The spleen in sickle cell anaemia during early childhood
In a study of the natural history of homozygous sickle cell (SS) disease 154 of 160 Jamaican children in whom SS genotype had been diagnosed by cord blood haemoglobin electrophoresis were followed to age 1 to 5 years. Seventeen girls and five boys died. Severe bacterial infections and acute splenic sequestration (ASS) were the principal causes of death. The incidence of each of these complications of SS disease was studied in relation to the natural history of splenomegaly and of splenic reticuloendothelial function. Splenomegaly was assessed by physical examination at each clinic visit. 37% SS children had had palpable spleens by age 6 months, 66% by age 12 months, 79% by age 24 months and 85% by age 36 months. Splenic reticuloendothelial function was assessed by estimating the percentage of pitted blood cells (pit count) using differential interference contrast microscopy. Pit counts in 139 control children with normal haeomoglobin genotype AA were always below 9%. Pit counts performed serially in 130 of the SS children (in 46 from birth) rose with age, and were greater than 9% in 23 SS children at age 1 year, 42% at age 2 years and 52% at age 3 years. Radioactive colloid spleen scans showed no splenic uptake of colloid in 11 SS children with palpable spleens and pit counts greater than 9%, confirming impairment of their splenic reticuloendothelial activity.