Bladder Obstruction (Blocked Bladder)

What happens when the bladder is blocked

Normally the bladder muscle squeezes while the bladder neck and urethra relax, and urine leaves in a strong stream. When something narrows the outlet, the bladder has to push harder.

• Early on, the bladder wall thickens to overcome the resistance. You may notice a weaker stream and needing to go more often and more urgently.
• Later, the muscle tires. Urine is left behind after each void (residual urine). This stale urine causes infections and bladder stones.
• Eventually, pressure backs up into the kidneys, causing swelling (hydronephrosis) and, if untreated, permanent kidney damage.

The term bladder outlet obstruction is used by urologists for blockage proven on pressure testing. Our bladder outlet obstruction page covers that diagnosis in depth. This page focuses on recognizing a blocked bladder and its causes in different groups.

Signs of a blocked bladder

Other clues of a blockage include straining to start, dribbling after you finish, a split or spraying stream, repeated urinary tract infections, and blood in the urine.

Causes of bladder obstruction

In men

• Benign prostatic hyperplasia (BPH): the prostate wraps around the urethra and enlarges with age. It is by far the most common cause after age 50.
• Urethral stricture: scar tissue narrows the urethra after infection, catheters, injury or surgery. It often causes a thin, spraying stream at a younger age than BPH. See urethral stricture.
• Prostate cancer or acute prostatitis.
• Bladder neck contracture after prostate surgery.

In women

Obstruction is less common in women, so it is often missed.

• Pelvic organ prolapse: a large cystocele (bladder drop) or uterine prolapse can kink the urethra. Women sometimes need to push the bulge back to pass urine.
• Previous incontinence surgery: a sling or bladder neck suspension placed too tight.
• Urethral diverticulum or stricture, and pelvic masses such as large fibroids.
• Primary bladder neck obstruction: the bladder neck fails to open, seen in younger women and men.

In children

• Posterior urethral valves: flaps of tissue in the urethra of baby boys. Often found on prenatal ultrasound as swollen kidneys.
• Severe constipation, a common and easily missed cause of incomplete emptying.
• Rarely, a ureterocele or tumor.

At any age

• Bladder stones that roll into the outlet, often causing sudden interruption of the stream.
• Blood clots from bleeding in the bladder (clot retention).
• Bladder cancer near the outlet.
• Fecal impaction pressing on the urethra, especially in older adults.

Look-alikes that are not true blockages

A bladder that cannot squeeze, from nerve damage or overstretching, produces the same symptoms without any blockage. This is an underactive or neurogenic bladder. Medicines such as antihistamines, decongestants, opioids and some antidepressants can also trigger urinary retention, especially in men with an enlarged prostate.

How bladder obstruction is diagnosed

1. History and examination: including a belly exam for a full bladder, a rectal exam of the prostate in men, and a pelvic exam for prolapse in women.
2. Post-void residual scan: a bladder ultrasound right after you urinate. A large residual confirms incomplete emptying.
3. Urine test: for infection and blood.
4. Blood tests: creatinine for kidney function, and PSA in men when appropriate.
5. Uroflowmetry: you urinate into a machine that measures flow speed. A low peak flow suggests obstruction.
6. Urodynamics: pressure measurements that separate a true blockage (high pressure, low flow) from a weak bladder (low pressure, low flow).
7. Cystoscopy and imaging: a camera inspects the urethra and bladder. Kidney ultrasound checks for back-pressure.

Treatment

Immediate relief

A sudden blockage is treated by passing a catheter through the urethra, or through the lower belly (suprapubic catheter) if the urethra is too narrow. Draining the bladder relieves pain within minutes. After long-standing retention, you may pass large volumes of urine for a day or two as the kidneys recover, so doctors watch fluids and blood salts.

Treating the cause

• Enlarged prostate: alpha-blockers such as tamsulosin relax the prostate muscle. 5-alpha-reductase inhibitors shrink the gland over months. Procedures such as TURP, laser enucleation and newer minimally invasive options remove or open the obstructing tissue.
• Urethral stricture: dilation or urethrotomy for short strictures, and urethroplasty (reconstruction) for longer or recurrent ones.
• Prolapse: a pessary or surgical repair.
• Stones and clots: removal through a cystoscope, and treating the bleeding source.
• Constipation: clearing the bowel often restores normal emptying.
• Posterior urethral valves: the valves are cut through a small camera shortly after birth.

Complications if left untreated

• Recurrent bladder and kidney infections
• Bladder stones
• A permanently weakened, stretched bladder
• Hydronephrosis and chronic kidney disease
• Overflow incontinence

Frequently asked questions

What does a blocked bladder feel like?

A sudden blockage feels like an intense need to urinate that you cannot relieve, with a painful, hard swelling above the pubic bone. A slow blockage is often painless. You may notice a weak stream, straining, dribbling and a feeling that the bladder never quite empties.

Is bladder obstruction an emergency?

Complete inability to pass urine is an emergency and needs a catheter the same day. Partial obstruction that has built up slowly is not an emergency, but it should be checked within weeks because it can quietly damage the kidneys and cause infections.

Can women get a bladder obstruction?

Yes, although it is much less common than in men. In women the usual causes are pelvic organ prolapse, previous incontinence surgery, urethral narrowing and pelvic masses. Because it is unexpected, it can take longer to diagnose. A bladder scan and urodynamics confirm it.

Can constipation block your bladder?

Yes. A rectum packed with hard stool presses on the bladder neck and urethra. This is a common cause of incomplete emptying and retention in children and older adults. Clearing the constipation usually restores normal urination.

How is a blocked bladder treated?

The bladder is drained first with a catheter. The cause is then treated: medicines or surgery for an enlarged prostate, dilation or reconstruction for a stricture, a pessary or repair for prolapse, and removal of stones or clots. Some people need a catheter until the definitive treatment is done.