Splenic septic emboli in endocarditis. The significance of septic emboli to the spleen is inferred by the frequency of septic emboli in general seen in patients with left-sided infective endocarditis who are referred for valve replacement. To determine the proper management of splenic infarcts and abscess due to septic emboli, we retrospectively reviewed the records of 108 patients with left-sided endocarditis who underwent valvular surgery at the University of Illinois Hospital from 1980 through 1988. Intravenous drug abuse was the etiology in 68% (n = 73). The incidence of splenic infarcts and abscess was 19% (n = 20), but an incidental finding of splenic infarcts was found in 38% (n = 11) of 29 asymptomatic patients who had computed tomograms. Streptococci and staphylococci were the causative organisms in 85% (n = 17). Localized findings were absent in 90% of splenic infarcts and abscesses. Abdominal computed tomograms were diagnostic of the sequelae of splenic septic emboli in 100%. No patient had intra-abdominal bleeding complications associated with cardiopulmonary bypass. Splenectomy was performed in 50% (n = 10) of patients 3-24 days (mean, 11.2 days) after valve replacement. Indications for splenectomy included persistent sepsis in 60% (n = 6), large (greater than 2 cm) and peripheral lesions in 30% (n = 3), and splenic rupture in 10% (n = 1). Perioperative mortality of patients who underwent splenectomy was 30% (n = 3). The following conclusions can be drawn: 1) Splenic septic embolus is common in endocarditis. 2) Abdominal computed tomography should be performed for all patients. 