PLAB PLAB Obstetrics & Gynecology 1 — Questions and Answers
Question 1: A 28-year-old woman at 32 weeks gestation presents with sudden-onset severe headache, visual disturbances, and BP of 160/110 mmHg. What is the most likely diagnosis?
- Migraine
- Pre-eclampsia (Correct answer)
- Tension headache
- Intracranial hemorrhage
Correct answer: Pre-eclampsia
Pre-eclampsia is defined by hypertension (≥140/90 mmHg) with proteinuria or end-organ dysfunction after 20 weeks gestation, and severe features include BP ≥160/110 mmHg with neurological symptoms.
Question 2: Which medication is first-line for cervical ripening and labor induction in a patient with an unfavorable cervix at term?
- Oxytocin IV infusion
- Misoprostol
- Dinoprostone (prostaglandin E2) (Correct answer)
- Mifepristone
Correct answer: Dinoprostone (prostaglandin E2)
Dinoprostone (prostaglandin E2) gel or insert is the standard first-line agent for cervical ripening in patients with an unfavorable Bishop score at term.
Question 3: A 35-year-old woman presents with sudden severe lower abdominal pain, shoulder tip pain, and a positive urine pregnancy test. Ultrasound shows no intrauterine pregnancy. What is the most likely diagnosis?
- Ovarian torsion
- Ruptured ectopic pregnancy (Correct answer)
- Placenta previa
- Appendicitis
Correct answer: Ruptured ectopic pregnancy
Ruptured ectopic pregnancy classically presents with acute abdominal pain, peritoneal irritation causing referred shoulder tip pain (diaphragmatic irritation from hemoperitoneum), and a positive pregnancy test without intrauterine pregnancy on ultrasound.
Question 4: Which investigation is most useful to confirm ovarian torsion in a woman presenting with acute unilateral pelvic pain?
- Serum CA-125
- Transvaginal ultrasound with Doppler (Correct answer)
- Diagnostic laparoscopy
- CT abdomen and pelvis
Correct answer: Transvaginal ultrasound with Doppler
Transvaginal ultrasound with Doppler flow studies is the first-line investigation for suspected ovarian torsion, assessing ovarian morphology and blood flow, though absence of flow is not always present.
Question 5: A primigravida at 38 weeks presents with mild contractions and her cervix is 4 cm dilated, fully effaced, with the fetal head at 0 station. What stage of labor is she in?
- Latent phase of first stage
- Active phase of first stage (Correct answer)
- Second stage
- Third stage
Correct answer: Active phase of first stage
The active phase of the first stage of labor begins at 6 cm dilation in most modern guidelines, but reaching 4 cm effaced with regular contractions is transitioning into active labor; cervical dilation ≥6 cm with contractions defines active phase per ACOG 2014 guidelines.
Question 6: Which antibiotic is recommended for Group B Streptococcus (GBS) prophylaxis during labor in penicillin-allergic patients with low anaphylaxis risk?
- Clindamycin
- Vancomycin
- Erythromycin
- Cefazolin (Correct answer)
Correct answer: Cefazolin
Cefazolin is the recommended alternative for GBS intrapartum prophylaxis in penicillin-allergic patients with low risk of anaphylaxis (no history of urticaria, angioedema, or anaphylaxis to penicillin).
PLAB PLAB Obstetrics & Gynecology 1
A 28-year-old woman at 32 weeks gestation presents with sudden-onset severe headache, visual disturbances, and BP of 160/110 mmHg.
What is the most likely diagnosis?