UPJ obstruction is a blockage at the junction of the kidney and ureter (the tube that drains the kidney to the bladder). Most commonly this is a congenital abnormality due to a narrowed segment within the urinary tract at the UPJ or due to compression from an extra blood vessel supplying the lower part of the kidney. This may be diagnosed during infancy but often is found in early adulthood. Because the affected kidney does not drain perfectly, urine accumulates in the kidney causing swelling (hydronephrosis) which is seen on ultrasound or other abdominal imaging. Although less common, UPJ obstruction can also develop secondary to kidney stones, urinary tract surgery, or chronic disorders causing inflammation of the urinary tract.
If present at birth, UPJ obstruction may be identified on prenatal ultrasound or noticed on exam by palpating an abdominal mass. A classic finding is some flank pain after drinking a large amount of fluid or diuretic such as caffeine or alcohol. Other presentations could be that of blood in the urine, urinary tract infection with fever, or kidney stones.
The diagnosis of UPJ obstruction may be suspected by seeing swelling of the kidney (hydronephrosis) on abdominal imaging with a nondilated ureter. A functional study such as a diuretic renal scan is usually necessary to confirm urinary blockage and also estimate the function of the kidney. Another helpful study is a CT scan or MRI with IV contrast to fully delineate the anatomy and look for other possible causes of obstruction of the urinary tract. On occasion, a diagnostic procedure to look into the bladder with a camera and inject dye up the ureter to the kidney is recommended prior to treatment.
Treatment options include surveillance versus surgery. An incidentally found UPJ obstruction in an adult may be followed. If there is no evidence of declining kidney function, recurrent pain, kidney infections or new stone formation, than watching it is reasonable. The classic treatment of UPJ obstruction is an open surgery called a pyeloplasty. This surgery involves reconstructing the UPJ which usually entails cutting out the diseased portion and reconnecting the two healthy ends. Minimally invasive surgical options have emerged that allow for a pyeloplasty to be done laparoscopically or robotically. The same surgery is performed through small incisions which allow for a shorter hospital stay, quicker return to normal activities, less pain, and better cosmetic outcome. A stent inside the ureter is typically left for 4-6 weeks and a drain that exits the side for less than a week. Another minimally invasive option is an endopyelotomy. This involves placing a camera through the bladder and up the ureter where the UPJ is visualized and cut, often with a laser.
Patients should have occasional followup whether they are on surveillance or after surgery. Evaluation usually included occasional imaging such as a kidney ultrasound or renal scan (nuclear medicine test) to look for either recurrence or progression.