Although only a fraction of men with infertility have a demonstrable distal ductal abnormality, it is crucial to identify these patients to determine if the defect is correctable and to avoid unnecessary testing in men with non-correctable abnormalities who should proceed to assisted reproduction. In the absence of retrograde ejaculation, neurologic disorders and diabetes, men with azoospermia and low ejaculate volumes (1.5 mL or less) should be examined for congenital anomalies or obstructive defects of the distal genital tract. Kuligowska and Fenlon evaluated the effectiveness of transrectal ultrasound in infertile men to evaluate its role in patient care.

Male patients with infertility, low ejaculatory volumes and azoospermia were evaluated. On the basis of the location and nature of the transrectal ultrasound findings, the men were selected for either surgery or radiologic intervention. Of the 276 men who underwent trans-rectal ultrasound examination, 70 (25.4 percent) had no anatomic abnormalities of the distal genital system. In the remaining patients, the most common abnormality was congenital bilateral absence or hypoplasia of the vas deferens (94 patients, or 34.1 percent), which was associated with nonvisualization of both ejaculatory ducts at transrectal ultrasound. Other abnormalities included occlusion of the vas deferens, seminal vesicles and ejaculatory ducts by calcification or fibrosis (43 patients, or 15.6 percent); unilateral absence or hypoplasia of the vas deferens (31 patients, or 11.2 percent); obstructing cysts (26 patients, or 9.4 percent); and distal ductal obstruction secondary to calculi (12 patients, or 4.4 percent).

Patients were selected for further intervention on the basis of the ultrasound findings. Congenital and acquired ductal anomalies may be amenable to radiologic or surgical intervention, depending on the nature and location of each abnormality. Cysts above the level of the prostate can be effectively treated with transrectal ultrasound-guided needle aspiration. Cyst aspiration can be therapeutic by relieving obstruction and providing sperm for in vitro fertilization. Congenital bilateral vas agenesis and diffuse ductal occlusion are nonsurgically correctable defects. By correctly identifying this particular cause of infertility with transrectal ultrasound, such patients can be spared further unnecessary investigation and inappropriate treatments.

The authors conclude that transrectal ultrasound is the ideal method for evaluation of potentially correctable genitourinary defects in infertile men. Normal distal ductal anatomy is easily depicted with this technique. Transrectal ultrasound offers an innovative diagnostic approach in infertile men with low-volume azoospermia.