Radiograph measurements and contralateral renal size in primary pelvic hydronephrosis.

Renal size was estimated from the radiographs in 47 cases of primary pelvic hydronephrosis. The area of functioning renal tissue of the side opposite to the disease was greater in patients with severe hydronephrosis treated by pheloplasty, compared with those with moderate disease (P less than 0.05). This suggests that compensatory hypertrophy had occurred in the contralateral kidney. This finding did not appear to affect the outcome of pyeloplasty. It is suggested that the finding of compensatory hypertrophy in the kidney opposite to a severe hydronephrosis is not a contra-indication to conservative surgery.