Hypertensive disorders in pregnancy

HYPERTENSIVE DISORDERS IN PREGNANCY

DESCRIPTION

Hypertension in pregnancy, pre-eclampsia and eclampsia may have very serious and fatal consequences for both the mother and the baby.

Hypertension is defined by:

  • A systolic BP ≥ 140 and/or a diastolic BP ≥ 90 mmHg measured on 2 occasions 4 hours apart.

OR

  • A systolic BP ≥ 160 and/or a diastolic BP ≥ 110 mmHg measured on a single occasion.
    (Always measure BP in the left lateral, and not supine position).

Hypertensive disorders of pregnancy can be classified as:

  • Chronic hypertension:
    • Hypertension diagnosed before pregnancy or < 20 weeks of pregnancy.
  • Gestational hypertension:
    • Hypertension without proteinuria, diagnosed ≥ 20 weeks of pregnancy.
  • Pre-eclampsia:
    • Hypertension with proteinuria, diagnosed ≥ 20 weeks of pregnancy (high risk patients include: nulliparity, obesity, multiple pregnancy, chronic hypertension, kidney disease, diabetes, pre-eclampsia in a previous pregnancy, advanced maternal age or adolescent pregnancy).
  • Eclampsia:
    • Generalised tonic-clonic seizures in women with pre-eclampsia.
  • Chronic kidney disease:
    • Proteinuria with/without hypertension, diagnosed at < 20 weeks of pregnancy.

LEVELS OF SEVERITY OF HYPERTENSION

Level of hypertension BP Level mmHg BP Level mmHg BP Level mmHg
Systolic Diastolic
mild 140-149 or 90-99
moderate 150-159 or 100-109
severe ≥160 or ≥110

REFERRAL

  • Chronic hypertension.
  • Severe gestational hypertension.
  • Pre-eclampsia (all levels of severity).
  • Chronic kidney disease.

CHRONIC HYPERTENSION

O10.0

Stop ACE-inhibitors when pregnancy is planned or as soon as pregnancy is diagnosed, change to methyldopa and refer for assessment and management.

MEDICINE TREATMENT

  • Methyldopa, oral, 250 mg 8 hourly.
    • Maximum dose: 750 mg 8hourly.

REFERRAL

Urgent

All cases.

LoEIII

GESTATIONAL HYPERTENSION: MILD TO MODERATE

O13

DESCRIPTION

Hypertension occurring for the first time at ≥ 20 'weeks' gestation with no proteinuria.

GENERAL MEASURES

  • May be managed without admission before 38 'weeks' gestation, provided no proteinuria.
  • Review the following on a weekly basis:
    • BP
    • height of fundus
    • weight
    • fetal heart rate and movements
    • urine analysis
  • Educate on signs requiring urgent follow-up (headache, epigastric pain, visual disturbances, vaginal bleeding etc.).

MEDICINE TREATMENT

  • Methyldopa, oral, 250 mg 8 hourly
    • Titrate to a maximum dose: 750 mg 8 hourly.
    • When using iron together with methyldopa, ensure that iron and methyldopa are not taken concurrently.

LoEIII [22]

REFERRAL

  • All patients with gestational hypertension at 38 weeks for delivery
  • Pre-eclampsia (all levels of severity)
  • Poor control of hypertension.
  • Severe hypertension.

GESTATIONAL HYPERTENSION: SEVERE

O13

DESCRIPTION

A systolic BP ≥ 160 and/or a diastolic BP ≥ 110 mmHg, with no proteinuria.
(Always measure BP in the left lateral and not supine position).

MEDICINE TREATMENT

Aim to reduce BP to 140/100 mmHg.

  • Nifedipine, oral, 10 mg (not sublingual) as a single dose.
    • May be repeated after 30 minutes if diastolic BP remains ≥ 110 mmHg.

REFERRAL

Urgent

All cases.

