Ureteral Endometriosis

When endometriosis tissue grows outside the uterus, it is diagnosed as endometriosis [1]. These benign growths can implant themselves in various locations within the body, often resulting in significant discomfort. While they are most commonly found in the pelvic region, endometriosis lesions can manifest in unexpected areas, including the intestines, brain, and lungs. A rare form of endometriosis occurring in approximately 1% of patients is ureteral endometriosis [2]. In this particular variant, the ureters are affected. Today, I will delve into the symptoms that these nodules at this location can cause and explore the available treatment options.

What is Ureteral Endometriosis?

Ureteral endometriosis can be categorized into two distinct forms:

  • Extrinsic Ureteral Endometriosis: In this variation, endometriosis tissue surrounds the ureter and infiltrates from the outside. This form is predominant in clinical practice when dealing with ureteral endometriosis [2].
  • Intrinsic Ureteral Endometriosis: In this form, endometriosis penetrates directly through the muscular layer or the topmost cell layer of the ureter [2]. This form is relatively rare.

It is worth noting that, often, only one ureter is affected. Interestingly, endometriosis occurs more frequently on the left ureter than right [3]. Additionally, research has pinpointed where endometriosis most commonly manifests. These endometriosis lesions are typically found in the lower third of the ureter, close to the urinary bladder, within the pelvic area. Individuals with ureteral endometriosis often have endometriosis lesions in other parts of the body [3, 4, 5].

Good to Know!

Typically, each person possesses two kidneys, and the ureters connect directly to them, carrying urine from the pelvic wall to the bladder [6]. Although endometriosis lesions on the ureter are relatively rare, they are more common in women with deep infiltrating endometriosis [4, 7, 3, 8].

Symptoms of Ureteral Endometriosis

If you are curious about recognizing endometriosis on the ureter, it is essential to understand that endometriosis can present a wide range of symptoms. Common indicators include:

  1. Pain during menstruation.
  2. Extended menstrual bleeding.
  3. Shortened menstrual cycles.
  4. Bowel movement issues.
  5. Pain during urination or sexual intercourse.
  6. Difficulty conceiving [9].

However, when endometriosis affects the ureter, it may not necessarily cause immediate symptoms.

In such cases, individuals may experience what is known as asymptomatic urinary retention in the kidney, a condition that can lead to kidney function loss as it progresses [8, 4]. Asymptomatic means that no apparent symptoms signal the complication. Urinary stasis in the kidney can occur when urine regurgitates from the urinary tract into the kidney or when there is an obstruction in urine outflow [10]. Endometriosis can alter the ureter in a way that hinders the normal drainage of urine. In these situations, endometriosis typically exerts pressure on the ureter from the outside, obstructing urine flow. This creates a backup, akin to a dam, causing urine to accumulate in the kidney and be unable to exit. If you have a blocked kidney, you may experience pain in your lower back or the side of your abdomen [10].

An ultrasound from the flank is a diagnostic tool that a doctor can use to detect urinary retention.

What Causes Ureteral Endometriosis?

The exact cause of ureteral endometriosis remains a mystery, and its development has not been definitively explained. However, experts have put forth several theories regarding its mechanisms. The hypothesis suggests that endometriosis cells spread through lymphatic channels or blood vessels, similar to metastasis, and attach themselves to urological structures. This mechanism may also be relevant in cases of endometriosis affecting the bladder.

Another theory proposes that stem cells transform, developing typical endometriosis lesions [2].

Several risk factors have been identified in connection with ureteral endometriosis:

  • Diagnosis of deep infiltrating endometriosis  [3, 4, 7, 8].
  • Presence of endometriosis node at the septum rectovaginale (the partition between the vagina and the rectum) larger than 3 cm [4, 7].
  • The existence of ‘kissing ovaries,’ where the ovaries touch in the midline [11].

