Episiotomy: What's the angle?

Abstract

In part four of his treatise, The Law, Hippocrates states: “There are in fact two things, science and opinion; the first begets knowledge, the second ignorance.” In this issue of the Journal, Kalis and colleagues [1] provide scientific data concerning an important issue that has been debated for many years: whether the angle of mediolateral incision when the fetal head is distending the perineum is different from the angle of the wound after the neonate has been delivered. Although at first this may seem to be a semantic argument, it has great importance. When an episiotomy is needed, some clinicians choose a mediolateral rather than a midline episiotomy, primarily to reduce the chance of anal sphincter rupture since it is well established that midline episiotomy carries a higher risk of sphincter laceration. This is a highly relevant issue because sphincter lacerations increase the chance that a woman may suffer fecal incontinence. The angle at which an episiotomy can be made is a continuous variable. If we consider midline to be 0 degrees and a lateral episiotomy (never used today) to be 90 degrees, then it is theoretically possible to choose any angle from 0 to 90 degrees. Which angle should we choose? If a mediolateral episiotomy is performed to reduce anal sphincter injury, then this angle must be great enough that the incision and any potential subsequent tearing are far enough away from the anal sphincters that they are not injured. Statements quoted in Kalis et al. [1] suggest specific angles to be used when employing the mediolateral technique.