What initial investigations should I perform for a male patient presen

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Initial investigations for a male patient presenting with infertility should include:

A detailed clinical history including lifestyle and sexual history to identify factors affecting fertility.
A semen analysis as part of the initial assessment, comparing results with World Health Organization reference values: semen volume ≥1.5 ml, pH ≥7.2, sperm concentration ≥15 million/ml, total sperm number ≥39 million per ejaculate, total motility ≥40% or progressive motility ≥32%, vitality ≥58%, and normal morphology ≥4%.
If the first semen analysis is abnormal, a repeat confirmatory test should be offered ideally 3 months later, or sooner if there is severe sperm deficiency such as azoospermia or severe oligozoospermia.
Screening for antisperm antibodies is not recommended as there is no evidence of effective treatment to improve fertility.
Men with hepatitis C should discuss treatment options with a specialist before conception.

What initial investigations should I perform for a male patient presenting with infertility?