Ureteropelvic Junction Obstruction (UPJ) in children
What is it?
This is a group of abnormalities that cause a narrowing at the junction of the renal pelvis and the ureteropelvic junction, preventing the outflow of urine. Urine accumulates in the pelvis, causing it to expand.
Urine is produced by the kidneys and collects in funnel-shaped cavities called renal territories or pelvis. From here, urine passes through a transition zone called the pyloro-ureteral junction and enters the ureters, long tubes that carry urine from the kidneys to the bladder.
Under normal conditions, urine passes from the renal pelvis to the ureters without any obstruction.
Causes and risk factors
Causes can be internal or external. In the first case, we are talking about the syndrome of stenosis of the pylorogheteral anastomosis, which is narrowed for congenital reasons.
In the second case, the pylo-ureteral junction is compressed from outside (e.g., by abnormal blood vessels).
Which are the symptoms?
Prenatal ultrasound may be used for early diagnosis of possible pelo-ureteral joint syndrome.
If an ultrasound scan was not performed or did not raise any doubts, the symptoms can be varied and depend on the age of the child.
In children and infants, symptoms are as follows:
- slowdown or stunted growth;
- poor appetite;
- body temperature over 38.5 °C;
- hematuria (blood in the urine).
In children and young people, symptoms are as follows:
- urinary infections;
- chronic nausea, sometimes accompanied by vomiting;
- abdominal pain, especially in the flanks;
- hematuria (blood in the urine) after minor trauma;
- growth retardation;
- arterial hypertension.
The renal pelvis is dilated if its anteroposterior diameter exceeds 5 mm. After birth, examined children with this dilatation have no syndrome or urologic problems: 95% of children with less than 10 mm dilatation have no urologic problems on the fifth day of life.
How is it diagnosed?
In the case of dilatation, the pediatric urologist decides whether this phenomenon should be monitored with repeated ultrasound scans over a period of time or whether an in-depth examination is necessary:
- intravenous urography: involves injecting a contrast agent (a substance visible on x-rays) into a vein and performing repeated x-rays in succession. This examination provides an anatomical and functional examination of the kidneys and urinary tract;
- renal scintigraphy: allows for a computerized study of renal function and assessment of possible urinary outflow obstruction using radioactive substances injected into a vein;
- cystoscintigraphy during urination or direct cystoscintigraphy: involves inserting a catheter into the bladder, filling the bladder with a contrast agent or radiolabeled substance, and taking some images while filling the bladder. This is a basic examination to check for concomitant vesicoureteral reflux.
How is it treated?
In this syndrome, the kidney is unable to excrete the urine it produces and becomes functionally impaired over time.
Surgical intervention consists of plastic surgery of the pyeloureteral junction: the renal pelvis and ureter are realigned to remove the stenotic segment and allow the passage of urine. In 95% of cases the problem is finally solved.
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