Does compensatory testicular enlargement predict monorchism?

In 37 boys 3 years old or younger with an impalpable testis the length and volume of the normally descended testis were measured. In 12 boys who had surgically proved monorchism the descended testis length and volume exceeded 2 cm. (mean 2.22) and 2 cc, respectively. This represented significant compensatory enlargement of the descended testis compared to the descended testis in 19 boys with normal sized (mean 1.51) or 6 boys with atrophic (mean 1.78) impalpable undescended testes. Histological examinations revealed that in no case in which the descended testis was greater than 2 cm. long was there histological evidence contralaterally of normal, recognizably abnormal or dysgenetic testicular tissue. In these patients compensatory descended testis enlargement with testis length exceeding 2 cm. (2 cc volume) defined monorchism.