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NBME OBGYN Form 4 - Answers & Explanations

Updated: Nov 16, 2019

1) Increasing her current anticonvulsant medication

• This patients phenytoin concentration is low - the dose should be increased

• Pregnancy → ↑ proteins that bind phenytoin → ↓ phenytoin concentration

• The benefits of treating with phenytoin outweigh the risks, as seizures in mom are dangerous for the baby; additionally, the majority of infants born to women who take phenytoin during pregnancy will not develop fetal hydantoin syndrome

• There is evidence that children exposed to multiple anticonvulsants may be at greater risk for birth defects

2) Hemoglobin electrophoresis

• This patient has microcytic anemia (MCV <80)

• Serum ferritin and iron are normal = no iron deficiency

• Hemoglobin electrophoresis should be used to check for other causes of microcytic anemia (eg, thalassemia)

3) Cervicitis • This patient is afebrile with postcoital bleeding from a new partner • Acute cervicitis commonly presents with postcoital bleeding, mucopurulent discharge, and a friable cervix

4) Normal labor

• Dilation of cervix + painful contractions = labor

• Closed cervix + painless contractions = Braxton-Hicks contractions

• Cervical insufficiency (incompetence) = painless dilation of cervix that can lead to 2nd trimester pregnancy loss

5) Cystic teratoma • Dermoid cysts are seen on U/S as a partially calcified mass (teeth) with multiple thin echogenic bands (hair) • Torsion (twisting of ovary around the infundibulopelvic and utero-ovarian ligaments) → acute-onset severe pain

6) Placement of an IUD

• IUDs are the most effective contraceptives options (~99% efficacy) • This patient is non-compliant with her HTN meds - this makes oral contraceptives (taken daily) and Depo-Provera (injections every 3 months) a poor choice

7) Intraductal papilloma • MCC of unilateral bloody nipple discharge

• No assocaited mass or LAD

8) BMI

• Low body weight, especially < 128lbs (58kg) → ↓ peak bone density → ↑ risk of fracture

• If the patient had suffered a previous fracture (not family history), then that would be the greatest risk factor for an osteoporotic fracture

9) Hysterectomy • Endometrial cancer tx: hysterectomy • Endometrial hyperplasia tx: hysterectomy or progestin

10) Uterine synechiae • Uterine synechiae = Asherman’s syndrome

• D&C → trauma to basal layer of endometrium → intrauterine scars → failure to respond to estrogen

11) Amenorrhea

• Suction and sharp curettage → denuded basal layer of endometrium → Asherman’s syndrome → 2° amenorrhea

• Diagnosis and treatment = hysteroscopy (lyse adhesions)

12) Down syndrome • Down syndrome (trisomy 21) is associated with Duodenal atresia (→ duodenal bubble)

13) Atelectasis • 5 W’s of post-op fever

• Wind (atelectasis) = Post-op day (POD) 1-2 • Water (UTI) = POD 3-5 • Walking (DVT) = POD 4-6 • Wound (infection of surgical wound) = POD 5-7 • Wonder (anything) = POD 7+

• Abdominal surgery (c-section) → pain on deep inspiration → shallow breathing → underutilization of lung bases → atelectasis

14) Vasa previa • Fetal bradycardia is an important distinguishing feature of vasa previa; occurs because hemorrhage is of fetal origin (vs. maternal origin in placenta previa)

15) Uteroplacental insufficiency • Uteroplacental insufficiency → Late decelerations (nadir of deceleration occurs after peak of contraction)

16) Vesicovaginal fistula • Pelvic surgery or irradiation → ↑ risk of vesicovaginal fistula

• Characterized by continuous, painless urine leakage form vagina (→ moist vaginal mucosa)

• Dx: Dye test, cystourethroscopy

17) Stress incontinence

• ↓ urethral sphincter tone and/or urethral hypermobility → stress incontinence → leakage of urine with ↑ abdominal pressure (eg, coughing, lifting, sneezing)

