The Intra Vas Device (IVD) is a set of tiny implants that block the flow of sperm. There are two IVD designs in clinical trials. One is a pair of soft, silicone plugs made by the Shepherd Medical Company in the United States. The other is a urethane tube lined with a tiny nylon sieve made by the Foshan Medical Company in China. Both of these designs were inspired by the 1980s work of Dr. Lourens Zaneveld, who showed in pilot studies that the IVD is a safe and effective method of male contraception.
The US design of the device is made in several sizes, and comes with a patented insertion tool (Burton 2004). In 2004, Shepherd Medical received funding to support their IVD research from the National Institutes of Health. In May 2006, Shepherd Medical announced FDA approval of a clinical trial designed to determine the effectiveness of the new IVD design. Four centers – St. Paul and St. Cloud, MN; Shreveport, LA; and Tampa, FL – have now filled the 90 slots in their Phase I clinical trial.
The Chinese design has already completed Phase II clinical trials. The trial compared the IVD to no-scalpel vasectomy (NSV), and found that the men with IVDs were more satisfied and reported fewer side effects (Song 2006).
Because the materials used in both IVD designs have been widely tested and shown safe for medical use, researchers hope that these IVDs will encounter few regulatory hurdles. When the US design hits the market, Shepherd Medical predicts that the combined cost of the device and the insertion procedure will be under $1,000. If all goes smoothly, Shepherd anticipates having European, Canadian and US approval by 2010. The IVD research team in China is currently conducting a 2 year follow-up study of the men who participated in the Phase II trial. They hope to test reversibility next (Gu 2006).
How does it work?
The US IVD is two sets of tiny, pre-formed, flexible silicone plugs which are inserted into the vasa deferentia, the tubes carrying sperm from the testes. The device is sized to the width of each recipient’s vas deferens, filling the lumen (the opening in the vas tube) but not stretching the tube. Two plugs are inserted in the same vas with a small space between them. If sperm pass around the first plug and enter the space between the two plugs, the second plug blocks them. In order to prevent the plugs from moving within the vas deferens, they are anchored with small sutures to the wall of the vas deferens itself. Once implanted, they can not be felt. The IVD is similar in function to a vasectomy, but it leaves the vasa deferentia intact.
The Chinese IVD is a flexible urethane tube with one closed end. The tube is lined with a medical-grade nylon mesh that acts as a sieve to capture sperm. One device is implanted in each vas deferens. A small hole near the closed end of the tube allows the fluid in the vasa deferentia to pass while the sperm stay trapped. When the IVD is implanted, the doctor ties two loops around the outside of the vas – one at the front and one at the back of the IVD – to hold it in place. Again, the device leaves the vasa deferentia intact. By allowing the fluid in the vas to pass, this design aims to prevent the accumulation of pressure on the epididymis, which some researchers hypothesize is a result of closed-ended vasectomy.
How is it delivered?
The technique for inserting an IVD could be performed by any trained vasectomy practitioner. A doctor exposes the vas using a no-scalpel procedure. Then the doctor makes a tiny opening in the wall of the vas. The doctor then inserts the device, which is less than an inch long. The US design includes a tool designed to make the insertion easier. The tool stretches the device lengthwise, making it momentarily narrower than the vas. When the device is released, it expands to its full width, blocking the vas. Finally, the IVDs are anchored in place, either with a tiny suture or with a loop outside the vas. This whole procedure is performed under local anesthetic and takes less than 20 minutes.
How long does it take?
In this respect IVDs are again similar to vasectomy. While the no-scalpel insertion procedure takes less than 20 minutes, it may take up to 3 months to confirm effective contraception. As with a vasectomy, a follow up visit to the doctor and a sperm count are recommended to confirm that the device is working properly. In pilot studies, earlier designs of the US IVD caused azoospermia or severe oligozoospermia within 2-3 months. In the trial of the Chinese design, doctors advised the men to continue using another form of contraception for 3 months after the insertion.
How effective is it?
The current US design of the IVD is now undergoing a test of its effectiveness. Men who received previous designs of the US IVD did not test them as contraceptives, but the men’s drastically reduced sperm counts suggest that the IVDs would have provided effective contraception. One early study showed no sperm in participants’ ejaculate, implying 100% effective contraception. Another study showed 90% of the men became azoospermic; the other 10% had very low sperm counts (Zaneveld 1999, Burton 2004). Shepherd Medical expects better results with the current design because the IVDs will be measured to fit each man’s vas. Their 18 month trial for 90 men is underway at 4 US centers. The researchers expect to collect data for 6 months before publishing their findings on how fast the IVD provided contraception.
