rupture of the capsule of the spleen, an organ in the upper left part of the abdomen, is a potential catastrophe that requires immediate medical and surgical attention. Splenic rupture permits large amounts of blood to leak into the abdominal cavity which is severely painful.and life-threatening. Shock and, ultimately, death can result. Patients typically require an urgent operation. Rupture of a normal spleen can be caused by trauma, for example, in an accident. If an individual's spleen is enlarged, as is frequent in mononucleosis, most physicians will not allow activities (such as major contact sports) where injury to the abdomen could be catastrophic.