Sperm characteristics vary over time, a five-year study reveals.


A five-year study looking at the sperm characteristics from ejaculates of men presenting to an infertility clinic suggests there is a wide range of intrapatient variation in sperm characteristics that does not appear related to abstinence interval or age at semen collection, according to investigators. Abstinence interval is the time since the last ejaculation.

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The finding suggests that clinicians need to conduct semen analyses more than once when evaluating infertility, said lead investigator Laura Detti, MD, a clinical fellow in the division of reproductive endocrinology and infertility at Wayne State University in Detroit. “Probably checking every three months and doing that two or three times would be advisable,” she said.


The study is one of the largest retrospective studies of its kind, Dr. Detti said. It enrolled 446 men who presented to the university’s clinical andrology laboratory between January 2001 and March 2006 for semen analysis. Each individual provided two to eight ejaculates, for a total of 1,036 samples, Dr. Detti reported.


She and her colleagues manually performed semen analyses using the modified World Health Organization (WHO 3rd and 4th Editions) and scored sperm morphology using WHO general guidelines (until November 2002). After that date, the investigators used Kruger strict criteria. They calculated the coefficient of variation (CV) as the standard deviation divided by the mean of each variable and then expressed it as a percentage.


‘A bit surprised’

“We knew that there was a substantial amount of intrapatient variation,” Dr. Detti said. “However, some other investigators had found there was a certain degree of stability in each patient’s semen parameters over time. In our study, we did not find that and we were a

bit surprised.”


Dr. Detti said she usually asks patients to undergo a semen analysis after two to three days of

abstinence because this is believed to be the optimal time for examination. “We showed that, even with ‘optimal’ abstinence interval, sperm quality can be very different when analyzed in different occasions,” Dr. Detti told Renal & Urology News. “For this reason, when evaluating a patient with a low sperm count or with a low percentage of normal forms, we should always endeavor to repeat the test a few months later, possibly after more than three months, which is the lifespan of sperm, before making a diagnosis and implementing a therapy.”