Endometriosis is the ectopic growth of endometrial glands and mesenchyme outside the uterine cavity, forming foci and causing the corresponding symptoms. Due to its invasive growth, it often involves the organs surrounding the cervix, resulting in associated signs and symptoms. Ureteral endometriosis refers to the ectopic growth of endometrial glands and mesenchyme around the ureter, encircling and compressing the ureter, and even invading the ureteral muscular layer and mucosa, causing ureteral stenosis or obstruction, resulting in the expansion of the ureter and pelvis above the obstruction site and fluid accumulation, and over time, the renal cortex atrophies due to the compression of the pelvis, resulting in the loss of renal function, and the renal function caused by the atrophy of the renal cortex Even if the ureteral obstruction is lifted, the kidney function cannot be restored to normal level. Ureteral endometriosis is often located in the pelvic segment of the ureter, especially in the area where the ureter crosses the uterine artery, and there are two types: endogenous and ectogenous. The latter means that the lesion invades the ureteral muscle layer or even the ureteral mucosa and destroys the ureteral wall structure. Both can cause ureteral obstruction. Ureteral obstruction caused by endometriosis is often unilateral and is more common on the left side. Ureteral endometriosis does not have its own specific symptoms and often has only the clinical manifestations of endometriosis, with dysmenorrhea, painful intercourse, and infertility predominating. Endometriosis causing ureteral obstruction often forms large nodules in the pelvis, often located lateral to the cervix, growing along the sacral and main ligaments toward the pelvic wall, and in some patients the nodules may extend to the pelvic wall. In most patients, the nodules are painful to palpation, and in some cases, they may be painless to palpation. In some patients, purple-blue nodules are visible in the lateral fornix on transvaginal examination, and in some patients, the vaginal mucosa may be intact. Since ureteral endometriosis has no specific symptoms of urinary tract, and due to the compensatory effect of the healthy kidney, patients do not have the manifestation of renal insufficiency such as low urine, elevated blood urea nitrogen and creatinine, which makes patients and doctors often focus only on the treatment of dysmenorrhea and infertility and neglect the examination of urinary tract with or without obstruction until severe ureteral fluid is found when ureteral obstruction is suspected to be caused by endometriosis. This is the main reason for the “silent” loss of renal function due to endometriosis. Ureteral endometriosis is difficult to diagnose when it does not cause ureteral obstruction and fluid, and often requires surgery to determine the relationship between the endometriosis lesion and the ureter. Once ureteral obstruction and fluid accumulation is caused, the diagnosis is very easy. Ultrasound, CT, MRI and other imaging examinations can find dilated fluid accumulation in the ureter of the affected pelvis, and when combined with the patient’s clinical manifestations of endometriosis and signs such as painful nodules, the diagnosis of ureteral endometriosis can basically be established. The treatment of ureteral endometriosis should be carried out early when it does not cause ureteral obstruction and fluid accumulation, and it is crucial to remove the focal tissue around the ureter and loosen the ureter to avoid obstruction, which requires us to pay attention to the ureter without obstruction when doing endometriosis surgery, and to remove it if there are foci around it, so as to avoid its development to cause ureteral obstruction, leading to the decline of renal function and kidney function is quietly lost. When the endometriosis lesion invades the ureter and ureteral obstruction has already occurred, ureteral resection, ureteral anastomosis or ureteral bladder implantation can be performed on the focal segment. Although the obstructed ureter can be recanalized, the lost kidney function is unlikely to be completely restored to normal.