → Condylomata acuminata • Tx: Podophyllin resin, Trichloroacetic acid

7) Admission to the hospital for intravenous antibiotic therapy • This patient has pelvic inflammatory disease (PID) • Indications for hospitalization include high fever, inability to take oral meds, and risk of non-adherence to treatment

8) Pelvic examination

• If the baby is not in the correct position (ie, fetal station of at least 0) and there is sudden rupture of membrane (SROM), there is risk of cord prolapse (there is space for it to fall out; if baby is in correct position, the head would prevent cord prolapse)

• Cord prolapse presents with rapid decrease in fetal HR

• Pelvic examination will allow you to feel/see the cord to confirm your dx

• Tx: Immediate cesarean section

9) Intraductal papilloma • MCC of unilateral bloody nipple discharge • Serosanguinous = contains both blood and serum

10) Measurement of serum β-hCG concentration • First step in work-up of secondary amenorrhea is to measure β-hCG to rule out pregnancy

11) Asherman syndrome

• ⊖ Progestin challenge can be either estrogen deficiency (ovarian failure) or asherman

• This patient has D&C history and normal FSH which points to asherman syndrome

12) Second administration of corticosteroids in 24 hours

• This patient has preterm premature rupture of membranes (PPROM) - ruptured of membranes <37 weeks gestation (preterm) and before labor has begun (premature)

• A course of antenatal corticosteroids consists of betamethasone (~12 mg) intramuscularly every 24 hours for two doses

• MgSO4 should also be give to prevent cerebral palsy

13) Maternal fever

• Fetal tachycardia is due to maternal fever (mother should be given antipyretic to reduce fever and subsequently improve the fetal tachycardia)

• Fetal anemia → sinusoidal pattern

• Fetal head compression → early decelerations

• Umbilical cord compression → variable decelerations

• Uteroplacental insufficiency → late decelerations

14) Squamous cell carcinoma of the cervix • Advanced cervical carcinoma often invades through the anterior uterine wall into

the bladder, blocking the ureters → obstructive uropathy (hydroureter)

15) Intravenous administration of ampicillin and gentamicin • This patient has endometritis, which is usually treated with clindamycin + gentamicin due to its broad-spectrum coverage

• Ampicillin can be used instead of clindamycin if there is clindamycin resistance, ⊕ GBS, or if infection persists after starting antibiotics

16) Wet mount preparation of the vaginal fluid • This patient has trichomoniasis • Wet mount would show motile trichomonads

17) X-ray of the chest • HIV patients with >5 mm induration = ⊕ PPD • CXR is the next best step for ⊕ PPD patients with a risk factor (ie, HIV), regardless of gestational age

18) Third measurement of serum β-hCG concentration in 1 week • This patient had an abortion and her β-hCG should be monitored weekly until it is undetectable

19) Pap smear • Women with HIV should have a Pap test at the time of HIV diagnosis (baseline), then every 12 months (some recommend a second test at 6 months as well). If the results of 3 consecutive test are normal, follow-up Pap test should be every 3 years.

20) Triphasic oral contraceptives • OCPs are contraindicated in smokers >35 years of age

21) ACTH oversecretion • This patient has congenital adrenal hyperplasia → virilization

• Male internal genitalia, Female external genitalia

• Phenotypically female at birth with virilization at puberty

23) Uterine inversion

• Uterine fundus prolapses through the cervix/vagina → smooth round mass protruding through the cervix/vagina

• Uterine fundus will be non palpable transabdominally

• Tx: aggressive fluid replacement, manual replacement of the uterus, uterotonic drugs after uterine replacement

24) Dichorionic • Thick septum = dichorionic (chorion = placenta) • Two yolk sacs = diamniotic (amnion = amniotic sac/yolk sac)

25) Measurement of serum cholesterol concentration • Father had MI at young age (39 yo) and she has other CVS risk factors (eg, obesity, smoking)

26) Testing for Chlamydia trachomatis • All sexually active females < 25 years old should be offered annual Chlamydia and Gonorrhea screening • This patient also uses condoms inconsistently

27) Pulmonary embolism

• This patient is 3 days postpartum, and thus PE is more likely (Virchow triad: hypercoaguable state from pregnancy, stasis from bed rest, and vascular insult)

• Amniotic fluid embolism would essentially occur In the immediate postpartum period

• Massive PE → circulatory collapse → metabolic acidosis

28) Torsion of an ovarian cyst

• Sudden abdominal pain in the context of an ovarian mass is torsion until proven otherwise

• Cystic and solid components = dermoid cyst, which has an ↑ risk of torsion due to heterogeneous composition

29) Detrusor instability • This patient has urge incontinence with nocturia • Fibroids would cause stress incontinence due to increased abdominal pressure → loss of urine with coughing, sneezing, valsalva

