PLAB 1 Obstetrics and Gynaecology — Questions and Answers
Question 1: A 28-year-old woman at 32 weeks' gestation presents with painless bright red vaginal bleeding. On examination, the uterus is soft and non-tender. What is the most likely diagnosis?
- Placental abruption
- Placenta praevia (Correct answer)
- Cervical ectropion
- Uterine rupture
Correct answer: Placenta praevia
Painless, bright red vaginal bleeding in the third trimester is the hallmark presentation of placenta praevia. The soft, non-tender uterus distinguishes it from placental abruption, which typically presents with constant pain and a woody-hard uterus. Digital vaginal examination is contraindicated.
Question 2: A 30-year-old primigravida at 34 weeks' gestation has a blood pressure of 165/110 mmHg, proteinuria of 3+, and complains of a severe headache and visual disturbances. What is the most appropriate immediate management?
- Discharge with oral antihypertensives and GP follow-up
- Admit, commence IV magnesium sulphate and IV labetalol, and plan urgent delivery (Correct answer)
- Prescribe bed rest at home and recheck BP in 1 week
- Start oral methyldopa and review in the antenatal clinic next week
Correct answer: Admit, commence IV magnesium sulphate and IV labetalol, and plan urgent delivery
This presentation — severe hypertension, significant proteinuria, headache, and visual disturbances — constitutes severe pre-eclampsia with imminent risk of eclampsia. NICE guidelines (NG133) recommend IV magnesium sulphate for seizure prevention, IV labetalol for BP control, and planned delivery.
Question 3: A 25-year-old woman presents at 7 weeks' gestation with vaginal bleeding and left iliac fossa pain. Her serum beta-hCG is 1,500 IU/L and transvaginal ultrasound shows an empty uterus. What is the most likely diagnosis?
- Complete miscarriage
- Ectopic pregnancy (Correct answer)
- Molar pregnancy
- Threatened miscarriage
Correct answer: Ectopic pregnancy
An empty uterus on transvaginal ultrasound with a beta-hCG above the discriminatory level (usually 1,500-2,000 IU/L), combined with pain and bleeding, is highly suspicious for ectopic pregnancy until proven otherwise. This requires urgent gynaecological assessment.
Question 4: According to NICE guidelines, what is the recommended method of induction of labour when the cervix is unfavourable (Bishop score <6)?
- Immediate ARM (artificial rupture of membranes)
- Vaginal prostaglandin E2 (dinoprostone) or oral misoprostol to ripen the cervix (Correct answer)
- Emergency caesarean section
- IV oxytocin infusion
Correct answer: Vaginal prostaglandin E2 (dinoprostone) or oral misoprostol to ripen the cervix
NICE recommends cervical ripening with vaginal prostaglandin E2 (dinoprostone) or oral misoprostol when the cervix is unfavourable (Bishop score <6). ARM and oxytocin are used once the cervix is favourable. Mechanical methods (balloon catheter) are also options.
Question 5: A 35-year-old woman presents with post-menopausal bleeding. She is on no hormone replacement therapy. What is the most appropriate initial investigation?
- Cervical smear
- Transvaginal ultrasound to assess endometrial thickness (Correct answer)
- CT abdomen and pelvis
- Serum CA-125
Correct answer: Transvaginal ultrasound to assess endometrial thickness
Post-menopausal bleeding requires investigation to exclude endometrial cancer. NICE recommends transvaginal ultrasound as the first-line investigation. If endometrial thickness is ≥4 mm, hysteroscopy with endometrial biopsy is indicated. All women with PMB should be referred via 2-week wait.
Question 6: During labour, a CTG shows late decelerations with reduced variability. What does this pattern most likely indicate?
- Normal fetal response to contractions
- Fetal head compression
- Uteroplacental insufficiency causing fetal hypoxia (Correct answer)
- Umbilical cord compression
Correct answer: Uteroplacental insufficiency causing fetal hypoxia
Late decelerations (decelerations that start after the peak of a contraction and return to baseline after the contraction ends) with reduced variability indicate uteroplacental insufficiency and fetal hypoxia. This is a pathological CTG pattern requiring urgent intervention.
PLAB 1 Obstetrics and Gynaecology
A 28-year-old woman at 32 weeks' gestation presents with painless bright red vaginal bleeding.
On examination, the uterus is soft and non-tender.
What is the most likely diagnosis?