In the patients of endometriosis, UE accounts for only 0.01–1.7% according to the reported cases in the literature.6 Most of the time, UE is very difficult to diagnose due to the absence of special symptoms. About half of the patients are found when accidental health examination. Our data also shows that 48% of patients were asymptomatic. For the symptomatic women of UE, the three most common symptoms are severe dysmenorrhea (75%), dyspareunia (70%) and pelvic pain (60%).4 In our study, flank pain is the most common symptom. The UE is usually unilateral. Some studies reported that the left UE was more than the right one.1, 4, 7 The distal third of the ureter is most frequently affected by endometriosis.
The pathogenesis of UE is still unknown. The hypothesis of retrograde menstruation is the most popular theory.8 However, this theory can’t completely explain the isolate UE without any other implants of endometriosis. Hydronephrosis is common in endometrial nodules larger than 3 cm.9, 10 The UE is found predominantly in women with hydronephrosis and/or in women with lesions larger than 4 cm.9 The UE lesions are very rarely isolated and are frequently associated with other kinds of endometriosis.11, 12
Although physical examination often has no positive findings in UE, the rectovaginal palpation is necessary which may provide a helpful indication of UE.11 There are two types of UE: extrinsic and intrinsic. The extrinsic compression of the ureteral wall is more common than the intrinsic invasion which may originate from lymphatic or venous metastases.13 When UE is suspected, all urologic causes of extrinsic and intrinsic ureteral stenosis should be considered, such as stones, primary megaureter, primary or secondary ureteral cancer, infections, retroperitoneal lymphadenopathy and idiopathic retroperitoneal fibrosis.6 For differentiating these conditions, the imaging techniques are needed.14 The transvaginal and abdominal ultrasonography are the first-line exam which can detect rectovaginal nodules at the distal third of ureter and evaluate the degree of hydronephrosis and the thickness of the renal parenchyma.15 The magnetic resonance imaging (MRI) is highly accurate to detect and predict the type of UE. MRI is more sensitive, but less specific than surgery in detecting intrinsic involvement which may overestimate the prevalence of intrinsic lesions.16 Multislice computed tomography is alternative to MRI, but it has irradiation and can cause discomfort for the eventual enema.6 Renal scintigraphy should be performed when a decision between kidney preservation and nephrectomy is being considered.
When intrinsic UE needs to be distinguished from the malignant ureteral tumor, a ureteroscopic biopsy may also be necessary to help a final choice. However, as it is invasive and it is not able to detect extrinsic lesions, it is now rarely used in clinical practice.17
The surgical treatment for UE is aim to relieve ureteral obstruction and protect renal function. The main procedures include ureterolysis, ureterectomy with UU, ureteroneocystostomy and excision of all other endometrial lesions. In our hospital, some simple UE cases which may just need ureterolysis were all treated by gynecological doctors. If a more invasive procedure was needed like UU or ureteral reimplantation, the surgery will be mainly performed by urologists. In this study, almost all cases were recommended from gynecological department to urological department. Sometimes, the treatment process needed multidisplinary team.
The choice of surgical procedure is determined by the severity and location of lesions. The patients with less extensive endometriosis undergo ureterolysis and excision of all other lesions. Compared with ureteroneocystostomy, UU and uretrolysis have higher restenosis rate (11% and 8% versus 3%).18 For women with moderate to severe diseases, radical surgery is often required, including segmental resection with UU or ureteral reimplantation.19 Furthermore, nephrectomy or nephroureterectomy should be performed when renal function is less than 10–15% with symptoms like flank pain, renovascular hypertension and recurrent urinary tract infections.20 In our study, two patients were considered as ureteral cancer and three patients were diagnosed as nonfunctional kidney who finally underwent nephoureterectomy.
In the past ten years, open procedure was the main type of surgery in our center. With the development of laparoscopic and robotic techniques,21, 22 we also did some difficult operations under laparoscopy or robot-assisted laparoscopy. Especially for the complex cases, the robotic surgery has special advantages on anastomosis. As the surgery shown in Fig. 1, it was unlikely to be done by open or laparoscopic approach.
In all patients, we noticed that a 72 years old woman who was suspected as malignant ureteral cancer preoperatively was finally diagnosed as UE by the postoperative pathology. As we known, the endometriosis tends to occur in women of childbearing age under 60 years. However, Haydon had reported one of the oldest patients with endometriosis, aged 78.23 This reminds us that UE can also occur in the elderly, although it is very rare.
Although cases of successful hormone therapy of UE have been reported,24, 25 medical treatment is not able to resolve the fibrotic component of the lesion, which is mainly responsible for the ureteral obstruction.26 Therefore, UE with obvious ureteral obstruction should be treated surgically. For some patients with severe diseases, postoperative adjuvant hormone therapy may be helpful.27, 28