Introduction
Pre-eclampsia management is one of the highest-yield topics in the UKMLA, appearing frequently in both the Applied Knowledge Test (AKT) and the Clinical and Professional Skills Assessment (CPSA). Mastering pre-eclampsia management is vital because it remains a leading cause of maternal morbidity.
For a junior doctor, the challenge lies in the nuance. You must be able to distinguish simple gestational hypertension from evolving pre-eclampsia, recognise the “red flags” of imminent eclampsia (seizures), and confidently prescribe high-risk medications like Magnesium Sulfate.
This guide breaks down the massive NICE Guideline NG133 into a logical 5-step protocol, ensuring you can manage the patient safely from the booking visit right through to the delivery suite.
Key Takeaways
Definitions Matter: You must clearly distinguish Pre-eclampsia (HTN + Proteinuria/Organ damage) from Gestational Hypertension (HTN alone).
Aspirin is Key: Know the specific NICE criteria for Aspirin prophylaxis (High vs. Moderate risk factors).
The Diagnostic Triad: New hypertension (>140/90) after 20 weeks is the trigger; look for Proteinuria (PCR >30) or end-organ dysfunction.
Severe Protocol: Severe pre-eclampsia (≥160/110) requires immediate admission, IV antihypertensives (Labetalol), and fluid restriction.
Seizure Prophylaxis: Magnesium Sulfate is the gold standard for preventing and treating eclampsia.
Step 1: Risk Assessment & Prophylaxis (The Booking Visit)
Prevention is better than cure. The UKMLA expects you to identify women at risk of pre-eclampsia at their booking visit (8-10 weeks) and prescribe prophylaxis.
The “Aspirin List”
NICE recommends Aspirin 75-150mg daily from 12 weeks until birth if the woman has:
ONE High-Risk Factor:
Hypertensive disease in a previous pregnancy.
Chronic Kidney Disease (CKD).
Autoimmune disease (e.g., SLE, Antiphospholipid syndrome).
Type 1 or Type 2 Diabetes.
Chronic Hypertension.
OR TWO Moderate-Risk Factors:
First pregnancy (Primiparity).
Age 40 years or older.
Pregnancy interval of more than 10 years.
Body Mass Index (BMI) of 35 kg/m² or more at booking.
Family history of pre-eclampsia.
Multiple pregnancy (Twins/Triplets).
Exam Tip: A common AKT trap involves a 38-year-old (not quite 40) with a BMI of 32 (not quite 35) in her first pregnancy. Count the factors carefully. (First pregnancy = 1 factor. Needs one more to qualify).
Step 2: Diagnosis & Classification
Hypertension in pregnancy is not a single entity. You must classify it correctly to decide on the appropriate pre-eclampsia management strategy
The Three Main Categories
Chronic Hypertension:
Hypertension present before 20 weeks gestation.
OR Hypertension present before pregnancy.
Gestational Hypertension:
New hypertension presenting after 20 weeks.
NO significant proteinuria.
NO features of pre-eclampsia.
Pre-eclampsia:
New hypertension (>140/90 mmHg) presenting after 20 weeks.
AND coexistence of one or more of the following:
Renal: Significant proteinuria (PCR ≥30 mg/mmol or ACR ≥8 mg/mmol). See Mastering the Urine Dipstick for interpreting results.
Haematological: Thrombocytopenia (Platelets <100).
Hepatic: Raised liver enzymes (ALT/AST >70).
Neurological: Visual disturbances (flashing lights), severe headache, clonus.
Step 3: Monitoring & Thresholds
Once diagnosed, the intensity of pre-eclampsia management depends on the blood pressure readings.
Mild to Moderate Hypertension (140/90 – 159/109 mmHg)
Admission: Admit if there are concerns about adherence or fetal wellbeing.
Monitoring: BP at least 4 times a day.
Treatment: Start oral Labetalol (first line) to keep BP <135/85 mmHg.
Fetal Surveillance: Ultrasound for fetal growth and amniotic fluid volume (pre-eclampsia causes placental insufficiency/IUGR) and Umbilical Artery Doppler.
Severe Hypertension (≥160/110 mmHg)
Status: This is a Medical Emergency.
Admission: Admit immediately (usually to Delivery Suite or HDU).
Action: BP must be lowered to prevent intracerebral haemorrhage (stroke).
