Endometriosis is a chronic condition characterized by the growth of tissue similar to the lining of the uterus (endometrium) in locations outside the uterine cavity. This misplaced tissue, called lesions or implants, causes inflammation and chronic pelvic pain. Bladder pain and other urinary issues are recognized symptoms that can be directly linked to the presence of endometriosis in the lower urinary tract.
Endometriosis of the Urinary System
Endometriosis lesions can affect various organs in the pelvic region. The urinary system is the second most common site outside of the reproductive organs, though overall involvement is relatively uncommon (about 1% of all endometriosis cases). The bladder is the organ most frequently affected, accounting for approximately 85% of urinary tract endometriosis cases.
This condition is categorized into two types based on tissue penetration. Superficial lesions grow on the outer surface of the bladder. Deep infiltrating endometriosis (DIE) is the second type, where the tissue grows into and through the muscle layers of the bladder wall. The presence of these implants causes bladder pain and dysfunction.
Mechanisms of Bladder Pain
The primary mechanism of bladder pain is the cyclical hormonal response of the ectopic tissue. These lesions respond to monthly hormonal fluctuations. During menstruation, the implants attempt to shed and bleed, causing localized irritation and inflammation within the bladder wall.
Repeated inflammatory cycles can trigger the formation of scar tissue (fibrosis) within the bladder muscle. This scarring reduces the bladder’s elasticity and capacity, contributing to persistent symptoms like urinary frequency and pressure.
Deep-seated lesions can also promote the growth of new nerve fibers (neuroangiogenesis) directly into the implants. The presence of these nerves, combined with inflammatory chemicals, sensitizes the local nervous system. This sensitization can lead to chronic pelvic pain that may be present consistently.
Recognizing Endometriosis-Specific Symptoms
Bladder pain caused by endometriosis is characterized by its timing. The most distinguishing feature is the catamenial nature of the symptoms, meaning they worsen or occur exclusively around the menstrual period. Patients often report increased urinary urgency, frequency, and pain with urination (dysuria) during their flow.
The pain is commonly felt in the suprapubic area, or just above the pubic bone, and may feel like a deep ache or severe cramping. Severe irritation can cause blood to appear in the urine (hematuria), which is specifically noticeable during menstruation.
Because these symptoms overlap with other common issues, bladder endometriosis is frequently misdiagnosed as a recurrent urinary tract infection (UTI) or Interstitial Cystitis (IC). Unlike a UTI, which responds to antibiotics, or IC pain, which relates to bladder fullness, endo-related symptoms are tied to the hormone-driven menstrual cycle. A persistent symptom pattern that does not resolve with standard UTI treatments should prompt an investigation into endometriosis.
Diagnosis and Management Strategies
Confirming bladder endometriosis begins with specialized imaging, including transvaginal ultrasound and magnetic resonance imaging (MRI). These tools can sometimes visualize the depth and size of a deep infiltrating lesion on the bladder wall. Imaging is not always conclusive, however, and may fail to detect superficial implants.
The definitive method for diagnosis remains laparoscopic surgery. A surgeon can visually inspect the outside of the bladder and excise any visible lesions. During the procedure, the surgeon may perform a cystoscopy, inserting a small scope into the bladder via the urethra, to view the inside lining and take a biopsy of suspicious tissue. A multidisciplinary approach, often involving both a gynecologist and a urologist, is necessary for complex cases.
Management strategies involve both medical and surgical pathways. Hormonal therapies, such as continuous oral contraceptives or GnRH agonists, are used to suppress the menstrual cycle and the cyclical bleeding of the implants. For deep lesions causing pain or compromising bladder function, surgical excision is the preferred treatment. This surgery involves carefully removing the implants, which may necessitate a partial cystectomy, where a section of the bladder wall is removed and repaired to preserve urinary function.