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PLAB 1 (Professional and Linguistic Assessments Board Part 1)

9.2 Antenatal & Peripartum Emergencies: Pre-Eclampsia & Haemorrhage

Q: A 32-year-old primigravida at 34 weeks gestation with severe pre-eclampsia is receiving an intravenous magnesium sulphate infusion for eclampsia prophylaxis. Two hours into the infusion, routine nursing observations demonstrate absent patellar reflexes, a respiratory rate of 9 breaths/minute, and an hourly urine output over the preceding two hours of 12 mL/hour. Her oxygen saturation is 91% on ambient air and blood pressure is 162/104 mmHg. What is the most appropriate immediate medical action?

Stop the magnesium infusion and give 10 mL of 10% calcium gluconate IV. Stopping the magnesium sulphate infusion and immediately administering 10 mL of 10% calcium gluconate intravenously over 10 minutes is the mandatory emergency intervention for magnesium toxicity. Magnesium is cleared almost exclusively by the kidneys; when oliguria (< 20 mL/hour) occurs, circulating magnesium levels rise rapidly into the toxic range. Magnesium toxicity manifests sequentially with loss of deep tendon (patellar) reflexes, followed by severe respiratory depression (< 12 breaths/minute), somnolence, cardiac conduction defects, and arrest. Intravenous 10% calcium gluconate directly antagonizes the neuromuscular and cardiovascular effects of hypermagnesaemia. Naloxone is an opioid receptor antagonist and has no physiological role in magnesium poisoning. Labetalol reduces blood pressure but fails to treat life-threatening respiratory depression. Administering rapid fluid boluses in severe pre-eclampsia risks precipitating fatal pulmonary oedema without reversing acute magnesium toxicity.

Q: A 31-year-old multigravida at 32 weeks gestation presents to the maternity assessment unit with sudden-onset painless, bright red vaginal bleeding that has soaked through two sanitary pads over the past hour. She reports no abdominal pain or cramping. On abdominal examination, the uterus is soft, non-tender, and completely relaxed between palpations. The fundal height corresponds to 32 weeks, but the fetal presentation is high and unengaged. Cardiotocography shows a reassuring fetal heart rate of 142 bpm with normal baseline variability. Which of the following is the most appropriate next clinical step?

Perform an urgent transvaginal ultrasound to localize the placenta and avoid digital vaginal examination. Arranging an urgent transvaginal ultrasound to localize the placenta while strictly avoiding digital vaginal examination is the correct clinical action. The classic triad of painless, bright red vaginal bleeding in the third trimester, an entirely soft and non-tender uterus, and an unengaged or abnormal fetal lie is characteristic of placenta praevia. Performing a digital vaginal examination in suspected placenta praevia is strictly contraindicated because placing a finger through the cervix can directly disrupt the low-lying placental cotyledons, triggering massive, catastrophic exsanguination. Transvaginal ultrasound performed by a skilled clinician is safe, highly sensitive, and the diagnostic investigation of choice. Ergometrine is a uterotonic agent used for postpartum haemorrhage, not antepartum bleeding with a fetus in utero. Category 1 emergency caesarean delivery is indicated only for severe maternal shock or non-reassuring fetal status, neither of which is present here.

Q: A 29-year-old woman with a background of pre-existing chronic hypertension gives birth via normal spontaneous vaginal delivery at 38 weeks gestation. Five minutes after placental expulsion, she develops severe primary postpartum haemorrhage with an estimated blood loss exceeding 800 mL. On examination, her uterus is soft, boggy, and palpated 3 cm above the umbilicus. Bimanual uterine compression is initiated and an intravenous bolus of 5 units of oxytocin is given followed by an oxytocin infusion, but the uterus remains poorly contracted. Her blood pressure is 168/106 mmHg and pulse rate is 108 bpm. Which of the following uterotonic medications is strictly contraindicated in this patient?