Step 4: Acute Management of Severe Pre-eclampsia
When a patient presents with severe hypertension or symptoms (headache, epigastric pain), you must act fast.
1. Antihypertensive Therapy
The goal is a gradual reduction in BP (avoid precipitous drops which compromise fetal perfusion).
First Line: Labetalol (Oral or IV).
Caution: Contraindicated in Asthma. See Prescribing Safely for the UKMLA for alternatives.
Second Line: Nifedipine (Modified Release).
Note: Do not use sublingual Nifedipine (causes rapid hypotension).
Third Line: Methyldopa.
Note: Too slow for acute emergencies; better for maintenance.
2. Fluid Restriction
This is critical. Pre-eclampsia causes “leaky capillaries.” If you overload these patients with IV fluids, the fluid leaks into the lungs, causing Pulmonary Oedema (a common cause of maternal death).
Protocol: Restrict total fluids to 80 ml/hour (including drug infusions).
3. Steroids
If the gestation is <34 weeks, give Antenatal Corticosteroids (e.g., Dexamethasone) to mature the fetal lungs in preparation for potential preterm delivery.
Step 5: Eclampsia & Magnesium Sulfate
Eclampsia is defined as the occurrence of seizures (convulsions) in association with pre-eclampsia.
Prophylaxis vs. Treatment
Magnesium Sulfate is used in two scenarios:
Treatment: To stop active seizures in Eclampsia.
Prophylaxis: To prevent seizures in women with Severe Pre-eclampsia who have symptoms of neurological irritability (hyperreflexia, clonus, severe headache).
The Magnesium Sulfate Regime
Loading Dose: 4g IV given over 5–10 minutes.
Maintenance Dose: 1g/hour IV infusion for 24 hours.
Monitoring for Toxicity
Magnesium has a narrow therapeutic index. You must monitor specific signs hourly. If toxicity occurs, respiratory arrest can follow.
| Parameter | Warning Sign (Toxicity) | Action |
|---|---|---|
| Respiratory Rate | < 12 breaths/minute | Stop infusion immediately. Give Oxygen. Prepare Antidote. |
| Tendon Reflexes | Loss of deep tendon reflexes (Patellar reflex) | Stop infusion. This is usually the first sign of toxicity. |
| Urine Output | < 30 ml/hour (Oliguria) | Magnesium is renally excreted. If urine stops, Magnesium levels spike. Stop infusion. |
The Antidote: Calcium Gluconate (10ml of 10% solution IV).
For more on assessing consciousness and airway during seizures, refer to our guides on Mastering the GCS and Unconscious Patient Management.
Delivery: The Ultimate Cure
The only definitive cure for pre-eclampsia is the delivery of the placenta.
<34 weeks: Aim to prolong pregnancy safely to allow steroids to work, unless there is severe maternal or fetal compromise.
34–36 weeks: Discuss planned delivery with the senior team.
≥37 weeks: Initiate delivery (Induction of Labour or Caesarean Section).
Mode of Delivery: Vaginal delivery is generally preferred unless there is an obstetric indication for C-section (e.g., breech, placenta praevia) or acute fetal distress.
Postnatal Care
The risk does not end at birth. Eclampsia can occur in the postnatal period.
Monitoring: Check BP regularly (at least 4 times a day while an inpatient).
Medication:
Avoid Methyldopa postnatally (increased risk of depression).
First Line: Enalapril (safe in breastfeeding, check renal function).
Alternative: Nifedipine or Amlodipine.
Discharge: Do not discharge until BP is controlled. Community Midwife to check BP.
Clinical Scenarios: Putting it into Practice
Scenario 1: The Headache at 38 Weeks
Patient: 38 weeks pregnant. Complains of “the worst headache of her life” (frontal) and “flashing lights” in vision. BP is 165/110. Urine Dipstick 3+ Protein. Diagnosis: Severe Pre-eclampsia with neurological involvement (Imminent Eclampsia). Action:
Call for Help (Obstetric Emergency).
Airway/Breathing: Ensure safety.
Drugs: Start IV Labetalol (BP control) and IV Magnesium Sulfate (Seizure prophylaxis).
Plan: Urgent delivery (likely C-section due to severity) once stabilised.
Scenario 2: The Asthmatic Patient
Patient: 34 weeks. BP 155/100. Diagnosis of Pre-eclampsia. She has severe asthma and uses inhalers daily. Management:
Labetalol is Contraindicated (non-selective beta-blocker can trigger bronchospasm).
