Injury to the perineum during vaginal childbirth affects millions of women. One half to three quarters of parturients undergo some degree of perineal laceration during vaginal childbirth. However, rates vary considerably by locale and provider (Low, 2000; Webb, 2002). Some lacerations occur spontaneously during delivery. Or, an obstetric provider may cut an episiotomy to increase the vaginal outlet size to aid the birth. Either may result in both short- and long-term symptoms and complications. Initially, most women experience at least temporary discomfort or pain after perineal lacerations, and one in five will report long-term issues, such as dyspareunia (Glazener, 1995). Additional complications include physical, psychologic, and social problems, which all may affect a woman’s ability to care for her newborn and family (Sleep, 1991). The most severe perineal lacerations involve the anal sphincter, and these are termed obstetric anal sphincter injuries (OASIs). These tears and their consequences are described in detail throughout this chapter.
Preventively, increasing data are available to guide health-care providers and patients in selecting the optimal perineal strategy for each woman’s delivery. No single strategy fits all patients, thus clinicians should devote time during antepartum counseling. Topics ideally include discussion of the risks and benefits of episiotomy, strategies that may minimize spontaneous OASIs, and expectations of pelvic floor function following delivery.
In this chapter, we review current literature and practices for antepartum, intrapartum, and postpartum perineal management. Specifically, data regarding risks and possible benefits of episiotomy, repair of obstetric lacerations, and their short- and long-term sequelae are presented.
Studies suggest that obstetricians may misclassify anal sphincter injuries. This is coupled with an increasing awareness of the association between OASIs and anal incontinence (Fernando, 2006; Sultan, 1995). For these reasons, the traditional classification system for perineal lacerations was modified to include more specific information regarding the anal sphincter complex. This updated system now contains internationally accepted nomenclature and is summarized in Table 20-1 and Figure 20-1 (Koelbl, 2009; Royal College of Obstetricians and Gynaecologists, 2007).
| Tear Type | Injury Description |
|---|---|
| First degree | Injury to perineal skin only |
| Second degree | Injury to the perineum involving the perineal muscles but not the anal sphincter |
| Third degree | Injury involves anal sphincter complex |
| 3a | Less than 50% of EAS is torn |
| 3b | More than 50% of EAS is torn |
| 3c | EAS and IAS are torn, but the anorectal epithelium is intact |
| Fourth degree | EAS, IAS, and anorectal epithelium are torn |
FIGURE 20-1
1. First-degree perineal laceration: injury only to perineal skin. 2. Second-degree perineal laceration: injury to perineum involving the perineal muscles but not to the anal sphincter complex. 3a. Third-degree perineal laceration: less than 50% of the external anal sphincter (EAS) is torn. 3b. Third-degree perineal laceration: more than 50% of the EAS is torn, but the internal anal sphincter remains intact. 3c. Third-degree perineal laceration: external and internal anal sphincters are torn. 4. Fourth-degree perineal laceration: injury to the perineum involves the entire anal sphincter complex and the anorectal epithelium.
By definition, OASIs include only third- and fourth-degree perineal tears. Intuitively, these are associated with significantly more maternal morbidity than first- and second-degree lacerations. Moreover, in recent years, litigation related to long-term maternal consequences of OASIs has increased (Eddy, 1999). In the report by the National Health Service Litigation Authority (2012) entitled Ten Years of Maternity Claims, perineal trauma was listed as the fourth most common indication for obstetric claims in the United Kingdom during a 10-year span (Jha, 2015).
Episiotomy is commonly performed in obstetrics and is among the most-debated procedures. Episiotomy refers to a surgical incision of the perineum usually performed during the second stage of labor to increase the diameter of the pelvic outlet. Episiotomy was thought to prevent perineal lacerations, aid delivery, and reduce the time for neonate delivery.
Sir Fielding Ould (1742), a Dublin midwife, recommended episiotomy to hasten prolonged labor when the external vaginal opening was deemed too narrow. In the United States, the first report of episiotomy was almost 110 years later. Namely, Taliaferro (1852) used a scalpel to cut a 1-inch left mediolateral episiotomy to aid delivery and avoid a rectal tear in a 16-year-old eclamptic patient.
