Hypertension in pregnancy and pre-eclampsia for physician exams: definitions, severe features, magnesium and timing

Why it appears in both exams

The EMREE blueprint includes obstetrics and gynaecology as a discipline section of 15 in 100, and hypertension in pregnancy is a standard emergency in any obstetric outline. DHA’s General Practice entry lists women’s health and emergency problems. Neither organiser publishes sample content for this topic, so this is a revision map. Meddex is independent and is not connected to the Dubai Health Authority (DHA) or Prometric.

This is exam-preparation revision, not clinical advice. In practice, follow your own organisation’s policies and the current guideline, and check every dose and threshold against them.

The definitions

Chronic hypertension is high blood pressure before 20 weeks or known before pregnancy. Gestational hypertension is new hypertension after 20 weeks, defined as 140 over 90 mmHg or above on two occasions, with no proteinuria and no other features. Pre-eclampsia is new hypertension after 20 weeks together with proteinuria or another sign of organ involvement, such as kidney, liver, blood or neurological features. Severe hypertension is usually 160 over 110 mmHg or higher. Details differ slightly between ACOG and NICE, so use the criteria in the question.

Severe features

Look for severe hypertension, a persistent headache or visual disturbance, upper abdominal or right upper quadrant pain, a low platelet count, raised liver enzymes, a rising creatinine and pulmonary oedema. Brisk reflexes and clonus suggest irritability. HELLP syndrome means haemolysis, elevated liver enzymes and low platelets. Eclampsia is a seizure in the setting of pre-eclampsia.

Which drugs, and which to avoid

First-line oral options in pregnancy are labetalol, nifedipine and methyldopa. Severe hypertension is treated promptly, with intravenous labetalol or hydralazine or oral nifedipine in many protocols, and the aim is a safe, steady fall, not a sudden drop. Avoid ACE inhibitors and angiotensin receptor blockers in pregnancy because of fetal harm. Women at high risk of pre-eclampsia are offered low-dose aspirin from early in the second trimester in many guidelines, with NICE advising 75 to 150 mg a day from 12 weeks.

Magnesium sulphate

Magnesium sulphate is the drug of choice to prevent eclampsia in severe pre-eclampsia and to treat an eclamptic seizure. A regimen in common use is a loading dose of 4 g intravenously over 5 to 15 minutes, followed by an infusion of 1 g an hour, but local protocols differ. While it runs, check the respiratory rate, patellar reflexes, urine output and oxygen saturation. Loss of reflexes and a respiratory rate below about 12 suggest toxicity, and calcium gluconate is the antidote. Kidney impairment raises the risk.

Timing of delivery

Delivery is the only cure. The timing depends on gestation, severity and the response to treatment. In severe disease or if maternal or fetal condition worsens, delivery follows stabilisation, whatever the gestation. For milder disease at term, planned delivery is usual. Before 34 weeks, corticosteroids are given to help fetal lung maturity when delivery is likely. Questions often ask for the next step, so read whether the woman is stable, which of the severe features are present and the gestation.

Example: the next step

Example, written by Meddex with invented numbers. A woman at 36 weeks has a blood pressure of 170 over 112 mmHg on repeat measurement, a severe headache and a platelet count that has fallen since last week. Options: A. repeat the blood pressure in a week, B. paracetamol and discharge, C. admit, treat the severe hypertension, give magnesium sulphate and plan delivery, D. start an ACE inhibitor. The best answer is C. The blood pressure and headache are severe features, and delivery at 36 weeks is reasonable once she is stable.

After birth

Blood pressure often peaks between three and six days after birth, and eclampsia can occur postpartum. Monitor and treat, and arrange follow-up. Enalapril and nifedipine are compatible with breastfeeding. Women who have had pre-eclampsia have a higher lifetime risk of cardiovascular disease, so counsel on lifestyle and follow-up. For the nursing side of the same topic, read maternal and newborn nursing for the DHA exam.

How to practise

Write the four definitions, the severe features, the three first-line drugs and the magnesium checks on one sheet. Then try questions in the EMREE paediatrics and obstetrics guide and the question bank.

Frequently asked questions