diagnosis and screening for pre-eclampsia

Last edited 08/2019

NICE have defined pre-eclampsia as (1):

• new onset of hypertension (over 140 mmHg systolic or over 90 mmHg diastolic) after 20 weeks of pregnancy and the coexistence of 1 or more of the following new-onset conditions:
  
  
  • proteinuria (urine protein:creatinine ratio of 30mg/mmol or more or albumin:creatinine ratio of 8mg/mmol or more, or at least 1 g/litre [2+] on dipstick testing) or
    
    
  • other maternal organ dysfunction:
    • renal insufficiency (creatinine 90 micromol/litre or more, 1.02 mg/100 ml or more)
    • liver involvement (elevated transaminases [alanine aminotransferase or aspartate aminotransferase over 40 IU/litre] with or without right upper quadrant or epigastric abdominal pain)
    • neurological complications such as eclampsia, altered mental status, blindness, stroke, clonus, severe headaches or persistent visual scotomata
    • haematological complications such as thrombocytopenia (platelet count below 150,000/microlitre), disseminated intravascular coagulation or haemolysis
      
      
  • uteroplacental dysfunction such as fetal growth restriction, abnormal umbilical artery doppler waveform analysis, or stillbirth

Severe pre-eclampsia

• pre-eclampsia with severe hypertension that does not respond to treatment or is associated with ongoing or recurring severe headaches, visual scotomata, nausea or vomiting, epigastric pain, oliguria and severe hypertension, as well as progressive deterioration in laboratory blood tests such as rising creatinine or liver transaminases or falling platelet count, or failure of fetal growth or abnormal doppler findings

Assessing pre-eclampsia:

Assessment of women with pre-eclampsia should be performed by a healthcare professional trained in the management of hypertensive disorders of pregnancy

Carry out a full clinical assessment at each antenatal appointment for women with pre-eclampsia, and offer admission to hospital for surveillance and any interventions needed if there are concerns for the wellbeing of the woman or baby. Concerns could include any of the following:

• sustained systolic blood pressure of 160 mmHg or higher
  
  
• any maternal biochemical or haematological investigations that cause concern, for example, a new and persistent:
  • rise in creatinine (90micromol/litre or more, 1mg/100ml or more) or
  • rise in alanine transaminase (over 70 IU/litre, or twice upper limit of normal range) or
  • fall in platelet count (under 150,000/microlitre)
    
    
• signs of impending eclampsia - convulsive condition associated with pre-eclampsia
  
  
• signs of impending pulmonary oedema
  
  
• other signs of severe pre-eclampsia
  
  
• pre-eclampsia with severe hypertension that does not respond to treatment or is associated with ongoing or recurring severe headaches, visual scotomata, nausea or vomiting, epigastric pain, oliguria and severe hypertension, as well as progressive deterioration in laboratory blood tests such as rising creatinine or liver transaminases or falling platelet count, or failure of fetal growth or abnormal doppler findings
  
  
• suspected fetal compromise
  
  
• any other clinical signs that cause concern

Consider using either the fullPIERS or PREP-S validated risk prediction models to help guide decisions about the most appropriate place of care (such as the need for in utero transfer) and thresholds for intervention

When using a risk prediction model, take into account that:

• fullPIERS is intended for use at any time during pregnancy
• PREP-S is intended for use only up to 34 weeks of pregnancy
• fullPIERS and PREP-S models do not predict outcomes for babies

NICE suggest a methodology for blood pressure measurement in pregnancy (2)

• remove tight clothing, ensure arm is relaxed and supported at heart level
• use cuff of appropriate size
• inflate cuff to 20-30 mmHg above palpated systolic blood pressure
• lower column slowly, by 2 mmHg per second or per beat
• read blood pressure to the nearest 2 mmHg
• measure diastolic blood pressure as disappearance of sounds (phase V).

Reference:

• NICE (June 2019). Hypertension in pregnancy - the management of hypertensive disorders during pregnancy
• NICE (March 2016). Antenatal care for uncomplicated pregnancies