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How and Why an Episiotomy Is Performed

Episiotomy used to be one of the most common procedures performed in obstetrics, but that has changed dramatically over the last decade. Research showed that the benefits of episiotomy were vastly overrated and it is well on its way out of obstetrical practice.

Episiotomy was though to prevent uncontrolled, jagged tears during delivery by artificially enlarging the external vaginal opening. The area under the vaginal opening was anesthetized with a local anesthesia (unless the mother has already had an epidural), and a scissors was used to cut into the space. The cut could be either straight up and down (median episiotomy), or, if the baby was very large or the space very short, the cut was made off to one side (mediolateral episiotomy), to avoid damaging the anal sphincter, which is the muscle that controls bowel continence. After delivery, the episiotomy is closed in layers with absorbable sutures. There is no need to remove stitches later on because they dissolve and are absorbed.

Doctors thought that episiotomy represented the solution to an engineering problem: The baby's head is often too large to fit through the external opening of the vagina without causing significant tearing of the vagina and the surrounding tissues (these tissues are called the perineum). In some women, the external opening of the vagina will stretch to accommodate the baby's head. However, in many women having their first baby, it will not stretch enough to prevent tearing. The rationale behind episiotomy was that fewer stitches would be needed to close an episiotomy than multiple jagged tears. Scientific research showed that this was not the case, and, in fact, an episiotomy might lead to additional tearing.

There are now only a few situations in which an episiotomy appears to be helpful. The first is when forceps are used to aid delivery in the second stage. Forceps are relatively large, and in order to apply them to the baby's head safely and properly, an episiiotomy is needed.

The second situation is when the baby is quite large and a shoulder dystocia could occur. Shoulder dystocia happens when the baby's head is born, but the shoulders become wedged behind the mother's pelvic bone. This is an emergency because the baby can't get oxygen through the umbilical cord, which is compressed between the baby and the walls of the vagina. It also cannot get oxygen by breathing because its chest is compressed by the walls of the vagina and it can't take in a breath. It is important to deliver the baby as quickly as possible and that often requires maneuvers to twist the baby so the shoulder will pass. An episiotomy makes more room for a practitioner to reach around the baby and release the shoulder.

The other major reason why episiotomy was thought to be beneficial was to prevent urinary incontinence in women after their childbearing years. As women age, the tissues in the pelvis relax and women may find that they have difficulty holding in urine. It is well known that previous vaginal deliveries make this problem more likely. Doctors thought that preventing the vagina from being stretched could prevent urinary incontinence. Unfortunately, that is not the case because it is the stretching of the ligaments inside the pelvis that probaly lead to weakening and subsequent problems with holding in urine.

Because of the lack of benefit, and, indeed, an increased risk of tearing, episiotomy should now be used only in specific situations and not for uncomplicated vaginal deliveries.