Ureteral endometriosis

When endometrial tissue grows outside the uterus, doctors call it endometriosis [1]. The benign growths can settle in many places in the body and cause severe discomfort. They are particularly frequently observed in the pelvis. However, endometriosis lesions can also occur in the intestines, brain and even lungs. A rare form that occurs in about one percent of patients is called ureteral endometriosis [2]. In this case, the ureters are affected. Today, I’ll tell you what symptoms the nodules at this site can cause and how they are treated.

What is ureteral endometriosis?

Ureteral endometriosis can be divided into two different forms:

  • Extrinsic ureteral endometriosis: In this case, endometriosis tissue surrounds the ureter and invades from the outside. This form dominates in everyday medical practice when it comes to ureteral endometriosis [2].
  • Intrinsic ureteral endometriosis: In this form, the endometriosis pushes directly through the muscle layer or the top cell layer of the urethra [2].
    This form is rather rare.

Often, only one ureter is affected. It is interesting to note that endometriosis occurs far more often on the leftUreter (ureter) than on the right.[3] Science also has an answer to the exact location where endometriosis occurs most often on the ureter. Thus, the endometriosis lesions can be identified mainly in the lower third of the ureter, quite close to the urinary bladder, in the pelvic area. Patients with ureteral endometriosis usually have endometriosis lesions in other body regions as well [3, 4, 5].

Good to know.

As a rule, each person has two kidneys. The ureters connect directly to them and have the function of carrying urine in the pelvic wall to the bladder [6]. Although endometriosis lesions on the ureter are comparatively rare, they are much more common in women with deep infiltrating endometriosis [4, 7, 3, 8].

Endometriosis on the ureter: symptoms

For sure you are interested in how to notice endometriosis on the ureter. Endometriosis, as you may know, can lead to a wide variety of symptoms. Leading symptoms include pain during periods, prolonged bleeding time, a shortened menstrual cycle, and problems with bowel movements. Pain during urination or sexual intercourse is also possible. In addition, some women suffer from an unfulfilled desire to have children [9]. If endometriosis tissue is located on the ureter, this does not necessarily trigger symptoms directly.

Often, in this context, there is a so-called asymptomatic urinary retention kidney, which can lead to a loss of kidney function in the further course [8, 4]. Asymptomatic means that no symptoms indicate the complication. Urinary stasis kidney may result when urine flows from the urinary tract back into the kidney or urine outflow is obstructed [10]. A ureter may actually be altered from endometriosis in such a way that there may be problems draining urine. Usually in this case, the endometriosis presses on the ureter from the outside, making it difficult for urine to flow through the ureter. This results in a backlog, like a dam, so that at some point the urine also backs up in the kidney and cannot be removed. If you have a congested kidney, you may notice pain in your lower back or in the side of your abdomen [10].

The doctor can see the urinary retention in the ultrasound from the flank!

What causes ureteral endometriosis?

The mystery surrounding the development of endometriosis of the ureter has not yet been solved. However, experts discuss various mechanisms of development. On the one hand, it is assumed that the endometriosis cells spread like metastases via the lymphatic channels or blood vessels and thus attach themselves to the urological body structures. This could also play a role in endometriosis on the bladder. On the other hand, there is a theory that stem cells transform into endometriosis cells, allowing the typical endometriosis lesions [2].

The following risk factors are cited:

  • deep infiltrating endometriosis has been diagnosed [3, 4, 7, 8].
  • there is an endometriosis node at the septum rectovaginale (partition between the vagina and the rectum) larger than 3 cm [4, 7].
  • the presence of so-called “kissing ovaries”, where the ovaries touch in the midline [11].

Ureteral endometriosis: diagnosis

Since endometriosis tissue on the ureter can remain undetected for a long time, a thorough diagnosis is important. In this context, risk factors should not be ignored. For example, if there is a palpable endometriosis node on the partition between the vagina and the rectum (can be felt through the rectum), it makes sense to also consider endometriosis on the ureter. The same applies if the pelvic wall shows endometriosis or an ultrasound is used to detect the so-called “kissing ovaries”. Even if you do not experience any symptoms with regard to the kidneys, a kidney ultrasound is recommended in these cases. The examination helps to assess kidney function. In the context of control examinations, this can be a useful procedure. Before and after surgery, a renal ultrasound is definitely useful. This allows the pre-op to see if there is congestion and to call in the urologists to prepare for surgery. If the ureter is suspected to be in distress, a urologist should examine the ureters closely. In some circumstances, such as congested renal pelvis or the intrinsic form of ureteral endometriosis, a scintigraphy of the kidneys or an MRI (magnetic resonance imaging) is indicated [2].

Good to know.

Medical professionals use different classifications to categorize the degree of endometriosis. While the rASRM provides information on the degree of spread of endometriosis, the ENZIAN classification is used to describe deep infiltrating endometriosis. If you have been diagnosed with ureteral endometriosis, the ENZIAN classification is very helpful and should be included on the operative report and physician’s note.

How ureteral endometriosis is treated

Basically, it is important to treat endometriosis as a whole.

Treatment of deep infiltrating endometriosis of the pelvis and endometriosis lesions on the ovaries is useful so that the ureters are not further affected. It can also prevent recurrences in the ureters [12]. Surgery is performed through three to four small incisions using a camera in the abdomen. Physicians call this a laparoscopic procedure and most endometriosis surgeries can be performed this way. In this way, the ureter can be exposed from the surrounding tissue layers and freed from unwanted tissue (ureterolysis). It may be possible to attach a catheter or ureteral splints prior to surgery [4, 5, 13]. However, this would be discussed with you in advance.

In many women, the endometriosis can be removed externally to the ureter and the ureter recovers from the narrowing caused by the endometriosis tissue.

In some circumstances, surgery may determine that part of the ureter needs to be removed [13]. Then the ureter is reconnected by a urologist. Reimplantation of the ureter (ureterocystoneostomy) into the bladder may also be necessary [14]. However, this is rarely the case, for example, when the ureter has been severely infiltrated by intrinsic ureteral endometriosis. Usually, an initial attempt is made to reopen the ureter by clearing it of unwanted tissue. Subsequently, it is observed how well the ureter recovers after the procedure. Usually, only after failure is an attempt made to remove or reimplant parts of the ureter [2].

It is important to perform a renal ultrasound before discharge after surgery on the pelvic wall, near the ureter or, of course, in the case of surgery for endometriosis on the ureter after surgery. This allows us to see not only an improvement in the previously existing urinary retention, but also a new urinary retention or a worsening, for example, due to a complication of surgery.

Short and to the point

Endometriosis of the ureter is comparatively rare. What is particularly insidious is that patients with such a diagnosis do not necessarily have to have complaints. If endometriosis of the ureter occurs, patients may experience low back or flank pain. However, these occur quite late. The mechanisms by which this occurs are still under discussion. Experts believe it is possible that endometriosis tissue spreads through the bloodstream or lymphatic system. The theory that there is a transformation of stem cells into endometriosis cells is also held by some experts. There appear to be several risk factors. Women with touching ovaries, deep infiltrating endometriosis, or endometriosis nodes on the partition between the vagina and rectum may be particularly affected by ureteral endometriosis. Ultrasound, MRI and scintigraphy may be helpful in diagnosis. Treatment is usually surgical, by freeing the ureter from the tissue. In severe cases, it may be necessary to reimplant the ureter or remove part of it.


  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
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