Ureteral Endometriosis and “Silent” Kidney Loss

When people think of endometriosis, they often think of pelvic pain, painful periods, pain during sex, or infertility. But endometriosis can sometimes affect organs beyond the reproductive system, including the urinary tract.

One rare but important form is ureteral endometriosis, where endometriosis involves one or both ureters — the narrow tubes that carry urine from the kidneys to the bladder.

Why does this matter? Because ureteral endometriosis can sometimes obstruct the flow of urine without causing obvious symptoms. If that obstruction persists, it can gradually damage the affected kidney and lead to irreversible loss of kidney function.

How can endometriosis affect the kidneys?

Your kidneys continuously produce urine, which travels through two narrow tubes — the ureters — before reaching the bladder. Think of a ureter like a small hose carrying water.

With ureteral endometriosis, endometriotic disease and associated fibrosis can involve the tissue around the ureter, compressing it from the outside. Less commonly, endometriosis can infiltrate the wall of the ureter itself.

Over time, this can narrow the ureter and make it harder for urine to drain from the kidney. As urine backs up, the ureter may become dilated (hydroureter) and the kidney may swell (hydronephrosis). If significant obstruction continues for long enough, pressure can progressively damage the kidney and reduce its function.

Why is it sometimes called “silent” kidney loss?

One of the challenges of ureteral endometriosis is that urinary obstruction may cause few, or even no, specific symptoms. Someone may therefore develop hydronephrosis without realizing that one of their ureters is obstructed.

Routine kidney blood tests can also be reassuring despite a problem affecting one kidney. Tests such as serum creatinine mainly reflect overall kidney function. If one kidney is functioning normally, it may compensate for reduced function in the other. This means normal blood tests alone cannot reliably exclude obstruction of one ureter or loss of function in one kidney. That is why imaging can be particularly important when ureteral involvement is suspected.

Who may be at greater risk?

Ureteral endometriosis is estimated to occur in about 0.08–1% of patients with endometriosis. It is most often associated with deep endometriosis, frequently affects the lower portion of the ureter, and is more often one-sided than two-sided.

Endometriosis involving structures close to the ureters — such as the uterosacral ligaments, parametrium, or pelvic sidewall — may raise particular concern for ureteral involvement.

Importantly, not everyone with endometriosis needs to assume their kidneys are at risk. The need to assess the urinary tract depends on the location and extent of disease, imaging findings, symptoms, and individual clinical circumstances.

What symptoms can occur?

Some people with ureteral endometriosis have no urinary symptoms at all. When symptoms do occur, they may include:

• pain in the flank, side, or lower back;
• pelvic pain;
• urinary discomfort;
• blood in the urine; or
• recurrent urinary tract symptoms.

Symptoms may also come from endometriosis elsewhere in the pelvis rather than directly from the ureter. Most importantly, the absence of urinary symptoms does not completely exclude ureteral obstruction.

How is ureteral involvement investigated?

Imaging is central to identifying ureteral obstruction and determining the extent of deep endometriosis.

Ultrasound

Transvaginal ultrasound performed by someone experienced in endometriosis imaging can assess the pelvis for deep endometriosis and may identify disease involving or compressing the ureter. Transabdominal renal ultrasound can assess the kidneys and upper urinary tract for hydronephrosis — an important sign that urine may not be draining normally.

Magnetic resonance imaging (MRI)

MRI can provide detailed mapping of deep endometriosis and its relationship with structures such as the ureters. It may be particularly useful when more extensive disease is suspected or for planning treatment.

Additional investigations

When obstruction or hydronephrosis is identified, additional investigations may be needed to determine how well each kidney is functioning and to define the site and severity of the obstruction. Depending on the individual situation, these may include functional renal imaging, such as a renal scan, or specialized urinary-tract imaging.

Can ureteral endometriosis be treated?

Yes — and treatment is highly individualized. When ureteral obstruction threatens kidney function, the priority is to relieve the obstruction and preserve renal function whenever possible. Surgical options can range from freeing the ureter from surrounding endometriosis and fibrosis (ureterolysis) to removing and reconstructing an affected segment of ureter in more extensive cases.

Hormonal treatments can help suppress active endometriosis in selected circumstances, but established fibrotic obstruction may not resolve with hormonal therapy alone. Significant obstruction or hydronephrosis therefore requires specialist assessment rather than relying on symptom improvement alone. Management may involve a multidisciplinary team, including specialists in endometriosis surgery and urology.

The key message

Ureteral endometriosis is rare, but its consequences can be serious. Because obstruction may develop without obvious urinary symptoms, ureteral involvement can progress before it is recognized.

This does not mean that everyone with endometriosis is at risk of kidney damage. Instead, it highlights the importance of considering the urinary tract when there is deep endometriosis, suspected ureteral involvement, hydronephrosis, or other clinical concern. Imaging of the kidneys and urinary tract can identify obstruction before further renal damage occurs.

Awareness of rare complications such as ureteral obstruction can help protect the kidney function of affected patients.