Colonic Neoplasms; Intussusception; Stents

78/F

A 77-year-old female patient was admitted with a chief complaint of aggravating constipation and abdominal fullness. On a physical examination, the abdomen was markedly distended.

Sigmoid colon cancer

Plain abdominal radiography showed multiple air fluid levels of the colon; however, small bowel loops were not dilated (Fig. 1). Abdominal computed tomography revealed a polypoid mass with stenotic segment in the sigmoid colon and suggested the presence of an acute malignant colonic obstruction due to sigmoid colon cancer. The patient underwent sigmoidoscopy that revealed a huge multilobulated exophytic mass with a proximal annular constricting lesion in the sigmoid colon located 28 cm from the anal verge (Fig. 2).

Erect plain abdomen radiograph shows multiple air-fluid levels of the colon.

Sigmoidoscopic finding. A huge multilobulated exophytic mass with a necrotic surface was noted at the sigmoid colon, 28 cm from the anal verge.

Under fluoroscopy, an uncovered SEMS measuring 10 cm in length and 22 mm in diameter (Hanarostent, M.I. Tech Co, Seoul, Korea) was successfully deployed. Patient symptoms improved immediately after stent insertion with passage of stools. The stent was optimally expanded and placed in the sigmoid colon, as demonstrated by plain radiography shortly after insertion (Fig. 3a). However, one day after the procedure, the patient complained of aggravating abdominal fullness. Follow-up plain radiography demonstrated the presence of the metallic stent at the rectum, and the colonic dilatations were not relieved (Fig. 3b). We thought this unsuccessful colonic decompression might be due to early stent migration, and we performed a second stent insertion proximal to the first stent under fluoroscopic guidance (Fig. 4). However, colonic dilatations persisted for 24 hours after the second stent placement. On pelvic MRI, the mass containing the stent had invaginated into the rectum 6.7cm from the anal verge (Fig. 5). The patient underwent emergency surgery, where a tumor that contained a segment of the proximal sigmoid colon (intussusceptum) had telescoped into the adjacent distal colonic segment (intussuscipiens) was seen (Fig. 6).

(a) The radiograph shows a metallic stent in the sigmoid colon shortly after procedure. (b) One day later, a follow-up plain radiograph shows a suspicious distal stent migration into the rectum.

Plain abdomen radiograph following re-stent insertion, another metallic stent was noted proximal to the first stent.

Sagittal T2-weighted MR image. The image shows a polypoid mass (white arrow) and metallic stent in the rectum. Mesenteric vessels are noted as linear signal voids (black arrow) along the metallic stent. This image was interpreted as an intussusception.

Intraoperative finding. A segment of the proximal sigmoid colon containing the tumor (intussusceptum, black arrow) with mesenteric fat had telescoped into the adjacent distal colonic segment (intussuscipiens, white arrow).

Therapeutic strategies for colonic obstructions have changed extensively since the placement of self-expandable metallic stent (SEMS) for acute malignant colonic obstruction was introduced in early 1990s. In the present case, unfortunately, we misdiagnosed intussusception as an early stent migration based solely on the findings of plain radiography. However, it is very difficult to diagnose a newly developed colonic intussusceptions in a patient with underlying colonic obstruction as the clinical manifestations of intussusception are superimposed on the underlying obstruction. Moreover, it is also difficult to differentiate a distal stent migration from intussusception on plain radiography. Therefore, we suggest that careful examination is necessary in cases with suspicious distal stent migration and an undecompressed bowel after colonic placement of SEMS in acute malignant colonic obstruction.

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