Ultrasound transmission gel in the vagina can impair sperm motility.

The effect of ultrasound transmission gel on sperm motility was assessed because of a few unsatisfactory post-coital tests, encountered after vaginal ultrasonography in otherwise normal couples. Swim-up samples of spermatozoa from donors and patients with asthenozoospermia were incubated in ultrasonic transmission gel at various concentrations. Sperm progressive motility and viability were checked. Donor sperm progressive motility declined from 90.9 +/- 2.5% (mean +/- SD) to 30.6 +/- 2.7% (P < or = 0.001) within 18 h at a gel concentration of only 10% (by volume). There were no progressive motile spermatozoa after incubation in 80% gel. In the swim-up fraction from asthenozoospermic patients, motility declined from 92.2 +/- 2.5% to 11.6 +/- 2.1% (P < or = 0.001) within 130 min at a gel concentration of 10% (by volume). Eosin staining for viability demonstrated that the loss of motility was mostly due to loss of viability. The use of ultrasound transmission gel should be avoided during follicular follow-up close to the date of expected ovulation in couples who practise dated natural intercourse or cervical insemination. Normal saline is an adequate substitute in this period with relatively large follicles.