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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