Obstetric Lacerations: Repair and Prevention

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Here’s the RoshReview Question of the Week!

After a forceps delivery of a 9 lb neonate, a perineal laceration is noted with both the external anal sphincter and internal sphincter torn. During the repair, a glistening white fibrous structure is sutured together in a continuous, nonlocking fashion. What tissue is this?

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Anatomic Review

  • Perineal body anatomy – most common site of injury

    • This is the fibromuscular mass in the middle line of the perineum at the junction between the urogenital triangle and the anal triangle  

      • Bulbospongiosus 

      • Superficial transverse perineal muscle 

      • Deep transverse perineal muscle 

    • Below this = anal sphincter complex 

      • External anal sphincter – voluntary control; provide squeeze pressure of the anal canal 

      • Internal anal sphincter – involuntary (autonomic) control and provides up to 80% of resting pressure of the anal canal. Very important for continence 

So how often do obstetric lacerations occur? 

  • Varying numbers, but about 53-79% of women will sustain some type of lac during delivery 

  • Types 

    • First Degree – injury to perineal skin only 

    • Second Degree – involves perineal muscles but not involving anal sphincter 

    • Third Degree – injury involves the anal sphincter complex 

      • 3a: <50% of external anal sphincter thickness torn 

      • 3b: >50% of external anal sphincter thickness torn 

      • 3c: Both external and internal anal sphincter torn 

    • Fourth Degree – injury involves anal sphincter complex and anal epithelium 

      • Studies show (obviously) that women with 4th degree lacs are at highest risk of reporting bowel symptoms at 6 months postpartum 

      • Report bowel control 10x worse than women with third degrees 

  • What about episiotomies? 

    • Surgical enlargement of the posterior aspect of the vagina by incision to the perineum to facilitate the second stage of labor 

    • Rates have decreased since 2006 

      • However, 12% of vaginal births include episiotomies based on 2012 data 

    • Difficult to separate contribution of vaginal birth, operative delivery, episiotomy, and OASIS to pelvic floor function and anatomy 

    • Systematic review showed that routine episiotomy offered no immediate or long-term maternal benefit in perineal laceration severity, pelvic floor dysfunction, or pelvic organ prolapse 

      • In other reviews though, episiotomy has been associated with increased risk of postpartum anal incontinence; seen in one meta-analysis: increased risk of anal incontinence even if no extension into anal sphincter complex 

    • Routine episiotomy did not improve self-reported sexual function outcomes; more likely to have pain with intercourse in months after pregnancy and slower to resume intercourse than women whom episiotomy use was restricted 

    • So… there is a time and place for episiotomies, but don’t routinely cut them 

What are the risks for higher order lacerations, ie. OASIS? 

  • Operative deliveries 

    • Forceps (OR 5.50), VAVD (OR 3.98) 

  • Midline episiotomy (OR 3.82)  

  • Increased fetal birth way (mean difference 192.88g) 

  • Midline episiotomy + forceps substantially increases the risk of 3rd and 4th degree laceration 

  • Other ones that are less modifiable: 

    • Primiparity 

    • Asian ethnicity (problematic)

    • Labor induction 

    • Labor augmentation 

    • Epidural use 

    • Persistent OP 

Ok, so now that we’ve talked about all the scariness, how do we prevent them? 

  • Antepartum or intrapartum perineal massage 

    • Thought is to decrease perineal muscle resistance and reduce likelihood of lacs 

      • In studies that compared antenatal perineal massage to no-massage, digital massage from 34 weeks gestation on was associated with modest reduction in perineal trauma that required suture repair (RR 0.91), and decreased episiotomy 

      • Perineal massage during second stage of labor may reduce 3rd and 4th degree lacs when compared with “hands off” methods but was not associated with significant changes in rate of birth with intact perineum 

    • Perineal support: data is so-so 

      • Meta-analysis with >6600 women – did not demonstrate protective effect for OASIS 

      • However, three nonrandomized studies showed significant reduction 

      • But techniques of support not well described 

  • Warm compress 

    • Meta-analysis with 1525 women 🡪 randomized to warm compress or no in second stage of labor 🡪 did reduce 3rd and 4th degree lacs 

    • Did not increase rate of women having intact perineums 

  • Birthing position 

    • Upright or lateral birth position compared with supine or lithotomy associated with fewer episiotomies and operative deliveries, but higher rates of second-degree lacs (overall low quality data) 

    • Meta-analysis of five randomized trials showed no clear benefit 

    • Recent randomized trial: lateral birth position with delayed was compared with lithotomy positions 🡪 lateral positive with delayed pushing more likely to deliver with intact perineum 

  • Delayed pushing – no difference in lacerations

How do we manage obstetric lacerations?