In the 20th century, more women delivered in hospitals, and this was accompanied by an increase in episiotomy rates (Thacker, 1983). DeLee (1920) recommended forceps-assisted vaginal delivery with mediolateral episiotomy for all nulliparas and claimed that episiotomy provided protection for both mother and fetus. He believed episiotomy would preserve the pelvic floor and introitus, prevent uterine prolapse and rupture of the vesicovaginal septum, and restore virginal conditions. Some also attribute women delivering in lithotomy position to the rise in episiotomy and OASIs during this period. Dorsal lithotomy is thought to place additional stress on the perineal body and lead to tears whether or not an episiotomy is cut (Bromberg, 1986; Thompson, 1987).
In the 1960s, rates of routine episiotomy decreased as opponents questioned its scientific benefits. Investigators argued that widespread use of routine episiotomy did not withstand scientific scrutiny; that episiotomy risks were largely ignored; and that women would likely decline routine episiotomy if adequately informed of the risks and benefits (Kitzinger, 1981; Thacker, 1983).
Population-based studies from the United States report that episiotomy rates have declined and were approximately 60 percent in 1979, 31 percent in 1997, and 25 percent in 2004 (Frankman, 2009; Weber, 2002). A recent study of vaginal deliveries in more than 500 hospitals found that episiotomy rates continued to decline from 17 percent in 2006 to 12 percent in 2012. That said, hospital-to-hospital variation remains high (Friedman, 2015). For example, the episiotomy rate was 34 percent in the 10 percent of hospitals in which episiotomy was done most frequently. This compared with a rate of 2.5 percent in the 10 percent of hospitals that used episiotomy the least.
Table 20-2 lists patient, practitioner, and delivery factors associated with higher episiotomy rates. In a study by Friedman and colleagues (2015), white women had an episiotomy rate of 15.7 percent compared with a rate of 8 percent for black women. Notably, factors were not stratified by parity. Gravidas with commercial insurance had a rate of 17 percent compared with Medicaid enrollees, whose rate was 11 percent. Moreover, rural and teaching hospitals had lower episiotomy rates compared with urban and non-teaching facilities. Faculty and private practitioners are two and four times, respectively, more likely than midwives to cut an episiotomy (Gerrits, 1994; Howden, 2004; Robinson, 2000). Likewise, episiotomy use is higher in nulliparas and those receiving epidural anesthesia (Hueston, 1996; Newman, 2001; Robinson, 2000). In contrast, upright or lateral maternal positions are associated with fewer episiotomies (Gupta, 2012). Last, episiotomy is also more common with operative vaginal than spontaneous vaginal deliveries (71 versus 33 percent) (Weber, 2002).
The indications for episiotomy vary widely and include those for the mother or the fetus. Of maternal indications, some argue that episiotomy should be considered to reduce spontaneous perineal lacerations and their sequelae. To address this, a Cochrane database review by Carroli and Mignini (2009) included eight randomized trials with 5541 women to assess the effects of routine use versus restrictive use of episiotomy. Seventy-five percent of women in the routine group had episiotomies compared with 28 percent in the restrictive group. Restrictive use of episiotomy was associated with lower rates of severe perineal trauma, suturing, and healing complications. No differences were identified in rates of severe perineal or vaginal trauma or later dyspareunia or in several measures of perineal pain. Women in the restrictive episiotomy group had a higher incidence of anterior perineal trauma. However, this was not associated with greater rates of urinary incontinence or pain. These results were consistent regardless of whether midline or mediolateral episiotomies were done. That said, no comparative trials that specifically compared midline with mediolateral episiotomy were available for their analysis. The authors concluded that episiotomies should be performed in a restrictive manner rather than routinely.
Regarding long-term effects, a prospective cohort study was designed to examine the effects of episiotomy on women whose first delivery was 5 to 10 years earlier. Investigators found that both forceps delivery and perineal lacerations, but not episiotomies, were associated with pelvic floor symptoms (Handa, 2012).
Of fetal indications, some recommend episiotomy to shorten second-stage labor for a category III fetal heart rate tracing and lower rates of poor neonatal outcome. As a second indication, episiotomy may aid resolution of shoulder dystocia and thereby lower associated fetal acidosis or trauma. In addition, proponents assert that episiotomy protects premature fetuses against intracranial hemorrhage during vaginal birth. Few published data address these fetal indications.
