Abdominal pain, which comprises about 5 to 10 percent of emergency department (ED) visits, continues to pose diagnostic challenges for emergency physicians because of the wide range of differential diagnoses, including gastrointestinal, gynaecological, genitourinary and cardiopulmonary causes . Adult intussusceptions poses a further challenge as they often present with nonspecific symptoms and run a chronic indolent course until bowel ischaemia supervenes .
Intussusceptions occur when one segment of the gastrointestinal tract (intussusceptum) telescopes into the lumen of an adjacent distal segment of the gastrointestinal tract (intussuscipiens). Adult intussusceptions represent only about 5% of all intussusceptions  and thus a rare cause of hospital admissions, accounting for only 0.005% .
Intussusception remains a rare clinical entity in adults. The mean age is 54.4 years, and the male-to-female ratio is 1:1.3 . In adults, cases can be either acute or chronic, and abdominal pain is the most common symptom (71-100%), followed by nausea and vomiting in 40-60% of the cases. Bleeding per rectum was seen in 4-33% of the cases . This wide range is usually based on the site of the intussusception, with colonic ones bleeding more frequently than the ileal varieties. Acute abdominal pain with guarding is present in only about 50% of the cases . Abdominal masses are palpable in less than 10% of patients .
A classification system exists according to the location of the intussusception. The four types are ileo-colic, ileo-ileo-colic, colo-colic and small bowel intussusception (jejuno-jejunal and ileo-ileal) . In adults, often there is an underlying trigger or nidus for the intussusception in around 90-95% of the cases . The majority of lead points in the small intestine consist of benign lesions, such as benign neoplasms, Meckel's diverticuli, appendix and adhesions. Twenty-five percent of small bowel intussusceptions are caused by malignant lesions, whereas in the large bowel this number increases to around 50% .
Abdominal CT is the most useful diagnostic tool not only for detecting an intussusception with a diagnostic yield of around 78%, but also helps in identifying the underlying cause . The CT appearance of an intussusception is often a complex sausage-shaped soft tissue mass with an eccentric area of fat density contained within, which represents the mesenteric fat. The mesenteric vessels may be visible . Plain abdominal x-rays and ultrasound are of limited diagnostic value in adults.
Treatment is almost always surgical in adults when compared to children and invariably leads to resection of the involved bowel segment with subsequent primary anastomosis. Gastroduodenal and coloanal intussusceptions are extremely rare and may require innovative surgical techniques . Intermittent intussusceptions are known to occur and are often seen in either barium follow-through studies or on CT scans in patients with celiac disease, Crohn's disease, intestinal tumours and malabsorption syndromes as a result of abnormal intestinal contractions . These transient ones can be managed conservatively in the absence of any severe abdominal symptoms.
Although, intussusceptions themselves have a good prognosis, it is often the nature of the lesion causing the intussusception on which the decisive factor is expected. Mortality for adult intussusceptions increases from 8.7% for the benign lesions to 52.4% for the malignant variety . In our case, no clear nidus or trigger was identified on histological examination of the resected segment.