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I have gone through your reports (attachment removed to protect patient identity). This level 2 anomaly scan is absolutely normal for the foetus pertaining to its growth and absence of any congenital anomalies.
The concern regarding the low lying placenta at 18-19 weeks of gestation is not alarming as by 32 -36 weeks the placenta tends to go up once the lower segment formation takes place over uterus. Low lying or placenta previa shall be considered then at 32-36 weeks if the distance is less than 25 mm from internal os.
High resistance flow in left uterine artery alone indicates a possible compression or hindrance in blood supply. There may be a subserosal fibroid or enlarged ovary probably which can cause external compression , but it is unlikely to affect the baby's growth as the other arterial flow is normal. At present this just needs to be followed up by a repeat uterine artery doppler after a month to check the same or increase in resistance flow.
Revert back to an obstetrician and gynaecologist online after a month --> https://www.icliniq.com/ask-a-doctor-online/obstetrician-and-gynaecologist