On November 16, 2009, Lesnar underwent surgery for his condition. The
surgeon had said that fecal matter was leaking into the abdominal cavity of Lesnar. This leakage was causing abscesses to develop, and it also forced Lesnar's immune system to work overtime. The anti-bodies of Lesnar's immune system were attacking the fecal matter as if it were a virus. The anti-bodies were not able to remove the fecal matter, and continued to attack it. Lesnar had become very susceptible to other illnesses and infection because his immune system was focused exclusively on his abdominal cavity. Surgeons went in, and closed up the perforations in his intestine that were leaking the fecal matter. This would not be the last surgery Lesnar would need for this condition.
In May of 2011, diverticulitis struck Lesnar again. Surgery was done once more, and Lesnar had a foot of his colon removed.