Vasectomy research eyes enhancement of method
New developments are arising on the vasectomy front, with researchers taking a look at the effectiveness of different methods of vas deferens occlusion and identifying chemical candidates to help speed up time to vasectomy success.
Vasectomy represents an important contraceptive option in the United States; nearly one in five white U.S. men married to women of childbearing age has undergone the procedure.1 It is safe and effective: Contraceptive Technology estimates the method has bout a 0.1% probability of pregnancy in the first year.2
Family Health International (FHI), a Research Triangle Park, NC-based research organization, and EngenderHealth, a New York City-based reproductive health organization, recently have completed a series of studies addressing the effectiveness of different methods of vas occlusion, reports David Sokal, MD, FHI associate medical director. In these studies, scientists have looked at sperm counts, rather than pregnancies, to define outcomes.
In a randomized controlled trial, findings suggest that fascial interposition, which calls for the sheath covering the vas to be pulled over one severed end and sewn shut to create a natural tissue barrier, significantly improves the outcomes of vasectomies done with ligation and excision, says Sokal. Partial results have been published,3 with the manuscript reporting the full results of the trial now submitted for publication.
Ligation and excision calls for a short segment of the vas (the tube which carries sperm from the testicles to the penis) to be cut and removed, and the remaining two ends tied. It is the most common method of vas occlusion used in developing countries. Recanalization is a spontaneous reconnection of the two ends of the vas that can occur following a vasectomy; data suggest that the risk of recanalization appears to be related to the surgical technique used for vas occlusion.4 The use of more effective surgical techniques, such as fascial interposition and cautery, can reduce this risk, scientists note.
U.S. clinicians are more familiar with cautery, which calls for burning the inside of the ends of the vas, and/or metal clips, often with fascial interposition, says Amy Pollack, MD, MPH, EngenderHealth president.
In 1995, about 71% total of the U.S. providers surveyed by EngenderHealth (then known as AVSC International) were using cautery only, or cautery with another technique, she states.5 EngenderHealth is performing another survey to obtain an updated view of what techniques are now in use, Pollack says.
Check waiting period
Typical recommendations on how long men should wait before relying on vasectomy using ligation and excision may need to be revised, according to a new study.6 Men in developing countries who have had a vasectomy usually are counseled to use a backup method of contraception either for 12 weeks following the vasectomy or until they have ejaculated 20 times.
Researchers in the new study examined 217 men who received ligation and excision vasectomies at three public health clinics in Mexico City. They found that the number of men who reached azoospermia was nearly 20% higher by 12 weeks than by 20 ejaculations.
The researchers also estimated that for every 100 men who undergo a vasectomy by ligation and excision, about 60 will reach azoospermia by 12 weeks, while only about 28 will reach azoospermia by 20 ejaculations. Results from the new study suggest that after use of the ligation and excision method of vasectomy, 12 weeks is a more reliable waiting period than 20 ejaculations. However, neither guideline is ideal, the study reports.6 Sokal adds that men should always be counseled that a vasectomy is not 100% effective. Pregnancies do occur after vasectomy procedures, especially among men who do not get a semen analysis to confirm that the procedure was successful, he states.
Contraceptive Technology reinforces this stance, reminding clinicians to counsel men that they are not sterile immediately, and that for many men, sperm will not be cleared from the vas tube until after about 20 ejaculations.1 The best way for men to determine whether they are sterile is to have a semen analysis after 20 ejaculations, states the book.1
Early research suggests that two chemicals now used in the medical field also may inhibit sperm function, which could lead to possible use in washing away residual sperm after a vasectomy.7 Use of the chemicals, diltiazem and methylene blue, as vas irrigants could decrease the time between vasectomy and sterility.
Researchers from FHI and the CONRAD program at the Eastern Virginia Medical School in Norfolk looked at five chemical compounds, and examined sperm from human volunteers to determine each chemical’s effects on sperm motility, viability, and ability to penetrate cervical mucus. Diltiazem, a calcium-channel blocker used to treat high blood pressure and chest pain, and methylene blue, a compound used to dye the vas during other surgical and diagnostic procedures, were identified as the most promising candidates for vas irrigants.7
More research will have to be performed to test the safety and efficacy of these compounds as vas irrigants, say Sokal and Pollack. Even if the compounds are found effective, some clinicians may continue to recommend a three-month waiting period before confirming vasectomy success due to the chance of recanalization, notes Sokal.
1. Abma J, Chandra A, Mosher WD, et al. Fertility, family planning, and women’s health: New data from the 1995 National Survey of Family Growth. Vital Health Stat 1997; 23:62-63.
2. Hatcher RA, Trussell J, Stewart F, et al. Contraceptive Tech-nology. 17th revised ed. New York City: Ardent Media; 1998.
3. Chen-Mok M, Bangdiwala SI, Dominik R, et al. Termination of a randomized controlled trial of two vasectomy techniques. Control Clin Trials 2003; 24:78-84.
4. Sokal DC, Irsula B, Chen-Mok M, et al. A comparison of vas occlusion techniques: Cautery vs. ligation and excision with fascial interposition. Presented at the annual meeting of the Association of Reproductive Health Professionals. La Jolla, CA; September 2003.
5. Haws JM, Morgan GT, Pollack AE, et al. Clinical aspects of vasectomies performed in the United States in 1995. Urology 1998; 52:685-691.
6. Barone MA, Nazerali H, Cortez M, et al. A prospective study of time and number of ejaculations to azoospermia after vasectomy by ligation and excision. J Urology 2003; 170:892-896.
7. Wood BL, Doncel GF, Reddy PR, et al. Effect of diltiazem and methylene blue on human sperm motility, viability and cervical mucus penetration: Potential use as vas irrigants at the time of vasectomy. Contraception 2003; 67:241-245.