Center for Male Reproductive Medicine & Microsurgery

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Semen Analysis

Semen specimens are obtained by masturbation into a sterile wide-mouth container after 2-5 days of abstinence and analyzed within 2 hr of collection . Two to three analyses, separated by at least a month, are required for a meaningful evaluation. In the setting of a recent febrile illness or exposure to gonadotoxic agents we would repeat the semen analysis no sooner than 3 months later. Semen is initially an opalescent coagulum that liquefies within 20-25 min of ejaculation. The coagulation protein derives from the seminal vesicle. Liquefaction is secondary to the action of prostatic proteases. Failure of liquefaction is due to abnormalities of the prostate or its ducts. Normal ejaculate volume is between 2 and 6 mL. Sixty-five percent of the volume is from the seminal vesicles, 30-35% from the prostate, and 3-5% from the vasa. Seminal fructose derives from the seminal vesicles. Azoospermia coupled with low ejaculate volume of nonclotting watery fluids fructose-negative, Usually implies an obstruction of the ejaculatory duct. If the vasa are Palpable a transrectal Ultrasound can be diagnostic. Patients who are not azoospermic but oligo- or asthenospermic with a low semen volume may have partial ejaculatory duct obstruction or retrograde specimen is obtained by first having ejaculation. A postejaculatory urine specimen is obtained by first having the patient empty his bladder prior to ejaculation and then voiding following ejaculation into a separate container. Retrograde ejaculation is commonly seen in diabetics as well as in men who have had transurethral surgery at or near the bladder neck.

Manual light microscopic evaluation of sperm concentration, motility, and morphology is still the gold standard. Computer-assisted semen analysis (CASA) is most useful as a research tool and yet has not provided information that alters therapy. Azoospermic specimens are frequently misread by the computer as oligospermic and computerized morphology has not been perfected. CASA provides interesting information on sperm velocity and angularity that is useful in a research setting. Because pregnancy can be achieved with only one sperm, specimens originally read as azoospermic should be centrifuged and the pellet examined for sperm. Specimens with head-to-head or tail-to-tail agglutination are evaluated for antisperm antibodies or infection. Infection may be inferred from the presence of leukospermia (>1x 106 WBC/mL). Men with agglutination or leukospermia should have their semen cultured for aerobic and anaerobic organisms as well as Chlamydia and Mycoplasma. The penis and scrotum should be washed with an antibacterial scrub Prior to culture to avoid inadvertent contamination with skin or fecal flora.

Proper interpretation of morphologic parameters requires an understanding of the scoring system and criteria employed by testing laboratory, Broadly viewed, profound abnormalities in morphology are associated with poor fertilizing capacity when strict criteria (Kruger) are used. Men with fewer than 40% perfectly shaped sperm usually failed to fertilize without micromanipulation. Large numbers of tapered sperm are seen in testes with elevated temperatures, such as varicocele, cryptorchid, or retractile testes, or in the testes of men who take saunas or hot baths. Antisperm antibodies bound to sperm are associated with lower pregnancy rates. Risk factors for antibodies include torsion, epididymitis, orchitis, unilateral or partial obstruction, and large varicoceles. These are all conditions associated with impairment of the blood-testis barrier that usually prevents sperm antigens (which appear at puberty) from being exposed to the general circulation. An immunobead assay detects antibodies on the sperm and in the serum. High levels of antibodies are most often seen with obstruction, in particular before (in serum) and after (in serum and on sperm) vasectomy reversal. Low levels of antibodies on sperm and moderate levels in serum are usually seen in men with large varicoceles. A postcoital test is useful for evaluating sperm-cervical mucus interaction. A fair to good semen analysis associated with a poor postcoital test is an indication for intrauterine insemination (IUI). Although IUI can overcome cervical mucus antibodies or decreased counts, the success of IUI is dependent on the sperm's ability to fertilize an egg, Therefore prior to instituting IUI, we obtain a sperm penetration assay (SPA) that assesses the sperm's ability to bind and penetrate hamster oocytes, which have been rendered zona pellucida-free. Tests are interpreted as percent oocytes penetrated or sperm penetrations per oocyte. These tests are not perfect but do correlate about 80% with the ability to penetrate human eggs in vitro.




Center for Male Reproductive Medicine & Microsurgery Weill Cornell Medicine
525 E 68th Street
New York, NY 10065