Obstetric Lacerations: Repair and Prevention
/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
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