Management of Hypertensive Disorders of Pregnancy

Antenatal visits

Prevention of pre-eclampsia

Hospital admission

Inpatient management of mild hypertension or pre-eclampsia

Controlling the blood pressure in pre-eclampsia

Indications for delivery of hypertensive women

Severe pre-eclampsia

Eclampsia

Imminent eclampsia

Giving magnesium sulphate

ANTENATAL VISITS 

Chronic and nonproteinuric hypertensives should attend 4 weekly up to 28 weeks, 2 weekly up to 36 weeks & weekly up to delivery. Women with pre-eclampsia must be admitted to hospital.

PREVENTION OF PRE-ECLAMPSIA

Give aspirin 100 mg orally daily from 12 weeks’ gestation to women with a history of previous pre-eclampsia.

HOSPITAL ADMISSION

Mandatory independent admission criteria for hypertensive patients

• Proteinuria ≥1+ on a midstream specimen
• Symptoms of imminent eclampsia
• Organ dysfunction e.g. thrombocytopenia, liver dysfunction, eclampsia
• Diastolic BP > 110 mmHg
• Systolic BP >160 mmHg
• Antepartum haemorrhage
• Pregnancy at ≥37 weeks

Admission procedure

1. Take blood for FBC & U&E
2. Order 4 hourly BP & daily urinalysis for protein
3. Order NST to be done in the ward if fetus is viable (≥26 weeks)
4. Order ultrasound with fetal weight estimation, with umbilical artery Doppler studies if gestation <34 weeks
5. Prescribe oral antihypertensive medication
6. If BP ≥160/110 mmHg, treat as for severe pre-eclampsia (see below)

INPATIENT MANAGEMENT OF MILD HYPERTENSION OR PRE-ECLAMPSIA

• Doctors' daily round - ask for symptoms of imminent eclampsia, fetal movements, check BP & urine chart, & adjust medication if needed
• Repeat U&E & FBC twice weekly
• Send urine for spot protein:creatinine ratio if urinalysis findings are equivocal
• Send urine for microscopy for casts, and for 24-hour protein estimation if renal disease is suspected
• Do NST on alternate days (if gestation ≥26 weeks)

Treat imminent eclampsia and severe pre-eclampsia as set out below

Discharging hypertensive pregnant patients from the antenatal ward

• The BP must be stable at <160/110 mmHg           
• There must be no proteinuria
• The pregnant woman & fetus must both be in generally good condition
• There must be no indication for delivery
• Ensure antihypertensive medication is prescribed
• A return date to antenatal clinic must be given
• A brief discharge summary must be written on the antenatal record

CONTROLLING THE BLOOD PRESSURE IN PRE-ECLAMPSIA

Emergency treatment (BP ≥160/110 mmHg)

• Admit to a high care area
• Preload with 300 mL Ringer-Lactate solution over 20 minutes
• Give nifedipine 10 mg orally as a single dose unless heart rate ≥120/min
• Consider adding magnesium sulphate
• Measure the BP every 30 minutes at first, then hourly
• Repeat nifedipine ½ hourly if necessary (BP still ≥160/110 mmHg)
• Aim for a BP of 140/90 mmHg
• Add maintenance treatment (below)

For unconscious or tachycardic patients, infuse labetalol 200 mg in 200 mL normal saline at 20 mL/hour (i.e. 20 mg/hour, increasing by 20 mg/hour every 30 minutes if necessary, to a maximum of 300 mg in 24 hours). Give 300 mL preload just before starting the infusion. A 20 mg starting bolus may be given.

Maintenance treatment (BP ≥150/100)

The drugs are usually prescribed in a stepwise fashion, depending on response.  Aim for a BP of 130-149/90-99 mmHg

• Step 1: Methyldopa 500 mg orally 12 hourly up to a maximum of 750 mg 8 hourly
• Step 2: Add amlodipine 5 mg daily, up to a maximum of 10 mg daily
• Step 3: Add hydralazine 10-50 mg orally 8 hourly 
• Step 4: Consider delivery 

For chronic hypertensive patients, discontinue beta-blockers, diuretics, & angiotensin converting enzyme inhibitors. Some chronic hypertensive women may not need any medication during pregnancy, because of the physiological fall in blood pressure

INDICATIONS FOR DELIVERY OF HYPERTENSIVE WOMEN

• Pregnancy at 37-40 weeks with gestational & essential hypertension
• Pregnancy ≥37 weeks with mild pre-eclampsia
• Pregnancy ≥34 weeks in severe pre-eclampsia
• Estimated fetal weight ≥1.5 kg in severe pre-eclampsia
• Pregnancy ≤24 weeks or fetus <600 g in severe pre-eclampsia
• Eclampsia
• Imminent eclampsia persisting after treatment with magnesium sulphate
• Cerebral oedema
• HELLP syndrome
• Renal dysfunction (serum urea >8 mmol/L, creatinine >100 µmol/L, urine output <500 mL/24 hours)
• Thrombocytopaenia (platelet count persistently <100´10⁹/L)
• Intrauterine growth restriction
• Fetal distress
• Dead fetus
• Abruptio placentae

SEVERE PRE-ECLAMPSIA

Initial management is as follows:

1. Arrange for transfer to a high care area
2. Start on Magnesium sulphate to prevent eclampsia
3. Insert a urinary catheter & monitor urine output hourly
4. Take blood for FBC, U&E, & AST. Do INR if there is thrombocytopaenia as caesarean section may need to be done
5. Assess gestational age & fetal weight by ultrasound, with umbilical artery Doppler studies at <32 weeks
6. If 24-33 weeks, give betamethasone 12 mg IMI stat, repeat after 12 hours
7. Do CTG if fetus is viable (≥26 weeks)
8. Treat the high BP
9. Arrange for delivery if indications exist & notify paediatricians if the baby is expected to weigh <1500 g.
10. If not for delivery, adjust oral antihypertensive medication
11. Discharge from high care area, remove IV lines & continue conservative management in the antenatal ward (below)
12. Always consider other causes of hypertension e.g. phaeochromocytoma

Exception:  Asymptomatic chronic hypertensive patients <20 weeks pregnant can be managed in the antenatal wards without IV lines and catheters.  