The Chinese IVD design has already been proven highly effective. The Phase II trial of that design provided 100% effective contraception starting 3 months after the insertion. The IVDs provided the same level of contraceptive reliability as no-scalpel vasectomy (Song 2006).
What side effects are there?
When compared directly to no-scalpel vasectomy (NSV) in the trial of the Chinese IVD design, the IVD had lower rates of side effects. Ten percent of the men reported pain or tenderness in the area of the procedure, as opposed to 20% in the NSV group. Only 3% formed granulomas (painful nodules of tissue), as opposed to 10% in the NSV group. There were no reports of congestive epididymitis (longer-term swelling and pain in the epididymis) or spontaneous reversal in the IVD group; respectively 5% and 2% of the NSV group reported these complications (Song 2006).
Side effects for the US design of the IVD have not yet been reported. Because the US design Is most similar in function to a closed-ended vasectomy, congestive epididymitis may be a concern. However, there has been no proper study to determine relative rates of congestive epididymitis with open- versus closed-ended vasectomies (Labrecque 2004). There is some evidence that closed-ended vasectomies have a higher rate of congestive epididymitis: 6% compared to 2% for open-ended vasectomies (Errey 1986, Moss 1992).
How long does it take to reverse?
The technique of IVD reversal compares favorably to vasectomy reversal, which is also known as vasovasostomy. The IVD can be removed by making a small incision over the plugs and removing them. Researchers anticipate that IVD reversal, like implantation, will be a fast outpatient procedure costing less than $1,000. By comparison, vasovasostomy costs $5,000 to $12,000 and requires 3-4 hours of microsurgery. Repeated use of IVDs by the same man is much more practical than multiple vasectomies, because IVDs can be both inserted and removed using a technique that will to cause little scar tissue (Burton 2004).
Because IVD reversal is a much simpler procedure, the researchers expect its reversal success rate will be significantly higher than vasovasostomy. However, we can expect that like vasovasostomy, IVD reversal’s success rate may also be affected by the time elapsed since insertion. After a vasovasostomy performed within one year of a vasectomy, an average couple has a 50% chance of conceiving. The success rate decreases 10% with each additional year. Researchers expect that the IVD reversal success rate will be significantly higher than vasovasostomy, but it remains to be tested.
IVD reversal has not yet been tested in humans. A study of IVD reversal in primates had promising results. Seven months after implantation, researchers removed an earlier design of the IVD from the monkeys. Within one month the primates returned to pre-implantation sperm count and motility (Zaneveld 1986).
- Burton, J, C Sievert, J Socha, B Stahele, J Stice, M Labrecque, N Pollock, J Pryor and L Zaneveld (2004) “Development and Evaluation of the Intra Vas Device (IVD).” Poster at the Future of Male Contraception Conference, September 29 - October 2, 2004, Seattle, WA.
- Errey, BB, and IS Edwards (1986) “Open-ended vasectomy: an assessment.” Fertility and Sterility 45(6): 843-6.
- Gu, YQ (2006) “Recent progress in clinical contraceptive efficacy study of male fertility control in China.” Asian Journal of Andrology 8(5 Suppl): 28-31.
- Labrecque, M, C Dufresne, MA Barone and K St-Hilaire (2004) “Vasectomy surgical techniques: a systematic review.” BMC Medicine 2: 21-32.
- Moss, WM (1992) “A comparison of open-end versus closed-end vasectomies: a report on 6220 cases.” Contraception 46(6): 521-5.
- Song, LM, YQ Gu, WH Lu, X Liang and Z Chen (2006) “A phase II randomized controlled trial of a novel male contraception, an intra-vas device.” International Journal of Andrology 29(4): 489-95.
- Zaneveld, LJD, JW Burns, SA Beyler, WA Depel and SW Shapiro (1986) “Development of a new reversible vas deferens occlusion device.” In Zatuchni (ed.), Male Contraception: Advances and Future Prospects, p. 201.
- Zaneveld, LJD, MC De Castro, G Faria, F Derrick and R Ferraro (1999) “The soft, hollow plug (“shug”): a potentially reversible vas deferens occlusive device.” In Rajalakshmi and Griffin (eds.), Male Contraception: Present and Future, p. 293.