Ergometrine. Ergometrine is strictly contraindicated in this patient due to her elevated blood pressure (168/106 mmHg) and history of chronic hypertension. Ergometrine causes potent, sustained smooth muscle contraction and intense peripheral arterial vasoconstriction via alpha-adrenergic receptors, which can precipitate malignant hypertensive crisis, acute heart failure, or intracranial haemorrhage in hypertensive individuals. For uterine atony refractory to oxytocin in hypertensive patients, appropriate second-line uterotonics include intramuscular carboprost (prostaglandin F2-alpha, provided the patient does not have asthma), rectal or sublingual misoprostol (prostaglandin E1), and intravenous tranexamic acid. Carboprost is contraindicated in asthma, not hypertension.

Key Takeaways

Gestational hypertension is new hypertension (BP ≥ 140/90 mmHg) presenting after 20 weeks gestation without proteinuria; Pre-eclampsia requires new hypertension after 20 weeks PLUS significant proteinuria (uPCR ≥ 30 mg/mmol or ACR ≥ 8 mg/mmol) or maternal end-organ dysfunction.
High-risk women (prior pre-eclampsia, CKD, chronic hypertension, diabetes, autoimmune disease) must receive prophylactic aspirin 75–150 mg daily from 12 weeks until delivery; oral labetalol is first-line for BP control (target 135/85 mmHg), substituting modified-release nifedipine if asthma is present.
Severe pre-eclampsia and eclampsia are treated with intravenous magnesium sulphate (4 g loading dose over 10–15 min, then 1 g/h for 24h); toxicity is detected by loss of deep tendon reflexes, bradypnoea (<12/min), and oliguria, and is reversed with 10% IV calcium gluconate.
Antepartum haemorrhage mandates distinguishing placenta praevia (painless, bright red bleeding, soft relaxed uterus, high fetal lie; digital vaginal examination is strictly contraindicated prior to scan) from placental abruption (painful, dark/concealed bleeding, rigid 'board-like' tender uterus, maternal shock out of proportion, fetal distress).
Primary postpartum haemorrhage (blood loss of 500 mL or more within 24 hours of any birth; major above 1,000 mL) is driven by the 4 Ts (Tone #1, Tissue, Trauma, Thrombin); uterotonic medical management employs IV oxytocin, ergometrine (contraindicated in hypertension), carboprost (contraindicated in asthma), misoprostol, and IV tranexamic acid.

Last updated: October 2026

Antenatal & Peripartum Emergencies: Pre-Eclampsia & Haemorrhage

Obstetric emergencies during the second half of pregnancy and the peripartum period are major contributors to maternal and perinatal morbidity. Accurate risk stratification, prompt diagnosis of hypertensive disorders, safe evaluation of antepartum bleeding, and rapid resuscitation during postpartum haemorrhage are vital competencies in UK clinical practice.

Hypertensive Disorders of Pregnancy

Blood pressure normally falls during the first and second trimesters, reaching a nadir at 20–24 weeks, before returning to pre-pregnancy levels by term. New hypertension developing after 20 weeks gestation is classified into distinct clinicopathological entities:

Gestational Hypertension: New-onset systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg arising after 20 weeks of gestation in the absence of significant proteinuria or end-organ dysfunction. Blood pressure characteristically normalises within 6 weeks postpartum.
Pre-Eclampsia: New-onset hypertension (BP ≥ 140/90 mmHg) occurring after 20 weeks gestation accompanied by one or more of the following newly developed features:
- Significant Proteinuria: Urine protein:creatinine ratio (uPCR) ≥ 30 mg/mmol, urine albumin:creatinine ratio (uACR) ≥ 8 mg/mmol, or 24-hour urine collection ≥ 0.3 g protein (or dipstick ≥ 2+).
- Maternal Organ Dysfunction:
  - Renal: Serum creatinine > 90 µmol/L (or doubling of baseline).
  - Hepatic: Elevated transaminases (ALT or AST > 70 IU/L, or > twice upper limit of normal) or severe persistent right upper quadrant / epigastric pain.
  - Haematological: Thrombocytopenia (platelets < 100 × 10⁹/L), DIC, or microangiopathic haemolysis.
  - Neurological: Severe intractable headache, persistent visual scotomata, photopsia, hyperreflexia with sustained clonus (≥ 3 beats), or eclamptic convulsions.
  - Respiratory: Acute pulmonary oedema.
- Uteroplacental Dysfunction: Severe fetal growth restriction (FGR), oligohydramnios, or abnormal umbilical artery Doppler waveforms.

