Objective To document the prevalence, clinical features, haematology and outcome of acute splenic sequestration (ASS) in homozygous sickle cell disease (HbSS).

Study design A cohort study from birth.

Setting The Medical Research Council Laboratories at the University of the West Indies, Kingston, Jamaica.

Patients 311 cases of HbSS detected during the screening of 100 000 deliveries at the main government maternity hospital between 1973 and 1981.

Interventions Long-term follow-up and free patient care focusing on ASS.

Main outcome measure Acute splenic sequestration.

Results There were 183 episodes of ASS in 105 patients representing 35% of the cohort. The median age for first event was 1.07 years. During ASS, median values for haemoglobin fell by 32 g/dL, reticulocytes increased by 8% and total nucleated cells increased by 10.5%. ASS recurred in 47 (45%) patients. Conservative therapy in 133 episodes of 85 patients was associated with five deaths and splenectomy in 20 patients with 50 episodes had no deaths. Symptoms were generally non-specific but acute chest syndrome occurred in 17, and blood cultures revealed coagulase negative staphylococci in 5. The ASS case fatality rate was 3.6% and may be higher if autopsy evidence of ASS is included. There was no seasonal pattern but higher levels of fetal haemoglobin predicted patients less prone to ASS and its later occurrence.

Conclusions ASS remains an important cause of morbidity and mortality in HbSS in developing societies. ASS appears to be a non-specific response to many possible risk factors including coagulase negative staphylococci.