Obstetric Anal Sphincter Injuries (OASIs): How Women’s Health Physiotherapy can help

You’re pregnant! You’ve attended antenatal classes and you’ve spoken to friends; perineal tearing has been discussed. It sends shivers down to your butthole and you are thinking, “I’m never going to be the same again…”

There is a real fear of perineal tears. However, the best way to address it is by talking about it and through strategies to reduce it. Birth is a natural process and many women give birth without medical intervention. Having this information doesn’t change the desire for a natural birth, it just empowers you to be an active participant in your delivery.


A perineal tear is an injury to the perineum, which is the area between the vagina and the anus. 85% of women will experience some level of perineal trauma following vaginal childbirth, although not all births cause significant injury. First and second degree tears are common. They may need stitches, but women tend to recover within a few weeks or months. An episiotomy is equivalent to a grade 2 perineal tear (some tissue and superficial muscle tearing).


An Obstetric Anal Sphincter Injury (OASIs) refers to third and fourth degree perineal tears and are more serious. These tears extend from the perineum to the anus or rectum and include the muscles that control the opening and closing of the anus.

A Grade 3 tear involves changes to the anal sphincter muscles and is further subdivided into:

3A- where <50% of the external anal sphincter is torn 3B- where >50% of the external anal sphincter is torn

3C- where the external and internal anal sphincters are torn

On the other hand, a grade 4 tear involves changes to the internal and external anal sphincters as well as the mucosa (the lining of the rectum).

Image credit: mypfm.com


5% of women having their first vaginal birth and 3% of multiparous women will experience a third or fourth degree perineal tear. Most women who sustain a third or fourth degree perineal tear recover well with appropriate treatment and support, although some will need specialised care to optimise their recovery. While not all third and fourth degree perineal tears can be prevented, it is possible to reduce the risk of their occurrence.

Women who suffer from OASIs complain of faecal urgency or faecal and flatal incontinence. Some may also experience perineal pain and/or dyspareunia (pain on intercourse). All OASIs require surgical repair by an experienced surgeon, in an operating theatre under good lighting and regional or general anaesthesia.


Women who are having their first vaginal delivery, are of South Asian ethnicity or birth heavier babies (4kg), are all at risk of a third or fourth degree tear. During labour, a persistent occipito-posterior position, a prolonged second stage of labour, shoulder dystocia, a midline episiotomy and/or an instrumental vaginal delivery are also risk factors for a third or fourth degree perineal tear.


  • Maintain an active and healthy lifestyle during your pregnancy (psst…did you know we run prenatal group exercise classes to support your pregnancy and beyond? Click here to learn more.)
  • Commencing perineal massage from 35 weeks, 2x a week for 10 minutes
  • Applying a warm compress to the perineum during the second stage of labour
  • Slowing the rate at which the baby’s head and shoulders emerge, as appropriate, with the help of your birth attendant
  • Attending an appointment with your women’s health physiotherapist during pregnancy to learn how to prepare your pelvic floor for delivery


In the initial stages after a third and fourth degree tear, it is important to manage pain and swelling. You should be given painkillers and laxatives to make bowel movements easier. You might be given antibiotics to reduce the risk of infection. The use of ice packs on the perineum is encouraged in the initial 72 hours to reduce swelling and promote healing. Sitting with a soft cushion underneath the thighs can help to raise and offload the perineum, and make sitting more comfortable, especially when feeding the baby. Feeding in the side-lying position may help to offload the recovering perineum too.

After a third and fourth degree tear, you might develop some issues with your bladder and bowel. It can be common to experience difficulty controlling wind or stool, bladder and/or bowel urgency and pain during intercourse. If you are experiencing any of these symptoms beyond 6 weeks, visit your women’s health physiotherapist.


Postnatally, your women’s health physiotherapist can help:

  • Perform a thorough assessment which in most instances will involve a pelvic floor examination
  • Assist in preparing your pelvic floor for delivery to minimise your risk of tearing
  • Provide advice on the management of perineal tears or episiotomies which may include hands-on therapy on the tear or wound, ultrasound, massage, and stretching techniques
  • Teach you how to wee (voiding dynamics) and poo (defecation dynamics) optimally
  • Prescribe a pelvic floor muscle training program to strengthen the sphincter and pelvic floor muscles, or in some cases, help you relax those muscles

It may take 4-6 sessions to see an improvement. Motivation and adherence are important factors in achieving your goals.

If you are recovering from a perineal tear or episiotomy and require care, please call/WhatsApp on 9780 7274 or get in touch over email to book an appointment or discuss your concerns.

You can also visit our website to learn about other women’s conditions we treat through physiotherapy and how we can help you.



Australian Commission on Safety and Quality in Healthcare. 2021. Third and Fourth Degree Perineal Tears Clinical Care Standard. [online] Available at: <https://www.safetyandquality.gov.au/standards/clinical-care-standards/third-and-fourth-degree-perineal-tears-clinical-care-standard?fbclid=IwAR0H_P9TL7j_RP9mC8fPucl1MvGuXXvua91sIY70-rmp-5tjELZLAEWLl9Q> [Accessed 29 April 2021].

Beckmann MM, Stock OM. Antenatal perineal massage for reducing perineal trauma. Cochrane Database of Systematic Reviews 2013, Issue 4. Art. No.: CD005123. DOI: 10.1002/14651858.CD005123.pub3. Accessed 24 May 2021

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