Kell sensitization in pregnancy.

Maternal anti-Kell antibody was found in 127 of 127,076 pregnancies during a 16-year period (0.1%). Thirteen Kell-sensitized pregnancies ended with a Kell-positive newborn infant, five of these had a poor perinatal outcome (hydrops, intrauterine or neonatal death, hemoglobin less than 7.9 gm, congestive heart failure). Mothers with Kell-positive infants and poor outcome had anti-Kell titers greater than or equal to 1:128 at delivery. With a maternal anti-Kell titer less than 1:32 at delivery, only one baby was Kell positive and mildly affected by hemolytic disease. Spectrophotometric analysis of amniotic fluid (delta optical density at 450 nm) in three of four pregnancies with poor perinatal outcomes revealed values of delta optical density at 450 nm in the high midzone of Liley within 1 week of delivery. Therefore, Kell-sensitized patients have to be managed differently from patients with rhesus sensitization. A management scheme to optimize perinatal outcome in Kell-sensitized pregnancy is described on the basis of this largest reported series of Kell-sensitized pregnancies.