Splenic function in inflammatory bowel disease: assessment by differential interference microscopy and splenic ultrasound.

The role of the spleen in patients with ulcerative colitis and Crohn's disease was assessed by counting pitted erythrocytes with differential interference microscopy and by splenic ultrasound. The findings were compared with those from age- and sex-matched controls and a group of splenectomized patients. The incidence of hyposplenism was lower than previously reported, being found in six of 29 patients with ulcerative colitis (of whom five had relapsed pancolitis and one had quiescent pancolitis) and two of 21 patients with Crohn's disease. Pitted erythrocyte counts were significantly higher in patients with ulcerative colitis compared with age- and sex-matched controls (p < 0.001), but there was no difference in counts between patients with Crohn's disease and controls. Patients with relapsed but not quiescent ulcerative colitis had significantly smaller spleens than controls. Patients with the highest pitted erythrocyte counts had the smallest spleens on ultrasound. More effective medical and surgical therapy may account for the lower incidence of functional hyposplenism observed in this study. Nonetheless, patients may show marked hyposplenism and remain at risk of overwhelming infection and operative complications. Differential interference microscopy is a simple technique that can be used to assess splenic function in patients thought to be susceptible to infection.