Background to preeclampsia

Definition

Preeclampsia (PE) is a multisystem syndrome developing during the second half of pregnancy. It is characterised by hypertension and proteinuria or in the absence of proteinuria the finding of maternal organ dysfunction.

Hypertension is systolic blood pressure of ≥140 mm Hg and/or diastolic blood pressure of ≥90 mmHg on ≥2 occasions 4 hours apart developing after 20 weeks’ gestation in previously normotensive women.

Proteinuria is the presence of ≥300 mg of protein in a 24-hour collection of urine or urinary protein to creatinine ratio of ≥30 mg/mmol or two readings of at least ++ on dipstick analysis of a midstream or catheter urine specimen.

In PE superimposed on chronic hypertension (history of hypertension before conception or the presence of hypertension before 20 weeks’ gestation) proteinuria or maternal organ dysfunction should develop after 20 weeks’ gestation.

Tranquilli AL, Dekker G, Magee L, Roberts J, Sibai BM, Steyn W, Zeeman GG, Brown MA. The classification, diagnosis and management of the hypertensive disorders of pregnancy: A revised statement from the ISSHP. Pregnancy Hypertens 2014; 4: 97-104.

Maternal organ dysfunction is defined by new onset of any of the following:

Renal insufficiency – serum creatinine ≥90 μmol/L.
Hepatic dysfunction – high serum hepatic transaminase levels (≥2 times the upper limit of normal) and / or severe persistent upper abdominal pain unresponsive to medication.
Neurological complications - eclampsia, stroke, confusion, hyperreflexia accompanied by clonus, severe headache accompanied by hyperreflexia, blindness or persistent visual scotomata.
Hematological complications - platelet count <150,000/dL, disseminated intravascular coagulation (DIC) or hemolysis.