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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

• Additionally, this woman is premenopausal and has normal ovarian function (she has enough estrogen)

• Raloxifene is not given to premenopausal women

36) Urethrocele

• ⊕ Q-tip test = stress incontinence; >30° of movement = urethral hypermobility

• Well supported anterior and posterior vaginal wall rules out cystocele and rectocele

37) Imperforate hymen • This adolescent girl likely has an imperforate hymen - amenorrhea and cyclic lower abdominal pain with an anterior central mass (hematocolpos)

38) Pregnancy test • Ruling out pregnancy is the most appropriate next step in diagnosis

39) Surgical exploration

• Fever + leukocytosis + right-sided abdominal pain → appendicitis

• Appendix perforation → fluid in paracolic gutter (which could potentially cause peritonitis/sepsis)

40) Administer a prostaglandin • Late- and post-term pregnancies are commonly complicated by oligo-hydramnios

• Aging placentas may have decreased fetal perfusion, which causes decreased renal perfusion and urinary output

• The presence of oligohydramnios is an indication for delivery • Cervix is not favorable yet, so ripen cervix with prostaglandin

41) Necrotizing fasciitis

• Bartholinitis (cellulitis) is a painful complication of Bartholin cysts, and more commonly, Bartholin abscesses

• Necrotizing fasciitis of the perineum (Fournier’s gangrene) is a severe complication of Bartholinitis associated with diabetics

42) Hydatidiform mole • Hydatidiform mole → ↑↑↑ β-hCG → ovarian hyper-stimulation → theca lutein cysts (resolve with decreasing β-hCG levels)

43) Indirect antiglobulin (Coombs) test

• Rh ⊖ mother in her 2nd pregnancy

• Indirect Coombs test detects presence of unbound antibodies in the serum (direct Coombs test detects antibodies attached directly to the RBC surface)

• Kleihauer-Betke test is used to check the dose of RhoD

44) Doppler ultrasonography of the umbilical artery • This baby has asymmetrical FGR • Doppler U/S of the umbilical artery can show absent or reverse flow, and determines the risk of IUFD

45) Cone biopsy of the cervix • This patients SCJ cannot be visualized meaning inadequate colposcopy result

• Non-pregnant women > 25 with CIN3 should be managed with LEEP or Cone biopsy of the cervix

• Pregnant patients should be managed with colposcopy + biopsy to confirm CIN3 (need to be sure before making a pregnant patient incompetent or stenosed)

46) Follicle-stimulating hormone

• ↑↑ FSH is specific for menopause (loss of negative feedback on FSH due to ↓ estrogen)

• Hypothyroidism can’t account for night sweats, anxiety, etc.

47) Test for Chlamydia trachomatis • All sexually active females < 25 should be offered annual Chlamydia and Gonorrhea screening

48) Autoimmune ovarian failure

• This patient has primary ovarian insufficiency, hypergonadotrophic hypogonadism (↑ FSH & ↓ Estrogen), in the setting of autoimmune disease

49) Ultrasonography • U/S is the next best step to exclude the possibility of incorrect dating • ↑ MSAFP is seen in multiple gestations, placental abruption, fetal abnormalities, or error in the date of gestation

50) Candida albicans • Candida vaginitis presents with a normal pH (3.8 - 4.5) ± thick ‘cottage cheese’ discharge • Risk factors: recent corticosteroid or antibiotic use, pregnancy, diabetes

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