Normal bladder function
The kidneys produce urine, which drains into your bladder. When you urinate, urine passes from your bladder through an opening at the bottom and flows out a tube called the urethra (u-REE-thruh). In women, the urethral opening is located just above the vagina. In men, the urethral opening is at the tip of the penis.
As your bladder fills, nerve signals sent to your brain eventually trigger the need to urinate. When you urinate, nerve signals coordinate the relaxation of the pelvic floor muscles and the muscles of the urethra (urinary sphincter muscles). The muscles of the bladder tighten (contract), pushing the urine out.
Involuntary bladder contractions
Overactive bladder occurs because the muscles of the bladder start to contract involuntarily even when the volume of urine in your bladder is low. This involuntary contraction creates the urgent need to urinate.
Several conditions may contribute to signs and symptoms of overactive bladder, including:
- Neurological disorders, such as Parkinson's disease, strokes and multiple sclerosis
- High urine production as might occur with high fluid intake, poor kidney function or diabetes
- Medications that cause a rapid increase in urine production or require that you take them with lots of fluids
- Acute urinary tract infections that can cause symptoms similar to an overactive bladder
- Abnormalities in the bladder, such as tumors or bladder stones
- Factors that obstruct bladder outflow — enlarged prostate, constipation or previous operations to treat other forms of incontinence
- Excess consumption of caffeine or alcohol
- Declining cognitive function due to aging, which may make it more difficult for your bladder to understand the signals it receives from your brain
- Difficulty walking, which can lead to bladder urgency if you're unable to get to the bathroom quickly
- Incomplete bladder emptying, which may lead to symptoms of overactive bladder, as you have little urine storage space left
Often, the specific cause of an overactive bladder isn't known.
Sept. 26, 2014
- Marinkovic SP, et al. The management of overactive bladder syndrome. BMJ. 2012;344:e2365.
- South-Paul JE, et al. Current Diagnosis & Treatment in Family Medicine. 3rd ed. New York, N.Y.: The McGraw-Hill Companies; 2011. http://www.accessmedicine. mhmedical.com/book.aspx?bookID=377. Accessed July 17, 2014.
- Overactive bladder. American Urological Association. http://www.urologyhealth.org/urology/index.cfm?article=112. Accessed July 17, 2014.
- What I need to know about bladder control for women. National Institute of Diabetes and Digestive and Kidney Diseases. http://kidney.niddk.nih.gov/kudiseases/pubs/bcw_ez/. Accessed July 17, 2014.
- Gormley EA, et al. Diagnosis and treatment of overactive bladder (non-neurogenic) in adults: AUA/SUFU guidelines. Journal of Urology. 2012;188:2455.
- Treatment of overactive bladder in women. Rockville, Md.: Agency for Healthcare Research and Quality. http://www.ahrq.gov/downloads/pub/evidence/pdf/bladder/bladder.pdf. Accessed July 17, 2014.
- DuBeau CE. Approach to women with urinary incontinence. http://www.uptodate.com/home. Accessed July 17, 2014.
- Urodynamic testing. National Institute of Diabetes and Digestive and Kidney Diseases. http://kidney.niddk.nih.gov/kudiseases/pubs/urodynamic/. Accessed July 17, 2014.
- DuBeau CE. Treatment and prevention of urinary incontinence in women. http://www.uptodate.com/home. Accessed July 17, 2014.
- Wein AJ, et al. Campbell-Walsh Urology. 10th ed. Philadelphia, Pa.: Saunders Elsevier; 2012. http://www.clinicalkey.com. Accessed July 17, 2014.
- Lightner DJ (expert opinion). Mayo Clinic, Rochester, Minn. July 29, 2014.
- McGrother CW, et al. Etiology of overactive bladder: A diet and lifestyle model for diabetes and obesity in older women. Neurology and Urodynamics. 2012;31:487.
- Rohrstad M, et al. Onabotulinum toxin A (Botox) in the treatment of neurogenic bladder overactivity. Nephro-Urology Monthly. 2012;4:437.
- Ellsworth PI. The pharmacologic management of idiopathic overactive bladder in primary care. Journal of Family Practice. 2014;63(suppl):S38.
- Cook AJ. Decision Support System. Mayo Clinic, Rochester, Minn. May 29, 2014.