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

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.