• Tx: Pelvic floor exercises, pessary

18) Placental dysfunction

• Fetal complications of maternal HTN include fetal growth restriction, oligohydramnios, and preterm delivery

• This patient has been receiving prenatal care since 8 weeks gestation - rules out incorrect gestational age

19) Amnioinfusion

• Maternal repositioning (eg, left lateral decubitus) is first-line intervention for variable decelerations as it may reduce cord compression and subsequently improve fetal placental blood flow

• Amnioinfusion is a possible second-line intervention - artificially creates more amniotic fluid which can reduce umbilical cord compression and decrease variable decelerations

20) Chlamydia trachomatis infection

Chlamydia → cervicitis → Inflamed, friable cervix

• Tx: Azithromycin and Ceftriaxone

21) 50% • Sickle cell is autosomal recessive

• Mom has it (aa), Dad is carrier (Aa)

22) Colonoscopy • Adults 50-75 years old should be screened for colorectal cancer with a colonoscopy q10y, Sigmoidoscopy q5y, or an FOBT yearly

23) Varicella-zoster immune globulin therapy

• Post-exposure prophylaxis for infants = human varicella-zoster immune globulin therapy

• Tx of disseminated infection in infants = IV acyclovir x 10 days

24) Arrest of active phase

• Recent ACOG guidelines state active phase starts at 6 cm (in an attempt to reduce the number of patients getting unnecessary c-sections)

• Prior guidelines set active stage at 4 cm (this question is outdated)

25) Pulmonary embolus • Sudden-onset pleuritic chest pain • Normal ECG helps rule out acute coronary syndrome

26) Fetal growth restriction • Preeclampsia arrow underdevelopment of spiral arteries → ↑ vascular resistance → utero-placental insufficiency → asymmetric fetal growth restriction

27) Detrusor hyperreflexia

• MS affecting UMNs → loss of inhibitory control over bladder → urge incontinence

• If this patients MS had affected LMNs → hypotonic bladder → overflow incontinence

• Low postvoid residual volume (< 150mL in women, < 50mL in men) rules out overflow incontinence

• Urgency incontinence sxs: sudden urge to urinate (urinary urgency)

• Urgency incontinence tx: antimuscarinic drugs

28) Pyelonephritis • Asx bacteriuria left untreated → pyelonephritis (→ ⊕ CVA tenderness) • Microorganisms may release cytokines and prostaglandins → uterine contractions

29) Prostaglandin production • During menses, endometrium → ↑ prostaglandins → uterine contractions and endometrial sloughing • ↑ endometrial prostaglandin production → uterine hypercontractility & hypertonicity → ischemia arrow primary dysmenorrhea

30) Oxytocin administration

• Too much oxytocin administration → uterine tachysystole (insufficient uterine relaxation between contractions) → spiral artery constriction → ↓ placental blood flow → fetal hypoxia → late deceleration

• Uterine tachysystole = contractions occurring ≤2 minutes apart or >5 contractions in 10 minutes

• Tx: maternal repositioning, tocolysis, discontinue uterotonic agents (eg, oxytocin)

31) Arrange for an immediate psychiatric evaluation • This patient has suicidal ideations and requires immediate in-patient management

• SSRIs take 4-6 weeks to kick in

32) Fetal sleep state • Fetal sleep is the MCC of a nonreactive nonstress test (eg, no accelerations)

• Fetal sleep cycle can last up to 40 minutes

33) Increased cervical cell vulnerability to infections

• Young women have ↑ columnar epithelium lining their cervix → ↑ susceptibility to Gonorrhea and Chlamydia infections

• Overtime this columnar epithelium is replaced with squamous epithelium → ↑ microbial resistance

• ↑ progesterone → thickening of cervical mucus plug → ↓ risk of infection

34) Previous cesarean delivery • Prior placenta previa and previous C-section (or other uterine surgeries) are the biggest risk factor for placenta previa; Multiparity and advanced maternal age are also risk factors

35) Vaginal metronidazole gel • Bacterial vaginosis → Thin grayish discharge, Clue cells, pH >4.5

