When the junction of a part of the kidney called renal pelvis (where urine is collected) to the tubes which carry urine into the bladder (called ureter) is blocked, it is called as Ureteropelvic junction obstruction(UPJO). The flow of the urine slows down due to the blockage in the drainage of kidney. As urine build up within kidney, it can damage the kidney.
UPJ obstruction is usually congenital (called as Primary UPJO), this means the kid is born with health issues but can manifest in infancy/childhood or adulthood, depending on the severity of obstruction. The blockage starts to occur when the kidney is in formation. It is not known how to prevent it but one in 1500 children are born with it.
Most cases these days are found before birth during Antenatal ultrasounds.
It may happen in adults (called as Secondary UPJO) if they had history of previous surgeries of kidney (like surgery for kidney stones).
Treatment is usually necessary, every expert has different opinions, but it is important to know that poor drainage in infants (less than 1 year of age) might improve till few months after birth.
In most of the cases, the obstruction might not improve at all and may get worse. This would require repeat ultrasounds and if any further concerns, repeat nuclear scans might be needed.
If urine flow does not improve for an infant and obstruction remains, Surgery is often required. Adults may find treatment as prescribed by the individual doctors.