Grand Rounds Vol 9 pages 9–13

Speciality: Radiology

Article Type: Case Report

DOI: 10.1102/1470-5206.2009.0003

� 2009 e-MED Ltd

Large bowel obstruction secondary to

gallstone impaction at a sigmoid diverticular

stricture: the radiological features

Saravanan Munusamy, Kumar Subramanian and Chris Loughran

Department of Neuroradiology, Barts and the London NHS Trust, London, UK

Corresponding address: Saravanan Munusamy, 10 Mere Bank Close,

Worsley, Manchester, M28 0AS, UK.

E-mail: msaravanan75@hotmail.com

Date accepted for publication 2 February 2009

Abstract

Intestinal obstruction secondary to displacement of a stone from the gall bladder into the

intestinal tract is relatively uncommon. The commonest site of calculus impaction is at the

ilio-caecal valve. Occasionally, however, the gall stone may either pass through the valve into

the colon or perforate directly into the transverse colon and impact in the distal colon. The

extruded calculus is often only faintly calcified and may be difficult to identify on plain

radiographs. We describe a case where multislice computed tomography of the abdomen enabled

an accurate diagnosis to be made. Prompt surgical treatment was subsequently undertaken.

We report the imaging findings with particular emphasis on the importance of computed

tomography in establishing the diagnosis.

Keywords

Gallstone; diverticular stricture; large bowel obstruction.

Introduction

Intestinal obstruction secondary to displacement of a stone from the gall bladder into the

intestinal tract is relatively uncommon. The commonest site of calculus impaction is at the ilio-

caecal valve. Occasionally, however, the gall stone may either pass through the valve into the

colon or perforate directly into the transverse colon and impact in the distal colon. The extruded

calculus is often only faintly calcified and may be difficult to identify on plain radiographs.

We describe a case where multislice computed tomography (MSCT) of the abdomen enabled

an accurate diagnosis to be made. Prompt surgical treatment was subsequently undertaken.

We report the imaging findings with particular emphasis on the importance of computed

tomography (CT) in establishing the diagnosis.

Case report

A seventy-five year old female presented with a 4 week history of colicky lower abdominal pain

which had become localised to the left iliac fossa. She felt feverish and had vomited once since

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the onset of the pain. She denied any blood or mucus per rectum. Her general practitioner

had commenced her on oral ciprofloxacin 1 week earlier. She had undergone an appendicectomy

50 years ago. On examination she was tender in the left iliac fossa with minimal guarding but no

signs of peritonism. Bowel sounds were present. A rectal examination was unremarkable.

Although a plain abdominal radiograph demonstrated gas in the biliary tree, acute diverticulitis

was thought a more likely clinical diagnosis (Fig. 1). A dynamic multislice enhanced CT scan of

the abdomen and pelvis was performed. (Toshiba Asteion, enhancement with 100ml of ioversol

300 at 3 ml/s). The scan confirmed gas within the biliary system and a laminated calculus

impacted in a markedly thickened loop of the sigmoid colon (Fig. 2). A putative diagnosis of

gall stone impaction in a segment of diverticular change was made. A water-soluble contrast

enema confirmed complete obstruction at the site of calculus impaction (Fig. 3). The patient

subsequently proceeded to laparotomy and underwent a Hartmann’s procedure. The resected

Fig. 1. Abdominal radiograph. Gas is shown in the biliary tract. There are dilated bowel loops and a radio-opaque stone is visiblein the pelvis (arrows).

10 S. Munusamy et al.

segment of sigmoid colon revealed an impacted gallstone proximal to a diverticular stricture.

Recovery was uneventful.

Discussion

Gall stone ileus is a condition in which gall bladder calculi erode into the intestinal tract. The

fistulous communication so created permits passage of intestinal gas into the biliary system, a

characteristic feature sometimes seen on plain radiographs. Usually the calculi erode into the

adjacent duodenum and migrate distally. The stones then impact – usually at the ileo-caecal

valve – and cause a distal small bowel obstruction. The stone itself is sometimes demonstrated in

one of the terminal ileal loops on plain abdominal films. A combination of these findings is

diagnostic of a gallstone ileus[1,2].

Other sites for impaction include the duodeno-jejunal flexure or at any small bowel stricture[3].

If large enough, they may impact proximally and cause duodenal obstruction. (Bouveret’s

syndrome). However, it is well recognised that calculi may rarely pass directly into the transverse

colon. The larger calibre of the colon permits passage of the stone into the distal large bowel. The

calculus is liable to impact if there is any distal colonic stricture. In this case the impacted

endoluminal gallstone occurred at a diverticular stricture and incited an acute diverticulitis.

The primary CT findings in uncomplicated diverticular change include thickening of the wall of

the involved segment of colon with visualisation of colonic diverticula[4,5]. In cases where there is

a complicating acute inflammatory change, there may be more marked bowel wall thickening,

stranding of the mesenteric fat and, in the most severe cases, peri-colic abscess formation. Other

visualised complications include free perforation, colo-vesical fistula and ureteric obstruction[4,5].

Pericolonic inflammation and segment involvement greater than 10 cm are very suggestive of

acute diverticulitis[6].

The ability to image pericolonic abnormalities makes CT arguably a better modality to evaluate

diverticulitis than barium enema[7,8]. The differential diagnosis of colonic wall thickening and

Fig. 2. CT scan of the lower pelvis. The laminated calculus can be seen clearly in the thickened loop of the sigmoid colon.

Large bowel obstruction secondary to gallstone impaction 11

pericolonic soft tissue stranding include inflammatory bowel disease, pseudo membranous colitis

and other infectious colitides. Other rarer causes include eosinophilic enteritis, lymphocytic

colitis and lupus colitis[9].

Teaching points

MSCT enabled precise identification of the location of the calculus in the intestinal tract. Although

a standard open laparotomy was pursued in this instance, the knowledge that the obstructing

stone was in the distal colon could have led to consideration of calculus fragmentation via an

endoscope and a lithotripter device – thus saving an open laparotomy.

A recent review of the use of CT scanning in the acute abdomen suggested that if used more

liberally there may be benefits, including a shorter hospital stay and reduced patient morbidity

and mortality[10]. This case reflects that opinion and highlights the potential for MSCT to establish

an accurate diagnosis even in unusual conditions such as that described.

References

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Fig. 3. Water-soluble contrast enema. The flow of contrast medium is obstructed at the site of impaction of the laminated stone(arrows). Associated sigmoid diverticular change is shown.

12 S. Munusamy et al.

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