  • Periclitoral, periurethral, labial lacerations 

    • Small tears of the anterior vaginal wall and labia are relatively common 

    • If superficial and no bleeding – can be left unrepaired 

    • However, if bleeding or distort anatomy, should repair and also consult experts if you do not feel comfortable with it 

  • First and second degree 

    • Insufficient evidence exists to recommend surgical or nonsurgical repair of first or second degree lacs 

    • A lot of data does not include long-term outcomes 

    • Use clinical judgement about repair 

      • Continuous suturing is preferred over interrupted suture 

      • Associated with less pain up to 10 days postpartum, less analgesia used, and lower risk of having suture material removed postpartum 

      • Use absorbable synthetic suture like polyglactin (ie. Vicryl) 

  • OASIS injuries 

    • Overt OASIS reported in 4% of women in the US

      • Occult OASIS may be later identified by endoanal ultrasonography, but have no clinical findings – occur in 27% of women after first vaginal delivery 

    • The first thing to do: really look! If you suspect, do a digital rectal exam. Examine the perineal body and also the vaginal mucosa. See if you can start to see fibers of the internal and external anal sphincter 

      • SIM has been shown to be helpful in helping providers identify and repair these 

    • How to repair for OASIS 

      • Anal mucosa – expert opinion varies on technique and suture material 

        • Subcuticular running repair that uses a transvaginal approach and interrupted sutures with knots tied in the anal lumen have been described 

        • Suggest using 4-0 or 3-0 polyglactin or chromic 

        • No comparative trials have been done 

      • Internal/external anal sphincter 

        • Identify the area of the internal and external anal sphincter 

        • Because of retraction, we will usually place an Allis on either side of the external anal sphincter muscle to bring them together. Can cross the Allis’s and do a rectal to see if you are bringing the right muscles together 

        • Suture fascial sheath as well as muscle! 

        • Methods: End-to-end and overlap repair 

          • Remember: overlap requires full thickness disruption and 1-1.5 cm torn muscle on either end, so don’t use it for 3a or partial thickness 3b sphincter injuries 

          • Expert opinion: use 3-0 or 2-0 polyglactin suture

          • Meta-analysis of six randomized controlled studies showed no difference between two techniques at 12 months of perineal pain, dyspareunia, or flatal incontinence, but there were lower incidence of fecal urgency and lower anal incontinence scores in women with overlap repair 

          • No significant difference in quality of life or anal incontinence symptoms 36 months after repair  

        • We tend to do end-to-end because of visualization; PISA technique

  • Antibiotics for OASIS 

    • Wound complications (ie. Infection, breakdown) are decreased when intrapartum antibiotics are administered 

    • So single dose of antibiotics (studies looked at single dose of second gen cephalosporin) is reasonable. Further research is needed to determine whether severe perineal lacerations warrant routine postpartum partum antibiotics to prevent complications 

Complications from severe perineal trauma 

  • First six weeks 

    • After OASIS, 25% of women experience wound breakdown, 20% experience wound infection 

    • Those with complications will have more pain than women with normal healing 

    • Possible to have fistulas (9% of rectovaginal fistulas in the US are associated with OB trauma) 

  • How to care for them? 

    • Pain control, avoid constipation, and evaluate for urinary retention 

    • In one study, use of oral laxative was associated with significantly less pain and earlier bowel movement 

    • Monitored frequently for wound healing 

    • Pelvic floor exercise + biofeedback physiotherapy has been suggested 

What about next pregnancies? 

  • Increased risk of OASIS in the next pregnancy, but absolute risk is low (3%) 

  • Can have elective cesarean 

    • But there is no difference when there is vaginal delivery or elective cesarean in fecal urgency, anal incontinence, or bowel-related quality of life