Congenital primary megaureter, nonrefluxing and unobstructed form is a rare condition in which the ureter (the tube that carries urine from the kidney to the bladder) is abnormally enlarged. This condition is usually present at birth and is caused by a defect in the development of the ureter. In this form of megaureter, the ureter is enlarged but does not cause urine to flow back up to the kidney (reflux) and is not blocked. Symptoms may include abdominal pain, frequent urination, and difficulty urinating. Treatment may include antibiotics, medications to relax the bladder, and surgery to correct the defect.