Risk Stratification & Aspirin Prophylaxis (NICE NG133)

Early prophylactic administration of aspirin 75–150 mg daily from 12 weeks of gestation until birth reduces the incidence of preterm pre-eclampsia in vulnerable women:

High-Risk Factors (Offer Aspirin if ≥ 1 Present)	Moderate-Risk Factors (Offer Aspirin if ≥ 2 Present)
• Hypertensive disease in a previous pregnancy	• First pregnancy (primigravida)
• Chronic kidney disease (CKD)	• Maternal age ≥ 40 years
• Autoimmune disease (SLE or Antiphospholipid Syndrome)	• Pregnancy interval > 10 years
• Pre-existing chronic hypertension	• Body mass index (BMI) ≥ 35 kg/m² at booking
• Diabetes mellitus (Type 1 or Type 2)	• Family history of pre-eclampsia (mother or sister)
	• Multiple pregnancy (twins, triplets)

Pharmacological BP Control

Antihypertensive pharmacotherapy is initiated when blood pressure reaches ≥ 140/90 mmHg, aiming for a target blood pressure of 135/85 mmHg:

First-line: Oral Labetalol (combined alpha- and beta-adrenergic blocker). Titrated up to 200–400 mg three times daily.
Second-line (or in Asthmatic Patients): Nifedipine modified-release (MR, dihydropyridine calcium channel blocker). Labetalol is contraindicated in asthma due to bronchospasm risk.
Third-line: Methyldopa (centrally acting alpha-2 agonist). Note: Methyldopa should be discontinued within 48 hours post-delivery due to high risks of postnatal depression.
Contraindicated Antihypertensives: ACE inhibitors, Angiotensin Receptor Blockers (ARBs), and thiazide diuretics are strictly contraindicated in pregnancy due to risks of fetal renal dysgenesis, oligohydramnios, skull hypoplasia, and intrauterine death.

Severe Pre-Eclampsia & Eclampsia Management

Severe pre-eclampsia is characterized by blood pressure ≥ 160/110 mmHg or pre-eclampsia accompanied by maternal symptoms of impending eclampsia (severe headache, visual disturbance, clonus, epigastric pain):

Acute Blood Pressure Lowering: Intravenous labetalol infusion or intravenous hydralazine infusion, accompanied by oral nifedipine MR.
Eclampsia Prophylaxis & Seizure Control: Intravenous Magnesium Sulphate ( $MgSO_4$ ) is the anticonvulsant of choice:
- Loading dose: 4 g IV over 10–15 minutes.
- Maintenance infusion: 1 g/hour IV for 24 hours following delivery or the last seizure.
Monitoring for Magnesium Toxicity: Magnesium is cleared almost exclusively by the kidneys. Hourly clinical surveillance must check:
1. Deep tendon reflexes: Loss of the patellar (knee-jerk) reflex is the earliest sign of toxicity.
2. Respiratory rate: Must remain ≥ 12 breaths/minute (respiratory depression indicates advanced toxicity).
3. Urine output: Must exceed 20 mL/hour. If oliguria develops, magnesium rapidly accumulates.
Magnesium Antidote: If toxicity occurs, immediately stop the infusion and administer 10 mL of 10% Calcium Gluconate intravenously over 10 minutes.

