Ureteral Endometriosis

Ureteral endometriosis is a form of urinary tract endometriosis (UTE). UTE is a rare form of deep infiltrating endometriosis (DIE) in which the growth of endometriosis (tissue resembling the endometrium) occurs in the bladder, ureters, and kidneys. DIE usually develops after ovarian endometriomas spill (cyst rupture) into other parts of the abdomen and pelvis.

Ureteral endometriosis can be either extrinsic or intrinsic. Extrinsic ureteral endometriosis results from endometriosis lesions occurring outside the ureter and compressing it. Intrinsic ureteral endometriosis, which accounts for nearly 20% of cases, occurs within the wall, muscle, and inner layers of the ureter.

Prevalence

UTE affects between 0.3% and 12% of endometriosis cases and between 20% and 52.6% of those diagnosed with DIE.

UTE predominantly occurs in the bladder (85%), but it can also affect the ureter (10%), kidneys (4%), and urethra (2%).

What causes ureteral endometriosis?

The exact cause for endometriosis itself is not fully clear. This makes it all the more complex to properly explain the cause of ureteral endometriosis. The common theories used to explain the origin of ureteral endometriosis include retrograde menstruation, stem cells, and immune factors.

In some women, UTE may also be iatrogenic, resulting from previous Caesarean sections.

What are the symptoms?

UTE lesions that often occur superficially on the peritoneum do not grow into the bladder. But they can cause pain when having a full bladder or when passing urine. However, distinguishing this pain from the one that arises as a result of other forms of pelvic endometriosis is difficult.

Superficial lesions can also occur on the ureters. They can impact the functioning of nerves that control the bladder, vagina, and bowel movements.

Symptoms of UTE overlap with that of peritoneal endometriosis. Women with UTE experience pelvic pain and dysuria (pain with urination) along with frequent urinary tract infections, changes to urination frequency, hematuria (blood in the urine), and rarely, urinary incontinence. Nearly 50% of ureteral endometriosis cases, however, are asymptomatic with about 25% of women experiencing flank pain and 15% having hematuria. Other symptoms include painful periods and intercourse.

The DIE forms of UTE also cause symptoms such as pelvic pain, dysuria, and in some cases, hematuria. Ureteral endometriosis can affect the free passage of urine from the kidneys to the bladder. This can result in hydroureter (dilation of ureters due to accumulation of urine) or even hydronephrosis (enlargement of kidneys due to blockage and accumulation of urine). Both of these can lead to severe back pain and potential kidney failure without timely intervention.

How does endometriosis affect the ureters?

Endometriosis can involve the ureters through the development of deep infiltrating lesions or dense fibrotic adhesionsthat compress or encase these urine-conducting structures. This involvement may result in partial or complete ureteral obstruction, particularly when endometriotic tissue infiltrates the pelvic sidewalls or extends around the uterine arteriesinto the retroperitoneal space.

Importantly, ureteral endometriosis may initially be asymptomatic, making early detection challenging. If unrecognized, progressive obstruction can lead to hydronephrosis—a condition marked by the swelling of the kidney due to urine backup—and ultimately compromise renal function. Some patients may develop flank pain, recurrent urinary tract symptoms, or signs of renal impairment such as elevated serum creatinine levels on routine blood tests. In some cases, laboratory abnormalities may be the only clue, underscoring the need for a high index of suspicion in at-risk individuals.

How can we recognize or assess ureteral involvement in endometriosis?

Ureter endometriosis is diagnosed through a combination of imaging studies that pinpoint ureteral obstruction, often confirmed by direct visualization via laparoscopy. Magnetic Resonance Imaging (MRI) of the pelvis offers high-resolution views, allowing us to see deep infiltrating endometriotic lesions that might be compressing or encasing the ureter. 

This imaging often reveals associated hydronephrosis (swelling of the kidney due due to urine backup). Ultrasound or Computed Tomography (CT) urography can further confirm the dilation of the renal collecting system and help us pinpoint the exact level of the blockage. For a functional assessment, a diuretic renogram helps us quantify any loss of kidney function caused by chronic obstruction.

How rare is ureteral endometriosis?

The prevalence of ureteral endometriosis (UE) varies widely, ranging from 0.01% to 1.7% among women with endometriosis, according to different case series reported in the literature. UE most commonly affects women between the ages of 30 and 35, and it is often discovered incidentally during laparoscopy for advanced or extensive endometriosis. However, it’s important to note that prevalence rates may be influenced by selection bias, as many clinical studies are conducted at tertiary referral centers that specialize in managing severe or complex endometriosis cases.

It’s crucial to maintain a high index of suspicion in patients who present with unexplained upper urinary tract dilation or flank discomfort. Advanced imaging techniques like MRI or CT urography, followed by diagnostic laparoscopy when indicated, allow for timely identification and focused treatment to preserve renal health.

Diagnosing ureteral endometriosis

Diagnosing ureteral endometriosis can be quite challenging. It is, therefore, is important to consult a surgeon who can listen to and understand your symptoms. Initial stages of diagnosis of endometriosis affecting any area include taking the patient’s medical history followed by pelvic examination and imaging techniques such as ultrasound, sonohysterography, or magnetic resonance imaging (MRI) to identify the location, and stage of the disease.

Intravenous pyelogram (IVP) is a good imaging technique to predict intrinsic forms of ureteral endometriosis. IVP also helps to evaluate ureter structure after treatment.

Transabdominal ultrasonography can help visualize ureter structure and obstruction in the pelvic region. It can also help see other potential sites of endometriosis lesions in the pelvis. When combined with transvaginal ultrasonography, it is possible to visualize the region from the anterior parametrium (the connective tissue that surrounds the uterus separating the cervix from the bladder) to the renal pelvis (upper end of the ureter).

Laparoscopic excision surgery followed by histological examination is the gold standard for confirming endometriosis in the urinary tract. The presence of other urinary tract infections and neoplasms (tumors) are excluded before confirming ureteral endometriosis.

Treatment

The aim of ureteral endometriosis treatment is to remove endometriosis lesions in the urinary tract and preserve renal function. In cases of mild ureteral endometriosis, medical management with GnRH analogs, combined oral contraceptives, progestin, and aromatase inhibitors may help. However, this is not recommended if disease progression or recurrence is expected in which case surgical methods are the best option.

Also, medical treatment alone cannot revert the fibrosis resulting from ureteral endometriosis that leads to ureter obstruction. Therefore, surgical intervention is usually necessary for both intrinsic and extrinsic forms of ureteral endometriosis.

The kidney can be preserved if it still has a greater than 10% glomerular filtration rate (GFR). GFR is a measure of how much blood passes through the kidney’s glomeruli (structures in the nephron that filter blood) per minute. A less than 10% GFR may mean that the kidney needs to be removed (nephrectomy).

Prior to any surgical procedure (as long as there is no complete ureteral obstruction), ureterolysis is performed to free the ureter from any pressure to avoid injury. The actual surgical procedure and anatomical corrections involved thereafter depend on the extent of damage, segment of the ureter involved, and renal function.

Dr. Seckin’s team is able to isolate and remove all forms of endometriosis, including the deep infiltrating forms in the ureter, using laparoscopic excision surgery for lasting relief. Using a patented Aqua Blue Contrast dye to easily identify endometriosis lesions combined with “cold excision” Dr. Seckin minimizes scarring compared to any of the other disease management methods.