Improvement of semen quality by nocturnal scrotal cooling in oligozoospermic men with a history of testicular maldescent.
Plain-language summary
This study looked at whether cooling the scrotum overnight improves semen quality in men with a history of undescended testicles and a low sperm count, a group with few options besides assisted reproduction. Twenty such men used a small pump that drew air through receptacles sitting on either side of the groin, every night for 12 weeks, and semen was analyzed at the start and again at weeks 4, 8 and 12. Another 20 men with the same history and the same diagnosis were followed without treatment, and that comparison group was assembled retrospectively rather than recruited and followed alongside, which limits what the comparison can carry. Cooling lowered scrotal temperature by a median of 0.8 degrees Celsius (1.4 degrees Fahrenheit). Total sperm count per ejaculate rose from a median of 23.9 million at the start to 38 million at week 8 and 39.6 million at week 12, and sperm concentration roughly doubled over the same period. Movement, shape and semen volume did not show a significant change, and neither did anything measured in the untreated men.
Key findings
- Overnight scrotal cooling lowered scrotal temperature by a median of 0.8 degrees Celsius (1.4 degrees Fahrenheit).
- Total sperm count per ejaculate rose from a median of 23.9 million at the start to 38 million at week 8 and 39.6 million at week 12, and both were significant changes.
- Sperm concentration roughly doubled by week 8 and was still about double at week 12, a significant change at both points.
- Progressive movement went from a median of 29% at the start to 36% at week 4, 40% at week 8 and 29% at week 12, which did not show a significant change.
- Normally shaped sperm went from a median of 3% at the start to 7% at week 4 and 11% at weeks 8 and 12, which did not show a significant change.
- Semen volume was a median of 4 mL at the start and stayed around 3 to 3.5 mL through follow-up, which did not show a significant change.
- The 20 untreated men showed no significant change in concentration, total count, movement, shape or volume over a comparable 7 to 16 weeks.
- The 20 untreated men were a retrospectively built control group rather than men recruited and followed alongside the treated group.
- The authors call for a controlled prospective study to test whether this affects pregnancy rates.
How to analyze the study yourself
- Study type
- This design tests an intervention in a specific group, so it can show whether the intervention worked in that group, but it cannot rule out other factors that might have influenced the results.
- Population
- 20 men with a history of undescended testicles and a low sperm count, compared against 20 men with the same history and diagnosis who were followed without treatment as a retrospectively built control group.
- Funding
- Not reported
- Takeaway
- In men with a history of undescended testicles and a low sperm count, this study found that cooling the scrotum overnight for 12 weeks raised total sperm count from a median of 23.9 million per ejaculate to 39.6 million and roughly doubled sperm concentration, while movement and shape did not show significant change. The untreated comparison group was put together after the fact rather than followed alongside, which is worth holding onto. If you have this history and are trying to conceive, it may be worth asking your doctor about keeping your testicles cool at night.