• Tx: Metronidazole or Clindamycin

36) Condylomata acuminata

• HPV 6, 11 → Condylomata acuminata

• HPV 16 and 18 are high risk strains

• Time frame of her partners syphilis (recently treated) helps rule out condyloma lata (2° syphilis), as it would not have progressed that quickly

37) Uteroplacental artery

• From mother to fetus: uteroplacental artery → placenta → umbilical vein

• Mothers blood doesn’t cross the placenta, therefore thrombosis must occur before the placenta

38) Recommendation for use of a lubricant

• Breastfeeding (↑ prolactin) → ↓ GnRH → ↓ LH, ↓ FSH → ↓ estrogen → vaginal dryness (atrophy)

• This short-term dyspareunia can be managed with lube

39) Ask the patient to convene a meeting of the church elders to discuss cesarean delivery

• This patient has decision-making capacity and can not be subjected to treatment against her will, regardless of the effect on the fetus

40) Testosterone • Lab findings of PCOS: ↑ testosterone, ↑ estrogen, imbalance of LH/FSH (often ≥2:1 ratio of LH:FSH)

41) Duplex venous ultrasonography • Leg swelling and ⊕ Homan sign (calf pain with dorsiflexion) = DVT

• U/S is used for DVT, Dopler is used for arterial insufficiency

42) Transvaginal incision and drainage • This adolescent girl likely has an imperforate hymen - amenorrhea and cyclic lower abdominal pain with an anterior central mass (hematocolpos)

43) Pedunculated submucous leiomyoma uteri • Submucosal fibroids arise under the endometrial lining and protrude into the uterine cavity → heavy and prolonged bleeding • They can prolapse through the cervical os → cervical dissension → labor-like pain

44) Carpal tunnel syndrome • More common during the 3rd trimester of pregnancy due to accumulation of fluid in carpal tunnel; usually resolves following delivery

45) 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

• Sexual abuse often leads to UTI → dysuria (which this patient does not have). Additionally, the physical exam shows no abnormalities (no signs of abuse).

46) Septic abortion

• Description of “unintended” pregnancy and the presence of cervical laceration implies there was an abortion, possibly with a non-sterile technique → infection

• Presents with fever, ↑ WBCs, abdominal pain, purulent foul smelling vaginal discharge

47) Endometriosis • Presents with chronic pelvic pain, dysmenorrhea, deep dyspareunia, and dyschezia • Physical examination reveals uterosacral ligament nodules and immobile uterus

48) Ruptured corpus luteum cyst • Sudden onset lower abdominal pain + free fluid in posterior cul-de-sac (culdocentesis) + absence of a mass

49) Breast • Progestin replacement is protective against endometrial hyperplasia

50) Ultrasonography • Most likely fetal malposition (eg, transverse lie) → U/S to confirm

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Unknown member
Nov 17, 2023

Hello, just found this amazing website, thank you for ur explanations dr

There are newer forms 7 and 8 for each subject. Did u do similar explanations to these?

Thank you in advance


For the question about a 21 y/o primigravid woman with ruptured membranes and thick meconium-stained fluid, FHR has variable decelerations. The answer was amnioinfusion, but I thought standard of care now shouldn't be amnioinfusion when theres meconium?


Jordan Abrams
Jordan Abrams
Aug 28, 2020

@Annalisa Lopez-Madrigal

The question is talking about hormonal replacement therapy (HRT), not OCPs. According to UpToDate: a few studies have shown a slight increase in ovarian cancer in those who take HRT, however, it is concluded that the absolute risk of ovarian cancer with HRT is very low. Therefore, HRT does not lower the risk of ovarian cancer like OCPs.


For #49, another reason is that combined OCPs can slightly lower the risk of uterine and ovarian cancer and raise the risk of breast cancer (slightly). So its another reason to pick "breast" over endometrial or ovarian.


Jordan Abrams
Jordan Abrams
Jan 26, 2020

Dr. Nworjih, thank you! This entire website was created with the goal of helping students through the complex journey of medical education - glad we're able to help!

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