Acute appendicitis and retroperitoneal abscess: rare complications of sigmoid diverticulitis

Diverticulitis is a common cause of an acute surgical abdomen and computed tomography has become an essential part of work up particularly to identify complications that commonly include intraperitoneal perforation, abscess and fistula formation. We report the case of an 81-year-old male who presented to the emergency department with acute lower abdominal pain and was found to have sigmoid diverticulitis with the rare complications of a diverticular abscess that had formed a sinus tract and perforated into the retroperitoneum and secondary acute appendicitis. Initial management was with intravenous antibiotics, a Hartmann's procedure and appendicectomy. Subsequently the retroperitoneal collection was drained percutaneously. The case was further complicated by the patient's multiple co-morbidities and unfortunately the patient died 6 weeks after admission from sepsis. This case highlights the role of computed tomography in the pre- and post-operative period to identify complications which are often clinically occult and require early surgical and interventional radiology management to optimize outcomes.