Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (257 page)

   Laboratory Findings

   If semen fructose is present, epididymal obstruction is likely, but fine needle aspiration or open biopsy of the testis should be considered to confirm normal testicular histology. If the histologic analysis is abnormal, the conclusion is a germ cell arrest or hypospermatogenesis.

   If semen fructose is absent, obstruction or absence of the vas deferens is likely, and ultrasound analysis of the seminal vesicles will allow one to distinguish an acquired obstruction (dilated seminal vesicles) from congenital absence (normal seminal vesicles).

Causes of acquired vas deferens obstructions include infection (gonorrhea, chlamydia, tuberculosis) and ligation (i.e., vasectomy). Only 2% of infertile men have congenital absence of the vas deferens, most stemming from mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene, although other findings typical of CF are absent. Primary ciliary dyskinesias (affecting cilia function and transport) are a genetically diverse group of congenital defects that lead to abnormal transport of sperm within the vas deferens.

Suggested Readings

Munro NC, Currie DC, Lindsay KS, et al. Fertility in men with primary ciliary dyskinesia presenting with respiratory infection.
Thorax.
1994;49:684–687.

Patrizio P, Asch RH, Handelin B, et al. Aetiology of congenital absence of vas deferens: genetic study of three generations.
Hum Reprod.
1993;8:215–220.

Wilton LJ, Teichtahl H, Temple-Smith PD, et al. Young’s syndrome (obstructive azoospermia and chronic sinobronchial infection): a quantitative study of axonemal ultrastructure and function.
Fertil Steril.
1991;55:144–151.

POSTVASECTOMY STATUS

   Definition

   Following a vasectomy, a series of semen analyses are performed for a defined period to determine the success or failure of the procedure. Azoospermia in a semen specimen is definitive evidence of a successful vasectomy.

   Who Should Be Evaluated?

   About four of five postvasectomy patients will be azoospermic after 3 months and 20 ejaculations. However, this period of time will be shorter if ejaculations are more frequent or if the patient is older.

   In a low percentage of cases, postvasectomy patients will consistently evidence nonmotile sperm, possibly reflecting an undue delay between ejaculation and laboratory analysis. Repeat testing after 1 and 2 months may confirm azoospermia, but the continued presence of rare, nonmotile sperm at this point is probably clinically insignificant.

   Laboratory Findings

   A fresh specimen should be examined using direct phase-contrast microscopy (25–50 high-power fields). If sperm are not seen on the initial slide, a centrifuged specimen should be evaluated.

   If motile sperm are present 3 months after the procedure and there have been more than 20 ejaculates, then the vasectomy is considered a failure.