Diagnosing Ureteral Endometriosis

Detecting endometriosis tissue on the ureter can be challenging, as it may go unnoticed for an extended period. A comprehensive diagnosis is crucial, especially when considering relevant risk factors. For instance, if there is a palpable endometriosis node on the septum between the vagina and rectum (which can be felt through the rectum), it is prudent to consider the possibility of ureteral endometriosis. The same consideration applies if endometriosis is evident on the pelvic wall or the ultrasound reveals ‘kissing ovaries.’ Even without kidney-related symptoms, a kidney ultrasound is recommended in such cases. This examination assesses kidney function and can be valuable for monitoring purposes. Both before and after surgery, a renal ultrasound is highly beneficial. It allows preoperative evaluation for any signs of congestion and facilitates coordination with the urologist if surgery is required.

When the ureter is suspected to be compromised, a urologist should conduct a thorough examination. In specific situations, such as congested renal pelvis or the intrinsic form of ureteral endometriosis, further diagnostic procedures like kidney scintigraphy or MRI (magnetic resonance imaging) may be warranted [2].

Good to Know!

Medical professionals employ various classification systems to assess the extent of endometriosis. While the rASRM classification provides information about the spread of endometriosis, the ENZIAN classification specifically describes deep infiltrating endometriosis. If a diagnosis of ureteral endometriosis is made, including the ENZIAN classification on the operative report and in the physician’s notes is highly beneficial.

How Ureteral Endometriosis is Treated

Treatment of ureteral endometriosis is typically approached within the broader context of addressing endometriosis as a whole.

The objective is to manage deep infiltrating endometriosis within the pelvic region and endometriosis lesions on the ovaries to prevent further harm to the ureters and minimize the risk of recurrences [12]. Surgery is the primary treatment method, typically performed through a laparoscopic procedure involving three to four tiny abdominal incisions and a camera. This minimally invasive approach allows physicians to expose the ureter from surrounding tissue layers and free it from unwanted endometriosis tissue, a procedure known as ureterolysis. Sometimes, a catheter or ureteral splints may be placed before surgery, although this would be discussed with the patient beforehand  [4, 5, 13].

Often, it is possible to remove the endometriosis tissue located externally to the ureter, facilitating the recovery of the ureter from the narrowing caused by the endometriosis tissue.

However, in certain situations, surgery may reveal that a portion of the ureter needs to be removed [13]. In such cases, a urologist can reconnect the ureter, and in rare instances, reimplantation of the ureter (ureterocystoneostomy) into the bladder may be necessary [14]. This is usually considered only when the ureter has been severely infiltrated by intrinsic ureteral endometriosis. The typical approach is to initially attempt to clear the ureter of unwanted tissue and observe its recovery post-surgery. Removal or reimplantation of parts of the ureter is typically considered only if other treatments prove ineffective [2].

It is essential to conduct a renal ultrasound before discharge following surgery on the pelvic wall, near the ureter, or specifically in cases of surgery for endometriosis on the ureter. This enables the assessment of improvements in pre-existing urinary retention and identifying new urinary retention or any worsening, which may be attributed to surgical complications.

In a Nutshell

Endometriosis of the ureter is a relatively rare condition, making it particularly insidious that patients may not necessarily experience symptoms. When symptoms arise, they often manifest as low back or flank pain, although these symptoms tend to occur later. The precise mechanisms underlying the development of ureteral endometriosis are still a topic of discussion in the medical community. There are a couple of prevailing theories, including the possibility of endometriosis tissue spreading through the bloodstream or lymphatic system. Another theory is that stem cells may transform endometriosis cells, an idea supported by some experts.

Several risk factors are associated with ureteral endometriosis, and individuals with specific characteristics may be more susceptible. Women with ‘kissing ovaries’, deep infiltrating endometriosis, or endometriosis nodes on the septum between the vagina and rectum are at a higher risk of developing ureteral endometriosis.

Diagnosis often involves various imaging techniques such as ultrasound, MRI, and scintigraphy.

The primary mode of treatment is typically surgical, aiming to free the ureter from surrounding endometriosis tissue. In more severe cases, reimplantation of the ureter or partial removal of the ureter may be necessary as part of the treatment process. It is important to emphasize that early diagnosis and appropriate management are crucial for preserving kidney function and overall well-being in individuals with ureteral endometriosis.


