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Definition of Microorchidism
Medically reviewed by Min Clinic Staff | Updated: January 2026
Microorchidism: Abnormally small testes. To determine if the testes are too small, a device called an orchidometer is used that permits the testes to be compared to a series of plastic ovals (like miniature American footballs) of differing sizes. Microorchidism is a diagnostic feature, for example, of the Prader-Willi syndrome and certain other multiple malformation syndromes. Microorchidism may also result from shrinkage (atrophy) of the testis due to damage, as from mumps.
The opposite of macroorchidism is microorchidism (abnormally small testes).