Based in part on the above evidence, the decision to perform an episiotomy should be individualized to each woman with thoughtful consideration of the established risks and potential benefits. Routine use of episiotomy is not supported by medical literature and is associated with increased maternal morbidity in most cases. Hospitals with high episiotomy rates should consider implementing education and quality improvement programs to educate the health-care team. One published literature review found that training courses, audits, a staff champion, and feedback to individual providers regarding their episiotomy rate could help reduce episiotomy rates (Faruel-Fosse, 2006).
Most experts now advocate for the restrictive use of episiotomy. The American College of Obstetricians and Gynecologists (2015) has concluded that restricted use is preferred to routine use of episiotomy. The National Quality Forum reported that limiting the routine use of episiotomy was an important quality and patient safety measure and noted increased rates of pain and anal incontinence with the procedure (Main, 2009).
There is no international consensus on how to define the different episiotomy techniques, and obstetric textbooks and organization guidelines differ considerably. Kalis and associates (2012) have presented a classification of these, 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. Their specific surgical steps are described and illustrated on page 324. To summarize, the midline episiotomy begins at the fourchette, incises the perineal body in the midline, and ends well before the external anal sphincter is reached. The mediolateral episiotomy begins at the midline of the fourchette but is angled toward either the right or the left ischial tuberosity. The lateral episiotomy begins at a point 1 to 2 cm lateral from the midline of the fourchette. It too is angled toward either the right or the left ischial tuberosity. Notably, in older texts, lateral episiotomy formerly described incisions that began at 9 o’clock on the perineum and extended directly laterally. This incision is no longer recommended as it fails to provide sufficient perineal relaxation and is associated with bleeding risks from the vestibular bulb and pudendal artery branches (Zuspan, 1988).
Comparing midline and mediolateral types, few data support the indicated use of one over the others. To date, only one randomized trial has compared midline and mediolateral episiotomies (Coats, 1980). Midline episiotomy was associated with a higher likelihood of OASIs, but with less scarring and a quicker return to sexual intercourse. Self-perceived pain scores and dyspareunia were similar in both episiotomy groups.
Most other comparisons of these two episiotomy types derive from case series and cohort studies. These investigations show an increased risk of OASIs with midline compared with mediolateral episiotomy. Namely, one metaanalysis identified higher rates of OASIs after midline compared with mediolateral episiotomy in both nulliparas and multiparas undergoing vacuum-assisted delivery (Sagi-Dain, 2015).
In comparison, both types result in similar rates of pain. Specifically, one prospective cohort study of 300 gravidas found no differences in postpartum pain scores or dyspareunia at 3 months among women receiving midline, mediolateral, or lateral episiotomy techniques (Fodstad, 2014).
There are even fewer studies that compare lateral episiotomy to either mediolateral or midline. One randomized trial compared lateral and mediolateral types in nulliparas. Groups did not differ in pain scores or in vaginal or perineal trauma, including OASIs (Karbanova, 2014a,b). The authors also reported that mediolateral episiotomies required less time and suture for the repair but that they lie closer to the anus.
In sum, in appropriately counseled women in whom episiotomy is indicated, mediolateral episiotomy may be the preferred incision type based on similar pain and dyspareunia outcomes, but reduced rates of OASIs. The American College of Obstetricians and Gynecologists (2015) concludes that mediolateral might be preferable to midline episiotomy in selected cases.
The very conditions that lead to indications for operative vaginal delivery also increase the likelihood of perineal lacerations. Episiotomy is reported in up to two thirds of vacuum-assisted deliveries, although rates vary widely. In their systematic review that included 350,764 vacuum-assisted deliveries, Sagi-Dain and Sagi (2015) found that the rate of OASIs nearly doubled in nulliparas (59 percent) compared with multiparas (34 percent). Of episiotomy types, lateral episiotomy decreased the risk of OASIs in nulliparas. With mediolateral episiotomy, OASIs rates were greater in multiparas, yet for nulliparas, there was a nonsignificant but protective trend. Last, midline episiotomy increased OASIs rates during vacuum-assisted delivery regardless of parity. Although the quality of evidence in this review was poor, these data suggest that the risk for OASIs during vacuum-assisted delivery varies according to parity and episiotomy type. For the fetus, this same review did not ascribe any fetal benefits to any type of episiotomy during vacuum delivery. Evaluated indicators included Apgar score, umbilical artery pH and base excess, neonatal intensive care unit (NICU) admission, and need for neonatal resuscitation.
