20th June 2026

Diagnosis and investigations

Diagnosis is based on the presence of the following after 20 weeks’ gestation:

Hypertension: SBP ≥ 140 mmHg and/or a DBP ≥ 90 mmHg on 2 occasions at least 4 hours apart
Proteinuria: ≥ 30 mg/mmol on PCR or ≥ 0.3g/24 hours or ≥ 1+ on a urine dipstick

After diagnosing pre-eclampsia, further testing should be performed, including foetal assessment for complications and maternal testing for systemic involvement. A summary of the investigations can be found in Table 1.

Table 8. Investigations for pre-eclampsia

Investigation	Notes
Blood pressure	At each antenatal visit
Urine dipstick for proteinuria	At each antenatal visit NICE recommends not routinely testing for 24-hour urine collection to quantify proteinuria in pregnancy. Alternative spot tests should be used, e.g. PCR
FBC	Anaemia can exacerbate hypertension Thrombocytopaenia is a potential complication of pre-eclampsia
LFTs	Hepatic dysfunction is a potential complication of pre-eclampsia Elevated liver enzymes may prompt further investigations
Renal function tests	Renal impairment is a potential complication of pre-eclampsia
Coagulation studies	Coagulopathy is a potential complication of pre-eclampsia
Serum uric acid	May be elevated in pre-eclampsia
Serum calcium	May be decreased in pre-eclampsia
Assessment of fetal well-being	Fetal movements CTG US examination of amniotic fluid volume and fetal growth, which can only be fully assessed by scans performed 2 weeks apart Umbilical artery doppler US on admission. If normal, repeat twice weekly. If abnormal, more intensive monitoring may be needed, e.g. Doppler assessment of other fetal vessels
Other	ECG for cardiac abnormalities CXR for pulmonary oedema Cranial imaging for cerebral haemorrhage or infarction Measurement of placental growth factor (PIGF): may reduce the delay in diagnosing pre-eclampsia Elecsys immunoassay sFIt-1/PIGF ratio as an alternative to PIGF-only testing

PCR, protein: creatinine ratio; PIGF, placental growth factor

Severity classification of pre-eclampsia:

Hypertension: BP of 140/90 – 159/109 mmHg
Severe hypertension: BP of ≥ 160/110 mmHg

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