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A 78-year-old man presented to the casualty department, complaining of recurrent and worsening constipation for the previous 2 months. This was associated with central, colicky abdominal pain and melena. In the last days, the symptoms worsened and the patient became partially obstructed, with nausea, vomiting and passing flatus but not stools for 72 h. The past medical history was unremarkable. The radiological findings of the plain abdominal film were consistent with mechanical small-bowel obstruction. CT scan revealed an intraluminal mass in the small bowel, which drew attention away from gross thickening of the caecal wall that was also present. A careful review of the images should not be omitted. One must be aware of a polymorphous appearance and the multiple causes of intestinal obstruction and avoid underestimating even the minor and less evident radiological findings.
Abdominal pain is one of the most frequent complaints of patients presenting to the emergency department.
Abdominal pain is often the first symptom of bowel obstruction and may be associated with a varying degree of bowel distension.
The diagnostic approach to a patient with abdominal pain and/or bowel obstruction should include an erect chest x-ray, a plain abdominal film and a US scan when indicated.1 Further assessment usually includes a CT scan, possibly with double (intravenous and oral) or triple contrast (enema) to assess the degree and level of the obstruction and to identify the possible cause.
Intussusception might constitute a diagnostic pitfall, because it rarely occurs in adults (5% of all intussusceptions).2 Instead, intestinal intussusception in children is a well described and frequently reported entity.3
Many factors may result in suboptimal performance of abdominal CT or inaccurate interpretation of the images. Improper technique, observers’ errors and lack of clinical information are major contributors to misdiagnoses.4
A 78-year-old man presented to the casualty department complaining of recurrent and worsening constipation for the previous 2 months. This was associated with central, colicky abdominal pain and melena. In the last days, the symptoms worsened and the patient became partially obstructed, with nausea, vomiting and passing flatus but not stools for 72 h. His past medical history included hypertension and benign prostatic hypertrophy but no previous surgical procedures. On physical examination the abdomen was slightly distended, with mild tenderness in the middle quadrants and right flank. Digital rectal examination revealed normal stools.
The laboratory results showed a white-blood-cell count within the normal range and a mild anaemia (Hb 10.2 g/dl). The plain abdominal x-ray showed dilated small-bowel loops, with air-fluid levels (figure 1). Abdominal CT scan was ordered, and the findings are shown in figure 1. On abdominal CT scan, the radiologist identified multiple air-fluid levels with dilated jejunal and ileal loops; his attention was drawn to the right iliac fossa, to thickened bowel loops with fatty tissue within, consistent with intussusception (figure 2, right red arrow). Large bowel was described as collapsed.
The differential diagnosis based on the CT findings in this case may include a stricture in terminal ileitis from Crohn's disease; a small-bowel foreign body (Phytobezoar, thricobezoar, etc.); other causes of small bowel obstruction, such as malignant ileal masses, inflammatory pseudotumour or adhesions; and the actual diagnosis of concomitant ileal lipoma, intussusception and caecal colon cancer.
False-positive and false-negative cases may affect the accuracy of CT scan interpretation. Due to inadequate oral administration of contrast material, normal structures (eg, bowel) may remain unopacified and simulate tumours. Repeat scanning with additional contrast material and sodium bicarbonate, at selected levels, and perhaps with changes in patient position, often reveals the true nature of pseudotumours in the gastrointestinal tract. To achieve accurate CT images of the small-bowel loops, adequate oral contrast material must be administered, with sufficient time before the examination. Repeat scanning at selected levels is often helpful in determining the true nature of findings, as the appearance of bowel will often change due to peristalsis. In examining the large bowel, a careful review of the preliminary scout image or repeat scanning performed with additional contrast (barium or the safer option of water-soluble contrast in case of acute obstruction or when a bowel perforation could be suspected) administered rectally is often helpful in avoiding misdiagnosis.4
During laparotomy, ileoileal intussusception was found 60 cm proximal to the ileocaecal valve; after loosening and unfolding the intussuscepted bowel, an intraluminal mass consistent with ileal lipoma could be clearly felt and identified (figure 3, see also movie). The bowel loops distal to the intussusception were also dilated, however (figure 4, intraoperative picture and movie). Manual palpation of the cecum revealed a solid, firm mass of the caecal wall, stenosing the ileocaecal valve. Ileal resection of a 20 cm long segment, including the intussuscepted segment and right colectomy, was performed, followed by double, ileo-ileal and ileo-colic, anastomosis. The pathology revealed a submucosal lipoma, causing the ileal intussusception, together with a 4 cm moderately differentiated colonic adenocarcinoma. This was ulcerated, exophytic, obstructing the ileocaecal valve and involving the entire colonic wall, with extension to the pericolic adipose tissue and nodal metastatic spreading (figure 4, pathology slides).
The postoperative course was uneventful, and the patient was discharged on the 9th postoperative day. He received adjuvant chemotherapy (oral capecitabine). After 1-year follow-up, he is alive with no evidence of disease.
Intussusceptions of the small bowel are usually caused by benign neoplasms5 6 (lipoma, leiomyoma, haemangioma, neurofibroma), adhesions, Meckel's diverticulum, lymphoid hyperplasia, trauma, coeliac disease, intestinal duplication or Henoch–Schonlein purpura. Malignant lesions causing intussusception of the small intestine account for about 15% of the cases2 and are more often metastatic (frequently melanoma7). Idiopathic intussusception occurs in about 20% of all small-bowel intussusceptions.
In adults, it is important to differentiate between small bowel and colonic intussusception; in fact, in 63% of cases of small-bowel intussusceptions, a benign underlying lesion can be found, whereas in 58% of cases of large-bowel intussusceptions, a malignant aetiology has to be expected.5
CT-scan diagnosis of intussusception is usually characteristic: a soft tissue mass containing outer intussusceptions and an inner intussusceptum.10 The lipoma appears on CT scan as a round, homogeneous mass with fat attenuation values, within the lumen of the intussusceptions. When a malignant lesion is suspected, CT scan might also be useful for staging. It can identify bowel dilatation, free fluid, metastases or lymphadenopathy.11 12
In middle-aged patients presenting with recurrent abdominal symptoms, unusual causes of intestinal obstruction should be considered, but a careful and thorough evaluation of the CT scan findings should warrant to avoid missed lesions. Finally, during surgery for bowel obstruction, if the bowel distal to the lesion is not collapsed and it does not distend up, then the area treated may not be the true point of obstruction.
The authors would like to acknowledge Dr Tim Buckeridge, from the Department of Surgery of Frenchay Hospital, North Bristol NHS Trust, for critically reviewing the manuscript and improving it for presentation in English.
Competing interests None.
Patient consent Obtained.