SPLEEN SIZING BY ULTRASOUND IN POLYCYTHEMIA AND THROMBOCYTHEMIA - COMPARISON WITH SPECT

Detection of non-palpable early splenic enlargement may aid diagnosis of primary polycythaemia (PP) and primary thrombocythaemia (PT). In th is study linear spleen sizing by ultrasound has been compared with spl een volume estimation by single photon emission computerized tomograph y (SPECT) in 26 patients, Spleen length by ultrasound correlated well with SPECT volume estimation. Ultrasound spleen length was also measur ed in 60 normal control subjects where the upper limit of the 95% refe rence range was 11.6 cm. Changes in spleen length with both age and bo dy weight were substantial and overshadowed the imperfect reproducibil ity of this method. Therefore, interpretation of an individual's measu red spleen length should be in relation to that predicted for adults o f the same age and weight, particularly at the extremes of the younger , heavier patients and also the older, lighter patients. Ultrasound sp leen lengths of different patient groups (21 PP, 26 PT. 17 idiopathic erythrocytosis, 12 secondary polycythaemia, nine apparent polycythaemi a) were compared both using the measured overall reference range and t he differences from the values predicted for their age and weight. The comparison showed that almost all patients with PP whose spleens were not palpable had spleen lengths greater than the upper limit for the normal control group, but separation from the other patient groups was incomplete. Detection of non-palpable splenomegaly by ultrasound leng th should remain a 'minor' criterion amongst the 'proposed modified di agnostic criteria' of PP.