PRE-ECLAMPSIA

O11/O14.0-2/O14.9

DESCRIPTION

  • A systolic BP ≥ 140 and/or diastolic BP ≥ 90 mmHg with proteinuria, after 20 weeks of pregnancy (significant proteinuria defined as ≥ 1+ proteinuria).
  • Severe pre-eclampsia is acute severe hypertension (systolic BP ≥ 160 and/or diastolic BP ≥ 110) with ≥ 1+ proteinuria, or any level of hypertension with 3+ proteinuria.
  • Imminent eclampsia is pre-eclampsia with severe persistent headache, visual disturbances, epigastric pain (not discomfort), hyper-reflexia or clonus.
  • The following indicate a higher risk of developing pre-eclampsia: nulliparity, obesity, multiple pregnancy, chronic hypertension, kidney disease, diabetes, pre-eclampsia in a previous pregnancy, advanced maternal age or adolescent pregnancy.

GENERAL MEASURES

  • Advise all pregnant patients to urgently visit the clinic if severe persistent headache, visual disturbances, epigastric pain (not discomfort).
  • If severe pre-eclampsia or imminent eclampsia:
    • Insert a Foley’s catheter and monitor urine output hourly.
    • Monitor BP and check reflexes every 30 minutes.

MEDICINE TREATMENT

Prevention of pre-eclampsia

From confirmation of pregnancy:

  • Calcium carbonate, oral 12 hourly (equivalent to 1 g elemental calcium daily).
    • Although the benefit is greatest in high-risk women, consider use of this agent in all pregnant women.
    • Calcium reduces iron absorption from the gastro-intestinal tract. Take supplements 4 hours apart from each other

LoEI [23]

Treatment

If severe pre-eclampsia or imminent eclampsia:

  • Magnesium sulfate, IV, 4 g as a loading dose diluted with 200 mL sodium chloride 0.9% and infused over 20 minutes.

AND

  • Magnesium sulfate, IM, 10 g given as 5 g in each buttock
    • Then IM, 5 g every 4 hours in alternate buttocks.

CAUTION: USE OF MAGNESIUM SULPHATE
Stop magnesium sulphate if knee reflexes become absent or if urine output <100 mL/4 hours or respiratory rate <16 breaths/minute.

If respiratory depression occurs:

  • Calcium gluconate 10%, IV, 10 mL given slowly at a rate not > 5 mL/minute.

AND

If systolic BP ≥ 160 and/or a diastolic BP ≥ 110 mmHg:

  • Nifedipine, oral, 10 mg (not sublingual) as a single dose.
    • May be repeated after 30 minutes if diastolic BP remains ≥ 110 mmHg.

LoEIII [24]

REFERRAL

Urgent

Severe pre-eclampsia and imminent eclampsia

Non urgent

All women with pre-eclampsia (within 24 hours).

ECLAMPSIA

O15.0-2/O15.9

GENERAL MEASURES

  • Stabilise prior to urgent referral.
  • Ensure safe airway.
  • Place patient in left lateral position.
  • Insert a Foley’s catheter and monitor urine output hourly.
  • Monitor BP and check reflexes every 30 minutes.

MEDICINE TREATMENT

  • Administer oxygen.
  • Magnesium sulfate, IV, 4 g as a loading dose diluted with 200 mL sodium chloride 0.9% and infused over 20 minutes.

AND

  • Magnesium sulfate, IM, 10 g given as 5 g in each buttock
    • Then IM, 5 g every 4 hours in alternate buttocks.

CAUTION: USE OF MAGNESIUM SULPHATE
Stop magnesium sulphate if knee reflexes become absent or if urine output <100 mL/4 hours or respiratory rate <16 breaths/minute.

If respiratory depression occurs:

  • Calcium gluconate 10%, IV, 10 mL given slowly at a rate not > 5 mL/minute.
    LoEIII [25]

If recurrent eclamptic seizures despite magnesium sulphate loading dose administration:

  • Magnesium sulfate, IV, 2 g over 10 minutes.

LoEIII [26]

If seizures still persist and are continuous, there may be another cause of the seizures: treat as for status epilepticus (see Seizures and status epilepticus ).

AND

If systolic BP ≥ 160 and/or a diastolic BP ≥ 110 mmHg and patient becomes alert:

  • Nifedipine, oral, 10 mg (not sublingual) as a single dose.
    • May be repeated after 30 minutes if diastolic BP remains ≥ 110 mmHg.

LoEIII

REFERRAL

Urgent

All cases.