PLGF Testing to diagnose suspected preterm preeclampsia at 20+0 to 36+6 weeks

NHS Borders clinical guidelines
NHS Borders

Scope

Hypertensive disorders of pregnancy affect 10-15% of the pregnant population. Pre-eclampsia affects 2.8% of women and birthing people, with 25% of cases in singleton pregnancies developing before 37 weeks gestation (Hurrell et al, 2024). Perinatal outcomes are poorest in this group, in part due to delay in accurate diagnosis.

Audience

Obstetrics/Gynaecology Staff, Midwives, and Laboratory Staff

PlGF and sFlt-1 Testing

 

Placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) are biochemical markers found in maternal plasma serum that can measure the health of the placenta, and can be used to diagnose suspected pre-eclampsia. sFlt-1/PlGF ratio testing offers a high diagnostic accuracy for predicting pre-eclampsia needing delivery and is now recommended by NICE (2023).

 

PlGF testing should be used to rule-out pre-eclampsia in women presenting with suspected pre-eclampsia between 20+0 and 36+6 weeks. The aim of the testing is to reduce over-diagnosis and unnecessary preterm delivery to optimise perinatal outcomes for mother and baby. It also has particular benefit in high risk groups, including women from African, Caribbean and Asian Backgrounds. Women presenting with new onset hypertension and significant proteinuria should be managed as having a diagnosis of pre-eclampsia, and PlGF testing not offered.

Criteria for use

All women attending with suspected pre-eclampsia should have the following initial tests performed/sent to lab:

  • Blood samples: FBC, LFTs, U&Es
  • Urinalysis: Dipstick midstream urine sample
  • Urine samples: Lab-verified urine PCR (protein: creatinine ratio) or ACR (albumin: creatinine ratio)

 

These tests should inform decision making on whether to offer sFlt-1/PlGF testing, using the below criteria. Lab-verified urine PCR or ACR values should be used when aiding diagnosis. If not available within 3 hours of sending, dipstick analysis values can be used.

Inclusion criteria

Women at 20+0 to 36+6 weeks gestation, presenting with one of the following:

  • New hypertension (>140/90mmHg) requiring treatment with slight proteinuria (PCR <30mg/mmol or ACR <8mg/mmol or ≤1+ on urinalysis)
  • Normal BP with new onset significant proteinuria (PCR >30mg/mmol or ACR >8mg/mmol or ≥2+ on urinalysis)
  • Worsening essential hypertension
  • Worsening proteinuria in pre-existing renal disease/diabetes
  • Suspected placental insufficiency (USS suggestive of SGA <10th centile or abnormal umbilical artery Doppler PI >95th centile or oligohydramnios)

Exclusion criteria

Women from 20+0 weeks presenting with hypertension (>140mmHg/90mmHg) and significant proteinuria (PCR >30mg/mmol or ACR >8mg/mmol or ≥2+ protein on urinalysis) should be managed as a confirmed diagnosis of pre-eclampsia and not offered sFlt-1/PlGF testing.

Guidance for sending sFlt-1/PlGF samples:

 

Taking the Sample

 

  • Discuss with Obstetric Consultant about appropriateness of PlGF testing.

 

Requesting the Order

 

  • Collect 1x serum gel tube (brown tube) sample, label with patient name & CHI;
  • Complete pink Blood Sciences request form with patient name, DOB, CHI & Sex, Consultant name, Labour Ward, date & time of sample, test requested = Placental Growth Factor & phone number of Labour Ward;
  • Phone Chemistry Lab, normal hours ext 26244, out of hours bleep 6244 to advise that you are sending a PlGF sample;
  • Deliver sample to Lab Reception without delay.

 

Please note:

 

PlGF samples from NHS Borders will be couriered to St John’s Hospital by the Laboratory team.The laboratory team within St. John’s will contact Labour Ward with result and will be available on NHS Lothian SCI store.

References

NICE diagnostics guidance DG49. PlGF-based testing to help diagnose suspected preterm pre-eclampsia (NICE, 2022). https://www.nice.org.uk/guidance/dg49/chapter/2-The-diagnostic-tests

NICE guideline NG 133. Hypertension in pregnancy – diagnosis and management (NICE, 2023). https://www.nice.org.uk/guidance/ng133

Hurrell et al, 2024. Repeat placental growth factor-based testing in women with suspected preterm pre-eclampsia (PARROT-2): a multicentre, parallel-group, superiority, randomised controlled. Lancet 2024; 403: 619-631. https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(23)02357-7.pdf

Appendix 1: Flow Chart

Presentation with suspected pre-eclampsia at 20+0 to 36+6 weeks

(with no immediate indication for delivery)

 

Presentation with suspected pre-eclampsia at 20+0 to 36+6 weeks

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Editorial Information

Next review date: 17/12/2028

Author(s): Darlow. K Guthrie. K.

Approved By: Women and Children’s Services Clinical Management Team

Reviewer name(s): Darlow. K Guthrie. K.

References
  • NICE diagnostics guidance DG49. PlGF-based testing to help diagnose suspected preterm pre-eclampsia (NICE, 2022). https://www.nice.org.uk/guidance/dg49/chapter/2-The-diagnostic-tests
  • NICE guideline NG 133. Hypertension in pregnancy – diagnosis and management (NICE, 2023). https://www.nice.org.uk/guidance/ng133
  • Hurrell et al, 2024. Repeat placental growth factor-based testing in women with suspected preterm pre-eclampsia (PARROT-2): a multicentre, parallel-group, superiority, randomised controlled. Lancet 2024; 403: 619-631. https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(23)02357-7.pdf