HELLP Syndrome

HELLP syndrome is a severe thrombotic microangiopathy complicating 10–20% of severe pre-eclampsia cases:

H (Haemolysis): Microangiopathic haemolytic anaemia with schistocytes/burr cells on blood film, elevated lactate dehydrogenase (LDH > 600 IU/L), and unconjugated hyperbilirubinaemia.
EL (Elevated Liver enzymes): ALT or AST > 70 IU/L; capsular hepatic distension causes epigastric pain and risks subcapsular haematoma rupture.
LP (Low Platelets): Consumptive thrombocytopenia with platelets < 100 × 10⁹/L.
Definitive Treatment: Prompt maternal stabilisation followed by urgent delivery regardless of gestational age.

Antepartum Haemorrhage (APH)

Antepartum haemorrhage is defined as genital bleeding occurring from 24 completed weeks of gestation until delivery of the infant. The two major obstetric causes are placenta praevia and placental abruption.

Clinical Parameter	Placenta Praevia	Placental Abruption
Underlying Pathology	Placenta implanted partially or wholly in the lower uterine segment over or near the internal os	Premature detachment of a normally sited placenta from the uterine decidua prior to birth
Nature of Bleeding	Painless, recurrent, typically bright red vaginal haemorrhage	Painful, continuous, typically dark red bleeding (may be concealed behind placenta in 20%)
Abdominal Palpation	Abdomen is soft, relaxed, and non-tender; uterine fundus matches dates	Uterus is tense, rigid, woody, and intensely tender ("board-like abdomen")
Fetal Presentation & Lie	Often abnormal lie (transverse, oblique) or high, unengaged presenting part	Normal lie; fetal parts difficult to palpate due to severe myometrial hypertonus
Fetal Heart / CTG	Usually normal and reassuring unless massive maternal hypovolaemia	Frequently abnormal: severe decelerations, fetal bradycardia, or absent heart tones
Maternal Shock	Proportional to visible external vaginal blood loss	Out of proportion to visible bleeding (due to extensive concealed retroplacental clot)
Coagulopathy (DIC)	Rare	Common (massive release of tissue thromboplastin into maternal circulation)

Caution

Strict Contraindication in APH: NEVER perform a digital vaginal examination in any woman presenting with antepartum haemorrhage until placenta praevia has been definitively excluded by ultrasound. Digital palpation can tear a low-lying placenta, precipitating catastrophic, fatal haemorrhage within minutes.

Postpartum Haemorrhage (PPH)

Primary postpartum haemorrhage (RCOG Green-top Guideline 52) is blood loss of 500 mL or more from the genital tract within 24 hours of birth, after either vaginal or caesarean birth. Minor PPH is 500–1,000 mL; major PPH is more than 1,000 mL (moderate 1,001–2,000 mL, severe more than 2,000 mL) or any blood loss with clinical shock. Secondary PPH is abnormal bleeding from 24 hours to 12 weeks after birth (often endometritis or retained tissue).

The 4 Ts of PPH Aetiology

Tone (~70–80% of cases): Uterine atony. The uterus is soft, boggy, and relaxed above the umbilicus. Risk factors include prolonged labour, multiparity, multiple pregnancy, polyhydramnios, and chorioamnionitis.
Tissue (~10%): Retained products of conception (cotyledons, succenturiate lobe, placenta accreta) or intra-cavitary blood clots preventing mechanical myometrial retraction.
Trauma (~20%): Lacerations of the perineum, vagina, or cervix, pelvic haematomas, uterine rupture, or acute uterine inversion.
Thrombin (~1%): Pre-existing coagulopathies (von Willebrand disease, haemophilia) or acquired coagulopathies (DIC secondary to abruption, sepsis, or amniotic fluid embolism).

