Interstitial Cystitis/Bladder Pain Syndrome

Excerpt

Interstitial cystitis/bladder pain syndrome (IC/BPS), formerly called interstitial cystitis, is a chronic (>6 weeks duration) pelvic condition that affects or appears to affect the urinary bladder with symptoms of discomfort, pressure, or pain. The condition is characterized by chronic inflammation and lower urinary tract symptoms, not due to infection or any other clearly identifiable cause. As the definition varies somewhat between different societies and organizations, we will use the American Urological Association (AUA) definition.

In many cases, because IC/BPS remains a diagnosis of exclusion, the condition is often identified late or misdiagnosed, particularly in men, as chronic prostatitis/chronic pelvic pain syndrome or overactive bladder.

Patients often describe pain in the bladder or suprapubic region, with an intense sensation of urinary urgency. This sensation is worsened by bladder filling but is temporarily relieved by passing urine, which typically results in severe urinary frequency. This may be during the daytime and/or overnight. The urinary frequency is generally refractory to standard overactive bladder therapy, which should suggest considering a diagnosis of IC/BPS.

There may also be other symptoms, such as pain or burning when passing urine (dysuria) and discomfort during sexual intercourse, causing dyspareunia in women and ejaculatory pain in men. These chronic symptoms profoundly impact the patient's emotional, psychological, and social well-being as well as their quality of life.

Anatomy

The urinary bladder is a hollow viscus organ located in the pelvis, anterior to the rectum in both sexes and the uterus in females. It is partially covered by the peritoneum on the superior surface. It is composed of 4 layers.

1. The mucosa, which contains the transitional epithelium, is the bladder lining and allows for the stretch of the urinary bladder. When stretched, the surface is smooth, but when relaxed, folds form in the mucosa, known as rugae. The mucosa also produces glycosaminoglycans (GAGs), making up the superficial coating that protects the mucosa from direct contact with potentially inflammatory urinary irritants.

1. The submucosa is composed of elastic connective tissue and further assists with the stretch of the bladder.

1. The muscularis layer (detrusor muscle) is composed of several layers (inner longitudinal, middle circular, and outer longitudinal) of smooth muscle oriented in multiple directions, which produce a uniform, simultaneous contraction that efficiently empties the bladder when a contraction is triggered.

1. The muscles also form a small band that encircles the area between the opening of the bladder and the urethra. This is known as the internal urinary sphincter and is controlled by the autonomic nervous system. Another distal band around the urethra controls conscious voiding, called the external sphincter, composed of skeletal muscle and innervated by the somatic nervous system.

1. In women, the external urethral sphincter is distal and inferior to the bladder neck. The clitoris and pubic bone are anterior, while the anterior vaginal roof is immediately posterior. The external sphincter in women is also known as the urogenital sphincter.

1. The fibrous connective tissue layer is the outermost covering of the bladder, except for the superior surface, which is covered by the parietal peritoneum.

The bladder floor also contains a fixed, triangular area called the trigone. The openings to each ureter and the outlet to the urethra form the trigone. There are 3 apices, with a ureteral orifice in each lateral wing and the third arm entering the urethra. The trigone is located at the posterior base, also known as the fundus of the urinary bladder.

The distal intramural portion of each ureter follows a shallow submucosal course as it travels through the detrusor muscle into the bladder. This anatomy acts as an anti-reflux mechanism or valve to prevent urine reflux into the kidney.