Third and Fourth Degree Perineal Tears Explained

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Published: 21 April 2021

Perineal tears, while common and usually minor, may cause significant complications if the injury is extensive.

What is a Perineal Tear?

perineal tears female genitalia diagram

A perineal tear occurs when the perineum - the area between the vagina and anus - is injured during childbirth (ACSQHC 2021a).

Tears are caused by the fetal head stretching the vagina and perineum during delivery (RCOG 2019a).

While perineal tears are common, occurring in over 85% of vaginal births (Goh, Goh & Ellepola 2018), most do not result in serious injury (ACSQHC 2021a).

However, third and fourth degree perineal tears (also known as severe perineal tears or obstetric anal sphincter injuries), which are experienced by approximately 3% of women giving birth vaginally and 5% of women giving birth vaginally for the first time, are more serious and may lead to complications (ACSQHC 2021a).

Third and fourth degree perineal tears may adversely affect physical, psychological and sexual wellbeing, and sometimes require surgery (ACSQHC 2021a).

While it is possible to reduce the risk of experiencing a perineal tear, they are not completely preventable. However, with effective treatment, including specialised care (if required), most patients who experience tears are able to recover (ACSQHC 2021a).

Perineal Tear Risk Factors

There are three categories of risk factors: maternal, fetal and intrapartum (relating to labour and birth) (Goh, Goh & Ellepola 2018).

Maternal risk factors include:

  • Giving birth for the first time
  • Being of South Asian descent
  • Being 20 years of age or under
  • Vaginal birth after a previous caesarean section
  • Short perineal length (less than 2.5 cm from the posterior fourchette to the mid-anus)
  • Having previously experienced a severe perineal tear.

(ACSQHC 2021a; Goh, Goh & Ellepola 2018)

Fetal risk factors include:

  • Birth weight of over 3.5 or 4 kg
  • Being in the occipito-posterior position for a prolonged amount of time
  • Shoulder dystocia.

(ACSQHC 2021a)

Intrapartum risk factors include:

  • Instrumental vaginal delivery (e.g. using forceps or vacuum)
  • Prolonged second stage of labour (more than 60 minutes)
  • Undergoing an epidural
  • Undergoing labour induction
  • Undergoing labour augmentation
  • Undergoing midline episiotomy
  • Being given oxytocin
  • Being in certain birthing positions (supine, lithotomy or deep-squatting).

(ACSQHC 2021a; Goh, Goh & Ellepola 2018)

Perineal Tear Classification

perineal tear classification

Perineal tears are classified depending on the extent of the injury, with first degree tears being the most minor and fourth degree tears being the most severe (QLD DoH 2018a).

Degree Description Treatment
1 A shallow injury that affects the skin only of the vaginal mucosa or perineum. May heal on its own or require stitches. Recovery is usually within the first few weeks or months after birth.
2 An injury that affects the perineal muscles. Usually requires stitches. Recovery is usually within the first few weeks or months after birth.
3 An injury that affects the perineal muscles and anal sphincter muscles. There are three sub-classifications: Usually requires stitches given in an operating theatre under anesthetic.
3A Less than 50% of the external anal sphincter is injured.
3B More than 50% of the external anal sphincter is injured.
3C Both the external and internal anal sphincters are injured.
4 An injury to the perineum that extends through the anal sphincter to the anal epithelium. Usually requires stitches given in an operating theatre under anesthetic.

(Goh, Goh & Ellepola 2018; QLD DoH 2018a, b; RCOG 2019b)

Consequences of Severe Perineal Tears

Those who experience third and fourth degree perineal tears may experience short-term or long-term adverse effects including:

  • Perineal pain
  • Infection
  • Incontinence (faecal and flatus)
  • Pain during sexual intercourse
  • Impaired quality of life
  • Depression
  • Impaired bonding between the mother and child due to pain and suturing time
  • Psychological distress and social isolation.

(ACSQHC 2021a; Ramar & Grimes 2020)

What is an Episiotomy?

An episiotomy involves making an incision in the perineum to increase the diameter of the vaginal opening. This creates more space for the fetal head, reducing the risk of a third or fourth degree perineal tear (ACSQHC 2021a; Goh, Goh & Ellepola 2018).

The incision made in an episiotomy is similar to a second degree perineal tear (QLD DoH 2018a).

An episiotomy should be performed using a medio-lateral technique with an incision angle of 60° from the midline (ACSQHC 2021a).

An episiotomy is indicated by the Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG) in the following situations:

  • There is a high risk of third or fourth degree perineal tear
  • The fetus is experiencing shoulder dystocia
  • The fetus is compromised and requires accelerated delivery
  • The patient requires operative vaginal birth
  • The patient has a history of female genital mutilation.

(RANZCOG 2017)

With the above situations as exceptions, RANZCOG does not encourage the routine use of episiotomy (RANZCOG 2017).

Repairing Perineal Tears

Perineal tears are usually repaired using stitches, with third and fourth degree tears being repaired in an operating theatre under anaesthetic (as this facilitates anal sphincter relaxation) (Goh, Goh & Ellepola 2018).

