Third degree tearing

Third degree tears are not common but can have long term effects on the woman’s health – find out how to minimise the risks of third degree tears.

What is a third degree tear?

The perineum –the muscle between the vagina and anus – may often be torn (sometimes called a perineal tear) during birth, but usually the tear stops well clear of the muscles around the back passage – the anal sphincter. Occasionally – in around 1% of vaginal births – the tear continues towards the back passage and the anal sphincter is torn also.

The severity of the tear varies greatly, so a classification has been devised by obstetricians who are expert in this –

First degree tears – involve only the skin of the perineum, they are usually self healing as any skin tear would be.

Second degree tears – involve the muscle also and therefore are usually repaired by the midwife or doctor after the birth, as the muscles needs to restore all of their previous strength to ensure a strong pelvic floor.

Third degree tears – involve the anal sphincter muscle which controls the passage of wind and faeces from the back passage, or rectum.

These vary in severity to include:

• just the edge of the external anal sphincter,
• the majority of the external anal sphincter
• the internal anal sphincter also.

Fourth degree tears – these more severe tears include the external anal sphincter, the internal sphincter and also the wall of the back passage.

These are very rare.

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What causes a 3rd degree tear?

A third degree tear may occur during a normal vaginal birth, a ventouse or forceps assisted delivery.

Certain factors can increase the risks of third degree tears, but remember these are rare and most women will birth without sustaining any long term damage to their pelvic floor.

Risk factors of third degree tears include:

• Large baby, over 4 kg
• Baby lying back to back with mum causing a larger part of the head to present first, occipito posterior position
• Epidural anaesthesia
• Midline episiotomy – a type of episiotomy which is directed straight towards the anus, but rarely practised in New Zealand
• Long second stage of labour (pushing for more than 1 hour)
• Shoulder dystocia (the shoulders of the baby do not deliver easily in the normal way)
• Forceps delivery – this carries the greatest risk of third degree tear

What can I expect to happen if I have a third degree tear?

After all childbirths the woman is asked to have her perineum looked at by the midwife or doctor to check for tears and the need for stitches.

If a third degree tear is suspected, then a thorough examination will be carried out, often by another maternity professional for a second opinion. If you do not have an epidural this will be uncomfortable, so you will be offered gas and air.

If the anal sphincter has been damaged then the following will occur:

• You will be transferred to theatre for the repair, to prevent infection and to provide excellent lighting for the doctor
• If you do not already have an epidural or spinal from the birth you will receive one now, to ensure your comfort and the relaxation of your muscles during the repair
• Your tear will be repaired by an experienced obstetrician

What are the risks and complications of third degree tears?

There are risks following a third degree tear, but they can be minimised with excellent repair and follow up care:

• Antibiotics will be prescribed to prevent infection
• Laxatives will be prescribed to prevent constipation, which would stress the wound
• Physiotherapy will be arranged to ensure that the muscle strength returns – they will advise you of exercises that you can do to aid the healing process
• A follow up visit to your obstetrician, usually at around 6 weeks after the birth, to ensure that the repair is healing well

Careful discussion about future childbirths – for some women an elective Caesarean section is advised, but much depends upon how well the wound and the muscles heal.

What can I do to help myself if I have a third degree tear?

Your pelvic floor muscles have to last you a lifetime! They provide strength to hold up all of your abdominal and pelvic organs; they minimise incontinence of urine, wind and faeces; and they are important for sexual intercourse and for childbirth.

Ensure that you follow the recommendations of your doctor, midwife and physiotherapist following the birth – their advice is aimed at minimising the complications of and assisting the repair of third degree tears.

Useful articles

For information on Episiotomies and Tears visit our Kiwi Families article

For information on how to prevent post natal problems check out Tips for Healthy Perineums.

Acknowledgement

The evidence for this article came from Green-top Guideline No 29, Royal College of Obstetricians and Gynaecologists: Management of Third and Fourth Degree Perineal Tears, March 2007, UK.