Endometriosis is a common disorder where tissue similar to the lining of the uterus, called the endometrium, grows outside the uterine cavity. This ectopic tissue responds to the body’s hormonal cycle, leading to inflammation and pain. Hematuria, the presence of blood in the urine, can sometimes be directly linked to this condition. When endometriosis lesions infiltrate the urinary tract, a rare but significant complication known as Urinary Tract Endometriosis (UTE) occurs, which can lead to blood being shed into the urine.
The Mechanism of Urinary Tract Endometriosis
Urinary Tract Endometriosis (UTE) is a rare form of the disease, affecting approximately 0.3% to 12% of people with endometriosis; this rate is higher in cases of deep infiltrating endometriosis. The bladder is the most frequent site of involvement, accounting for about 70% to 85% of UTE cases. Endometrial implants invade the bladder wall, which can cause symptoms like painful urination, urinary frequency, and hematuria.
The mechanism for hematuria in UTE is directly related to the hormonal responsiveness of the ectopic tissue. Like the normal endometrium, implants in the bladder or ureter respond to cyclical hormonal changes during the menstrual cycle. This causes the tissue to proliferate and then bleed or “shed” during menstruation. Because the blood is contained within the urinary structure, it mixes with the urine, resulting in cyclic hematuria that coincides with the menstrual period.
While the bladder is the most common site, the ureters are the second most common location, involved in about 9% to 23% of UTE cases. Endometriosis in the ureter is particularly concerning because the lesions can grow around or into the ureteral wall, leading to obstruction. This blockage, known as hydroureter, causes urine to back up, which can then lead to swelling of the kidney, a condition called hydronephrosis.
Ureteral obstruction can be silent, with nearly 50% of ureteral endometriosis cases being asymptomatic, but it can ultimately cause permanent kidney damage if not identified and treated. The hematuria from ureteral involvement is less frequent than with bladder involvement, and when it does occur, it is typically a result of the intrinsic type of ureteral endometriosis where the implant directly involves the lining. Therefore, while hematuria is a direct sign of urinary tract involvement, the absence of this symptom does not rule out potentially serious ureteral disease.
Diagnostic Procedures for Confirming the Source
When a person of reproductive age presents with hematuria, a detailed diagnostic workup is necessary to distinguish the cause from more common sources like infection or kidney stones. The initial steps involve a urinalysis and urine culture, which are performed to rule out a urinary tract infection (UTI) as the source of the bleeding. If the urine culture is negative for bacteria, the focus shifts to non-infectious causes. A detailed patient history is crucial, particularly noting if the hematuria is cyclical, worsening specifically around the time of menstruation, as this strongly suggests endometriosis.
Imaging studies are employed next to visualize the urinary tract and look for masses or obstructions. Computed Tomography (CT) scans or Magnetic Resonance Imaging (MRI) are used to detect endometriotic nodules on the bladder or check the ureters for signs of deep infiltrating endometriosis. MRI is helpful for mapping deep lesions, providing a clear view of the extent of invasion into the bladder wall or surrounding tissues. To evaluate the upper urinary tract and check for ureteral obstruction, specialized imaging like an Intravenous Pyelogram (IVP) or CT/MR urography may be necessary.
The definitive diagnosis of bladder endometriosis often requires a procedure called a cystoscopy, where a thin, lighted tube with a camera is inserted into the bladder. This allows a urologist to visually inspect the bladder lining for suspicious lesions, which often appear as bluish, reddish, or nodular masses. If a lesion is found, a biopsy is taken during the cystoscopy to obtain a tissue sample. The presence of both endometrial glands and stroma in the biopsy confirms the diagnosis of endometriosis as the source of the hematuria, ruling out other concerns like bladder cancer.
Management and Treatment Approaches
Once Urinary Tract Endometriosis is confirmed as the source of hematuria, treatment strategies aim to manage symptoms, prevent disease progression, and preserve organ function. Medical management typically involves hormonal suppression therapy. Medications such as Gonadotropin-Releasing Hormone (GnRH) agonists, which temporarily suppress ovarian function, or continuous low-dose oral contraceptives are frequently used to induce a hormone-suppressed state. This approach often provides relief from cyclic hematuria and other urinary symptoms by preventing the implants from shedding.
While hormonal therapy can effectively manage the symptoms, it generally does not remove the endometriotic lesion itself, and symptoms often return once the medication is stopped. For lesions that are large, cause severe symptoms, or, most importantly, are causing ureteral obstruction, surgical intervention is often necessary. The specific surgical procedure depends heavily on the location and depth of the endometriotic invasion.
For lesions limited to the bladder, surgery involves the excision of the endometriotic nodule. If the lesion has infiltrated deeply into the bladder muscle, a partial cystectomy (removal of a portion of the bladder wall containing the implant) may be required. For ureteral involvement, the surgical approach is more complex due to the risk of compromising kidney function. Procedures can range from ureterolysis (dissection to free the ureter from surrounding scar tissue) to more extensive measures like segmental resection followed by reanastomosis or ureteral reimplantation into the bladder. The goal of surgery for ureteral endometriosis is to restore the free flow of urine and prevent kidney failure.