Closing the Baby Factory: Male and Female Sterilization

Sterilization consists of surgical interventions that doctors perform to prevent conception and consequently to prevent pregnancy. This is for people who do not wish to have any more children. If you are interested in this option, it is very important that you and your partner receive counseling, since the procedures produce permanent sterilization. This is something that is important to understand from the beginning. You need to make a completely informed decision. Although there are instances in which sterilization procedures can be reversed, such reversal procedures generally have a low success rate. Additionally, depending on which country is your home, there typically are issues of coverage for sterilization reversals by government health care or by private insurance.

One very popular sterilization procedure is tubal occlusion. This is a female sterilization procedure since it involves intentional occlusion of both fallopian tubes. These are a pair of tubes, one on each side of the uterus that act as conduits for ova (eggs) traveling from the ovaries to the uterus. Normally, you release one egg each cycle when you ovulate. It’s possible that there can be two or more, which, if fertilized, each by a different sperm cell, can lead to multiple gestation (multiple pregnancy). If it’s twins, this is called a dizygotic pregnancy, since two separate zygotes are produced, which are genetically as similar as any siblings. It’s also possible for a single zygote to split, leading to monozygotic twins —identical twins— or monozygotic higher order gestation. Normally, fertilization occurs in the fallopian tube, so an ovum leaves the ovary, begins traveling through the tube toward the uterus, then is fertilized, so now a zygote is moving through the tube. The zygote undergoes cell division and develops into a blastocyst, which implants into the endometrium (the inner lining) of the uterus around five to six days after fertilization. If your tubes are closed, however, in a tubal occlusion procedure, an ovum cannot travel all the way through the tube and sperm cells cannot swim far enough through the tube to meet up with the ovum. Since the ovum is not fertilized, there is no zygote to develop and grow in the tube, no blastocyst to get stuck in the closed tube, producing a tubal pregnancy, a type of ectopic pregnancy. The unfertilized ovum just dies and gets absorbed.

Typically, obstetrician gynecologists performed tubal occlusion by means of laparoscopic surgery. This is what doctors call minimally invasive surgery. Tubes are inserted through very small incisions and special instruments are operated through the tubes. It can be done either under general anesthesia, or under what doctors call neuraxial anesthesia, meaning that the anesthesiologist administers local anesthetic through a needle in your lower back and this blocks sensation in everything below a certain level. Occlusion of the tubes is achieved by means of special clips, called Filshie clips. Another way to occlude the tubes is to tie them up, which is called tubal ligation. Alternatively, the tubes can simply be removed. Sometimes, such procedures are done as an elective procedure during a cesarean section in a woman who wants this to be her final baby. Tubal occlusion is more than 99 percent effective. Another way to say this is that the failure rate is 1 per 200. Alternative contraception is required until the next menstrual period, since there already may be an ovum released and ready for fertilization downstream from where the tube was occluded.

Let’s move onto the male sterilization procedure, which is called a vasectomy. In this procedure, the surgeon cuts the vas deferens to prevent sperm traveling from the testes to merge into the ejaculation fluid on its way from the prostate. This prevents sperm from being released into the vagina, which is why the procedure prevents pregnancy. Effectiveness of vasectomy is more than 99 percent and the failure rate are only 1 per and 2,000 procedures. Vasectomy is performed under local anesthesia. It usually takes only 15 to 20 minutes and is less invasive compared with female sterilization. For this reason, many couples choose vasectomy as a permanent route to contraception rather than tubal occlusion. After vasectomy, a man must wait two to three months for semen to be tested to confirm that there is no more sperm before he can rely on the vasectomy to prevent pregnancy. Generally, semen testing conducted at 12 weeks after the procedure to make sure that all the sperm has cleared. A second sample may be taken just to confirm that sperm no longer gets through. During these transition weeks, you and your male partner need to use an alternative form of contraception.

David Warmflash
Dr. David Warmflash is a science communicator and physician with a research background in astrobiology and space medicine. He has completed research fellowships at NASA Johnson Space Center, the University of Pennsylvania, and Brandeis University. Since 2002, he has been collaborating with The Planetary Society on experiments helping us to understand the effects of deep space radiation on life forms, and since 2011 has worked nearly full time in medical writing and science journalism. His focus area includes the emergence of new biotechnologies and their impact on biomedicine, public health, and society.

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