Ureteral outlet stenosis is often discovered during screening ultrasounds during pregnancy as an increased accumulation of fluid in the renal pelvis (hydronephrosis). This is an hourglass-shaped narrowing (stenosis) at the transition from the renal pelvis to the ureter. This stenosis leads to varying degrees of dilation of the renal pelvis and the renal calices.

The question of whether the kidney tissue will be damaged in the long term by this build-up of urine and the widening of the renal pelvis cannot be predicted with certainty at the time of diagnosis, as around 50% of findings regress spontaneously over the years. After careful initial diagnostics, we therefore check the enlargement of the renal pelvis using clinical, sonographic (ultrasound) and nuclear medicine examinations, which can be used, for example, to measure the exact function of each individual kidney and the outflow of urine from the kidney into the bladder.
In most cases, the results of these examinations show us whether the patient will benefit from an operation. During this operation, the constriction at the junction of the renal pelvis and the ureter is removed. This procedure (Anderson Hynes renal pelvisplasty) is a routine operation that can be performed open or minimally invasively ("laparoscopically") with a success rate of over 95%.

If hydronephrosis was diagnosed before birth, the children come to us during the first weeks of life. A detailed ultrasound examination is then carried out first, which can be supplemented by a nuclear medicine examination (so-called isotope nephrography or "ING") after the 6th week of life. The latter can be used to determine the percentage function of each individual kidney and the outflow of urine from the renal pelvis into the ureter. However, in children under one year of age, this should always be carried out as part of a short inpatient stay (1 overnight stay). If the results of the nuclear medicine examination confirm the ultrasound findings, the treatment plan can usually be determined without further diagnostic measures. If the outflow of urine from the renal pelvis is impaired but still sufficient (> 50% of normal), we speak of "compensated outflow conditions". In this case, we can wait for spontaneous development and repeat the ING after 3, 6 or 12 months, depending on the severity of the outflow obstruction. In special cases, it may be necessary to choose a shorter interval between these examinations.

 

 

If there is no spontaneous improvement in the course of the treatment, we aim to perform a surgical correction as soon as possible. Otherwise, irreversible damage to the kidney tissue can occur. We usually perform the operation using a minimally invasive approach ("laparoscopic"). The pediatric surgeon makes a small incision in the navel through which a thin tube (trocar) is inserted into the abdominal cavity. Air is blown into the abdominal cavity through the trocar and a camera is inserted (laparoscopy). This allows the entire abdomen to be inspected. The operation follows the same principle as the open procedure, except that instead of the long flank incision, further working channels (trocars) are inserted into the abdomen via two 3 mm long skin incisions. The narrow section of the ureter is removed (resected) and the normally wide ureter is then sutured back to the renal pelvis (anastomosed). As a splint and for urine drainage, a small plastic tube is passed out of the skin at the level of the kidney and connected to a urine bag. The plastic tube is removed a week later, which does not cause any pain. Once your child has recovered and you have mastered the use of the urine bag, your child can be discharged home in the meantime and will only return to the ward to have the tube removed. You decide whether you would like to use the fast-track service or prefer continuous inpatient care.

Follow-up treatment is carried out by your pediatrician and by us. Initially, we will only carry out sonographic checks, and if the renal pelvis becomes blocked again, a nuclear medicine examination will be performed. The urine flow from the renal pelvis should be normal. Any necessary follow-up examinations depend on the respective findings.