Perineal lacerations (tears) can happen spontaneously during labor or due to an episiotomy and are classified from first to fourth degree tears. First and second degree lacerations are more frequent. Third and fourth degree lacerations are rare, occurring in only about 5% of women. 

Perineal Tears During Labor

What are lacerations?

  • First degree: damage to the skin in the vagina or perineum (space between the vaginal and the anal openings), but no muscle damage 
  • Second degree: damage to the muscles of the perineum and vagina 
  • Third degree: damage to anal sphincter complex (external anal sphincter and internal anal sphincter) the muscles used to open and close the anus 
  • Fourth degree: tears to the inner anal mucosa (lining) and the anal sphincter complex 

Why do lacerations happen?

Lacerations occur during labor as the muscles of the vagina are stretched by the baby’s head as it is passing through the opening of the vagina. There are risk factors that increase the likelihood of increased severity (degree 3 and 4) lacerations, these include: 

  • First pregnancy or vaginal birth after cesarean section 
  • Forceps during delivery 
  • Midline episiotomy during delivery 
  • Large baby/shoulder dystocia 

How can I prevent lacerations ?

There are some methods during delivery that may help prevent tearing 

  • The care provider may have you stop pushing/ do smaller controlled pushes at the time of delivering the baby’s head. This allows the uterus to push out the head with control which may decrease severe tearing
  • Supporting the perineum and using perineal massage during delivery   
  • A sitting or kneeling position at the time of delivery may decrease chances of tearing compared to standing 
  • The use of a vacuum compared to forceps if instrumentation is needed during delivery 

It is important to note that there is no evidence that perineal massage before delivery, position during pushing, water birth or delayed pushing protect against severe lacerations 

How are lacerations managed after your delivery?

  • First degree tears may not require management and can heal without intervention; at times, a small stich may be needed. 
  • Second degree tears are managed by stitching the torn tissues back together; first the muscles are connected and then the skin will be stitched together  
  • Third and fourth degree tears may be repaired in the delivery room or the operating room, the anal muscles edges will be sutured first, then the muscles of the perineum and finally, the vaginal and perineal skin will be stitched back together. Additionally, you will be given a single dose of antibiotics to prevent infections at the site of repair and laxatives to soften bowels movements as the area of the tear heals. You will likely receive some pain medications (acetaminophen and NSAIDs) during your recovery.  

What complications may occur?

  • There are little to no longer term complications with first and second degree tears 
  • Third and Fourth Degree: 
    • Short Term
      • In the time right after delivery women with severe tears are more likely to have difficulty urinating and may require the short time use of a catheter 
      • Increased pain with bowel movements
    • Long Term
      • Fecal incontinence
      • Fecal urgency

Long Term Management of Lacerations 

  • Women should see a pelvic floor physiotherapist if they develop anal incontinence (involuntary bowel loss) after lacerations during delivery, even one that has been repaired, as this is often a successful intervention 
  • Avoidance of loose stool with the use of fibres to improve bulk of stool is effective in managing anal incontinence
  • Women with severe lacerations during delivery should have follow up with a trained physician to check up on the repair and monitor for complications 

How does this effect future pregnancies?

  • Women with previous severe tear have an increased risk of another tear compared to women who have not had a 3-4th degree tear but the majority (95%) of women with previous severe tear will not have another 
  • Anal incontinence may worsen in women with previous 3rd – 4th degree tear, after second vaginal delivery in the presence of a poor anal muscle function  
  • Women with previous 3rd – 4th degree tear will be offered to undergo anal function testing to aid in the decision regarding route of next delivery; an elective Cesarean section may be offered in some situations, with appropriate discussion of risks and benefits 

Reference: SOGC Guideline: Obstetrical Anal Sphincter Injuries (OASIS): Prevention, Recognition, and Repair