Strict morphology is
not designed to be a screening test for male infertility. It is far too sensitive for that
indication. In fact, using strict
morphology, only 5% of men will have normal sperm and thus be considered
fertile. Rather than use strict
morphology, W.H.O 3rd edition morphologies are designed for
screening populations of men for infertility.
Under this classification system, up to 50% of m en will have normal
sperm.
In the 1950’s, McLeod, an andrologist, began to examine the
shape of sperm in men of proven fertility and sterility. His research led to a classification
system. Under McLeod’s classification
system, only the shape of the sperm head mattered and 50% of men had normal
sperm morphology.
Things sure have changed.
Now most labs use Strict Morphology—also known as Kruger
Morphology—or the World Health Organization standard, the W.H.O 4th
edition. These methods take sperm head,
midpiece, and tail features into consideration.
In the early 1990s, when these categorization schemas were developed, 20
to 50% of men had abnormal sperm morphologic features. Now, only about 5% of men will have “normal”
sperm when these strict criteria are applied.
Why is that?
Well, no one knows for sure, but one can infer that part of
the problem lies in the way that sperm morphology information is used. Strict morphology is used to decide on when
to send a couple for ICSI rather than standard IVF. Couples with less than 5% normal forms have
better fertilization rates with ICSI compared to IVF. Used In this way, morphology assessments can
only determine which treatment option to pursue.
Strict morphology is not designed to be a screening test for
male infertility. Iit is far too
sensitive for that indication. In fact,
using strict morphology, only 5% of men will have normal sperm. Rather than use strict morphology, W.H.O 3rd
edition morphologies are designed for screening populations of men for
infertility. Under this classification
system, up to 50% of men will have normal sperm.
Ask if your lab can do both Strict and
W.H.O 3rd and report them simultaneously. That way doctors can get the information they
need and patients can avoid unnecessary worry.
Thanks,