Of other evidence, a population-based study found that lateral episiotomy was associated with a 46-percent decreased incidence of OASIs in nulliparas who delivered with vacuum assistance (Räisänen, 2012). Similarly, data from the Danish Medical Birth Registry found that in vacuum-assisted deliveries, mediolateral episiotomy was protective compared with no episiotomy (Jangö, 2014).
Forceps delivery is associated with an increased risk for OASIs that ranges from 10 to 35 percent (Bofill, 1996; de Vogel, 2012; Johnson, 2004). Likewise, in a large prospective cohort study of women who sustained OASIs, two thirds of third- or fourth-degree lacerations were associated with forceps deliveries (Lewicky-Gaupp, 2015). A retrospective study evaluated OASIs rates and fetal head position prior to forceps delivery. Bradley and coworkers (2013) showed a lower OASIs rate during forceps delivery if fetuses were rotated from occiput-posterior (OP) to occiput-anterior (OA) head position compared with delivery from an OP position. Thus, clinicians may consider rotation of the fetal head to an occiput-anterior position to decrease OASIs rates if forceps are needed.
Retrospective studies suggest that mediolateral episiotomy may provide protection for the anal sphincter during operative delivery, including forceps delivery (de Vogel, 2012; de Leeuw, 2008). Two recent studies found that mediolateral episiotomy during operative deliveries (forceps and vacuum) decreased the odds of OASIs, with one study showing a sixfold reduction of OASIs (Bharucha, 2014; Jangö, 2014). However, routine use of mediolateral episiotomy has not been shown to reduce risk of OASIs.
In sum, forceps delivery is a well-established risk factor for OASIs. Moreover, as with any vaginal delivery, episiotomy use is restricted unless clinical indications are present, and women are counseled regarding increased risks. If episiotomy is done, a mediolateral incision is preferable for many cases (de Leeuw, 2008; de Vogel, 2012; Hirsch, 2008).
Prior to performing an episiotomy, a clinician ensures adequate patient anesthesia from an epidural, spinal, or pudendal block. To supplement these, 1-percent lidocaine or other suitable anesthetic agent can be injected as needed into the perineum and surrounding tissues. The incision is typically initiated late in the second stage of labor and as the fetal head crowns and distends the perineum. Prior to incision, the clinician insinuates two fingers between the fetal head and perineal body. These digits exert additional outward pressure on the perineum to flatten it and also protect the presenting fetal part. In most cases, straight Mayo scissors are used to cut the perineum.
With mediolateral episiotomy, the incision begins at the fourchette in the midline. It is directed toward the ipsilateral ischial tuberosity and lies along a line at least 60 degrees from the midline (Fig. 20-2). As such, after delivery, the angle becomes more acute, approximately 45 degrees, because the perineum is no longer stretched by the fetal head. Studies have shown that larger angles are associated with lower risks of OASIs. To better understand the angle of the mediolateral episiotomy incision, investigators compared trigonometric characteristics of the final perineal scars. The ideal angle of the final healed scar ranged from 30 to 60 degrees (Eogan, 2006; Stedenfeldt, 2012). Specifically, Gonzalez-Diaz and coworkers (2015) found that a healed scar that lay at an angle >20 degrees from the sagittal midline correlated with an 87-percent lower risk of OASIs.
The incision should be sufficiently deep to remove perineal resistance for fetal delivery and should extend at least 3 to 4 cm onto the perineum. If the episiotomy is placed too laterally, it will not provide the desired relaxation of the median portion of the levator plate. The anatomic structures traversed during a mediolateral episiotomy include the vaginal epithelium, superficial transverse perineal muscle, bulbospongiosus (formerly, bulbocavernosus) muscle, and perineal skin. Large episiotomies may also expose ischiorectal fat.
With midline episiotomy, the perineum is incised in the midline from the posterior fourchette toward the anus. However, the incision stops well short of the external anal sphincter. The position of the sphincter is easily ascertained by visualization and palpation.
