Giant colonic diverticula

May 24, 2007
Surgical Rounds®, May 2007, Volume 0, Issue 0

Yasheka Nicholson, Resident, Department of Surgery; Luz P. Angel, Assistant Professor, Department of Surgery; Frank C. Caliendo, Assistant Professor, Department of Surgery; John A. Procaccino, Chief, Division of Colon and Rectal Surgery, Department of Surgery, North Shore University Hospital, Manhasset, NY

Yasheka Nicholson, MD

Resident

Department of Surgery

Luz P. Angel, MD

Assistant Professor

Department of Surgery

Frank C. Caliendo, MD

Assistant Professor

Department of Surgery

John A. Procaccino, MD

Chief, Division of Colon and Rectal Surgery

Department of Surgery

North Shore University Hospital

Manhasset, NY

Diverticular disease is a common affliction in Western society, occurring in approximately 50% of people older than 60 years. Diverticula are pockets of tissue (sacs) that push out from the colon walls. The disease is usually limited to the sigmoid colon, with diverticula averaging less than 1 to 2 cm in diameter. Rarely do sigmoid diverticula enlarge to such a degree that they are termed “giant colonic diverticula.” The literature to 1998 contained only 108 reports of giant colonic diverticula.1 Management of the condition has ranged from conservative treatment, diverticulectomy, and resection. We report the cases of two patients seen at our institution for giant colonic diverticula and discuss the clinical presentation, pathogenesis, and management of this rare complication of diverticular disease.

Case report

Case 1

—A 70-year-old man with a medical history of hypertension, benign prostatic hypertrophy, and nephrolithiasis went to the emergency department because of a 2-day history of fevers, intermittent abdominal discomfort, rectal bleeding, and diarrhea. A colonoscopy performed a few months earlier was notable only for diverticulosis. His medications included tamsulosin and metoprolol. On presentation, his temperature was 101.2°F, his abdomen was nontender on palpation, and he had guaiac-positive, brown stool in the rectal vault. Laboratory evaluations were within normal limits. An abdominal radiograph showed a large, gas-filled, cystic structure in the mid-abdomen (Figure 1A). Computed tomography (CT) scans of the abdomen and pelvis showed a 7.3 x 6.8-cm giant sigmoid diverticulum with pericolonic inflammatory changes (Figure 1B). The patient was admitted to the hospital for bowel rest and intravenous antibiotics. He improved rapidly, tolerated a low-residue diet, and was discharged home on oral antibiotics.

Approximately 6 weeks later, he underwent a laparoscopic-assisted anterior resection. Intraoperative findings consisted of a giant diverticulum arising from the antimesenteric border of the sigmoid colon (Figure 2). Pathologists confirmed the specimen to be a giant diverticulum with a diverticular wall comprised of fibrous connective tissue with lymphocytic infiltration (Figure 3). No muscular structures were seen. The patient recovered well after surgery and was discharged home on postoperative day 6.

Case 2

—A 57-year-old man with a medical history of hypertension was treated by his internist for diverticulitis with oral metronidazole and levofloxacin. A colonoscopy 1 year earlier revealed diverticulosis. Because of worsening abdominal pain, the patient underwent an outpatient abdominal and pelvic CT scan, which showed a possible pelvic fluid collection adjacent to the sigmoid colon (Figure 4). He was referred to the emergency department, where he reported lower abdominal discomfort and urinary urgency. On physical examination, the patient was afebrile with left lower quadrant and suprapubic tenderness on palpation. His white blood cell count was 12.1 x 109/L, and the urinalysis was positive for trace blood. A review of the patient’s CT scan found a 7.0 x 7.0-cm perisigmoid fluid collection containing hyperdensities and extensive inflammatory changes adjacent to the bladder wall, which appeared thickened and irregular (Figure 4).

The patient received piperacillin intravenously and underwent aspiration of the pelvic fluid collection, but only a minimal amount could be aspirated. Cytology of the aspirate was negative for malignancy. To determine the etiology of the collection, a Gastrografin enema was performed, and sigmoid diverticulitis with a large communicating giant sigmoid diverticulum was found (Figure 5).

A follow-up CT scan taken a few days later confirmed the presence of the giant sigmoid diverticulum and showed decreased inflammatory changes. Approximately 6 weeks later, the patient underwent an elective anterior resection after a mechanical bowel preparation. The giant diverticulum arose from the antimesenteric border of the sigmoid colon and adhered to the bladder. There was extensive inflammatory reaction of the bladder wall. The pathologic findings showed benign fibrous connective tissue with chronic active inflammation, consistent with a giant diverticulum (Figure 6). No muscular structures were seen. The patient’s postoperative recovery was uneventful.

Discussion

In 1946, Bonvin and Bonte were the first to describe giant colonic diverticula.2 Seven years later, Hughes and Greene described a “solitary air cyst” and reported the first radiological findings of such diverticula in the American literature.3 Many terms have been used to describe giant colonic diverticula over the years, including solitary air cysts, giant air cysts, encysted pneumatoceles, and pneumatocysts of the colon.

