Perineal Tears

Question 1

When does a perineal tear occur?

Answer 1

A perineal tear occurs where the external vaginal opening is too narrow to accommodate the baby. This leads to the skin and tissues in that area tearing as the baby’s head passes.

Perineal tears can range from a graze, to a large tear involving the anal sphincter (third-degree) and rectal mucosa (fourth-degree).

Question 2

Risk factors for perineal tears?

Answer 2

Perineal tears are more common with:

First births (nulliparity)
Large babies (over 4kg)
Shoulder dystocia
Asian ethnicity
Occipito-posterior position
Instrumental deliveries

Question 3

Classification of perineal tears?

Answer 3

There are four degrees of perineal tear, each involving injury to tissue beyond the previous:

First-degree – injury limited to the frenulum of the labia minora (where they meet posteriorly) and superficial skin
Second-degree – including the perineal muscles, but not affecting the anal sphincter
Third-degree – including the anal sphincter, but not affecting the rectal mucosa
Fourth-degree – including the rectal mucosa

Third-degree tears can be subcategorised as:

3A – less than 50% of the external anal sphincter affected
3B – more than 50% of the external anal sphincter affected
3C – external and internal anal sphincter affected

Question 4

Management of perineal tears?

Answer 4

First-degree tears usually do not require any sutures. When a perineal tear larger than first degree occurs, the mother usually requires sutures to correct the injury. A third or fourth-degree tear is likely to need repairing in theatre.

Additional measures are taken to reduce the risk of complications:

Broad-spectrum antibiotics to reduce the risk of infection
Laxatives to reduce the risk of constipation and wound dehiscence
Physiotherapy to reduce the risk and severity of incontinence
Followup to monitor for longstanding complications

Women that are symptomatic after third or fourth-degree tears are offered an elective caesarean section in subsequent pregnancies.

Question 5

Complications of perineal tears?

Answer 5

Short term complications after repair include:

Pain
Infection
Bleeding
Wound dehiscence or wound breakdown

Perineal tears can lead to several lasting complications:

Urinary incontinence
Anal incontinence and altered bowel habit (third and fourth-degree tears)
Fistula between the vagina and bowel (rare)
Sexual dysfunction and dyspareunia (painful sex)
Psychological and mental health consequences

Question 6

What is an episiotomy?

Answer 6

An episiotomy is where the obstetrician or midwife cuts the perineum before the baby is delivered. This is done in anticipation of needing additional room for delivery of the baby (e.g. before forceps delivery). It is performed under local anaesthetic. A cut is made at around 45 degrees diagonally, from the opening of the vagina downwards and laterally, to avoid damaging the anal sphincter. This is called a mediolateral episiotomy. The cut is sutured after delivery.

Question 7

What is perineal massage?

Answer 7

Perineal massage is a method for reducing the risk of perineal tears. It involves massaging the skin and tissues between the vagina and anus (perineum). This is done in a structured way from 34 weeks onwards to stretch and prepare the tissues for delivery.