An accurate medical history and directed physical examination are essential in diagnosis
of male infertility. We review the hormonal assessments and specific genetic analyses
that are useful additional tests, and detail other evidence-based examinations that
are available to help guide therapeutic strategies. By contrast with female infertility
treatments-especially hormonal manipulations to stimulate or enhance oocyte production-spermatogenesis
and sperm quality abnormalities are much more difficult to affect positively. In general,
a healthy lifestyle can improve sperm quality. A few men have conditions in which
evidence-based therapies can increase their chances for natural conception. In this
second of two papers in The Lancet Diabetes and Endocrinology Series on male reproductive
impairment, we examine the agreements and controversies that surround several of these
conditions. When we are not able to cure, correct, or mitigate the cause of conditions
such as severe oligozoospermia, non-remedial ductal obstruction, and absence of sperm
fertilising ability, assisted reproductive technologies, such as in-vitro fertilisation
(IVF) with intracytoplasmic sperm injection (ICSI), can be used as an adjunctive measure
to allow for biological paternity. Not considered possible just two decades ago, azoospermia
due to testicular failure, including 47,XXY (Klinefelter syndrome), is now treatable
in approximately 50% of cases when combining surgical harvesting of testicular sperm
and ICSI. Although genetic fatherhood is now possible for many men previously considered
sterile, it is crucial to discover and abrogate causes as best possible, provide reliable
and evidenced-based therapy, consider seriously the health and wellness of any offspring
conceived, and always view infertility as a possible symptom of a more general or
constitutional disease.