The outcome of pregnancy in Kell alloimmunisation

Objective To assess management and outcome of pregnancies with anti-Kell in the West Midlands in the UK over 13 years. Design A retrospective review of casenotes. Setting A regional referral clinic for red cell alloimmune disease and fetal medicine unit at a university hospital. Population Sixty-five pregnancies were identified in 52 Kell-sensitised women with Kell positive partners from the records of the Birmingham Blood Transfusion Centre. Methods Information from the casenotes was entered on a database and comparisons were made using the SPSS for Windows statistics package. Main outcome measures Mode of sensitisation, degree of fetal or neonatal anaemia, need for transfusion, gestation at delivery, birthweight and pregnancy outcome. Results Alloimmunisation was transfusion-related in 29 pregnancies and pregnancy-induced in 33. The cause could not be identified in three cases. There were 22 proven Kell positive fetuses, of which 18 were affected, in which alloimmunisation was pregnancy-related in 12 cases and transfusion-related in five. Antibody titres and amniotic fluid OD450 were not helpful in management. Severe or very severe disease occurred in 50% of the affected pregnancies (9/18). There was no difference in pregnancy outcome between transfusion or pregnancy induced sensitisation. Conclusions Anti-Kell alloimmunisation is an uncommon cause of serious anaemia in a significant proportion of affected pregnancies. There appears to be no difference between that caused by pregnancy or transfusion. Estimation of fetal haemoglobin concentration by cordocentesis is recommended, as antibody titres and amniocentesis are not helpful.