• Additionally, leiomyomas regress in the setting of menopause - if she had a fibroid, it was probably present for several years and shouldn’t be causing a new onset of urinary sxs

30) Neural tube defects • Anti-epileptic drugs (eg, Valproate, Carbamazepine, Phenytoin, Phenobarbital) → NTDs

31) Cervical incompetence • Previous LEEP surgeries + “funneled internal os” = cervical incompetence • Cervical incompetence → premature cervical shortening → bleeding as cervix is stretched

32) Cyclic progestin therapy • This patient likely has irregular menses due to anovulation - endometrium is stuck in proliferative phase due to missing ovulation/progesterone • OCPs are contraindicated because this patient is a smoker >35 years of age (and has HTN)

33) Hysterosalpingography • Hysterosalpingography rules out tubal occlusion and assesses the uterine cavity

• Multiple sexual partners → STIs → PID → adhesion/obstruction

• She has regular periods indicating that her HPO acts is intact, so we don’t need LH, FSH, Progesterone or Estrogen tests

34) Pulmonary hypoplasia • Oligohydramnios → lack of normal alveolar distention by aspirated amniotic fluid → pulmonary hypoplasia

35) Type 2 diabetes mellitus • ‘Velvety pigmented skin over the axillae’ = Acanthosis nigricans • Acanthosis nigricans is associated with insulin resistance → ↑ risk of DMII

36) Wound infection • Erythema and induration indicate wound infection as the cause of this patients post-op fever

37) Laparoscopy • Laparoscopic visualization is the only way to definitively diagnose endometriosis

38) Respect the patient’s wishes and schedule a follow-up visit in 1 week • Parental consent is not required for: contraception, STIs, pregnancy, substance abuse, and emergencies/trauma

39) Ultrasonography • This patient has a suspected twin pregnancy • IVF (oocyte donation) is a risk factor for twin pregnancy, and this patient has a fundal height > gestational age

40) Decreased estrogen and follicle-stimulating hormone (FSH) concentrations

• This patient has functional hypothalamic amenorrhea

• Excessive training, low-calorie diet, anorexia → ↑ Ghrelin, ↓ Leptin → ↓ GnRH → ↓ LH, ↓ FSH → ↓ Estrogen → amenorrhea, bone loss

41) Antibiotic therapy if delivery has not occurred 18 hours after rupture of membranes

• Indications for Intrapartum GBS prophylaxis: • 1) previous infant with invasive GBS disease • 2) GBS bacteriuria during any trimester of current pregnancy • 3) ⊕ GBS screen culture during current pregnancy • 4) Unknown GBS status at the onset of labor plus any of the following:

• Delivery at <37 weeks gestation • Intrapartum fever • Rupture of amniotic membranes for ≥18 hours

42) Nonstress test

• Smoking → uteroplacental insufficiency → IUGR • Nonstress test should be the next step for fetal monitoring; late decelerations indicate uteroplacental insufficiency

43) Vaginal foreign body • Should be managed by irrigation with warmed fluid (after application of a topical anesthetic in the vaginal introitus) or removal with a swab • Speculum examination should not be performed in prepubertal girls

44) Gestational diabetes • Previous big baby (macrosomia)

45) Androstenedione to estrone • Androstenedione is converted to estrone in adipose tissue via aromatase (this patient has a BMI of 34) • ↑ estrogen → ↑ risk of endometrial cancer

46) Fluorescent treponemal antibody absorption test

• Next step for ⊕ VDRL is FTA-ABS

47) Uteroplacental insufficiency • HTN in mother → Intrauterine growth restriction (IUGR)

48) Polyhydramnios

• Diabetes → polyhydramnios → fundus larger than gestational age

• This patient has received prenatal care since 7 weeks gestation and has had no abnormalities until 24 weeks gestation - multiple gestations, pelvic tumors, and errors in gestational age would have been picked up before this point in time.

49) Androgen insensitivity syndrome • X-linked mutations of androgen receptor; Karyotype 46,XY • Differentiated from Mullerian agenesis (karyotype 46, XX) by lack of axillary & pubic hair

50) Haemophilus ducreyi

• Large deep ulcers with gray/yellow exudate, well-demarcated border, soft friable base

• Other painful genital lesion is HSV (genital herpes), which is not an answer choice

• Granuloma inguinale (donovanosis), Syphilis, and Lymphogranuloma venereum have non painful initial lesions

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I really appreciate these NBME reviews!

Just a small note on #49: both cAIS and Mullerian agenesis have normal breast development. cAIS from peripheral testosterone conversion as you wrote, and Mullerian agenesis from normal ovarian estrogen production. Therefore, the likely ways we will have to differentiate the two on a vignette are:

1) pubic and axillary hair growth in Mullerian agenesis ONLY

2) XY karyotype and presence of intra-abdominal testes in cAIS

3) possibility of renal abnormalities in Mullerian agenesis

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