The most recent data on obstetric lacerations during vaginal delivery have been incorporated into recommendations from the American College of Obstetricians and Gynecologists (ACOG), published in the July issue of Obstetrics & Gynecology. However, guidance on prevention and repair of severe perineal lacerations and on indications for episiotomy remains largely hampered by insufficient evidence.
An estimated 53% to 79% of women will experience some type of laceration during vaginal delivery, most commonly in the perineal body. Although most of these are first- and second-degree lacerations, the more severe third- and fourth-degree lacerations that result in obstetric anal sphincter injuries (OASIS) may occur in up to 11% of women giving birth vaginally. In 2014, ACOG published precise classifications of perineal lacerations to standardize clinical definitions and improve data collection on incidence.
The practice bulletin indicates that several trials have shown a reduced likelihood of laceration at delivery with perineal massage. However, ACOG fell short of recommending perineal support, as there was insufficient information regarding the description and quality of different methods.
Warm compresses on the perineum during the second stage of labor, however, did significantly reduce third- and fourth-degree lacerations. One recent randomized controlled trial also found an increased likelihood of delivery with an intact perineum in women who birthed in the lateral position with delayed pushing. Delayed pushing on its own appears to have no significant effect on perineal laceration or episiotomy rates.
Evidence on episiotomy is mixed, although there are adequate data to recommend restrictive use, based on clinical considerations, over routine use. Whereas one systematic review found no benefit in perineal laceration severity, pelvic floor dysfunction, or pelvic organ prolapse for routine episiotomy (over restrictive use), a smaller, lower-quality meta-analysis found 74% greater odds of anal incontinence from episiotomy compared with no episiotomy.
“Current data and clinical opinion suggest that there are insufficient objective evidence-based criteria to recommend episiotomy, especially routine use of episiotomy, and that clinical judgment remains the best guide for use of this procedure,” the bulletin states.
Further, too little evidence exists to support criteria for determining when episiotomy is indicated, and even in cases of shoulder dystocia and operative vaginal delivery, not enough clinical data exist to clearly determine benefit or harm from its use.
Clear data on the effect of episiotomy on higher-degree perineal lacerations is complicated by studies that frequently combine midline and mediolateral procedures. Some data suggest a slightly reduced risk for anal sphincter injuries with mediolateral episiotomy in primiparous women and significantly greater odds of OASIS with midline episiotomy in primiparous women (adjusted odds ratio, 4.2; 95% confidence interval, 1.8 – 10.0) and multiparous women (adjusted odds ratio, 12.8; 95% confidence interval, 5.4 – 30.3). If a clinician determines episiotomy is needed, mediolateral may be superior to midline, given the latter’s association with OASIS, but weak evidence also suggests a possible risk for perineal pain and dyspareunia from mediolateral cuts.
In terms of repairing lacerations, the common, minor tears of the anterior vaginal wall and labia can be left unrepaired, but clinicians should repair “periclitoral, periurethral, and labial lacerations that are bleeding or distort anatomy.” Too little evidence exists to determine whether or not to repair first- or second-degree lacerations, so the recommendations leave this decision up to clinical judgment.
If a clinician decides to repair these lacerations, recommended sutures are absorbable synthetic ones, such as polyglactin, and continuous suturing is best over interrupted suturing, the bulletin states. “For full-thickness external anal sphincter lacerations,” the bulletin recommends, “end-to-end repair or overlap repair is acceptable.” The bulletin also recommends a single dose of antibiotics at the time of repair of OASIS.
ACOG does not recommend routine endoanal ultrasonography immediately postpartum to identify occult OASIS, but clinicians can better detect overt OASIS “when a trained clinical research fellow repeats a perineal and rectal examination after the delivery attendant’s assessment but before suturing of the perineum,” according to two studies. Detection of overt OASIS may improve with education programs aimed at better identification of severe perineal lacerations, the bulletin stated.
Severe perineal trauma can result in retained sponges or needles, preventable with before and after counts, and in wound breakdown or wound infection. Perineal–rectal and rectal–vaginal fistulas can also result from lacerations that are not treated or that heal poorly.
Additional recommendations regarding prevention and treatment of obstetric lacerations in the bulletin rely on consensus or expert opinion.