Adult intussusception may present with a variety of acute, intermittent, or chronic symptoms, thus making its preoperative diagnosis difficult. The classic triad of intussusception consisting of abdominal pain, palpable sausage-shaped mass, and heme-positive stools is rarely present. The majority of studies confirm that computerized tomography (CT) is the most accurate diagnostic tool for preoperative diagnosis of intussusception. As Figure 1 shows, the CT findings characteristic of intussusception include the appearance of a bowel-within-bowel configuration with or without fat and mesenteric vessels incorporated. Pseudo-kidney or sausage appearance on longitudinal sections and target or bulls eye sign on transverse sections are other reliable radiological indicators of intussusception.
Between 70% and 90% of cases of intussusception requiring surgery have a specific identifiable ‘lead point’ such as a benign or malignant neoplasm . Secondary intussusception is caused by organic lesions, such as inflammatory bowel disease, postoperative adhesions, Meckel’s diverticulum, benign and malignant lesions, metastatic neoplasms or even iatrogenically, due to the presence of intestinal tubes . Recent studies using CT and magnetic resonance imaging scans have shown that small bowel intussusception can occur without a demonstrable pathological cause . Transient intussusception is more common in the proximal small bowel where the peristaltic activity is normally greater .
Inflammatory fibroid polyp (also known as Vanek’s tumour) is an uncommon cause of adult intussusception. It is a rare, benign, solitary polypoid or sessile lesion which was first described by Vanek in 1949 as a “gastric submucosal granuloma with eosinophilia” . Although the term inflammatory fibroid polyp was introduced by Helvig and Renier  to indicate the non-neoplastic nature of this lesion, recent studies suggest that these lesions should be considered as PDGFRA-driven benign neoplasms indicating that the term inflammatory fibroid tumour may be more appropriate [8, 9]. It may develop in various parts of the gastro-intestinal tract but most commonly in the gastric antrum and the ileum. The majority of Vanek’s tumours are asymptomatic and discovered as incidental findings during endoscopy. Vanek’s tumours arising within the stomach produce symptoms of pyloric obstruction or anaemia while those within the small bowel may rarely present with obstruction or intussusception . Although radiological investigations are useful in identifying the intussusception, the definitive diagnosis of small bowel Vanek’s tumour requires histological confirmation following operative resection.
Using modern imaging techniques to evaluate patients with various abdominal symptoms, there has been a twofold increase in the incidence of recognized intussusceptions secondary to idiopathic and incidentally detected intussusception . Some authors suggest that intussusceptions that lack a pathologic cause of obstruction on CT are likely self-limiting and do not require operation . Although incidental intussusceptions have become much more common, the majority of adult intussusception cases are still associated with a pathologic lead point which, in many patients, is malignant.
It is important to differentiate between small bowel and colonic intussusception. Adult colonic intussusception is associated with primary carcinoma in 65–70% of cases, while adult small bowel intussusceptions are secondary to a primary malignancy in only 30–35% of cases [13, 14]. A common cause of benign intussusception is colonic polyps . Adverse prognostic factors associated with colonic polyps include overexpression of regenerating gene Iα, α-methylacyl-coenzyme A racemase and p16 [15, 16]. The benefit of reduction before resection is decreased length of resected bowel. In cases of malignancy, concern exists that a reduction manoeuvre may cause the underlying tumour to spread. Several recent large series of adult intussusception have advocated en bloc resection without initial reduction in order to remove an involved colonic segment because most large bowel intussusceptions are malignant whereas most small bowel intussusceptions are benign . The fundamental surgical consideration is to distinguish between benign and malignant lesions preoperatively. Pre-operative imaging in this case suggested that a lipoma was the cause of the jejunal intussusception and therefore a trial of laparoscopic reduction was initially performed.
Most surgeons accept that adult intussusception requires surgical intervention because of the large proportion of structural anomalies and the high incidence of associated malignancy. However, the extent and timing of bowel resection and the manipulation of the intussuscepted bowel segment during reduction remains controversial. When a preoperative diagnosis of a benign lesion is safely established, the surgeon may reduce the intussusception by milking it out in a distal to proximal direction. This may be carried out using laparoscopy in suitable cases. Reduction should not be attempted if there are signs of inflammation or ischemia of the bowel wall. Primary malignant neoplasms are more commonly found in colocolonic and ileocolic intussusceptions, and hence, resection is well-advised.
The optimal surgical management of adult small bowel intussusception varies between reduction and resection. Reduction can be attempted in small bowel intussusceptions provided that the segment involved is viable and malignancy is not suspected.