When ‘just hold it’ becomes a serious medical condition.
The urge to urinate isn't likely something you've thought about very often. After all, urination is seemingly automatic for most people – it's simply something we know how to do. But for people with urinary retention, that urge to urinate can be thwarted by an inability to "go." Several causes can result in urinary retention, so knowing the condition and what to look out for is essential.
To understand urinary retention, an important place to begin is understanding the body's ability to urinate in the first place. Bean-shaped organs called kidneys are in a constant state of urine manufacturing, and urine is continuously draining down into the bladder throughout a 24-hour cycle. When the bladder fills close to capacity with urine (which can be at different intervals depending on the individual), then a person will receive a "signal" via an urge to urinate, indicating it's time to find a bathroom and empty the bladder. This signal is generated within the body's complex nervous system called the Autonomic Nervous System (ANS).
Essentially, as the bladder becomes more enlarged with urine, the nerves of the bladder that detect the bladder muscle becoming stretched will send signals via the ANS up the spinal cord to the brain. Subsequently, the brain picks up the nerve signals and translates them to an urge to urinate. Simultaneously, while the urge to urinate is being detected, the brain sends signals through the autonomic nerves back down to the bladder via the spinal cord, preventing the bladder from reflexively contracting and emptying its contents on to ourselves so that we can get to a bathroom. Once ready to urinate, the brain then withdraws its inhibitory signals. Instead, it sends signals to allow the bladder to contract while also encouraging relaxation of the pelvic floor muscles (to open the valves), thereby causing the urine to exit the body safely into a toilet.
Urinary retention is a condition in which the bladder is complete but cannot empty its contents. In general, if a person's sensory component of their ANS is intact, but they are experiencing retention, they will have a constant urge to urinate without physically being able to. As one can imagine, the experience of urinary retention is a very uncomfortable sensation. The urge becomes stronger and stronger, but no matter what the person tries, they will not be able to urinate.
There are some situations where a person will be experiencing urinary retention and will have no urge. Some neurological issues and bladder muscle disorders can prevent a person from experiencing urinary urge or bladder fullness. These situations are rarer than the typical situation described above.
In terms of specific causes of urinary retention, there is quite a bit of variation. The most common cause of urinary retention in men is an enlarged prostate. As the prostate grows, it can obstruct the urethra and will prevent the urine from emptying. In women, the most common cause of urinary retention is pelvic prolapse. With pelvic prolapse, the urethra becomes angulated or "kinked," leading to difficulty with emptying the bladder. Other causes of urinary retention may include UTI, a stroke, spinal cord injury, spinal cord diseases like multiple sclerosis, nerve impingement, bladder diseases like loss of bladder muscle tone, paralysis of the bladder muscle, atonic bladder, diabetes, recent surgery (anesthesia can cause temporary paralysis of the bladder), and pelvic cancers that cause physical obstruction – including prostate cancer and bladder cancer, urethral cancer, and gynecologic cancers.
The treatment for urinary retention is centered around first identifying the root cause of the issue. For example, in cases of an enlarged prostate, there are medications called alpha-blockers that can help or surgeries to reduce the size of the prostate gland. In cases where pelvic prolapse is the concern, one will need to undergo surgery to correct the underlying problem. When UTI causes urinary retention, the person will need antibiotics to take care of the underlying issue to relieve the urinary retention issues. In some cases, over-the-counter herbal remedies may help keep the prostate healthy and possibly reduce the likelihood of developing urinary retention, such as Saw palmetto, Pygeum, or Beta-Sitosterol.
No matter the cause of urinary retention, proper diagnosis, and appropriate treatment is crucial. Without addressing the underlying causes of retention, the issue may cause kidney failure, sepsis, stone formation in the urinary tract, and possibly other complications. Urinary retention is not a condition to "wait and see" if it resolves. If you or someone you know cannot urinate for more than 4 - 6 hours, they should seek immediate medical attention like going to the ER, calling their urologist (if they have one), or making an urgent call to their primary doctor.
Sources:
Dr. Ramin’s email answers from 5/28/22 Livestrong interview.