Action: Prescribe Nifedipine (modified release) as the first-line antihypertensive.
For a broader overview of obstetric conditions, see Obstetrics & Gynaecology Essentials for UKMLA.
Practice Exercise: Test Your Knowledge
Question 1: A 30-year-old woman attends her booking scan at 10 weeks. It is her first pregnancy. Her BMI is 36. Her mother had pre-eclampsia. What is the appropriate management regarding pre-eclampsia prophylaxis?
A) No prophylaxis needed.
B) Aspirin 75mg daily from 12 weeks.
C) Aspirin 75mg daily from 20 weeks.
D) Labetalol 100mg bd immediately.
E) Vitamin C and E supplements.
Correct Answer: B. She has TWO moderate risk factors: First pregnancy + BMI >35. (Family history is also a moderate factor, so she actually has three). She qualifies for Aspirin from 12 weeks.
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Question 2: A woman with severe pre-eclampsia is on a Magnesium Sulfate infusion. The nurse reports her respiratory rate has dropped to 8 breaths/minute. What is the first pharmacological intervention?
A) IV Labetalol.
B) IV Fluid bolus 500ml.
C) IV Calcium Gluconate.
D) IV Diazepam.
E) IM Adrenaline.
Correct Answer: C. This is Magnesium Toxicity (respiratory depression). The antidote is Calcium Gluconate.
Frequently Asked Questions (FAQ) about Pre-eclampsia Management
HELLP stands for Haemolysis, Elevated Liver enzymes, and Low Platelets. It is a severe variant of pre-eclampsia. Patients often present with epigastric pain (liver capsule distension). It requires urgent senior management and usually prompt delivery.
Hyperreflexia (brisk reflexes) and clonus (rhythmic beating of the foot when dorsiflexed) are signs of “cortical irritability.” They suggest the brain is swelling or irritated, indicating a high risk of an impending eclamptic seizure.
No. ACE inhibitors (e.g., Ramipril, Enalapril) are teratogenic in the second and third trimesters (associated with fetal renal failure and oligohydramnios). They are generally avoided in pregnancy but are safe and effective in the postnatal period for breastfeeding mothers.
Patients often describe “flashing lights” (photopsia), blurred vision, or sometimes temporary loss of vision (cortical blindness). This is due to cerebral oedema affecting the occipital lobe.
NICE guidelines recommend continuing Aspirin from 12 weeks until the birth of the baby. Some local guidelines may stop it at 36 weeks to reduce bleeding risk, but “until birth” is the standard NICE answer.
Oedema (swelling) of the feet and ankles is very common in normal pregnancy and is no longer part of the diagnostic criteria for pre-eclampsia. However, rapid onset swelling of the face and hands, or sudden significant weight gain, can be a red flag.
On a urine dipstick, “3+” indicates a high concentration of protein. While dipsticks are good for screening, the diagnosis should ideally be confirmed with a PCR (Protein:Creatinine Ratio). A PCR >30 mg/mmol confirms significant proteinuria.
Rarely, yes. Seizures can occur with only mild hypertension or sometimes before the BP spikes, though this is atypical. However, in the vast majority of cases, severe hypertension precedes the seizure.
If a woman had pre-eclampsia in a previous pregnancy, she is high risk (approx. 16% risk) for developing it again. If she had severe early-onset pre-eclampsia (<34 weeks), the risk is even higher (up to 25-50%). This is why she automatically qualifies for Aspirin.
Use the RCOG Patient Information approach: “It is a condition involving the placenta that raises your blood pressure. It can put strain on your kidneys and liver. The only way to cure it completely is to deliver the baby, but we can use medicines to keep you safe until the baby is ready.”
Conclusion
Pre-eclampsia management requires a cool head and adherence to protocol. Whether you are prescribing Aspirin in the clinic or managing an airway in the emergency room, the principles remain the same: Identify Risk, Control Blood Pressure, Prevent Seizures.
Your Next Steps
Check the BNF: Review the doses for Labetalol and Nifedipine in pregnancy.
Practice the Regimes: Write out the Magnesium Sulfate loading and maintenance doses from memory.
Review ABGs: Ensure you can spot metabolic acidosis, which can occur in severe cases (see Interpreting an ABG).
