Bilateral ureters

　　First, the cause of the disease:

　　1. Embryological development:During the fourth week of embryogenesis, the ureteric bud rapidly grows, with its proximal part forming the ureter and its distal part covered by the primitive renal tissue mass, developing into the renal pelvis, calyces, and collecting tubules. If the distal branches of the ureter exceed 2, a duplicated renal pelvis is formed; if the branching is too early, an incomplete bilateral ureter is formed, with the ureter taking a Y-shape. In addition, if another ureteric bud (or accessory ureteric bud) is born at the lower end of the mesonephros, and it rises in parallel with the normal ureteric bud, a complete bilateral ureteral duplication anomaly occurs.

　　2. Genetics:Bilateral ureters may be autosomal dominant inheritance with incomplete penetrance. The incidence of bilateral ureters in pedigrees with parents or siblings having bilateral ureters ranges from 1 in every 125 people to 1 in every 8 to 9 people. There are also reports that environmental factors may affect the occurrence of bilateral ureters.

　　Second, pathogenesis

　　According to the position relationship of the duplicated ureters, they can be divided into 3 types:

　　1. Incomplete Duplication of Ureters:The upper and lower renal ureters fuse into one ureter in the shape of 'Y', and open into the normal position inside the bladder, with the point of convergence located at any part of the ureter.

　　2. Complete Duplication of Ureters:The two ureters are completely separated, respectively draining the urine of the upper and lower kidneys, and opening into the bladder trigone area simultaneously. Generally, the lower renal ureter opens into the normal position inside the bladder, while the upper renal ureter crosses over the lower renal ureter before entering the bladder and opens below or at other locations outside the lower renal ureter opening (Weigert-meyer law).

　　3, Complete double ureter with upper pole:Ectopic opening of the ureter, that is, in complete double ureters, the lower renal ureter opens into the bladder, and the upper renal ureter opens into a location outside the bladder. In males, it often opens at the posterior urethra, seminal vesicle, vas deferens, etc., while in females, it can open at the urethra, vagina, perineal vestibule, cervix, etc.

　　One-third of the renal parenchyma is drained by the upper collecting system. The average number of minor calyces in a single-system draining kidney is 9.4, while in a supernumerary kidney, it is 11.3. On average, the upper pole has 3.7 minor calyces, and the lower pole has 7.6 minor calyces (Privett et al., 1976). Ninety-seven percent of kidneys with a single-system drainage are normal on imaging, while 29% of those with duplicated anomalies have scars and/or dilatations. If excretory urography is performed, reflux is common in those with duplicated anomalies, accounting for 42%, while in those without duplicated anomalies, it accounts for only 12%. The lower pole often has hydronephrosis due to concurrent reflux, but there are also cases of concurrent renal pelvis and ureteral junction obstruction. There are also many opportunities for other anomalies, in the Nation group, 27 cases (12%) had other urinary tract anomalies, including renal hypoplasia or dysplasia and various types of ureteral anomalies, including 4 cases of upper ureteral ectopia (accounting for 3% of complete ureters). In the Campbell group, 129 of the 342 cases of double ureters had concurrent urinary tract anomalies, and 63 had no urinary tract anomalies. The types of urinary tract anomalies are also similar to those in the Nation group, with 22 cases having contralateral renal anomalies.

　　Clinical symptoms vary greatly with gender, due to embryological differences, male ectopic ureters mostly open at the bladder neck, prostate, seminal vesicle, epididymis, and vas deferens, all located above the external urinary sphincter, so urinary system infection symptoms are generally present, such as constipation, posterior pubic pain, discomfort during ejaculation, etc., and may also be accompanied by urgency, frequency, and occasionally infertility, but urinary incontinence is rare. In females, the most common opening site is the vestibule, which can also be located in the upper vagina, uterus, and ovaries. Since the ectopic openings are often located distal to the external urinary sphincter, they often manifest as persistent urinary incontinence after normal urination. Another characteristic of female ectopic ureter openings is the persistent presence of vaginal discharge. Most female patients have acute and chronic urinary tract infections, a few have renal pelvis and ureteral hydronephrosis, and occasionally, patients present with abdominal masses.

