Ureteropelvic Junction Obstruction

Excerpt

The kidneys have a crucial role in regulating fluid and electrolyte balance, as well as blood pressure and hemoglobin levels. During fetal life, the kidneys develop from the metanephric mesoderm up to the distal tubules. The collecting duct, major and minor calyces, renal pelvis, and ureters arise from the ureteric bud, which originates from the mesonephric duct during the fifth week of the intrauterine phase. This explains that the ureteropelvic junction (UPJ) is wholly made by the ureteric bud rather than the fusion of two different mesenchymal tissues.

Ureteropelvic junction obstruction (UPJO) is a well-recognized clinical entity that impairs urine flow from the renal pelvis into the ureter and, if undetected and untreated, can lead to complete loss of the affected kidney. UPJO is most commonly a congenital condition that can be detected by routine antenatal ultrasound during the second trimester, but is also commonly identified incidentally during workup for recurrent UTIs in childhood and adolescence. It can also be caused by entities such as retroperitoneal processes or post-surgical ureteral scarring. Causes of this vary between children and adults.