Endometriosis is a condition where tissue similar to the lining of the uterus grows outside the uterus. This misplaced tissue thickens, breaks down, and bleeds with each menstrual cycle. Since the blood has no way to leave the body, this leads to irritation, inflammation, and scar tissue formation. While pelvic pain and painful periods are widely known symptoms, frequent urination is often overlooked but can significantly impact quality of life.
The Endometriosis-Urination Connection
Endometriosis can directly cause frequent urination when lesions develop on or near the urinary tract, a condition known as urinary tract endometriosis. The most common site is the bladder itself (vesical endometriosis), accounting for approximately 85% of urinary tract cases. Even lesions located on adjacent structures, such as the uterosacral ligaments or the peritoneum near the bladder, can still cause symptoms.
This misplaced tissue is hormonally responsive; lesions swell and bleed during the menstrual cycle, leading to cyclical irritation of the bladder wall. This irritation makes the bladder more sensitive, triggering the urge to urinate more often, even when the bladder is not full. The frequency and urgency often worsen leading up to and during the menstrual period, suggesting the symptoms are linked to the underlying disease.
Endometriosis lesions can also affect the ureters, the tubes that carry urine from the kidneys to the bladder. While less common than bladder involvement, this is a serious issue that can lead to an obstruction of urine flow, causing pain in the lower back or kidney area. The proximity of pelvic organs means disease activity in one area can affect the function of another.
Mechanisms of Urinary Frequency
The feeling of needing to urinate frequently, even when the bladder is not full, results from several processes triggered by endometriosis. One primary mechanism is chronic inflammation, a hallmark of the disease. The endometrial-like tissue releases inflammatory mediators, such as prostaglandins and cytokines, into the surrounding environment.
These chemical signals irritate the sensory nerves lining the bladder wall, making them hypersensitive. This increased nerve sensitivity causes the bladder to signal “full” prematurely, leading to a frequent sensation of urgency. This irritation can also make the bladder muscle more reactive, resulting in spasms and the frequent need to empty.
Another significant cause is the formation of adhesions, which are bands of scar tissue that develop as the body attempts to heal from internal bleeding and inflammation. These adhesions can physically tether or pull on the bladder, restricting its normal expansion and reducing its functional capacity. When the bladder cannot expand fully, it reaches its limit more quickly, translating to urgency and increased frequency of urination.
In cases of deeply infiltrating endometriosis (DIE), lesions can physically invade the muscle wall of the bladder. This direct invasion causes structural damage, reducing the bladder’s elasticity and overall volume. The physical presence of a nodule within the bladder wall acts as a constant source of irritation, leading to pain that may worsen as the bladder fills and a persistent need to empty.
Ruling Out Other Causes
While endometriosis is a potential cause of frequent urination, many other conditions produce similar symptoms, making a proper diagnosis necessary. Urinary Tract Infections (UTIs) are the most common cause of sudden urinary frequency, urgency, and painful urination, and must be ruled out with a simple urine test. Endometriosis symptoms often mimic those of a UTI, but without the presence of bacteria.
Other common causes include Overactive Bladder (OAB), a syndrome characterized by urgency, frequency, and nocturia without a clear underlying pathology. Interstitial Cystitis (IC), also known as bladder pain syndrome, causes chronic bladder pressure and pain, often overlapping with endometriosis symptoms. Individuals with endometriosis have an increased risk of developing IC, further complicating diagnosis.
Systemic conditions like diabetes can also cause frequent urination, as the body attempts to excrete excess sugar through the urine, leading to a higher volume of fluid output. Hormonal changes, such as the drop in estrogen levels associated with menopause, can affect the lining of the urethra and bladder, contributing to frequency and urgency. A detailed medical history, physical examination, and specific diagnostic tests are necessary to distinguish between these possibilities and determine the true cause of the urinary symptoms.
Managing Urinary Symptoms in Endometriosis
Treatment for frequent urination linked to endometriosis focuses on managing the underlying disease to stop bladder irritation. Hormonal suppression is a common medical approach aimed at reducing the growth and activity of the endometrial lesions. Medications like oral contraceptives, progestins, or Gonadotropin-releasing hormone (GnRH) agonists create a low-estrogen environment, which can cause lesions to shrink and relieve associated inflammation.
For more severe or deeply infiltrating vesical endometriosis, surgical intervention is often the most effective treatment. The goal of surgery is the complete excision of the endometrial tissue from the bladder wall and surrounding structures. This is typically performed using minimally invasive laparoscopic techniques by a surgeon specializing in endometriosis.
If the lesion has deeply penetrated the bladder muscle, a procedure called partial cystectomy may be required, which involves surgically removing the affected section of the bladder. Following surgery, a temporary urinary catheter or ureteric stent may be placed to allow the bladder to heal properly. Combining surgical removal with subsequent hormonal therapy can offer the best long-term relief for these urinary symptoms.