Bladder Diverticulum

Overview

A bladder diverticulum is a pouch or sac that protrudes outward from the bladder wall. These pouches form when the inner lining of the bladder pushes through weakened areas of the muscular wall. Urine collects in these pouches and fails to drain properly during normal voiding, creating conditions that favour infection, stone formation, and potentially cancer development.

Bladder diverticula are classified as either congenital or acquired. Congenital diverticula are present from birth and typically occur as single pouches near the ureteric orifice (known as Hutch diverticula). These true diverticula contain all bladder wall layers and may be associated with vesicoureteral reflux. Acquired diverticula develop later in life, usually as a result of bladder outlet obstruction. Unlike congenital forms, acquired diverticula are typically multiple, lack the muscle layer (false diverticula), and are most common in older men with benign prostatic hyperplasia.

The prevalence of acquired bladder diverticula ranges from 1.7% to 6% in older men, with incidence increasing with age. They are less common in women. Congenital diverticula are rare and often discovered incidentally during investigation for urinary tract infection or other urological complaints.

Symptoms

Many bladder diverticula cause no symptoms and are found incidentally on imaging studies. Small diverticula are particularly likely to remain asymptomatic. When symptoms do occur, they typically relate to incomplete bladder emptying and urine stagnation within the pouch.

The hallmark symptom is double voiding, where a person urinates, then feels the need to void again shortly afterward as the diverticulum empties. Patients may also experience a persistent sensation of bladder fullness after voiding, as urine retained in the diverticulum creates the impression that the bladder hasn’t emptied completely.

Recurrent urinary tract infections are common because bacteria thrive in the stagnant urine trapped within the diverticulum. These infections may prove resistant to standard antibiotic treatment because the pouch acts as a reservoir where bacteria persist despite therapy. Patients may also experience haematuria, lower abdominal or pelvic discomfort, and symptoms of the underlying obstruction such as frequent urination and weak urinary stream.

Causes

The vast majority of bladder diverticula in adults develop as a consequence of bladder outlet obstruction. In men, benign prostatic hyperplasia is the most common underlying cause, though prostate cancer and urethral stricture can also be responsible. In both sexes, neurogenic bladder conditions that cause high-pressure voiding and dysfunctional voiding patterns may lead to diverticulum formation.

The mechanism of formation follows a predictable sequence. When obstruction increases bladder pressure during voiding, the bladder muscle works harder and thickens (hypertrophies). As muscle bundles become prominent (trabeculation), the inner bladder lining begins to herniate through weak points between muscle bundles. These herniations gradually enlarge into the pouches we call diverticula.

Congenital diverticula arise from developmental weakness in the bladder wall, typically near the ureteric insertion point. They may be associated with abnormalities of the ureterovesical junction and are more common in boys.

Diagnosis

Ultrasound is typically the first imaging test and shows diverticula as fluid-filled sacs adjacent to the bladder. However, small diverticula may be missed. The examination also measures post-void residual urine volume, which is often elevated.

Voiding cystourethrography (VCUG) is considered the gold standard for demonstrating bladder diverticula. Contrast material fills the bladder and any diverticula, clearly showing their size, number, and location. The dynamic nature of the test during voiding provides information that static imaging cannot capture.

CT urography provides detailed anatomical information, shows the relationship of diverticula to the ureters, and can detect bladder stones within the pouches. When the wall of a diverticulum appears irregular, CT can suggest the presence of tumour. MRI offers excellent soft tissue detail and is particularly useful for assessing tumour involvement and planning surgery.

Cystoscopy allows direct visualisation of diverticula and is essential for inspecting the interior for tumour growth. However, entering the diverticulum may be difficult when the neck is narrow. If a neurogenic cause is suspected, urodynamic studies assess bladder pressure and document the presence and degree of obstruction.

Treatment

The first priority is treating the underlying obstruction. For men with benign prostatic hyperplasia, this may involve medications such as alpha-blockers or 5-alpha-reductase inhibitors, or surgical procedures like transurethral resection of the prostate (TURP) or holmium laser enucleation (HoLEP). Urethral strictures require dilation or urethroplasty, and neurogenic bladder conditions need appropriate management. Relieving obstruction prevents new diverticula from forming, may allow some to regress, and reduces symptoms.

Small, asymptomatic diverticula without complications may be managed with observation alone. This approach requires regular monitoring with imaging and cystoscopy to surveil for tumour development. Given the 2% to 10% risk of cancer developing within bladder diverticula, ongoing surveillance is essential even when the diverticulum itself causes no symptoms.

Surgical excision (diverticulectomy) is indicated for large symptomatic diverticula, recurrent infections, stones within the diverticulum, suspicion of tumour, or failed conservative management. Surgery can be performed through open, laparoscopic, or robotic approaches, with minimally invasive techniques offering faster recovery. Transurethral (endoscopic) treatment, which involves incising the narrow neck to improve drainage and fulguration of the lining, may be appropriate for selected cases but is not always definitive. Diverticulectomy is often performed at the same time as surgery to relieve prostate obstruction.

If bladder cancer is found within a diverticulum, treatment depends on the stage but may require partial cystectomy (removing the bladder wall segment containing the diverticulum) or radical cystectomy for invasive disease. Cancer within diverticula tends to be diagnosed at a more advanced stage because the absence of a muscle layer means tumours can invade surrounding tissues more readily.

When to See a Doctor

You should seek medical attention if you experience blood in your urine, recurrent urinary tract infections that don’t respond to treatment, or new urinary symptoms such as difficulty emptying your bladder or double voiding. Fever associated with urinary symptoms requires prompt evaluation as it may indicate a serious infection. Persistent pelvic pain should also be investigated.

If you have been diagnosed with a bladder diverticulum and are being managed with observation, keep all follow-up appointments and attend for scheduled imaging and cystoscopy examinations. These surveillance measures are important for detecting complications, particularly cancer, at an early stage when treatment is most effective.