Obstetric Anal Sphincter Injury (OASI) Compensation Claims
An Obstetric Anal Sphincter Injury (OASI) can have life-changing effects if not treated and managed properly. If you are suffering as a result of an OASI that has not been repaired or diagnosed properly, our birth injury solicitors may be able to help you claim compensation.
What is an Obstetric Anal Sphincter Injury (OASI)?
OASI is a type of perineal injury which occurs during childbirth and damages more than just the perineum (the space between the vaginal opening and the anus), with the tear extending to the anal sphincter. An OASI is also described as a third or fourth-degree tear. Click here to see a diagram.
These severe tears can lead to chronic pain, sexual dysfunction and incontinence of the bladder, bowels and wind, which can sometimes be permanent.
- A third-degree tear means there is a partial injury extending into the anal sphincter muscle.
- A fourth-degree tear means there is a complete tear of the anal sphincter, and the tear has extended further still into the lining of the anus.
Unlike small tears around the vagina (sometimes described as first or second degree tears), which are common during birth, Obstetric Anal Sphincter Injuries are rare. According to the Royal College of Obstetricians & Gynaecologists, OASI affects 6% of first-time mothers and less than 2% of women who have had a vaginal birth before.
How does an OASI happen?
Third or fourth-degree tears happen during childbirth. An OASI happens when tissue around the vagina tears and spreads across the perineum, into the anal sphincter.
Some factors increase the risk of an OASI, including:
- When a woman is having a vaginal birth for the first time
- If the baby is large
- If the baby is delivered via instrumental delivery, e.g. forceps
- If the baby’s head gets stuck
- If there is a prolonged ‘pushing’ stage of labour
- If the mother/birthing person is South Asian
- A previous third or fourth-degree tear
How is an OASI treated?
If you sustain a third or fourth-degree injury, you should be transferred to an operating theatre as soon as possible. In theatre, you will have stitches to repair the tear and, following surgery, will recover with antibiotics and pain relief.
Repairs of first or second-degree tears are often appropriately repaired by midwives in the delivery room, but guidance says that only an appropriately trained clinician with sufficient surgical competence should repair a third or fourth-degree tear; this often means it should be repaired by an obstetrician.
Recovery can take between four and six weeks. Read more about how OASI is treated here.
When is an OASI negligent?
Suffering an OASI alone is not necessarily negligent. Substandard medical care, such as a delay in diagnosis or treatment, could be an indication of medical negligence, and you may be able to claim compensation.
Examples of OASI negligence could include:
- Failure to offer C-section delivery in appropriate cases, thereby avoiding vaginal delivery altogether
- Failure to take specific evidence-based preventative measures, such as perineal protection
- Failure to examine the mother after giving birth, either properly or at all
- Failure to diagnose a third or fourth-degree perineal tear
- A misdiagnosis of a severe tear or injury (for example, grading it incorrectly as a third-degree tear when it is a fourth-degree tear)
- Failure to effectively repair and/or treat an OASI, or repair/treat it at all
If an OASI is not diagnosed and treated properly, it can lead to long-term and debilitating symptoms, including bowel incontinence. Sometimes, this impaired bowel function can mean the person is unable to work or has to change their hours or job, leading to financial losses.
Why choose Barcan and Kirby for your OASI compensation claim?
Our medical negligence solicitors work with clients across the UK from our offices in Bristol and South Gloucestershire. We have proven expertise in a number of areas, from birth injuries to cerebral palsy claims and delayed diagnosis claims.
Barcan and Kirby’s Medical Negligence team is band 1-ranked by Chambers and Partners UK, and holds a top-tier ranking in Legal 500.
“They were very clear in explaining parts that I was unsure about during the claim, which made me feel easy during this stressful period.”
– Chambers and Partners UK 2026
“The team dealing with my case has made an incredibly stressful process bearable, and collaborated well to ensure I had the best chance of success.”
– Legal 500
Our team is led by panel members of Action Against Medical Accidents (AvMA) and the Law Society’s Clinical Negligence Accreditation Scheme.
We pride ourselves on supporting clients during what can be one of the most stressful and emotional times in their lives. From the moment you first get in contact, our medical negligence lawyers will take the time to listen to what has happened to you and guide you through the process of making a claim.
Claiming compensation for an OASI
Obstetric Anal Sphincter Injuries are a serious and life-changing type of birth injury if not dealt with properly and promptly.
If you received negligent maternity care during childbirth and have suffered from the symptoms of an OASI as a result, you may be able to claim compensation.
Although compensation cannot change what happened to you, it can help you to get back on your feet, for example, in terms of recovering a loss of earnings or claiming for the cost of treatments, therapies, medical supplies or equipment. Making a claim for an OASI can also make a difference to future birth parents and prevent the same mistakes from being made to someone else.
OASI case studies
- Substantial compensation for a first-time mother who suffered a misdiagnosed third-degree perineal tear
- Negligently repaired third-degree perineal tear leads to continence issues
Contact our medical negligence solicitors
Medical professionals owe their patients a duty of care, and if that duty is breached, resulting in harm, you are entitled to take legal action.
If you have an OASI or another type of birth injury, and you believe it was not treated or diagnosed properly, we may be able to help you claim compensation.
Call our medical negligence lawyers on 0117 325 2929 or fill out our online enquiry form.