Muscles Exposed During Episiotomy and Obstetrical Perineal Laceration Repair
During episiotomy and obstetrical perineal laceration repair, the bulbocavernosus and transverse perineal muscles are the primary muscles exposed and reapproximated during the procedure. 1
Anatomical Structures Involved in Repair
Second-Degree Laceration/Episiotomy Repair
When performing repair of a second-degree perineal laceration or episiotomy, the following structures are exposed and repaired in sequence:
- Vaginal epithelium - First layer closed
- Underlying muscularis - Deep tissue layer
- Rectovaginal fascia - Supporting tissue
- Perineal muscles:
- Bulbocavernosus muscle - Primary muscle exposed and repaired
- Transverse perineal muscle - Secondary muscle exposed and repaired
Surgical Technique for Muscle Repair
The repair of the perineal muscles follows a specific technique:
- After closing the vaginal epithelium, the surgeon transitions into the axial plane, parallel to the perineal muscles
- The bulbocavernosus and transverse perineal muscles are reapproximated in a running, continuous, nonlocking fashion 1
- This muscle layer repair is critical for restoring perineal body strength and function
Clinical Significance of Proper Muscle Repair
Proper identification and repair of these muscles is crucial for:
- Restoring normal perineal anatomy
- Preventing pelvic floor dysfunction
- Reducing risk of future prolapse
- Minimizing postoperative pain and dyspareunia
More Complex Repairs
In third and fourth-degree lacerations (OASIS - Obstetrical Anal Sphincter Injuries), additional muscles may be involved:
- External anal sphincter
- Internal anal sphincter
- Levator ani complex
These more complex repairs often require specialized techniques and may benefit from being performed in an operating room setting rather than the labor suite 1.
Surgical Considerations
- Adequate exposure and visualization are essential for proper muscle identification
- Regional or general anesthesia is typically required for optimal muscle repair
- Proper suturing technique of the muscle layer helps prevent excessive tension that could lead to tissue edema and necrosis
Understanding the muscular anatomy of the perineal body is essential for performing effective repairs that minimize short and long-term morbidity following obstetrical lacerations.