Poster Presentation - SOMANZ ASM Society of Obstetric Medicine of Australia and New Zealand ASM 2023

Could the sFlt-1/PLGF ratio have added benefit in the Detection and Management of Small for Gestational Age and Fetal Growth Restriction? A prospective blinded observational study. (#51)

Ruth Hughes 1 2 , Joanna Gullam 1 3 , Ian Phillips 4
  1. Department of Obstetrics and Gynaecology, University of Otago, Christchurch, New Zealand
  2. Obstetrics and Gynecology , Waitaha Canterbury, Christchurch Women's HospitalTe Whatu Ora, Medical doctor: Specialist, New Zealand
  3. Obstetrics and Gynecology , Waitaha Canterbury, Christchurch Women's HospitalTe Whatu Ora, Medical doctor: Specialist, New Zealand
  4. Chemical Pathology, Canterbury Health Laboratories, Christchurch, New Zealand

Background: Placental growth factor (PlGF) and the soluble FMS-like tyrosine kinase 1 (sFlt-1)/PlGF ratio are markers of placental insufficiency.  These tests have prognostic utility in suspected preeclampsia and there is mounting evidence of their prognostic utility in pregnancies complicated by isolated suspected fetal growth restriction (FGR) and small for gestational age (SGA). 

Aims: To investigate the value of sflt-1/PLGF in suspected FGR and SGA, in a NZ population, in predicting perinatal outcome and the association with placental histological findings.

Materials and Methods: This is a subgroup analysis of a prospective cohort study of singleton pregnancies at 20+0-36+6 weeks gestation with suspected preeclampsia as defined by Society of Obstetric Medicine Australia and NZ (SOMANZ) criteria.  The subgroup of pregnancies with isolated suspected SGA or FGR (NZ criteria) at recruitment were eligible. The sFlt-1/PLGF ratio was measured at recruitment and at intervals until birth, clinicians and investigators were blinded to the results.

Results: At the time of consent, 76 had isolated suspected FGR or SGA. A sFlt-1/PLGF  >38 at recruitment was associated with worse perinatal outcome compared with a normal sFlt-1/PLGF: preterm birth <32 weeks 28.6% v 1.8% p<0.001, emergency caesarean section 66.7% vs 10.9% p<0.001, mean (IQR) customised birth weight centile 0.8 (0.3-2.7) vs 8.3 (1.75-15.85) p 0.004, admission to neonatal intensive care 81.0% vs 14.5% p <0.001.  Preeclampsia subsequently developed in 47.5% of those with suspected SGA or FGR and an elevated sFlt-1/PLGF. Placental histology was assessed in 14 of 27 pregnancies with an elevated sFlt-1/PLGF, the most common finding was maternal vascular malperfusion (MVM) and / or a small placenta with infarcts.  Nine pregnancies with normal sFlt-1/PLGF had placental histology, inflammation being the most common finding, non had MVM.

Conclusions:  An elevated sFlt-1/PLGF ratio in pregnancies with suspected FGR or SGA occurred most commonly in those with MVM and/or a small placenta with infarcts, and was associated with a high rate of adverse perinatal outcome. sFlt-1/PLGF is a further tool to help distinguish between a fetus that is growth restricted from placental insufficieny from a constitutionally small fetus.