oligozoospermia

Oligozoospermia, also called oligospermia, is the condition of a lower than normal concentration of sperm in semen. The World Health Organization considers a normal sperm concentration to be at least 15 million sperm per milliliter; concentrations below this threshold are described as oligozoospermia. Some guidelines further classify severity as mild (about 10–15 million/mL), moderate (about 5–10 million/mL), and severe (less than 5 million/mL), though exact cutoffs can vary.

Causes of oligozoospermia are diverse and can be categorized as genetic, hormonal, anatomic, infectious or inflammatory, obstructive, or lifestyle-related. Genetic factors include Y-chromosome microdeletions and conditions such as Klinefelter syndrome. Hormonal issues involve imbalances in the hypothalamic-pituitary-gonadal axis, such as low FSH or testosterone. Testicular injury or infection, obstruction of the ducts, varicocele, certain medications, chemotherapy, radiation, and lifestyle factors (smoking, obesity, excessive alcohol, heat exposure) can also reduce sperm production.

Diagnosis typically begins with semen analysis, usually repeated after an interval to confirm persistently low counts. Evaluation may include assessment of semen volume, pH, and sperm motility and morphology, as well as hormonal profiling (FSH, LH, testosterone, prolactin) and genetic testing (karyotype, Y-chromosome microdeletions) when indicated. Imaging or biopsy may be used to assess testicular structure and spermatogenesis.

Management focuses on the underlying cause when possible. Reversible factors such as varicocele or lifestyle factors may be addressed to improve counts. Lifestyle changes (weight management, smoking cessation, limiting heat exposure) can help. In many cases, assisted reproductive technologies (ART) such as ICSI with retrieved or ejaculated sperm are options. Donor sperm is considered in cases of persistent nonreversible oligozoospermia. Prognosis varies with the cause and availability of ART.