What percentage of infertility cases are unexplained?

• A. 5%
• B. 10%
• C. 20%
• D. 25%

Answer: (B)

Unexplained infertility refers to couples who meet the medical criteria for infertility after a full fertility workup, yet no definite cause is found from standard tests. The figure commonly cited in practice is about 10% of infertile couples. This reflects the reality that even with thorough evaluation—confirming regular ovulation, open fallopian tubes, and normal semen parameters—some factors are subtle, transient, or not captured by routine testing. For example, mild or intermittent male-factor issues, subtle endometriosis, or variations in egg quality can escape standard assessments, and contemporary tests have limitations in sensitivity and scope.

Five percent would underrepresent how often no clear cause is identified, while twenty or twenty-five percent would overstate it relative to most guidelines and studies. Knowing that around 10% of cases are unexplained helps clinicians counsel couples about prognosis and options, such as timed intercourse, targeted therapies like intrauterine insemination, or proceeding to assisted reproduction when appropriate.