Intra- and inter-observer variability in the assessment of testicular descent.

Measurements of the distance between the testis and the pubic tubercle have been used to differentiate retractile testes from "real" cryptorchidism and to measure the effect of therapy. The intra- and inter-observer variation of these measurements was determined in 21 boys with incompletely descended testes treated with placebo. Patients were investigated in supine and squatting position, before and during moderate caudal traction. In squatting position the average distance is 20 mm greater than in supine position. The intra-observer SD is approximately 10 mm. It is doubtful if quantitative measurements can be used to define retractile testes. The wide prediction intervals should be taken into account in interpreting results of therapy.