  1. Dietrich, Klaus: Gynaecology and Obstetrics (Springer Textbook) 2nd edition, Springer Verlag.
  2. German Society of Gynecology and Obstetrics: Guideline Program. Diagnosis and therapy of endometriosis. August 2020.
  3. Alves J, Puga M, Fernandes R, Pinton A, Miranda I, Kovoor E, Wattiez A. Laparoscopic Management of Ureteral Endometriosis and Hydronephrosis Associated With Endometriosis. J Minim Invasive Gynecol. 2017 Mar-Apr;24(3):466-472. doi: 10.1016/j.jmig.2016.11.018. Epub 2017 Jan 12. PMID: 28089810.
  4. Knabben L, Imboden S, Fellmann B, Nirgianakis K, Kuhn A, Mueller MD. Urinary tract endometriosis in patients with deep infiltrating endometriosis: prevalence, symptoms, management, and proposal for a new clinical classification. Fertil Steril. 2015 Jan;103(1):147-52. doi: 10.1016/j.fertnstert.2014.09.028. Epub 2014 Oct 28. PMID: 25439849.
  5. Barra F, Scala C, Biscaldi E, Vellone VG, Ceccaroni M, Terrone C, Ferrero S. Ureteral endometriosis: a systematic review of epidemiology, pathogenesis, diagnosis, treatment, risk of malignant transformation and fertility. Hum Reprod Update. 2018 Nov 1;24(6):710-730. doi: 10.1093/humupd/dmy027. PMID: 30165449.
  6. Wie funktionieren die Nieren? | Gesundheitsinformation.de
  7. Leone Roberti Maggiore U, Ferrero S, Candiani M, Somigliana E, Viganò P, Vercellini P. Bladder Endometriosis: A Systematic Review of Pathogenesis, Diagnosis, Treatment, Impact on Fertility, and Risk of Malignant Transformation. Eur Urol. 2017 May;71(5):790-807. doi: 10.1016/j.eururo.2016.12.015. Epub 2016 Dec 28. PMID: 28040358.
  8. Seracchioli R, Raimondo D, Di Donato N, Leonardi D, Spagnolo E, Paradisi R, Montanari G, Caprara G, Zannoni L. Histological evaluation of ureteral involvement in women with deep infiltrating endometriosis: analysis of a large series. Hum Reprod. 2015 Apr;30(4):833-9. doi: 10.1093/humrep/deu360. Epub 2015 Jan 12. PMID: 25586785.
  9. Endometriose-Vereinigung:Broschuere Begleiterkrankungen 2019
  10. Pschyrembel Online | Harnstauungsniere
  11. Ghezzi F, Raio L, Cromi A, Duwe DG, Beretta P, Buttarelli M, Mueller MD. “Kissing ovaries”: a sonographic sign of moderate to severe endometriosis. Fertil Steril. 2005 Jan;83(1):143-7. doi: 10.1016/j.fertnstert.2004.05.094. PMID: 15652900
  12. Li L, Leng JH, Lang JH, Liu ZF, Sun DW, Zhu L, Fan QB, Shi JH. [Diagnosis and treatment of ureter endometriosis]. Zhonghua Fu Chan Ke Za Zhi. 2011 Apr;46(4):266-70. Chinese. PMID: 21609579
  13. Mereu L, Gagliardi ML, Clarizia R, Mainardi P, Landi S, Minelli L. Laparoscopic management of ureteral endometriosis in case of moderate-severe hydroureteronephrosis. Fertil Steril. 2010 Jan;93(1):46-51. doi: 10.1016/j.fertnstert.2008.09.076. Epub 2008 Nov 5. PMID: 18990377.
  14. Ceccaroni M, Ceccarello M, Caleffi G, Clarizia R, Scarperi S, Pastorello M, Molinari A, Ruffo G, Cavalleri S. Total Laparoscopic Ureteroneocystostomy for Ureteral Endometriosis: A Single-Center Experience of 160 Consecutive Patients. J Minim Invasive Gynecol. 2019 Jan;26(1):78-86. doi: 10.1016/j.jmig.2018.03.031. Epub 2018 Apr 12. PMID: 29656149.
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Dipl.-Ges.oec. Jennifer Ann Steinort