Understanding Semen Analysis

Semen analysis is not a test for fertility. Fertility determination is a couple-related phenomenon that requires the initiation of a pregnancy. The patient cannot be considered fertile based only on normal semen analysis. It was shown that 30% of all patients with normal semen analysis have abnormal sperm function.

Semen specimen are obtained by masturbation into a sterile wide-mouth container after 2-5 days of abstinence and analyzed within 1 hour of collection. Therefore, the patients should be strongly recommended to collect samples within clinic area. If intercourse is the only way to collect sample, special nonreactive condoms are available.

Typically two to three semen analyses are obtained over a 3 month period prior to making any final conclusion regarding baseline sperm quality or quantity. However, if the first semen analysis is normal, the repeat test is not required. Recent febrile illness or exposure to gonadotoxic agents may affect spermatogenesis for up to 3 months, therefore semen analysis has to be postponed.

Normal ejaculate volume is between 2 and 6 ml. 65%of the volume is from seminal vesicles, 30-35% is from the prostate and only 5% from the vasa. Low volume is associated with absence or decrease of seminal vesicle component of ejaculate( absence of SV, complete or partial obstruction of ejaculatory ducts) or retrograde ejaculation

Normal semen pH is 7.2-8.0. Prostatic secretion is acidic while seminal vesicle fluid is alkaline (seminal fructose is derived from seminal vesicles). Acidic ejaculate (pH<7.2) may be associated with blockage of seminal vesicles. Infection is usually associated with alkaline ejaculate (pH >8.0_ Azoospermia with low ejaculate volume, fructose negative and acidic may imply obstruction of the ejaculatory ducts. pH over 8.0 may indicate infection. The semen is initially in liquefied state but quickly coagulate by the action of protein kinase secreted by the seminal vesicles. Proteolytic enzymes from the prostate liquefy coagulum in 20-25 minutes. Abnormal liquefaction may be cased by prostatic abnormalities, e.g. prostatitis. Increased viscosity may affect sperm motility

Concentration: Concentration: evaluated in Mackler or Cell-VU chambers. Azoospermic specimen contains no sperm, oligospermic specimen reveals concentration of less than 20x106 and normospermic specimen contains more than 20x106.

Motility and forward progression: normally >50% of sperm in the specimen are motile. Forward progression describes how fast the motile sperm are moving (normal 2+ in the scale from 0 to 4)

Morphology = shape of spermatozoa: Several techniques have been described to evaluate sperm morphology. Sperm are classified into normal-oval shaped, tapered, amorphous, duplicated and immature. Normal spermatozoid must have an oval form with smooth contour, acrosomal cap encompassing 40-70% of head, no abnormalities of midpiece, or tail and no cytoplasmic vacuoles of more than half of the sperm head. Head size is 5-6m M x 2.5-3.5m M. Any borderline sperm are counted as abnormal( amorphous, tapered,duplicated, immature, coiled tail, blunted tail, midpiece abnormalities). The predictive value of sperm morphology in determining pregnancy rates is low

a. WHO criteria: >30% normal forms ( 100 cells evaluated)
b.Strict criteria (higher predictive value in determining rates of pregnancy in IVF program) are based on the morphology of postcoital spermatozoa found at the level of the internal cervical os. 100 cells evaluated for only normal sperm (>14% normal forms). Men with fewer than 4% normal forms usually failed to fertilize without micromanipulation. Strict criteria for normal sperm morphology include:

Sperm head: Smooth oval configuration. Length-5-6 microns. Width:2.5-3.5 microns. Acrosome comprises 40-70% of the anterior sperm head
Midpiece: Axially attached, 1.5 times the head length, £ 1m m in width
Tail: Straight, uniform, slightly thinner than the midpiece, uncoiled, ± 45m m long

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