Protecting the Perineum

What is the Perineum?

The perineum refers to the area extending between the anus and the vaginal opening or the anus and the scrotum.  During the birthing process, trauma can occur in the perineal area through episiotomies and spontaneous lacerations.

There are 4 classifications of perineal tears.  A first degree tear is considered the least severe and involves the skin around the opening of the vagina.  A second degree tear involves trauma to the muscles between the vagina and anus and often requires stitching.  A third degree tear extends into the muscles that surround the anal sphincter.  A fourth degree tear is considered the most severe and extends through the vaginal muscles into the anal canal and rectum.   

Perineal tearing occurs in about ½- ¾ of people with a vaginal birth.  The rate of a 3rd or 4th degree tear is 3-7%.

 

What are the risk factors for severe tearing?

There is an increased risk for severe tearing if you are giving birth for the first time, higher birth weight of the baby, use of forceps, vacuum or episiotomy, a prolonged or very short pushing phase, shoulder dystocia of the baby, and if baby is facing to the front of the pelvis rather than the back.  A study by Kopas et al.  found that the rate of tearing was lower at birth centers and home births versus at the hospital. However, rates of third or fourth degree tears did not differ significantly between home, birth center, or hospital settings.  

Of those who experience tearing, around 50% of those will report moderate to severe levels of pain at time of discharge from the hospital, and 60% report pain with sex at 3 months postpartum.  Evidence suggests that there is increased risk of postpartum depression, stress, and inflammation with second degree tears and higher.

 

What are the strategies that have been shown to reduce perineal tearing?

Avoiding Episiotomies

For many years, episiotomies were routinely performed as they were thought to help prevent severe tearing and facilitate childbirth.  An episiotomy is an incision or surgical cut that is made within the perineum.  The midline incision has a slightly increased risk of extending into the anal muscles whereas the mediolateral incision does not.  Trauma extending into the anal area increases the risk of bowel complications such as infection, fecal and/or gas incontinence and difficulty with emptying bowels.  The mediolateral incision tends to be more complicated to repair compared to a midline incision.  Complications associated with perineal tearing and an episiotomy include the need for stitching and can result in the development of adhesions and scar tissue.  Scarring decreases the elasticity and mobility of the perineal muscles and may contribute to pain with sex, prolonged postpartum perineal pain, and can contribute to pelvic muscle weakness.    

Klein et al. performed a randomized trial in 1992 and followed these participants up to 3 months postpartum.  The study found that the routine and regular use of episiotomies did not prevent severe tearing and, in fact, caused the opposite.  Episiotomies were associated with a 22x higher risk of severe tearing.  The study concluded that the routine use of episiotomy be abandoned.  A Cochrane review published in 2017 supported this finding by stating routine episiotomies are not justified by current evidence and offer no benefits for either baby or the birthing person.  

Although episiotomies are not routinely performed anymore, there are situations when an episiotomy is recommended.  The health care provider should discuss with you the reasons behind this recommendation and include:

When baby’s shoulder is stuck behind the pelvic bone (shoulder dystocia)
When baby is showing signs of distress such as an altered heart rate during delivery
When there is a need to use forceps or vacuum

Birthing Positions

Several studies have investigated the effects of different birthing positions on perineal trauma.

Birthing in upright positions include various postures such as squatting, hands and knees, and kneeling.  Evidence suggests that birthing in upright positions without an epidural in the second stage of labour has been shown to decrease the risk of episiotomies, forceps or vacuum use.  These positions may also help shorten the pushing phase, and decrease the risk of severe perineal trauma.  Alternatively, evidence suggests upright birthing positions with an epidural appear to show no significant difference in use of vacuum or forceps, length of pushing phase or frequency of perineal tears requiring stitching.  One specific study (Walker et. al 2012) reported birthing in side lye with an epidural and delayed pushing strategies demonstrated a higher rate of an intact perineum compared to those who pushed in the lithotomy position and pushed immediately (40% versus 12%).

Warm Compresses

A Cochrane review including 4 trials with a large number of participants found that warm compresses to the perineum during the second stage of labour reduced the rate of severe (third or fourth degree) tearing by 50%.  

Perineal Massage

Perineal massage is a common and easily administered technique taught by midwives and pelvic physiotherapists to those who are preparing for childbirth.    This technique focuses on using fingers to massage and stretch the perineal muscles to increase elasticity of the tissue, decrease muscle tension, and increase blood flow.  This exercise also helps the person who is preparing for childbirth to experience a stretching sensation at the vaginal opening while learning how to support and facilitate pelvic muscle relaxation at the same time.  A Cochrane Review published in 2013 investigated the effects of perineal massage initiated at 35 weeks.  The massage technique was performed as little as once to two times a week.  It was determined that perineal massage decreased the likelihood of perineal trauma including the use of episiotomies and ongoing postpartum perineal pain.  The research showed strong support for those who were birthing for the first time and was a bit weaker for those who have birthed previously.      

Some of the adverse outcomes associated with perineal trauma from birth include a higher risk of infection, increased risk of pelvic organ prolapse, long term incontinence, and pain with sex.  Therefore, it is understandable that one would want to avoid or minimize their risks of injury to the perineum.  Pelvic physiotherapists are part of your support network to provide you with the evidence and best practices associated with reducing your risk.     

 

References:

https://evidencebasedbirth.com/evidence-birthing-positions/

https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD005123.pub3/full

https://onlinelibrary.wiley.com/doi/abs/10.1111/jmwh.12199

https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD006672.pub3/full

https://pubmed.ncbi.nlm.nih.gov/1343606/

https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD000081.pub3/full

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