Most instances of splenic rupture due to infectious mononucleosis occur during the first 3 weeks of illness.

The information provided in this handout does not necessarily reflect the views of the University of Minnesota Medical School physicians and faculty. These materials are provided for informational purposes only and are in no way intended to take the place of the advice and recommendations of your personal health care provider. You use the information provided in these handouts at your own risk.No study provides high level of evidence on this subject; therefore, clinical judgment is still essential. Splenic enlargement is common in infectious mononucleosis (IM), but rupture is an uncommon sequelae. A systematic review of case reports/ series demonstrates a majority of splenic ruptures occurring in the first 3 weeks. In an afebrile patient with resolving symptoms, return to “non-contact” activity is appropriate at that time. Level of exertion should be guided by patient’s energy. Return to “contact” activity should have a delay of at least 3 weeks. Physical exam cannot accurately detect splenomegaly. Imaging with serial U/S to monitor changing spleen size may be considered in a patient with early resolution of IM symptoms who is considering early return to activity