Inter-observer variation in assessment of undescended testis. Analysis of kappa statistics as a coefficient of reliability.

In a prospective study the inter-observer variation in the diagnosis of undescended testis was analysed. Two physicians assessed independently the position and motility of the testes of 37 boys referred for undescended testis. The boys were examined in the supine and squatting positions. The observed agreement rate between the observers was 0.90 to 0.97. Using kappa (kappa) statistics, the values were adjusted for the expected chance agreement; kappa values between 0.47 and 0.81 were obtained, slightly higher values for patients in the supine position. Complete agreement on all observations was reached in 13.5% of the patients. Inter-observer variation may be a substantial source of bias in diagnosing the undescended testis and one of the reasons for the varying results in studies of hormonal treatment of this condition. It is also a fact that the number of orchiopexies in some countries exceeds the incidence of this condition.