Testicular volume does not predict germ cell count in patients with cryptorchidism

A germ cell count of less than 0.2 germ cell per tubule on the prepubertal biopsy of cryptorchid testes predicts abnormal spermiograms and decreased fertility in adulthood, and may be used to select patients for post-orchiopexy hormonal therapy. Testicular volume directly correlates with testicular function and spermiogenesis. We determined whether testicular volume would predict the total germ cell count accurately enough to replace testicular biopsy in the modern management of cryptorchidism.

At our hospital 723 patients younger than 9 years with cryptorchidism (unilateral in 619 and bilateral in 104) underwent orchiopexy and bilateral testicular biopsies. These patients had not undergone groin surgery or hormonal therapy previously and had at least 50 tubules in each testicular biopsy. Testicular volume and position, patient age and germ cell counts were analyzed. The generalized estimating equation was used to determine whether a correlation existed between testicular volume and germ cell count.

The generalized estimating equation demonstrated a direct correlation between testicular volume and germ cell count. However, germ cell counts predicted from testicular volume varied widely within the 95% confidence intervals. Testes with less than 0.2 germ cell per tubule cannot be reliably distinguished from those with greater than 0.2 germ cell per tubule.

Testicular volume does not accurately predict the germ cell count in patients with undescended testes, cannot be used to select patients for post-orchiopexy hormonal therapy and cannot replace testicular biopsy in the modern management of cryptorchidism.