Emergency Resuscitation & Medical Escalation Ladder

When primary PPH is diagnosed, the multidisciplinary obstetric emergency team must be summoned immediately:

Initial Resuscitation: ABCDE approach, 15 L/min high-flow oxygen via non-rebreather mask, two large-bore (14G) IV cannulae, urgent bloods (FBC, coagulation screen, fibrinogen, crossmatch 4–6 units), warmed crystalloids, and insertion of a Foley catheter to decompress the bladder.
Mechanical Compression: Continuous bimanual uterine compression (one gloved hand in the anterior vaginal fornix pressing the anterior uterine wall, the other hand compressing the fundus abdominally) combined with firm uterine fundal rubbing ("rubbing up a contraction").
Pharmacological Uterotonics:
1. Oxytocin: First-line. Administer 5 units slow IV bolus, followed by an oxytocin infusion (40 units in 500 mL normal saline at 125 mL/hour).
2. Ergometrine: 500 mcg slow IV or IM. Induces sustained tetanic uterine contractions. CONTRAINDICATED in women with hypertension or pre-eclampsia due to severe acute vasospasm and hypertensive crisis.
3. Carboprost (15-methyl PGF2-alpha): 250 mcg deep IM repeated every 15 minutes (maximum 8 doses = 2 mg). CONTRAINDICATED in patients with active asthma due to severe bronchoconstriction.
4. Misoprostol: 800–1000 mcg per rectum or sublingually (synthetic PGE1 analogue).
5. Tranexamic Acid (TXA): Administer 1 g IV over 10 minutes within 3 hours of delivery (reduces maternal mortality from bleeding without increasing thrombotic complications).
Tamponade & Surgical Interventions: If uterotonics fail, escalate rapidly to intrauterine balloon tamponade (Bakri balloon), surgical haemostatic brace suturing (B-Lynch suture), bilateral uterine artery ligation, interventional radiological arterial embolisation, or emergency peripartum hysterectomy as a lifesaving final measure.

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Emergency Escalation Algorithm for Primary Postpartum Haemorrhage

Test Your Knowledge

A 32-year-old primigravida at 34 weeks gestation with severe pre-eclampsia is receiving an intravenous magnesium sulphate infusion for eclampsia prophylaxis. Two hours into the infusion, routine nursing observations demonstrate absent patellar reflexes, a respiratory rate of 9 breaths/minute, and an hourly urine output over the preceding two hours of 12 mL/hour. Her oxygen saturation is 91% on ambient air and blood pressure is 162/104 mmHg. What is the most appropriate immediate medical action?

Stop the magnesium infusion and give 10 mL of 10% calcium gluconate IV

Increase the intravenous crystalloid infusion rate to 250 mL/hour to flush the kidneys

Administer intravenous labetalol 50 mg over 5 minutes

Administer intravenous naloxone 400 mcg stat bolus

Test Your Knowledge

A 31-year-old multigravida at 32 weeks gestation presents to the maternity assessment unit with sudden-onset painless, bright red vaginal bleeding that has soaked through two sanitary pads over the past hour. She reports no abdominal pain or cramping. On abdominal examination, the uterus is soft, non-tender, and completely relaxed between palpations. The fundal height corresponds to 32 weeks, but the fetal presentation is high and unengaged. Cardiotocography shows a reassuring fetal heart rate of 142 bpm with normal baseline variability. Which of the following is the most appropriate next clinical step?

Perform immediate digital vaginal examination to determine cervical dilatation and fetal station

Administer intramuscular ergometrine 500 mcg stat

Perform an urgent transvaginal ultrasound to localize the placenta and avoid digital vaginal examination

Perform immediate emergency category 1 caesarean section

Test Your Knowledge

A 29-year-old woman with a background of pre-existing chronic hypertension gives birth via normal spontaneous vaginal delivery at 38 weeks gestation. Five minutes after placental expulsion, she develops severe primary postpartum haemorrhage with an estimated blood loss exceeding 800 mL. On examination, her uterus is soft, boggy, and palpated 3 cm above the umbilicus. Bimanual uterine compression is initiated and an intravenous bolus of 5 units of oxytocin is given followed by an oxytocin infusion, but the uterus remains poorly contracted. Her blood pressure is 168/106 mmHg and pulse rate is 108 bpm. Which of the following uterotonic medications is strictly contraindicated in this patient?

Misoprostol

Carboprost tromethamine

Tranexamic acid

Ergometrine

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9.3 Common Gynaecological Presentations & Gynaecological Oncology

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