Diverticula, that is, sac-like protrusions in the wall of large bowel are the most frequent anatomical alteration in the human colon. Colonic diverticulosis (hereafter referred to as diverticulosis) refers to the presence of diverticula in the colon. For many years, the western lifestyle has been considered a key factor for the development of diverticulosis, owing to its comparatively high prevalence in developed countries. Indeed, the global prevalence of diverticulosis is increasing in both developed and developing countries, presumably as a result of changes in diet and lifestyle.[1,2] The pathogenesis of diverticulosis is not completely understood but several changes are known to occur in the architecture of the colon wall, including loss of elasticity function and deposition of immature collagen fibres in the extracellular matrix, which are implicated in the formation of diverticula². The colonic wall consists of mucosa, submucosa, muscular and serosal layers. Diverticulitis is a common complication of diverticular disease and can lead to formation of abscess or colocutaneous fistula. (3,4) Here we present a rare case of sigmoid diverticulitis presenting as bladder wall abscess

53-year-old male presented with lower abdominal pain for 5 days with no constipation or loose stools. There was no history of Malena or pain while passing stools. He did not have any dysuria or hematuria. There was no fever, vomiting or abdominal distension.He was not a known diabetic or hypertensive. There were no past surgeries or any medication use. He did not smoke or consume alcohol. Bowel bladder habits were normal and there was no loss of weight or appetite. No similar complaints in family. On examination, he was found to have stable vitals with unremarkable general physical examination

Per abdominal examination was normal with no suprapubic tenderness and per rectal examination did not reveal any tenderness, bogginess or growth. Rest systemic examination was within normal limits. Ultrasound of the abdomen was done for evaluation which showed a collection along the posterior wall of the bladder.

Contrast enhanced CT scan of the abdomen and pelvis was done for further evaluation and it showed a long segment sigmoid wall thickening with diverticula and surrounding fat stranding. It also showed a collection along the superior and posterior wall of urinary bladder measuring 5.5x5.7x6.3 cm. Patient was planned for exploration under anaesthesia and underwent a cystoscopy. Cystoscopy showed a large bulge over the posterior wall of bladder(fig.1) with normal urethra and ureteric orifices.

Figure-1: Cystoscopy showing a large bulge over the posterior wall of bladder with normal urethra and ureteric orifices.

Figure-2: Intraoperative mass lesion along anterior wall of sigmoid

He underwent an exploratory laparotomy which showed a mass lesion anterior to the sigmoid and adherent to the posterior urinary bladder and surrounding ileum. (Figure-2) He underwent sigmoid resection and anastomosis with partial cystectomy and augmentation. Postoperatively the patient developed wound infection which was managed conservatively with antibiotics and dressings. Bowel sounds and function returned on day 3. He was started on oral diet on day 4 and gradually increased to normal diet. Discharged on day 20 with normal diet and stable condition.

Diverticular disease of the colon is seen commonly among adults and its incidence increased with increase in age. Diverticulitis is a common complication of diverticulosis and is usually  managed conservatively. (5,6)In some patients, uncontrolled infection can lead to abscess formation and may even cause perforation of the diverticula with generalised peritonitis. Treatment options include percutaneous and open drainage of the abscess with peritoneal lavage. (7)Resection of the perforated segment with primary anastomosis or colostomy is done depending on the health of bowel mucosa and patient general condition. PSimilar to the patient in the Silberman et al. [8] case report, our patient had increased red blood cells in the urinalysis sample. Such findings suggest pathophysiological similarities to the per rectal bleeding seen in colonic diverticulitis. In contrast to colonic diverticulitis, however, the physiologically sterile contents of the urinary bladder reduce the chance of abscess formation. Other differential diagnoses related to hematuria and pain may commonly include pyelonephritis, urolithiasis, and renal or urinary tract malignancies.The abnormal liver serum biochemistry results at the time of presentation (raised AST, ALT, and GGT) were deemed attributable to hepatic steatosis, which was revealed on CT.

Rothenbuehler et al[9]. reported a case series of 5 patients with inflammatory processes of the abdominal wall and thigh, all caused by diverticulitis. This number of patients was observed during 11 years and after 263 patients had been operated for diverticulitis. These numbers show how rare the extraperitoneal spread of diverticulitis is. Four out of the five patients reported by Rothenbuehler et al. had diverticulitis of the sigmoid like our patient and one had the disease localized in the ascending colon. All patients had abdominal pain for 2 to 8 weeks before hospital admission and increased white blood cell count. Local drainage was performed in all patients and was followed by resection of the affected part of the colon.

Zhou J et al[10]. also published  cases with thigh abscess due to diverticulitis and colorectal cancer .

Our patient had an uneventful recovery with antibiotic treatment. Subsequent procedures such as cystoscopy may be performed after the acute illness resolves. No operation is needed to treat this condition, although further treatment for chronic bladder obstruction may be helpful to prevent recurrence.

Previous literature review shows varying presentationsof diverticular perforations including peritonitis and abdominal wall abscess formation.[11,12]Here we present a rare case of sigmoid diverticulitis presenting as a urinary bladder wall abscess. The perforation of the diverticula was probably insidious and subclinical and was controlled by the natural defence mechanisms which lead to a localised collection which infiltrated the posterior urinary bladder wall .The patient presented with minimal symptoms and had no significant bowel or bladder complaints. The diagnosis would have been missed if not for imaging. This re-iterates the fact that even patients with minimal symptoms could be masking a grave disease and adequate evaluation is necessary if clinical suspicion is present. Sigmoid diverticulitis can present with varied presentations and care should be taken to rule out this condition in patients presenting with unexplained pelvic symptoms.

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