A local board of review at each hospital examines the records of every operation to determine whether the surgical procedure was necessary.

The variation is unrelated to factors (other than the surgical procedures themselves) that influence the incidence of diseases for which surgery might be considered.

There are several categories of surgical procedure(other than hysterectomies, prostatectomies, and tonsillectomies)that are often performed unnecessarily.

For certain surgical procedures.it is difficult to determine after the operation whether the procedures were necessary or whether alternative treatment would have succeeded.

With respect to how often they are performed unnecessarily, hysterectomies, prostatectomies, and tonsillectomies are representative of surgical procedures in general.