Midline episiotomy was historically performed in the United States because of perceptions that it was easier to repair and associated with less pain. However, as noted earlier, limited data suggest a higher risk of OASIs with midline compared with mediolateral episiotomy yet similar postpartum pain. Although the data are insufficient to determine the superiority of either approach, mediolateral may be preferred if an episiotomy is necessary.
With this episiotomy, the incision begins at the introitus but at a point 1 to 2 cm lateral to the midline. Similar to the mediolateral type, it is directed toward the ipsilateral ischial tuberosity (Kalis, 2012).
To properly select an appropriate suture for episiotomy repair, clinicians should be familiar with principles of wound healing and properties of commonly used sutures. These are detailed in Chapter 1 (p. 4). Ideally, closure strives to approximate damaged tissues, promote healing by primary intention, control bleeding, and minimize infection. Most perineal wounds heal by primary intention within 2 weeks of repair. If the sutures remain longer, they can act as a foreign body and initiate an inflammatory response. In turn, this response can potentially lead to poor or delayed wound healing or pain. Thus, the ideal suture material prompts minimal tissue reaction and is quickly absorbed once the tissues are healed. Different tissues will take longer to heal, and these therefore need sutures that maintain their tensile strength for varying lengths of time.
Of absorbable suture materials, two broad categories are catgut, which is absorbable, and synthetic materials, which are considered delayed-absorbable. These differ primarily in the way in which they are absorbed. Catgut is absorbed by phagocytosis and incites a greater inflammatory reaction. Plain catgut elicits a greater inflammatory response than chromic catgut.
Synthetic, delayed-absorbable sutures are absorbed by hydrolysis. Polyglactin 910 (Vicryl) is commonly used in episiotomy and perineal repairs. It maintains its tensile strength for 30 days and is totally absorbed in 90 days. Certain layers of the repair such as the perineal body require sutures to hold their tensile strength longer than the vaginal epithelium. Other important synthetic sutures for episiotomy repairs include Monocryl (poliglecaprone 25) and Vicryl Rapide. The latter is identical in composition to polyglactin 910 but is absorbed faster. Thus, Vicryl Rapide maintains its tensile strength and supports tissues for approximately 14 days and is completely absorbed within 40 days. Monocryl has low tissue reactivity and maintains high tensile strength with a half-life of 7 to 14 days. It is hydrolyzed by approximately 90 days.
One Cochrane review investigated absorbable and delayed-absorbable sutures for repair of episiotomies and second-degree perineal lacerations (Kettle, 2012). These reviewers found that standard synthetic sutures such as polyglactin 910 were associated with less immediate postpartum pain and less analgesia use than catgut sutures. However, not surprisingly, based on suture properties, more women with standard synthetic sutures required removal of unabsorbed suture material. When standard synthetic sutures were compared with rapidly absorbing synthetic sutures, pain outcomes were similar. However, more women in the standard suture group required suture removal.
With more extensive lacerations involving the internal and external anal sphincter muscles, a monofilament delayed-absorbable suture, such as polydioxanone (PDS II) or polyglyconate (Maxon), are additional options. Delayed-absorbable sutures offer the benefits of an absorbable suture and extended wound support (up to 6 weeks). At 4 weeks, 65 to 90 percent of polydioxanone’s original strength is retained and absorption is complete between 180 and 240 days.
Initially, any vaginal and/or cervical lacerations proximal to the episiotomy site that require suturing are repaired first. Similarly, atony is resolved and manual exploration of the uterus, if needed, is completed prior to episiotomy suturing. With this strategy, upper genital tract bleeding that might obscure episiotomy visualization is minimized. Second, early resolution of these avoids the later need for hands or retractors in the vagina, which can tear a completed episiotomy repair.
Essential steps to repair include good maternal pain control, ideal lighting, and gauze or suction to clear blood from the field. Adequate inspection of the perineum, posterior vaginal wall, and rectum is necessary to ensure that the episiotomy or perineal laceration did not extend into the anal sphincter and/or rectum. Rectal examination is strongly recommended in all cases of significant perineal injury to ensure that defects in the internal anal sphincter and rectal epithelium are not missed.
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