Definitions
The guidelines recommend management of common obstetric conditions at primary and referral level, based on local experience and evidence-based practice. They are not intended as strict protocols nor as standard operating procedures, but rather as a guide to safe effective management of common obstetric problems. The guidelines should be most useful to interns, medical officers and registrars.
Hypertensive disorders of pregnancy are a frequent cause of maternal mortality in South Africa. Early detection & timely intervention are essential to prevent maternal & perinatal complications.
Measurement of blood pressure in pregnancy
Definition of hypertension
A systolic BP ≥140 mmHg or a diastolic BP ≥90 mmHg, on 2 occasions ≥4 hours apart, or a single BP ≥160/110 mmHg
Definition of proteinuria
The presence of ≥1+ proteinuria on reagent strip (dipstick) testing on 2 clean catch urine specimens taken ≥4 hours apart, or protein excretion ³300 mg in a 24 hour specimen of urine
Definitions of hypertensive disorders of pregnancy
ssential hypertension: hypertension without proteinuria, diagnosed before 20 weeks of pregnancy, or a history of essential hypertension prior to the pregnancy
Chronic renal disease: hypertension with proteinuria, diagnosed before 20 weeks of pregnancy, or a history of chronic renal disease prior to the pregnancy
Pre-eclampsia (gestational proteinuric hypertension, pre-eclamptic toxaemia): hypertension, detected after 20 weeks of pregnancy with any of the following:
- Proteinuria
- Renal insufficiency - serum creatinine ≥100 µmol/L
- Liver disease - AST or ALT >40 U/L
- Neurological problems – severe headache, hyperreflexia, convulsion
- Thrombocytopaenia <100 x 109/L or haemolysis
- Placental insufficiency – asymmetric IUGR
Gestational hypertension: hypertension without proteinuria or any features of pre-eclampsia, detected after 20 weeks of pregnancy
Unclassified hypertension: hypertension detected in a woman in whom the BP was not measured before 20 weeks of pregnancy. This may present as pre-eclampsia or as apparent gestational hypertension
Superimposed pre-eclampsia: pre-eclampsia that develops in a woman with chronic hypertension
GRADES OF PRE-ECLAMPSIA
Severe pre-eclampsia: pre-eclampsia, with a systolic BP ≥160 mmHg or a diastolic BP ≥110 mmHg measured on 2 occasions ≥4 hours apart, or a diastolic BP ≥120 mmHg, or organ dysfunction irrespective of the level of BP, e.g. renal dysfunction, raised liver enzymes or thrombocytopaenia
Mild pre-eclampsia: pre-eclampsia that is not severe
Imminent eclampsia: symptoms and signs that develop in a pre-eclamptic woman: severe headache, visual disturbances, epigastric pain, hyperreflexia, dizziness and fainting, vomiting
Eclampsia: generalized tonic-clonic seizures after 20 weeks of pregnancy and within 7 days after delivery, associated with hypertension and proteinuria, in the absence of other causes of convulsions
HELLP syndrome: the presence of Haemolysis, Elevated Liver enzymes and Low Platelets, almost always in association with hypertension and proteinuria
MEASUREMENT OF BLOOD PRESSURE IN PREGNANCY
- The right and left semi-lateral, and sitting positions are acceptable. The supine position (lying flat on the back) should not be used after 24 weeks
- The sphygmomanometer cuff must be at the level of the heart
- A “large adult” cuff must be used for an arm with a circumference ≥34 cm, and an “adult thigh” size cuff must be used for an arm circumference ≥44 cm
- The diastolic BP is taken at the point where the sounds disappear (Korotkoff phase 5). In women where the sounds do not disappear, the point of muffling (Korotkoff phase 4) is used.
- A mercury sphygmomanometer is preferred, because automated devices may under-record the BP in pregnant women