Ultrasonographic surveillance in red blood cell alloimmunization

OBJECTIVE: This study was undertaken to audit ultrasonographic measurements of fetal liver length and middle cerebral artery peak velocity in cases of red blood cell alloimmunization between 1986 and 1999. STUDY DESIGN: A total of 200 fetuses at risk for anemia because of red bloo d cell alloimmunization underwent ultrasonographic measurement of the lengt h of the right lobe of the liver, 45 underwent Doppler recording of middle cerebral artery peak velocity, and 119 underwent fetal blood sampling. RESULTS: The overall survival was 188 of 200 (94%). Among 69 fetuses found to have anemia, liver length values in 64 (93%) were at the 95th percentile or greater, and the other 5 were in the upper part of the normal range. Th e middle cerebral artery peak velocity was greater than or equal to 95th pe rcentile in 15 of the 19 cases of anemia in which this value was measured ( 79%). Among those measured within 1 week of birth, all liver lengths were a t least in the upper part of the normal range, with most greater than or eq ual to 95th percentile, including 1 case with a cord blood hemoglobin conce ntration <90 g/L. CONCLUSIONS: All fetuses with anemia identified at fetal blood sampling had enlarged livers with 93% at <greater than or equal to>95th percentile. The peak velocity in the middle cerebral artery was abnormal in most fetuses w ith anemia.