Intussusception remains a rare condition in adults, representing 1% to 3% of bowel obstructions, 1,2 and it is a different entity in adults than in children. In adults, a diagnosis of intussusception is often difficult and not often made before laparotomy. 1 A demonstrable etiology is found in 70% to 90% of cases in adult intussusceptions, and about 40% of them are caused by a primary or secondary malignant neoplasm. 2–8 Computed tomography (CT) scan is now widely used in the evaluation of abdominal masses and nonspecific abdominal pain and may be the first examination performed in a patient in whom an intussusception is present. The CT findings are sufficiently characteristic to warrant a confident diagnosis based on this radiologic appearance alone. 2,9–11
Most surgeons have limited experience with such clinical entities and with the various considerations involved in diagnosis and management. Although most authors agree that surgical resection is mandatory, the extent of resection and whether the intussusception should be reduced before resection is controversial. We report our experience in an attempt to clarify the usefulness of CT scan and the optimal treatment in adult intussusception.
PATIENTS AND METHODS
The records of all patients 18 years of age and older with a preoperative or intraoperative diagnosis of intussusception at Tone Chuo Hospital from 1991 to 2001 were reviewed retrospectively. Details concerning the presentation, diagnosis, management, and pathology were analyzed. Patients with intussusceptions caused by intestinal intubations, agonal intussusceptions, rectal or stomal prolapses, and jejunogastric intussusceptions after gastroenterostomies were excluded from this study.
Seven patients were identified who had a diagnosis of intussusception. The presenting clinical picture of these patients is shown in Table 1. The average age of the patients was 65.1 years, with a range of 22 to 92 years. Five were female and two were male. The majority of the patients presented with nonspecific symptoms and signs of bowel obstruction, including either nausea, vomiting, abdominal pain, or abdominal distension. All seven patients presented within 5 days after the onset of symptoms, but four had chronically recurrent abdominal complaints. Six patients showed signs of partial or complete intestinal obstruction.
The diagnosis was correctly made preoperatively in four of the seven patients. Computed tomography scan was used in four patients, and it made the diagnosis in all four patients (Fig. 1). Ultrasonography (US) was used in four patients, and it made the diagnosis in three patients (Fig. 2). The diagnosis of intussusception was made preoperatively in four patients by CT scan and/or US. In one of them, the correct diagnosis was made by CT scan and US preoperatively, but the intussusception resolved spontaneously before surgery. One patient underwent colonoscopy, but a correct diagnosis was not made. On plain abdominal radiographs of seven patients, air–fluid levels in dilated bowel loops were shown in five patients, and scant colonic gas was seen in five, but no soft mass was shown. None of them underwent a barium study.
Four patients had the lead point of the intussusception in the small bowel: two in the jejunum and the other two in the ileum. The two jejunal lead points resulted in jejunojejunal intussusception and the two ileal lead points resulted in ileoileal intussusception. Three patients had colonic lead points. The one cecal lead point resulted in ileocolic intussusception, and the two colonic lead points resulted both in one colocolic and one sigmoid-rectal intussusception. Six patients were antegrade intussusception and another one was retrograde.
A pathologic lesion was identified in five patients, and all pathologic lesions were the lead points. Malignant neoplasms accounted for three of seven patients. Inflammatory fibroid polyp, inverted Meckel's diverticulum, postoperative intussusception, and idiopathic intussusception accounted for one each of the others. In three malignant neoplasms, two were primary cecal or ascending colon cancer and one was primary jejunal cancer.
All seven patients underwent laparotomy, but intussusception improved without surgical intervention in only one. The type of procedure was determined by location, underlying cause, and viability of the involved bowel. Three of four patients with small bowel intussusception underwent reduction before resection. The other one underwent resection without reduction because of severe ischemic bowel. The mean resection of small bowel was 17.8 cm, with a range of 8.0 to 40.0 cm. Right hemicolectomies without reduction were performed in two patients with colonic cancer, and Hartmann's operation without reduction was performed in one patient with idiopathic sigmoid-rectal intussusception.
The clinical courses after surgery in all seven patients were uneventful. At last follow-up, there was no recurrence. Two patients with a malignancy were alive without evidence of disease 4 and 11 years after surgery. One patient with cecal cancer was still alive 2 years postoperatively, but had both lung and bone metastases.