When a perineal tear is being repaired:

  • The procedure should be performed as soon as possible in order to reduce the risk of infection and blood loss
  • The procedure should be performed by an experienced clinician
  • The procedure should be performed in a clean, suitable environment with adequate lighting and access to equipment
  • An adequate amount of anesthesia should be administered
  • Each layer of the injury should be repaired independently
  • The repair should be performed in a cephalocaudal direction (from the top down) to ensure access to superior sites
  • The rectum should be assessed after repair to ensure sutures have not been inserted through the anorectal mucosa
  • Sutures used should be resorbable. The knots of each layer should be buried to reduce the risk of postoperative dyspareunia and vaginal discomfort.

(Goh, Goh & Ellepola 2018; ACSQHC 2021a)

Postoperative Management Following the Repair of Perineal Tears

perineal tear postoperative management pelvic floor exercise

This may include:

  • Antibiotics to reduce the risk of infection or wound dehiscence
  • Analgesia:
    • Topical cold packs used at 10 to 20-minute intervals for the first 24 to 72 hours after surgery
    • Paracetamol and nonsteroidal anti-inflammatory drugs (NSAIDs)
    • Urinary alkalinisers
  • Urinary catheterisation
  • Laxatives to reduce the risk of wound dehiscence
  • Stool softeners for the first 10 days after surgery
  • Positioning to reduce perineal oedema for the first 48 hours after surgery (lying on a flatbed while resting, lying on the side while breastfeeding and avoiding being seated too often)
  • Avoiding activities that increase intra-abdominal pressure for the first 6 to 12 months after birth
  • Commencing pelvic floor exercises two to three days postoperatively (or when the patient feels comfortable enough to do so)
  • Referral to a physiotherapist who specialises in perineology
  • Wound care (washing and patting the wound dry after toileting, inspecting the wound daily, using a washer instead of toilet paper).

(Goh, Goh & Ellepola 2018; ACSQHC 2021a)

Following repair, the patient may need to be referred to an obstetrician if they are experiencing:

  • Wound dehiscence
  • Severe pain during sexual intercourse
  • Constipation
  • Excessive straining
  • Feeling of incomplete emptying
  • Feeling of obstruction
  • Digitation
  • Faecal incontinence
  • Urge incontinence
  • Passive or post-defecation incontinence.

(Goh, Goh & Ellepola 2018)

Reducing the Risk of Perineal Tears

Strategies to reduce the risk of experiencing a perineal tear include:

  • Massaging the perineum during late pregnancy (after 34 weeks)
  • Pelvic floor muscle exercises
  • Regular exercise and eating a healthy diet to maintain a healthy maternal and fetal weight.

(QLD DoH 2018a; ACSQHC 2021a)

During labour and birth, strategies include:

  • Giving birth in certain positions (lying on one side, kneeling, standing or being on hands and knees)
  • While pushing, avoiding squatting, sitting, or using a birth stool for prolonged periods of time
  • Having a warm compress on the perineum during the second stage of labour
  • Pushing in a slow and controlled way, and listening to the midwife and doctor
  • Perineal massage by the midwife during the second stage of labour
  • Reducing the speed at which the neonate's head and shoulders emerge.

(QLD DoH 2018a; ACSQHC 2021a)

Third and Fourth Degree Perineal Tears Clinical Care Standard

In April 2021, the Australian Commission on Safety and Quality in Health Care launched the Third and Fourth Degree Perineal Tears Clinical Care Standard. This standard aims to improve the prevention, recognition and management of third and fourth degree perineal tears (ACSQHC 2021b).

The Standard comprises the following seven Quality Statements:

Quality Statement 1: Information, shared decision making and informed consent Patients are appropriately informed about the possibility of experiencing a third or fourth degree perineal tear by the third trimester. This information is individualised and provided to the patient in a way they can understand
Quality Statement 2: Reducing risk during pregnancy, labour and birth During pregnancy, patients are advised on how to reduce the risk of a severe tear. During labour, the clinician uses evidence-based strategies to reduce the risk.
Quality Statement 3: Instrumental vaginal birth When an instrumental delivery is indicated, the clinician considers clinical need and the potential benefits and risks (including the risk of a severe perineal tear).
Quality Statement 4: Identifying third and fourth degree perineal tears Patients are examined after vaginal birth for perineal tears by an appropriately qualified clinician. Any identified tears are appropriately classified and documented.
Quality Statement 5: Repairing third and fourth degree perineal tears Third and fourth degree tears are quickly repaired in an appropriate environment by an appropriately qualified clinician.
Quality Statement 6: Postoperative care Patients receive postoperative care after repair of a severe tear. This should comprise debriefing, physiotherapy and psychosocial support.
Quality Statement 7: Follow-up care post-discharge Patients receive individualised follow-up care after repair of a severe tear to optimise physical, emotional, psychological and sexual health. They are referred to a specialist if required.

(ACSQHC 2021a)

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