Urinary retention can be caused by an obstruction in the urinary tract or by nerve problems that interfere with signals between the brain and the bladder. If the nerves aren’t working properly, the brain may not get the message that the bladder is full. Even if you know that your bladder is full, the bladder muscle that squeezes urine out may not get the signal that it is time to push, or the sphincter muscles may not get the signal that it is time to relax. A weak bladder muscle can also cause retention.
Nerve Disease or Spinal Cord Injury
Many events or conditions can damage nerves and nerve pathways. Some of the most common causes are
In addition, some children are born with nerve problems that can keep the bladder from releasing urine.
Prostate Enlargement: Benign Prostatic Hyperplasia
As a man ages, his prostate gland may enlarge. Doctors call the condition benign prostatic hyperplasia (BPH), or benign prostatic hypertrophy.
As the prostate enlarges, the layer of tissue surrounding it stops it from expanding, causing the gland to press against the urethra like a clamp on a garden hose. As a result, the bladder wall becomes thicker and irritable. The bladder begins to contract even when it contains small amounts of urine, causing more frequent urination. Eventually, the bladder weakens and loses the ability to empty itself, so urine remains in the bladder.
Infections cause swelling and irritation, or inflammation. A urinary tract infection (UTI) may cause retention if the urethra becomes inflamed and swells shut.
During surgery, anesthesia is often administered to block pain signals, and fluid is given intravenously to compensate for possible blood loss. The combination may result in a full bladder with impaired nerve function. Consequently, many patients have urinary retention after surgery.
Many medicines work by calming overactive nerve signals. Various classes of drugs that block various signals may be used to treat allergies, stomach cramps, muscle spasms, anxiety, or depression. Some medicines are used to treat urinary incontinence and overactive bladder. The drugs that may cause urinary retention include
- fexofenadine (Allegra)
- diphenhydramine (Benadryl)
- chlorpheniramine (Chlor-Trimeton)
- cetirizine (Zyrtec)