Monday 17 December 2007

Sperms & The Laboratory

Laboratories performing sperm "counts", in general, vary in the details that they provide the physician requesting the "count". A general sperm count as part of a fertility evaluation should include the total density or count (20 million per ml or above), and the motile density (8 million per ml or higher). The motile density is perhaps the most important part of the semen analysis, as it reports the total number of sperm thought capable of progressing from the site of sperm deposition to the site of fertilization. This value is essential in both allowing a determination regarding whether or not a semen analysis is "normal", as well as in providing prognostic information should advanced reproductive medical assistance be required. (Numbers in italics are what "normal" values should be.)

Definitions of "abnormal" counts:
• Polyzoospermia: Excessively high sperm concentration.
• Oligozoospermia: Sperm count less than 20 million/ml
• Hypospermia: Semen volume < 1.5 ml
• Hyperspermia: Semen volume > 5.5 ml
• Aspermia: No semen volume
• Pyospermia: Leukocytes (germ fighter cells) present in semen
• Hematospermia: Red blood cells present in semen
• Asthenozoospermia: Sperm motility < 40%
• Teratozoospermia: > 40% of sperm seen are of abnormal form
• Necrozoospermia: Nonviable ("dead") sperm
• Oligoasthenozoospermia: Motile density < 8 million sperm/ml

Sperm Morphology (Shape and Appearance)
The evaluation of sperm size, shape and appearance characteristics should be assesed by carefully observing a stained sperm sample under the microscope. The addition of colored "dyes" (stains) to the sperm allow the observer to distinguish important normal landmarks (characteristics) as well as abnormal findings. Several methods of staining sperm are used, and the method employed should be one with which the examiner is comfortable and experienced.

Several different shapes or forms of human sperm have been identified and characterized. These forms fall into one of four main categories: normal forms, abnormal head, abnormal tail and immature germ cells (IGC).
Normal forms
Normal sperm have oval head shapes, an intact central or "mid" section, and an uncoiled, single tail.

Abnormal heads
Many different sperm head abnormalities may be seen. Large heads (macrocephalic), small heads (microcephalic) and an absence of identifiable head are all seen in evaluations. Tapering sperm heads, pyriform heads (teardrop shape) and duplicate or double heads have been seen. Overall (gross) abnormalities in appearance may be termed "amorphous" changes.

Abnormal tails
Coiling and bending of the tail are sometimes seen. Broken tails of less than half normal length should be categorized abnormal. Double, triple and quadruple tails are seen and are abnormal. Cytoplasmic droplets along the tail may indicate an immature sperm.

Immature germ cells (IGC's)
White blood cells (WBC's, germ fighters) in the semen should rarely be seen. It is very difficult to distinguish between an immature germ cell and a WBC. Because the presence of WBC's in the semen (pyospermia) can be a serious concern, if a report of "many IGC's" is delivered, it becomes very important to assure that these cells are not, instead, WBC's.

Sperm "Motility" (Movement)
Sperm motility studies identify the number of motile (moving) sperm seen in an ejaculate specimen. Here again, as in many other sperm studies, many laboratories use "normal" values that are out of date and inaccurate. Many labs will assess sperm motility upon receipt of the specimen, and again at hourly time intervals for four to twenty four hours. It is well known that sperm motility is a temperature dependent sperm function, so the handling and processing of specimens is critical. It is for this reason that we, except in very rare instances, require that specimens be evaluated only in a laboratory such as our own, where we are able to tightly control laboratory conditions. We have found the repeated testing of sperm over time for motility adds little to the evaluation of motility over the initial sperm motility assessment. Sperm are known not to survive well for extended periods of time in semen, and in nature, sperm very rapidly leave the semen to enter the cervical mucus. Many laboratories consider "normal" sperm motility to be 60% or greater. Our own studies, in agreement with many others have found men with 50% or greater sperm motility to be "normal".

Decreased sperm motility. If found to be present, exam should be repeated to assure that laboratory conditions did not cause the problem. Frequent causes: abnormal spermatogenesis (sperm manufacture), epididymal sperm maturation problems, transport abnormalities, varicocele. These conditions should all be looked for if sperm motility is repeatedly "low".

A total absence of moving sperm. It is vital, if sperm are seen, but are not moving, to carry out studies (vital stains) to see if the sperm seen are alive. It is possible to have sperm with normal reproductive genetics that are deficient in one or several of the factors necessary to produce motility. We have achieved several successful pregnancies employing microinjection of healthy, non motile sperm directly into the egg (ICSI).

Chemical and Biochemical Semen Characteristics
Semen acid-base balance (pH)
The pH of semen is measured using a specially treated paper blot that changes color according to the pH of the specimen that it is exposed to. The pH of normal semen is slightly alkaline ranging from 7.2 to 7.8. Prostatic secretions are acidic while the secretions of the seminal vesicles are alkaline. Therefore, alterations in pH may reflect a dysfunction of one or both of these accessory glands. The pH of semen has not been generally found to have a major influence on a man's fertility potential.

Color and Turbidity
Semen is normally translucent or whitish-gray opalescent in color. Blood found in semen (hematospermia) can color the semen pink to bright red to brownish red. The presence of blood in semen is abnormal and should be reported. The presence of particles, nonliquified streaks of mucus or debris requires further evaluation.

Semen is normally produced as a coagulum. The specimen will ususally liquify within 30 minutes. The failure to liquify within one hour is abnormal. Excellent methods for correcting this problem in the laboratory are available.

Nonliquefaction and excessive viscosity are two separate conditions. Viscosity is measured after complete liquefaction has occured. Viscosity is considered "normal" if the liquefied specimen can be poured from a graduated beaker drop by drop with no attaching agglutinum between drops. The role of hyper (excessive) viscosity is being studied, but it seems possible that htis condition may interfere with the ability of sperm to travel from the site of deposition into the cervix or uterus.

No comments: