Pyeloureteral stenosis

Pyeloureteral stenosis is a congenital anomaly that causes narrowing of the ureter (duct leading from the kidney to the bladder), resulting in progressive dilatation of the child's renal pelvis. It is a very common pathology, usually diagnosed during pregnancy.

Within the urinary system, the kidney is responsible, among other functions, for filtering the blood and the ureters, on the other hand, conduct the urine from the kidney to the bladder. When a narrowing occurs in any part of the ureters, the area prior to the obstruction is dilated.

The pyeloureteral junction is the most proximal segment of ureter, between the pelvis and the beginning of the ureter.

Symptoms of pyeloureteral stenosis

Pyeloureteral stenosis may manifest with urinary tract infection, abdominal pain or vomiting but may also be symptomless.

In some asymptomatic patients, urinary tract obstruction may lead to loss of renal function. Close follow-up by a pediatric urologist is important to detect the need for treatment to prevent deterioration of renal function.

The causes of this disease can be diverse, but the most frequent are: 

• Intrinsic stenosis: this is due to the fact that the segment of the ureter at the junction with the renal pelvis is narrow or does not move normally, making urine outflow difficult and causing dilatation of the renal pelvis.

• Extrinsic stenosis: this is due to an artery or vein crossing over the junction between the pelvis and the ureter, compressing it and hindering the passage of urine. This type of stenosis often manifests at a later age and occurs intermittently.

Diagnosis of pyeloureteral stenosis

Until a few years ago, pyeloureteral stenosis was diagnosed after manifestation of any of the symptoms described above. Today, ultrasound monitoring during pregnancy makes it possible to detect dilatation of the urinary tract and to follow these patients during growth.

Often, dilatation of the urinary tract detected on prenatal ultrasound does not require treatment and even disappears during the first months of life. On other occasions, dilatation increases progressively and it is necessary to complete the study with other imaging and renal function tests.

It is important to be evaluated by a pediatric urologist who will determine the need for the following tests:

• Serial Voiding Cystography (SCUMS): In this test, a catheter is placed in the child's bladder to fill the bladder with contrast and to perform serial radiographs. Radiological protection is used and exposure is minimized as much as possible. This study makes it possible to rule out the presence of vesico-ureteral reflux, to see the bladder morphology, to rule out the presence of diverticula and to study the anatomy of the urethra.
• MAG-3 or DMSA: nuclear medicine tests that provide information on kidney function and the presence or absence of obstruction (in MAG-3). To perform these tests, a line is taken from the patient through which a contrast dye is injected to hydrate the child and, in some cases, a diuretic drug to help the child urinate. A gamma camera is used to identify which part of the kidney is functioning normally, the presence of renal scarring and obstruction of the urinary tract.

These studies are always performed in a quiet and comfortable environment for the child, with highly qualified staff with extensive experience in dealing with pediatric patients to try to make the experience as satisfactory as possible.

Treatment of pyeloureteral stricture

Surgical treatment of pyeloureteral stenosis is indicated in those patients with symptoms or in whom tests show worsening of obstruction and renal function.

Pyeloureteral stenosis surgery

Anderson-Hynes dismembered pyeloplasty: The gold-standard procedure to treat this disease. It consists of resecting the narrow part and joining the pelvis and ureter. This surgery can be performed through an incision in the lumbar region or laparoscopically, depending on the patient's age and personal characteristics.

Endopyelotomy: consists of dilating the stricture endoscopically, using a guidewire and a balloon that we will inflate in the narrowed area. After dilatation, we will leave a tutor in the ureter that will be removed later. This ureteral tutor is simply a very thin tube that serves to ensure that urine can be eliminated without difficulty and that no further narrowing occurs during healing.

Laparoscopic Vascular Hitch: can be performed when the pyeloureteral stenosis is caused by a polar vessel (vessels that come out of the renal artery or aorta and carry blood to the renal pole). It consists of changing the position of the vessels to avoid compression of the urinary tract in its narrowed area.

After the operation, the patient will remain in hospital for 24-48 hours for observation and pain control. Depending on the technique used in each case, the ureteral tutor will be removed from 1 to 4 weeks after the operation. During this time, the patient will take antibiotic prophylaxis to avoid infectious complications.

The choice of the best technique for each patient must be made on an individualized basis, informing the family of the options and accompanying them through each step of their child's diagnosis and treatment.

Prognosis and follow-up

Pyelureteral stenosis resolves after surgery, so it is not a chronic disease. The children will be able to lead a normal life.

The follow-up of these patients continues after the intervention, although each time in more spaced visits, until the child's growth is complete. In this way, we can assess the long-term outcome and ensure ultrasound monitoring of the kidney and its function.