Left uterine PI is low in Anomaly scan.

Uterine artery doppler(PI and RI) in simple terms is a surrogate marker to determine the quality of the placental blood flow to the growing foetus. If the PI is increased significantly more than it indicates decreased flow to the foetus and that there might be possibility of foetal growth restriction. This may be associated with hypertension in mother as well. However, there are other markers as well to measure along with Uterine artery PI to confirm the same which are not available in the question. Basically, we need to monitor the PI to look out for any worsening and use other USG markers to confirm any growth restriction. Regarding queries on medication and in depth explanation of the same, your Obstetrician with experience in foetal medicine would be the best guide.

Review with Obstetrician with foetal medicine experience.