Abstract
The mainstay of management of an Rh isoimmunized pregnancy is the early identification
of fetal anemia. Ultrasound middle cerebral artery-peak systolic velocity (MCA-PSV)
Doppler measurements are very useful to diagnose severe disease, to time delivery/serial
intrauterine transfusions, and eliminate need of amniocentesis/cordocentesis. Fetal
blood sampling is done if the fetus is hydropic or MCA-PSV is >1.5 MoM. Blood is kept
ready for transfusion if fetal anemia is detected (hematocrit <30 %). Intravascular
transfusion is preferred, especially in hydropic fetuses. Rarely, intraperitoneal
transfusion is performed in certain situations when the approach to cord is difficult—posterior
placenta, obesity, and very early gestation. Blood is absorbed through the lymphatics.
Ultrasound and color Doppler is done for fetal heart activity, placental site, cord
insertion, and accessible site. The needle path is mapped and decision is taken on
where to enter the cord—cord insertion/free loop/intrahepatic portion site. A 20 gauge
long needle is inserted under continuous ultrasound guidance into the umbilical vein,
2–3 mL blood aspirated for hemoglobin, packed cell volume, and blood group. Necessary
volume of packed O-ve, irradiated red blood cell (hematocrit of 75–80 %) is then transfused.
Fetal monitoring is done by serial ultrasound for anemia, MCA-PSV to time next transfusion,
and fetal wellbeing—daily kick counts, ultrasound, and electronic biophysical profile.
Neonatal management is by intensive fetal anemia and jaundice monitoring, use of intravenous
immunoglobulin, exchange transfusion, and phototherapy. The improvement in outcome
of Rh immunized fetuses is primarily due to improved expertise, better ultrasound
machines, intrauterine blood transfusion, and improved neonatal care. From July 1997
to September 2015, there were 1022 transfusions performed in one Unit at AIIMS, with
an overall successful outcome of 90–94 %. Fetal survival is low if hydropic or with
first transfusion at 20 weeks or less. Care during the procedure will help to further
improve safety. In conclusion, treatment of fetal anemia in Rh isoimmunization by
ultrasound-guided fetal blood transfusions is relatively safe in experienced hands,
permits a near-term delivery in majority of cases of this potentially life-threatening
fetal disease.
Keywords
Rh isoimmunization - Ultrasound - MCA-PSV - Intrauterine transfusion
