Laboratory Diagnosis of Male Infertility

Laboratory testing is an important part of the male infertility evaluation.

Urinalysis
A urinalysis is a simple test that can be performed during the initial office visit. It may indicate the presence of infection, hematuria, glucosuria, or renal disease, and as such may suggest anatomic or medical problems within the urinary tract.

Semen Analysis

A carefully performed semen analysis is the primary source of information on sperm production and reproductive tract patency. However, it is not a measure of fertility. An abnormal semen analysis simply suggests the likelihood of decreased fertility. Studies have established that there are certain limits of adequacy below which it may be difficult to initiate a pregnancy. These semen analysis values were identified by the World Health Organization (1992) and are considered the minimum criteria for “normal” semen quality (

Table 42-6). It is statistically more difficult to achieve a pregnancy if a semen parameter falls below any of those listed. Of these semen variables, the count and motility appear to correlate best with fertility.

A. Semen Collection
Semen quality can vary widely in a normal individual from day to day, and semen analysis results are very dependent on collection technique. For example, the period of sexual abstinence before sample collection is a large source of variability. With each day of abstinence (up to 1 week), semen volume can rise by up to 0.4 mL, and sperm concentration can increase by 10-15 million/mL. Sperm motility tends to fall when the abstinence period is longer than 7 days. For this reason, it is recommended that semen be collected after 48-72 h of sexual abstinence.

To establish a baseline of semen quality, at least 2 semen samples are needed. Semen should be collected by self-stimulation, by coitus interruptus (less ideal), or with a special, nonspermicidal condom into a wide-mouthed, clean (not necessarily sterile) glass or plastic container. Because sperm motility decreases after ejaculation, it is important to have the specimen analyzed within 1 h of procurement. During transit, the specimen should be kept at body temperature.

B. Physical Characteristics and Measured Variables
Fresh semen is a coagulum that liquefies 5-30 min after ejaculation. After liquefaction, semen viscosity is measured and should not show any stranding. Ejaculate volume should be at least 1.5 mL, as smaller volumes may not sufficiently buffer against vaginal acidity. Low ejaculate volume may indicate retrograde ejaculation, ejaculatory duct obstruction, incomplete collection, or androgen deficiency. Sperm concentration should be > 20 million sperm/mL. Sperm motility is assessed in 2 ways: the fraction or percentage of all sperm that are moving and the quality of sperm movement (how fast, how straight they swim). A normal value for sperm motility is 50-60% motile and quality or progression score of at least 2 (on a scale of 0 [no movement] to 4 [excellent progression]).

Sperm cytology or morphology is another measure of semen quality. By assessing the exact dimensions and shape characteristics of the sperm head, midpiece, and tail, sperm can be classified as “normal” or not. In the strictest classification system (Kruger morphology), only 14% of sperm in the entire ejaculate are truly normal looking. In fact, this number correlates with the success of egg fertilization in vitro and thus is ascribed real clinical significance. In addition, it is accepted that sperm morphology is a sensitive indicator of overall testicular health, because the sperm morphologic characteristics are determined during spermatogenesis. The role of sperm morphology assessment in the male infertility evaluation is to complement other information and to better estimate the chances of fertility.

C. Computer-assisted Semen Analysis (CASA)
In an effort to remove the subjective variables inherent in the manual semen analysis, there have been attempts to quantify sperm motility, concentration, and morphology with computers. Computer-aided semen analyses couple video technology with digitalization and microchip processing to categorize sperm features by algorithms. Most commonly, CASA systems report sperm concentration, motilities, and velocities (curvilinear, straight-line) and can be used to analyze sperm shape by examination of nuclear features. Although the technology is promising, when manual semen analysis findings are compared with those from CASA on identical specimens, CASA can overestimate sperm counts by 30% in the presence of high levels of contaminating cells such as immature sperm or leukocytes. In addition, at high sperm concentrations, motility can be underestimated with CASA. At this point, CASA has accepted value in the research setting and is gaining further clinical acceptance.

D. Seminal Fructose and Postejaculate Urinalysis
Fructose is a carbohydrate derived from the seminal vesicles and is normally present in the ejaculate. If absent, the condition of seminal vesicle agenesis or obstruction may exist. Seminal fructose testing is indicated in men with low ejaculate volumes and no sperm. A postejaculate urinalysis is a microscopic inspection of the first voided urine after ejaculation for sperm. If sperm are found in the voided urine, then retrograde ejaculation is diagnosed. Such an analysis is indicated in diabetic patients with low semen volume and sperm counts; patients with a history of pelvic, bladder, or retroperitoneal surgery; and patients receiving medical therapy for prostatic enlargement. In general, the semen analyses of infertile men have patterns that may suggest a diagnosis (

Table 42-7).

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Provided by ArmMed Media
Revision date: June 18, 2011
Last revised: by David A. Scott, M.D.