Abdominal pain is the most common symptom of adult intussusception, and the variability of the clinical manifestations makes diagnosis difficult. The most common cause of adult intussusception is a potential secondary lesion, which are tumors, followed by inflammatory lesions. adult intussusception can occur anywhere in the digestive tract, most commonly in the ileocolus, followed by the small intestine. CT provides a comprehensive observation and assessment of the intestinal obstruction in adult intussusception. Surgical resection of intestinal lesions is the main treatment for adult intussusception, and laparoscopic surgery for adult intussusception is a safe and feasible treatment for experienced physicians.
Briggs et al. reported that adult intussusception patients are more common in males (male: female ratio 2.9:1) with an average onset age of 40 years . The current data showed that there were more females than males, the ratio of males to females was 0.7(1:1.4), and P > 0.05 indicated no statistical significance. However, the average age of adult intussusception in the current study was 57.50 ± 15.88 years, indicating that adult intussusception might not be related to the gender of patients. Presently, the pathogenesis of intussusception is not clear, and the pathological changes and inflammatory stimulation in the intestinal lumen could alter intestinal luminal peristalsis. The abnormal changes in the intestinal wall are usually the starting point of intussusception, moving to the adjacent segment of the intestinal wall peristalsis, resulting in intussusception . Although gastrointestinal, ileocolonic, and colonic intussusception also occurs, the small intestine type intussusception accounts for the majority of the adult patients . In the current study, the ileocolonic type is the most common, followed by the small intestine type, which was similar to the report by Goh et al. . In addition to the classification based on location in the intestine, intussusception can also be classified by etiology or root cause: idiopathic, benign, or malignant . In the current study, tumors accounted for 62.7% (32/51), malignant for 39.2% (20/51), and benign for 23.5% (12/51). About 25.5% (13/51) of lesions were due to inflammatory diseases of the intestine. It can be seen that the most common intussusception of adult intussusception is the ileocolonic type, and benign or malignant tumors are the most common causes of adult intussusception. The clinical manifestations of adult intussusception vary and are usually occult and intermittent rather than acute . Symptoms include abdominal pain, bloating, nausea and vomiting, changes in bowel habits, and bleeding in the lower gastrointestinal tract. Abdominal pain is considered the most common symptom, occurring in 70–100% of patients . When tumors cause intussusception, symptoms include weight loss, black stools, or a palpable abdominal mass . In this study, abdominal pain was the most common symptom. The symptoms of intussusception are largely nonspecific and periodic, which makes the diagnosis difficult. Typically, adult intussusception is only detected during exploratory surgery. Some studies reported that the preoperative diagnosis rate was < 50% .
The abdominal plain film shows dilated bowel loops and fluid-gas planes, similar to the features of intestinal obstruction, but often fails to identify the cause of the obstruction. Plain abdominal films are useful when an obstruction is suspected . In the current study, plain abdominal films were used in 15 patients, which could not be identified as adult intussusception and had specific limitations. On abdominal ultrasonography, intussusception showed a concentric circle sign and target ring syndrome, which is useful in evaluating the intussusception in adults presenting a palpable abdominal mass, with a > 90% accuracy rate . However, the main disadvantages of ultrasound are that it relies on the operator and is difficult to interpret in the presence of air, which often occurs in the case of intestinal obstruction and has some limitations. Furthermore, 15 patients were examined by abdominal ultrasound, with a diagnostic rate of 53.5%. On the other hand, a colonoscopy may be a useful diagnostic tool for patients with subacute or chronic intermittent ileus [ 17]. It is the most useful method for adult intussusception involving the colon, terminal ileum, and cecum that confirms intussusception, location, and biopsy with respect to the diagnosis and the planning of surgery [18, 19]. In this study, 7 patients with adult intussusception (confirmed mass) underwent colonoscopy, while the procedure should be avoided in patients with acute obstruction as it may increase the risk of perforation . The CT findings of intussusception were target sign, concentric circle sign, and pseudorenal sign (Fig. 1). CT displays the length and diameter of intussusception, the three-dimensional view of the intestine and surrounding organs, the starting point, type, and position of intussusception, mesenteric vascular system, the possibility of strangulation, and the possibility of partial or complete intestinal obstruction . Currently, CT is the most sensitive scan for diagnosing intussusception in adults, with a diagnostic accuracy of 58–100% . In addition, CT can determine the most appropriate treatment method and avoid unnecessary surgery . In the current study, 27 patients underwent abdominal ultrasound, with a diagnostic rate of 92.2%. CT scan can determine the severity of adult intussusception and the best treatment, thereby providing strong evidence for the diagnosis of intussusception. Also, colonoscopy is recommended to supplement the treatment of colic intussusception.
Currently, surgical treatment is the primary treatment for most adult intussusception patients . However, the optimal surgical approach remains controversial because the main reason for the original recommendation of whole intussusception resection was the theoretical risk of venous embolization of tumor cells during intestinal canal operation and the risk of penetrating the ischemic, fragile, and edematous intestinal canal, which might lead to the implantation of tumor cells and microorganisms into the peritoneal cavity [18, 25]. In recent years, due to the progress of laparoscopic equipment and surgical technology, as well as its advantages of rapid recovery, less pain, and minimal scarring , laparoscopic surgery for adult intussusception is being increasingly performed and has been reported to be feasible for adult intussusception . Laparoscopic exploration is effective for the diagnosis of adult intussusception, avoiding unnecessary incisions. However, there is no consensus on the safety and effectiveness of laparoscopic surgery for adult intussusception. Tartaglia et al.  reported that laparoscopic surgery for adult intussusception is a safe and feasible treatment, especially when the preoperative diagnosis is unclear . In the current study, we did not find any significant differences in the duration of surgery and the incidence of postoperative complications between the laparoscopic and open groups (P > 0.05). Postoperative incision infection was the most common postoperative complication in the open group. The laparoscopic group had fewer complications than the open group. Siow et al.  showed that segmentectomy for intussusception in adults cannot be removed because most of the lesions may have pathological causes, and conservative treatment may be ineffective. Our experience indicated that surgery is the predominant treatment for intussusception in adults. In some cases, laparoscopy is a useful adjunct to open surgical techniques . Although laparotomy or laparoscopic enterectomy is the ideal method, patients using laparoscopic techniques have no postoperative complications, leading us to put forth that laparoscopy-assisted surgery is safer and more effective than open surgery. Finally, our study showed that surgery, including the whole resection of the intussusception segment, remains the primary treatment for adult intussusception. For experienced physicians, laparoscopic techniques are the preferred treatment for adult intussusception. However, we recommend caution to patients with acute obstruction of flatulence, as the visibility of flatulence may be poor and intestinal manipulation may further increase the risk of perforation and the incidence of surgery . The current study was a retrospective design with a small sample size, and hence there was the possibility of selection and recommendation bias.