Women with a prior OASIS have a higher recurrence rate compared with multiparas without prior OASIS (Baghestan, 2012; Edozien, 2014; Elfaghi, 2004). That said, the risk mirrors that of primiparas in the general population and is low (Basham, 2013; Boggs, 2014; Priddis, 2013). Fetal macrosomia and operative vaginal delivery are notable risks in this cohort of parturients and can influence counseling in future pregnancies. Speciically, patients may choose to deliver by cesarean to avoid repeat OASIS. his consideration may be most pertinent for those with prior postpartum anal incontinence, with OASIS complications requiring corrective surgery, or with psychological trauma (American College of Obstetricians and Gynecologists, 2016b). However, planned cesarean delivery is balanced against its associated operative risks discussed in Chapter 30 (p. 568).
In contrast to spontaneous lacerations, perineotomy is intended incision of the perineum. Episiotomy is incision of the pudendum-the external genital organs. In common parlance, however, the term episiotomy often is used synonymously with perineotomy, a practice that we follow here. Obstetrical textbooks and organizational guidelines difer considerably in their description of episiotomy techniques. Kalis and associates (2012) have presented a classification, and we agree with the need for terminology standardization.
Midline and mediolateral episiotomies are the two main types and vary by the angle of perineal incision. Involved structures mirror those found with second-degree laceration, and their repairs are analogous. The midline episiotomy begins at the fourchette, incises the perineal body in the midline, and ends well before the external anal sphincter is reached. he incision length varies from 2 to 3 cm depending on perineal length and degree of tissue thinning. The mediolateral episiotomy begins at the midline of the fourchette and is directed to the right or left at an angle 60 degrees of the midline (Fig. 27-14). This angle accounts for perineal anatomy distortion during crowning and ultimately yields an incision 45 degrees of the midline for suturing (El-Din, 2014; Kalis, 2011). The lateral episiotomy begins at point 1 to 2 cm lateral from the midline. It too is angled toward either the right or the left ischial tuberosity.
Before episiotomy, analgesia may be provided by existing labor regional analgesia, by bilateral pudendal nerve blockade, or by local infiltration of I-percent lidocaine. Some instead advocate 2.5-percent lidocaine-prilocaine cream (EMLA cream), but this requires application an hour before expected delivery, which may be logistically diicult (Franchi, 2009; Kargar, 2016).
If episiotomy is performed unnecessarily early, incisional bleeding may be considerable before delivery. If it is performed too late, lacerations will not be prevented. Typically, episiotomy is completed when the head is visible during a contraction to a diameter of approximately 4 cm, that is, crowning. When used in conjunction with forceps delivery, most perform an episiotomy after application of the blades.
Few data directly compare midline and mediolateral types. As noted, midline episiotomy has a greater likelihood of associated anal sphincter lacerations (Coats, 1980; de Leeuw, 2001). Shortterm rates of self-perceived pain and dyspareunia are similar or increased with mediolateral episiotomy (Fodstad, 2013, 2014; Sartore, 2004).