Cryptorchidism (over 90% in some studies). Even after orchiopexy, these may also affect sperm maturation and motility at an older age. The most common diagnostic dilemma in otherwise normal boys is distinguishing a retractile testis from a testis that will not descend spontaneously into the scrotum. Retractile testes are more common than truly undescended testes and do not need to be operated on. In normal males, as the cremaster muscle relaxes or contracts, the testis moves lower or higher ("retracts") in the scrotum. This cremasteric reflex is much more active in infant boys than older men. A retractile testis high in
Users' Guides to the Medical Literature Users' Guides to the Medical Literature The Users’ Guides to the Medical Literature is a series of articles originally published in the "Journal of the American Medical Association", later rewritten and compiled in a textbook, now in its third edition. The guides provide practical, clinician-friendly advice on all aspects of evidence-based medicine. During the late 1970s a group of clinical epidemiologists at McMaster University including Dr. David Sackett prepared a series of articles to assist clinicians interpreting clinical research. These articles, introducing the term "critical appraisal", appeared in the "Canadian Medical Association Journal" beginning in 1981. In 1990 Dr. Gordon