15th July 2024

Characterisation and diagnosis

Pre-eclampsia is a hypertensive disorder of pregnancy. It is defined as a new diagnosis of hypertension (systolic >= 140mmHg/diastolic >= 90mmHg) after 20 weeks of pregnancy, with organ dysfunction, manifested as one of:

• Proteinuria – detected via dipstick and confirmed by albumin: creatinine ratio above 8 mg/mmol or protein: creatinine creatinine ratio above 30 mg/mmol
• Maternal organ dysfunction
• Renal insufficiency – new rise in creatinine
• Hepatic impairment – increased liver transaminases
• Neurological complications – signs elicited on examination and the progression to eclampsia with seizures
• Uteroplacental dysfunction – foetal hypoxia, growth restriction, premature labour, placental abruption or in-utero demise caused by oxidative stress

For women with known CKD, diagnosing pre-eclampsia is more complicated.

• In cases where there is pre-existing non-proteinuric CKD, superimposed pre-eclampsia should be should be suspected after 20 weeks if new hypertension develops (systolic >= 140mmHg/diastolic >= 90mmHg) with new proteinuria or other evidence of maternal organ dysfunction.
• For women with CKD who have either pre-existing hypertension and/or proteinuria, there is no increase in either of these that are diagnostic for pre-eclampsia.
• However, women with chronic hypertension and proteinuria that develop severe, sustained hypertension (systolic >= 160mmHg/diastolic >= 1100mmHg) should be investigated for superimposed pre-eclampsia.
• Women with pre-eclampsia and CKD are at increased risk of pulmonary oedema peripartum.

Most cases of pre-eclampsia are based on the above clinical diagnostics. Increasingly, biomarkers also play a role in diagnosis. The National Institute for Health Care and Excellence (NICE) recommends offering tests for placental growth factor (PIGF) in suspected PET between 20 to 35 weeks’ gestation.