Intussusception is common in the pediatric population but is quite uncommon in adults. 2–5,8 Because most cases will not be diagnosed before laparotomy, it is important for the surgeon to be informed with regard to the various diagnoses and treatment options available for this entity. The clinical findings are variable: acute intestinal obstruction is not common and most patients present with subacute, chronic, or intermittent symptoms in adults. 4 The classic clinical triad of conventional intussusception consisting of abdominal pain, a palpable sausage-shaped mass, and heme-positive stools is rarely present 2–4,7 and was not seen in any of our patients.
Although the correct diagnosis is often based on intraoperative findings, modern noninvasive and invasive imaging techniques can be very helpful in precisely identifying these lesions preoperatively. 2,3,5,9–20 AG is more invasive than CT scan and US. Barium studies are obviously contraindicated if there is the possibility of bowel perforation or ischemia. In this series, the CT scan proved to be the most useful, with US being the second most accurate. The CT scan has been used to evaluate patients with intestinal obstruction or an abdominal mass in whom intussusception is the final diagnosis. 2,3,7,9,10 The dense nature of the intussuscepted mass that is compromised of edematous bowel wall and mesentery within the lumen gives it a characteristic target sign or sausage-shaped appearance. 2,3,7,9,21 In our series, the CT scan was performed in four patients, and in all four patients, the diagnosis was confirmed. It therefore appears that the CT scan is very useful and simplifies making the diagnosis.
Ultrasonography has been used to evaluate suspected intussusception in both children and adults. 22 It is easy to perform, more reproducible, and less invasive than the other methods. 16 The classic features of intussusception include the “target” and “donut” signs in the transverse view and the “pseudokidney” sign in the longitudinal view. 23–25 The major limitation of US for evaluating acute abdomens is the presence of air in the bowel, which leads to poor transmission and difficulties in image interpretation. Sonographic examiners need enough clinical experience for them. In our series, US was performed in four patients; in three, the preoperative diagnosis was confirmed.
Colonoscopy is also a useful tool for evaluating intussusception, especially when the presenting symptoms indicate a large bowel obstruction. 26–28 In our series, colonoscopy was performed in only one patient, but we could not make the correct diagnosis.
In about 90% of adult intussusceptions, there is a lead point, which is a well-definable pathologic abnormality. 4 The malignancy (either primary or metastatic) of small bowel intussusception accounts for 14% to 47% of cases. On the other hand, that of large bowel intussusception accounts for 43% to 80%. 2–5,7,8 In our series, two of three patients with large bowel intussusception and one of four patients with small bowel intussusception had a malignancy.
The optimal treatment of adult intussusception is not universally agreed upon. All authors agree that laparotomy is mandatory, in view of the likelihood of identifying a pathologic lesion. Weilbacher et al. 4 established the principle of resection without reduction whenever possible. This was based on a high incidence of underlying malignancy that could not be confirmed either preoperatively or intraoperatively. Recently, several reports have recommended a selective approach to resection. Eisen et al. 7 have reported that colonic lesions should not be reduced before resection because they most likely represent a primary adenocarcinoma. They have also reported that small bowel intussusception should be reduced only in patients in whom a benign diagnosis has been made preoperatively or in patients in whom resection may result in short gut syndrome. Azar et al. 2 have reported that formal bowel resection with the associated lymphovascular mesocolon should be performed for all colonic intussusceptions. In cases in which the bowel is inflamed, ischemic, or friable, it is advisable not to attempt operative reduction but to proceed directly with resection. The danger in reduction of externally vital bowel with mucosal necrosis, intraluminal seeding, or venous embolization of malignant cells has been pointed out. 4,8 In most cases of ileocolic, ileocecocolic, and colocolic intussusception, primary resection without reduction should be performed, especially in patients more than 60 years of age because of the high incidence of malignancy. 5,8,29 In patients with small bowel intussusception, reduction should always be initially attempted unless signs of bowel ischemia or inflammation are present or a malignancy is not suspected. 3 Benign enteric lesions that are not associated with adhesions and benign colonic lesions require resection to prevent recurrent intussusception.
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