Sickle cell anaemia is one of the variants of disorders of haemoglobin synthesis inherited from both parents in an autosomal recessive fashion It is characterised by chronic anaemia and or hand foot syndrome in the first few years of life This anaemia is exacerbated during periods of rapid red blood cell destruction failure of the erythroid cell line in the bone marrow or in acute sequestration episodes Nigeria with a population of about 120 million is the most populous country in Africa 1 It has the largest concentration of patients with sickle cell anaemia in the whole world 2 The disorder is uniformly distributed among its various ethnic groups The prevalence of the carrier state Hb AS is about 25 3 4 About 2 of newborn babies suffer from sickle cell disease mainly Hb SS and SC diseases 5 In Eastern Nigeria where sickle cell haemoglobin SC disease is uncommon Kaine and Udeozo6 estimated that 30 000 Igbo preschool children suffer from sickle cell anaemia This enormous number is likely to place a burden on the health care delivery system that is not adequately equipped to deal with the problem Four major types of crises are recognised in sickle cell anaemia aplastic acute sequestration hyper haemolytic and vaso occlusive crises Hyper haemolytic crises are less commonly reported in literature from the temperate climates 7 9 This continues to be a major problem among patients with sickle cell anaemia in tropical Africa where the natural history of the disease is somewhat complicated with recurrent episodes of malarial infection 10 12 Apart from the vaso occlusive crises the first three listed above could lead to severe anaemia in patients with sickle cell anaemia In Nigeria the average haemoglobin concentration in patients with sickle cell anaemia is 72 g l 13 At the University of Nigeria Teaching Hospital Enugu such patients are not normally transfused until the haemoglobin concentration falls below 50 g l unless they also have features of circulatory collapse This level is considered to be severe anaemia The majority of these children are seen in the children s emergency room CHER in a moribund state and die before blood transfusion Sickle cell anaemia is therefore not only a major cause of morbidity but also of mortality among those affected with the problem This study was designed to identify 1 the commonest types of anaemic crises in those patients with sickle cell anaemia attending the paediatric sickle cell clinic of the University of Nigeria Teaching Hospital Enugu and 2 where possible the immediate precipitating factor s of anaemic crises in these patients METHODS The methodology for this study has been described elsewhere 14 This study was carried out at the University of Nigeria Teaching Hospital Enugu Eastern Nigeria Enugu lies in the equatorial rain forest belt and was the former capital of Eastern Nigeria The paediatric sickle cell clinic serves Enugu and its environs Before patients are accepted into the clinic their haemoglobin genotypes are confirmed with cellulose acetate haemoglobin electrophoreses and sickling tests to rule out undetected coexisting abnormal haemoglobins Their glucose 6 phosphate dehydrogenase G6 PD status is also determined On average patients are seen in the sickle cell clinic 4 6 times annually Those with acute medical problems are managed in the paediatric wards or the CHER During each clinic visit an interval history is obtained and a full physical examination performed noting the presence of pallor jaundice hepatomegaly and splenomegaly The liver was measured from the coastal margin along the mid clavicular line while the spleen was measured along its long axis of enlargement also from the mid clavicular line Blood is then drawn from a peripheral vein for FBC blood smears including thick and thin films for malaria parasites MCH MCV reticulocyte count and split bilirubin levels All the patients are routinely placed on folic acid 5 mg daily and the antimalarial drug pyrimethamine 12 5 25 mg weekly Patients are given enough of the drugs from the hospital pharmacy to last them until their next clinic appointment Definitions Steady state this is defined as that period when the patient with sickle cell anaemia is free of infection pain or other disease processes Aplastic crisis significant change in blood picture characterised by a precipitous fall in the haemoglobin level 20 g l beyond steady state level and reduced 1 or absent reticulocytes in the peripheral blood The total white blood cell or platelet counts may or may not be affected In addition there is no significant increase in the unconjugated fraction of serum bilirubin Acute sequestration crisis significant change in blood picture characterised by a precipitous fall in the haemoglobin level and accompanied by a rapidly enlarging spleen or liver greater than 2 cm from the steady state level and reticulocytosis above the steady state level for each individual patient Signs of acute circulatory insufficiency such tachypnoea tachycardia and hypotension may or may not be present Hyper haemolytic crisis significant change in blood picture characterised by a precipitous fall in the haemoglobin level associated with jaundice marked reticulocytosis and polychromasia on the blood smear increased unconjugated hyperbilirubinaemia and increased urobilinogen content in urine above the steady state level for each individual patient Inclusion criteria All paediatric patients 16 years with sickle cell anaemia Hb SS admitted to the paediatric wards or the children s emergency room of the University of Nigeria Teaching Hospital Enugu who met the criteria for anaemic crises All newly diagnosed paediatric patients 16 years with sickle cell anaemia Hb SS admitted to the children s emergency room or the paediatric wards of the University of Nigeria Teaching Hospital Enugu with severe anaemia haemoglobin 50 g l requiring blood transfusion All such patients were then followed up in the paediatric sickle cell clinic for a period not less than three months from date of diagnosis in order to establish their steady state parameters Exclusion criteria All newly diagnosed paediatric patients 16 years with sickle cell anaemia Hb SS admitted to the children s emergency room or the paediatric wards of the University of Nigeria Teaching Hospital Enugu with severe anaemia requiring blood transfusion but who were either lost to follow up or could not be followed up for periods greater than three months from the date of