Why Can Sperm Quality Be Different Between Two Tests?

Getting the results of a semen analysis can already feel stressful, so seeing very different numbers when the  test is repeated can be even more confusing. Perhaps the first result showed low sperm count or poor  motility, while the next looks noticeably better. Or everything seemed normal the first time, only for the  second test to raise questions. It is easy to wonder which result you should trust. 

Semen quality can naturally change from one sample to another. A semen analysis gives doctors useful  information, but it is also a snapshot of what was happening at that particular time. 

Sperm Numbers Are Not Fixed

Sperm production is happening continuously, and several measurements can vary between samples. These  include sperm concentration, total count, motility, and morphology. Even in the same person, the numbers  are unlikely to be identical every time. 

This is one reason fertility specialists may recommend repeating a semen analysis when the first result is  outside the expected range. Looking at more than one sample can provide a clearer picture than relying on  a single test. (Source: Science Direct)  

The Time Between Ejaculations Matters

Something as simple as when you last ejaculated can influence the result. Clinics normally give instructions  about how long to abstain before providing a sample. If the period is particularly short or long,  measurements such as semen volume, sperm concentration, and motility may be different. Following the  clinic's instructions each time makes it easier to compare one result with another. 

Recent Illness Can Affect Sperm Too

A fever or illness in the weeks or months before testing can sometimes affect sperm production. Because  sperm take several weeks to develop, the effect may not appear immediately. This can explain why a semen  analysis suddenly looks worse even though nothing obvious has changed in everyday life. Medication, smoking, heavy alcohol use, heat exposure, and other health or lifestyle factors may also  influence sperm quality. If something has changed since your previous test, it is worth mentioning it to your  fertility specialist. (Source: NCBI)  

What If the Second Result Is Better?

A better result is encouraging, but doctors will still look at both tests rather than simply choosing the more  favorable one. The same applies when the second result is worse. One disappointing test does not  necessarily mean sperm quality has permanently declined. Instead, your fertility specialist will consider the  pattern in the results alongside your medical history and both partners' fertility. Further testing may be  recommended if the results remain significantly abnormal. 

Looking Beyond One Set of Numbers

Semen analysis is an important part of fertility testing, but the numbers on the report do not exist in isolation.  They help doctors understand what may be happening and whether further investigation or treatment could  be useful. (Source: Mate Health)  

Seeing different results between two tests can be unsettling, but variation does happen and is one reason  repeat testing is sometimes needed. Rather than focusing too heavily on whether one result was "good" and  another was "bad," the more useful question is what the results reveal when considered together. That gives  your fertility team a much better foundation for deciding what, if anything, should happen next. 

Sources:  

ScienceDirect - https://www.sciencedirect.com/science/article/pii/S266633412100043X NCBI - https://pmc.ncbi.nlm.nih.gov/articles/PMC3114587/ 

Mate Health - https://mate.health/blogs/blog-posts/what-semen-analysis-may-reveal-abou...