　　It may be autosomal dominant inheritance with incomplete penetrance. Family studies show that the incidence increases from 1 case in every 125 people to 1 case in every 8 to 9 people among those with duplicated ureters in parents or siblings. Environmental factors affect the occurrence of duplicated ureters. To prevent the occurrence of genetic diseases in children: one is to do genetic testing, and the other is to pay attention to reproductive health care, especially during pregnancy, to avoid contact with teratogenic and mutagenic harmful factors as much as possible.

　　The diagnosis mainly relies on intravenous urography and cystoscopy. It is advocated to use high-dose intravenous infusion of urography, and children can directly inject the contrast agent into the vein with a syringe to control the injection time. High-dose intravenous infusion can avoid the use of abdominal pressure bandage and is more satisfactory for displaying the entire ureter.

　　If the upper renal segment function of the duplicated kidney exists, the full picture of the anomaly can be clearly seen in X-ray contrast. The higher the convergence point of the two ureters, the clearer the display; if the convergence point is too low, the display is often poor, and it is sometimes difficult to distinguish whether the duplicated ureters are complete or incomplete. If the function of the upper renal segment is poor, a follow-up film should be taken, even up to 24 hours. If the function of the upper renal segment is nearly completely lost, one should pay close attention to and analyze the morphology of the renal pelvis and calyces of the lower renal segment. Generally, the upper renal calyx is absent, the renal pelvis inclination is increased, resembling a drooping flower, and it is away from the edge of the vertebral body. The ureter of the lower renal segment is often pushed laterally or medially by the dilated and twisted ureter of the upper renal segment, and sometimes it descends in an 'S' shape. In cases where the upper renal segment is non-functional, the lower renal segment is often much smaller in shadow than the normal kidney (contralateral), and sometimes it may be misdiagnosed as a small kidney anomaly or renal hypoplasia. In follow-up films, the phenomenon of ureter-to-ureter reflux may sometimes be seen.

　　During cystoscopy, if two or more ureteral orifices are found, the diagnosis of duplicated ureteral anomaly can be established. If it is possible to insert a ureteral catheter for retrograde contrast enhancement, the diagnosis will be more definite. Of course, even if there are only two ureteral orifices at the bladder trigone, one cannot completely exclude a duplicated ureteral anomaly, because incomplete duplicated ureteral anomalies may have normal ureteral orifices; in addition, one ureteral orifice may be ectopic, but it is not necessarily open into the bladder. Sometimes, retrograde phenomena are found in one of the duplicated ureters during cystography, and combined with intravenous urography films, it can explain the location of the problem.

　　Regarding the diet of patients with duplication of ureters:

　　1. Pay attention to the following in daily life:Regular life, reasonable diet, keeping bowel movements smooth, regulating psychology, family care, preventing colds, preventing anger, preventing fatigue, etc.;

　　2. Pay attention to dietary health care:You can eat more nutritious, easily absorbable, and digestible foods, such as light-tasting, fresh vegetables and fruits, beans, mushroom foods, more soup and stew foods, and you can eat pork, duck meat, pigeon meat. Do not eat mutton, lamb, dog meat, chicken, fish and shrimp, chili, and other spicy foods. Do not eat cold, greasy, fried, pickled, and smoked foods, etc.

　　Patients with bilateral ureteral anomalies without symptoms such as urinary tract infection, obstruction, or dribbling urinary incontinence, and without severe complications such as severe hydronephrosis, reflux, and calculi, do not require treatment. Clinically, such cases account for about half of the total. The principles of surgical treatment usually include the following three points.

　　1. Incomplete Duplication of Ureters:For patients with the function of the upper renal segment and associated ureteroureteral reflux: ① If the convergence point of the duplicated ureters is at the upper 1/3, perform a longitudinal ureteral side-to-side anastomosis; ② If the convergence point of the duplicated ureters is at the lower 1/3, perform the reimplantation of the upper renal segment ureter into the bladder.

　　2. Complete Duplication of Ureters:For patients with the function of the upper renal segment and associated vesicoureteral reflux, perform ureteral bladder reimplantation surgery, plus anti-reflux surgery.

　　3. Partial Nephrectomy:For those with uncontrollable urinary tract infections, or with slight dribbling urinary incontinence (with ectopic opening), or with almost complete loss of upper renal segment function, a partial resection of the upper renal segment can be performed. The ureter can be cut near the convergence point (incomplete duplication of the ureter) or at the lowest level, and a total ureterectomy (complete duplication of the ureter) can also be performed.