Manual sperm analysis vs. computer system (CASA) — why do we choose manual precision?

When it comes to assessing male fertility, qualitative semen analysis is key. There are two main methods:
- Manual analysis — performed by an experienced embryologist with a microscope
- CASA (Computer Assisted Sperm Analysis) — automated computer system.

While technology is evolving, we continue to prefer the manual approach in our clinic. Why?

1. Manual analysis takes into account reality, not just pixels

CASA systems are based on algorithms that analyze pixels and motion. But they often:
- overestimate stationary cells if they are in the shade or move slightly;
- can not distinguish glued or overlapping spermatozoa;
- have difficulty in samples with a high concentration of cells or impurities.

However, the human eye understands the context — it knows when to correct, when to exclude artifacts, when to mark something as “clinically significant.”

2. Morphology — the gold standard remains man

CASA systems generally do not make reliable morphological analysis. They:
- do not use coloring according to Kruger strict criteria;
- do not distinguish fine details — vacuoles, acrosomal defect, neck, etc. ;
- can not comment on “borderline” forms.

Manual morphological analysis remains an essential method in clinical practice — when real expertise is required.

3. Experience and responsibility cannot be automated

An embryologist is personally responsible for the analysis. He has:

• years of experience;
• understanding of the clinical context;
• possibility to adapt the judgment according to the specific case.

The computer system does not know that this is the only sample of a patient with severe oligoasthenoteratozoospermia. Man knows — and watches with an attention that a machine cannot imitate.

4. High price, dubious benefit

CASA systems are expensive — and while they look modern, they don't always provide better information. Patients deserve quality, not just technology.

5. Flexibility and personalization

In the manual analysis we can:
- choose a method according to the sample
- we use different lenses, cameras, colors
- we comment on additional findings — inflammatory cells, agglutination, etc.

Conclusion

CASA has its place — especially in research and standardized environments. But when it comes to real clinical practice, for patients with individual cases and for precise judgment — the good old human eye, the experienced hand and the professional conscience remain the gold standard.
Therefore, in our clinic, semen analysis is not just “data” — it is a precise, responsible and personal assessment.

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