Conservative management of severe pre-eclampsia (24-33 weeks)

Following stabilisation of BP:

• Continue oral antihypertensive medication
• Twice weekly FBC, U&E, AST, more frequently if necessary
• 6 hourly NST if possible
• Ultrasound fetal assessment for liquor volume & umbilical artery Doppler studies every 2 weeks
• 4 hourly BP, & daily urinalysis for protein

HELLP syndrome

• Initial management is as for severe pre-eclampsia
• In women <34 weeks, plan for delivery within 24-48 hours to allow betamethasone to take effect
• Deliver as soon as possible if <26 weeks or ≥34 weeks
• If platelet count is <50 x 10⁹/L and caesarean section is planned, give platelet transfusion 1 megaunit at operation

ECLAMPSIA

Principles of care are control of convulsions, reduction of BP, clinical & laboratory assessment, & delivery

Immediate management of eclampsia

1. Call for help
2. Turn the woman onto her side (left lateral)
3. Clear the airway – ensure that it is open & remove secretions or vomitus
4. Give oxygen by mask
5. Prevent injuries, e.g. use cot sides, & remove sharp objects
6. Insert an oropharyngeal airway if necessary
7. Start an intravenous drip & give magnesium sulphate
8. With persistent convulsions or restlessness, give additional magnesium sulphate 2 g IV or clonazepam 1 mg IV over 5 minutes
9. Phenytoin has no role in the prevention or management of eclamptic convulsions
10. Insert a urinary catheter
11. Admit to a high care area

Management of eclampsia after fits have been controlled

1. Take blood for FBC, U&E, AST and INR
2. Treat the BP if ≥160/110 mmHg
3. Continue intravenous fluids (Ringer-Lactate or normal saline) at 70 mL/hour
4. Monitor BP, urine output & level of consciousness hourly
5. Monitor level of consciousness 2 hourly using GCS or AVPU
6. Intubate if GCS ≤8 or responding only to pain
7. Assess fetal condition with CTG, & fetal size by ultrasound
8. Continue magnesium sulphate infusion at 1 g/hour until 24 hours after delivery or 24 hours after the last convulsion, whichever is later, in a high care area
9. Deliver the baby as soon as possible (maximum 12 hours) after the first fit:
   1. By caesarean section if there is fetal distress or the cervix is unfavourable
   2. Vaginally if the woman is in labour or if the cervix is favourable for induction (soft, 2-3 cm dilated, fully or almost fully effaced)
10. Vacuum extraction or forceps delivery may be necessary in the second stage
11. Do not use ergometrine in the third stage (use oxytocin 10 units IM)
12. Expect return to full consciousness within two hours of the last fit
13. Investigate women with persistent coma or localising signs – call a neurologist to assess and arrange for a computerized tomography (CT) scan of the brain
14. Take blood for FBC & U&E on the day after delivery
15. Keep in hospital for at least 3 days after delivery

The Glasgow Coma Scale

IMMINENT ECLAMPSIA

1. Exclude other causes of headache or abdominal pain – abruptio placentae, simple headache, & send to a high care area. Give paracetamol 1 g orally
2. Insert an intravenous drip, give magnesium sulphate (below) & treat the hypertension if BP ≥150/100 mmHg
3. Insert a urinary catheter & monitor urine output hourly
4. Take blood for U&E, FBC
5. Run intravenous fluids at 70 mL/hour  
6. Do CTG
7. Reassess hourly. If imminent eclampsia persists, arrange for delivery

GIVING MAGNESIUM SULPHATE*

Loading dose

• Add magnesium sulphate 4 g to 200 mL normal saline & run the infusion rapidly.

Maintenance dosage

• Add magnesium sulphate 10 g to 200 mL normal saline & run the infusion at 20 mL/hour, equivalent to 1 g/hour.

Alternative regimen

• Dilute magnesium sulphate 4 g (8 mL) in 12 mL saline & give IV over 4 minutes, with 5 g IM in each buttock with 1 mL 1% lidocaine (total 14 g). Maintenance is 5 g IM 4 hourly, in alternate buttocks, with lidocaine.

Precautions during magnesium sulphate infusion

Maintenance doses should only be continued if the following hourly observations are made & confirmed:

• Presence of patellar reflexes,
• The respiratory rate is ≥12 breaths/minute, &
• Urine output is ≥100 mL in the last 4 hours 

Treatment of suspected overdose

• The symptoms & signs of overdose are a feeling of extreme weakness, decreased respiratory rate, & absent tendon reflexes
• Take blood for magnesium level
• Give 10% calcium gluconate 10 mL IV slowly, then observe closely

Blood magnesium levels

• Normal range 0.7-1.0 mmol/L, therapeutic at 1.25-3.25, absent reflexes at 4-5, respiratory depression at 6-8, cardiac arrest at >15 mmol/L