ANALYSIS OF MANAGEMENT OF RAISED PULSATILITY INDEX (PI) IN PREGNANCY

Problem statement
Following raised pulsatility index (PI)> 95th centile, pregnant women must undergo serial investigations and monitoring to reduce the rate of stillbirth and perinatal morbidity. While detecting raised PI in pregnancy plays an important role in identifying perinatal outcome in fetus with intrauterine growth restriction, this implementation has increased the burden of ultrasound resources and the patients’ enormous efforts to visit the healthcare service for review.

Methods
This is a retrospective analysis of 21 patients with raised PI in pregnancy at St Mary’s Hospital from 1st August 2020 to 9th July 2021. This study has included pregnant women with raised PI (>95th centile) at any gestation who have no or multiple risk factors of fetal growth restriction (FGR) with presence of end-diastolic flow in the umbilical artery of the fetus.

Results
94.1% patients with first raised PI had repeat Doppler scan within one week unless delivery is appropriate. Of these patients, over half of the patients (64.7%) had normal PI on repeat Doppler scan. Furthermore, 85.0% patients with raised PI had their growth scans within 2 weeks unless delivery is indicated.
While raised PI is associated with FGR, our study illustrates 73.3% patients with raised PI delivered normal birthweight infants. None of the patients with infants with static growth <20g/day from 34 weeks delivered small-for-gestational-age (SGA) neonates. Despite this, it picked up 4 SGA neonates in this audit. It is not surprising to observe half of the patients who delivered SGA infants had normal PI finding on repeat Doppler scan because most PI readings are normal in the context of late-onset FGR.

Conclusions
1) Frequency of repeat PI could be reduced in patients with raised PI and a review on different reference charts for umbilical artery PI to classify abnormal PI could be considered to allow more recommendations for the management of raised PI.
2) This audit highlights the need for further audits on the role of different Doppler scans in late-onset FGR.
3) Implementing a tool for calculating interval growth and estimated fetal weight (EFW) could be considered to improve adherence to local guidelines.