Surgical problems are a risk in typhoid fever, most commonly perforation of the small intestine or bleeding. Perforation occurs in around 2% of cases but has a higher incidence in parts of Africa. It typically involves a single ulcer perforating the terminal ileum in the third week of illness. Diagnosis involves signs of peritonitis. Management may involve conservative treatment if the patient's general condition is poor or surgery to repair the perforation. Bleeding occurs in 10-20% of cases in the third week and usually responds to conservative management without surgery. Other less common surgical risks include complications affecting the hepatobiliary system, pancreas, spleen, genitourinary system or bones.