Diverticula are considered giant when they measure 4 cm or larger. Although their size may vary over time, most measure between 7 and 15 cm.4-8 The largest reported giant colonic diverticula measured 29 cm in diameter, and multiple diverticula can arise in a single patient.9,10 Giant colonic diverticula occur equally in both sexes and have been reported in patients ranging from 38 to 86 years of age. While 90% occur in the sigmoid colon, they have been reported in other areas, such as the transverse colon.11 Giant colonic diverticula usually occur on the antimesenteric border of the sigmoid colon. Evidence of diverticular disease, such as muscle hypertrophy and other small diverticula, is typically present.

The pathogenesis of giant colonic diverticula remains unknown, and several pathogenic mechanisms have been proposed. Boijsen’s ball-valve theory suggests that a ball-valve mechanism develops at the base of a diverticulum, which enables intestinal gas to enter under high pressure and remain trapped.12 The colonic inflammation narrows the outlet and results in progressive dilatation. The lesion then slowly emerges as giant colonic diverticula during acts of straining. Another theory suggests that gas-producing microorganisms cause the diverticulum to expand after the stalk has become obliterated.13-15 Rabinowitz and colleagues hypothesized that giant diverticula result from an abscess that develops around an infected preexisting pseudodiverticulum.16 After the mucosa and serosa have been destroyed completely by the infection, granulation tissue constitutes the wall of the abscess.

Pathologically, mucosa is usually absent from the diverticulum, and its wall shows signs of an intense inflammatory reaction. The smooth muscle fibers end at the neck of the diverticulum. The presence of mucosa or, more significantly, muscle, suggests that the lesion is likely a true diverticulum or duplication cyst. The neck of the diverticulum is often small and sometimes can be observed only on microscopic examination.

The diverticulum generally has one opening into the colon, but double openings have been known to occur. The opening is often occluded, which accounts for the 75% of cases in which no contrast medium refluxes into the diverticulum during a barium enema study. If the opening remains patent, the diverticulum can deflate spontaneously or change in size.

Patients with giant colonic diverticula have been described as having two types of clinical manifestation: those who present acutely, often with peritoneal signs, and those who have a long history of vague abdominal pain. Symptoms that result in hospital admission vary from nonspecific constitutional symptoms to complications of an acute abdomen, such as perforation, bleeding, focal infarction, torsion, or obstruction. Carcinoma arising from the wall of the cyst also has been reported.17,18 Giant colonic diverticula often adhere to another organ, including other parts of the colon, the omentum, or the small bowel, which results in a mass effect. One of our patients had urinary symptoms because the diverticulum adhered to his bladder.

Established giant colonic diverticula tend to increase in size over time. The patient may present initially with a tympanic abdominal mass that contains air and later deflates. This finding is consistent with the hypothesis of a ball-valve mechanism at the neck of the diverticulum and may explain the variation in clinical symptoms. Gastrointestinal bleeding also has been reported but, since no arteriographic studies were conducted, it is unclear whether the source of the bleeding was the giant diverticulum or the small, scattered diverticula.19 In rare cases, patients are asymptomatic except for the presence of an abdominal mass.

The differential diagnosis of a giant colonic diverticulum includes intestinal duplication, giant duodenal diverticulum, large cystic Meckel’s diverticulum, jejunal diverticula, emphysematous gallbladder, volvulus of the colon, fistula between the gallbladder and gastrointestinal tract, pneumatosis intestinalis, mesenteric cyst, pancreatic pseudocyst, and emphysematous cystitis due to gas-forming bacteria or a fistula to the bladder. Plain abdominal radiography can be pathognomonic if a large, gas-density lesion is observed; the lesion is usually located anteriorly in the mid-abdomen. Occasionally, radiography studies are normal, and the giant diverticulum is discovered after use of a barium enema. The diagnosis is straightforward when communication with the colon is open, allowing the barium to reflux into the diverticulum. Barium has been reported to enter giant diverticula 66% of the time.20 On a CT scan, a smooth, thin-walled cyst that contains air and usually overlies the area of the sigmoid colon suggests the diagnosis.

Early surgical intervention is advised for giant diverticula because of the complications that can result, such as perforation, bleeding, focal infarction, torsion, or obstruction. The treatment of choice is a segmental sigmoid resection that includes the cyst, followed by a primary colorectal anastomosis. Thaler and colleagues confirmed earlier findings that a colorectal (not colosigmoid) anastomosis for diverticular disease is essential to further reduce the 5% postoperative recurrence rate.21 A diversionary stoma is usually unnecessary. Resection of the diverticulum with two-layer closure of the colon can be done, as supported by Al-Jurf and Foucar, but this is not recommended because of the remaining diverticular disease and the possibility of fistula formation.22

Resection of the diverticulum along with the involved colon is the procedure of choice because of the persistent inflammation in the adjacent wall of the colon. To date, there is one case in the literature of a recurrent giant colonic diverticulum occurring after a diverticulectomy.23 Medical management should be reserved only for patients with minimal symptoms who are poor surgical candidates.

Conclusion

Giant colonic diverticula are a complication of diverticular disease. Radiologic studies can aid in diagnosis and help differentiate this condition from others, such as intestinal duplication. Once the diagnosis has been established, surgical resection is recommended to avoid complications associated with this condition, such as perforation.

Acknowledgment

We thank Gae O. Decker-Garrad for her assistance in preparing this manuscript.

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