Kidney endometriosis refers to very unusual instances where tissue resembling that which normally lines the uterus (endometrial tissue) grows around or inside the kidneys. The incidence of kidney endometriosis is extremely rare in women, accounting for 1% of all cases of urinary tract endometriosis, which itself is rare among those with endometriosis.

What is kidney endometriosis

The endometrial tissue that grows in the kidneys responds to hormonal changes during the menstrual cycle, and breaks down and bleeds in the same way as the normal lining of the uterus but is unable to exit the body. This causes inflammation and other complications. Repeated bleeding over various menstrual cycles can result in the formation of endometrial cysts or endometriomas in the kidneys.

The endometriomas form a fibrous layer surrounding the kidneys and cause pain. In cases of urinary tract endometriosis, they can block or constrict the ureter, the tube that connects the kidneys and the bladder, damaging the kidneys and causing renal colic. Endometrial cysts can distort the shape of the kidneys and affect kidney function.

Symptoms of kidney endometriosis

Potential symptoms of kidney endometriosis are:

  • Pain in the lower back and legs, and renal colic due to blocked ureter generally coinciding with the menstrual cycle
  • Blood in the urine (hematuria) during the menstrual cycle
  • Difficulty urinating
  • Urinary tract infections that recur

Diagnosis of kidney endometriosis

Diagnosis of kidney endometriosis can be tricky and the condition can sometimes be confused with kidney cancer. An initial diagnosis is based on symptoms such as lower back pain and blood in urine during the menstrual cycle. These symptoms tend to disappear with hormonal treatment.

Imaging techniques such as ultrasonography, contrast-enhanced computed tomography (CECT), and magnetic resonance imaging (MRI) can help locate endometrial lesions and cysts in and around the kidneys. But they are not used to establish an official diagnosis because the images obtained cannot conclusively differentiate between endometriosis and a malignancy.

The most definitive diagnosis can be reached via a histopathologic examination of kidney tissue, but this requires an invasive biopsy that carries a risk of complications.

Treatments of kidney endometriosis

Kidney endometriosis needs to be treated; otherwise, it can lead to complications such as kidney failure. Treatment options depend on the location of the endometriosis and the lesions, whether superficial or deep infiltrating.

In many cases, patients are treated with hormonal therapies, such as human gonadotropin-releasing hormone (GnRH) receptor agonists or oral contraceptive pills.

In extreme cases where there are large kidney endometriomas or the presence of persistent obstruction of the ureter, laparoscopic surgery is preferred. This needs to be performed by surgeons specializing in gynecological, adrenal, and urological laparoscopic surgery to remove endometrial cysts or lesions. Invasive surgery, however, can lead to complications resulting from damage to the bowel, bladder, ureter, and the blood vessels supplying these organs.


Last updated: August 4, 2019


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