Describing the morphology of the sperm in a semen specimen is an essential part of the microscopic examination. The presence of abnormal forms along with low counts and/or poor motility contributes to a poor prognosis in infertility cases. There are several different methods for determining morphology. The most common are the WHO III (WHO III manual, 1992)assessment and the Strict Morphology method found in the WHO IV manual (1999).

A specimen is considered normal if 30% or more of the sperm are normal morphology according to WHO III criteria. If strict morphology criteria are used then the specimen is considered normal if it has 14% or more normal forms.