Clinical inquiries. Can we prevent splenic rupture for patients with infectious mononucleosis?

■ Evidence summary The annual incidence of infectious mononucleosis is somewhere between 345 and 671 cases per 100,000 in the US; it is highest in the adolescent age group. Splenic rupture is the leading cause of death in infectious mononucleosis, occurring in 0.1% to 0.2% of all cases. Based on this figure, approximately 100 cases of rupture may occur yearly in the US, only a few of which are reported. A retrospective analysis of 8116 patients with infectious mononucleosis at the Mayo Clinic estimated the risk of spontaneous splenic rupture to be 0.1% of cases, correlating with rates found in other studies. The study’s criteria for definite spontaneous rupture are: no recent trauma; recent symptoms; hematologic, serologic, and histologic (splenic) evidence of infectious mononucleosis. Five patients with rupture (average age, 22) were identified; 3 were male. Splenectomy was performed for all patients. Follow-up over 33-years found all patients healthy with minimal subsequent illness. A review of 55 cases found almost all splenic ruptures occurred between the fourth and twenty-first days of illness, and that all affected spleens were enlarged, although only half were palpable on exam. Ninety percent of the ruptures occurred in males, and more than half were nontraumatic. There was no correlation between severity of illness and suscepBrett H. Foreman, MD Carolina Family Practice and Sports Medicine, Cary, NC