In a G2P1, Rh negative mother with previous history of hydrops fetalis, now ICT is positive at 20 weeks. What is the next line of management?

Hydrops fetalis in the previous pregnancy and positive ICT now is suggestive of maternal isoimmunisation Now the next step is to quantify fetal anemia/ fetal hemolysis. This is best done by MCA PSV measurement on fetal doppler since it is very sensitive and non invasive. Methods for detection of fetal anemia are: MCA peak systolic velocity: very sensitive, non invasive Amniocentesis and bilirubin estimation: invasive Cordocentesis: most invasive technique , associated with fuher fetoplacental bleed, thrombosis, fetal bradycardia and IUD. Hence not preferred. Done in cases of: fetal hydrops Zone 3 on Liley's cha MCA PSV of >1.5 MoM Intrauterine Exchange transfusion: Done when fetal hematocrit on cordocentesis is < 30 %