What is an OASI?
OASI stands for obstetric anal sphincter injury, which can happen after childbirth. It is an injury to the anal sphincter that is relatively common in people who have had a vaginal delivery (it affects 1 in 5).
What is the OASI clinic?
This is one-stop clinic where the specialist, multi-disciplinary team aims to review all patients with an OASI.
Why do I need to attend an OASI clinic?
It is not mandatory for you to attend the clinic, however it is considered best practice to make sure you receive the best possible care. It is recommended by the the Royal College of Obstetricians and Gynaecologists. By assessing your symptoms, how you are healing, and giving you advice, this will help minimise your future risk of anal incontinence (not being able to control bowel movements).
When and where will my appointment be?
It will be at Southmead Hospital, Cotswold outpatients, on a Wednesday afternoon. It will usually be 12 weeks after giving birth.
Who will I see in the clinic?
You will see Consultant Gynaecologist Miss Sen, and Consultant Colorectal Surgeon Miss McCarthy. You may also see a physiotherapist, specialist nurses, and clinical scientists. There may be trainee doctors in clinic who are there to observe.
What happens at my appointment?
You will have your first consultation with the specialists. You will be asked direct questions about your recovery including wound healing, bladder and bowel function (going to the toilet), and sexual activity.
We will then ask for consent to do an intimate vaginal and rectal examination, and there will be a chaperone in the room. The two tests will take about 10 minutes.
Endo anal ultrasound scan
This is an ultrasound test which uses sound waves to create images of structures in your body. This scan checks the integrity of your anal sphincters. A probe is inserted 5cm into your back passage (anal canal). It lets us see your sphincter repair and gives us valuable information about how it is healing. It is not painful but might be slightly uncomfortable. It is similar to a trans vaginal ultrasound which you may have had before.
Anorectal manometry
This test will feel similar to the ultrasound. A small catheter (18mm) will be passed a short distance into your lower rectum. It is not usually painful.
We will take some pressure measurements from your anal canal when you are resting, and you will be asked to squeeze for around 10 seconds. You will do this twice. It might feel uncomfortable if have had difficulty doing pelvic floor exercises after giving birth.
The final part of the test involves blowing up a balloon at the tip of the catheter inside the rectum. It is usually inflated with 60ml of air and most patients will be aware of the sensation of needing to evacuate (go to the toilet). We will ask you to expel the balloon if you are able to.
These measurements give us a good idea about the function of your anal sphincters. It will help us decide if you may benefit from a course of pelvic floor physiotherapy.
Will the examination and tests hurt?
They may be uncomfortable but should not be painful. We won’t do the tests if it would be painful. All tests and examinations will be done with consent, and a chaperone present, and we will be guided by you.
What will happen after the examinations and tests?
You will return to the consultation room where we will discuss the results of the tests, and the function and anatomy of your anal sphincter. We will talk about any future plans for pregnancy, and you will have plenty of opportunity to ask and questions you have.
It can be worrying for you to come to the clinic. You may have had difficulties in birth that you haven’t had a chance to process. In clinic you may also find it worrying to hear words such as anal sphincter, injury, and OASI. If there is anything you don’t understand or are concerned about, we would be happy to see you again.
You don’t need to do any preparation before the tests. There is a small risk of injury to the rectum, and we advise you to look out for rectal bleeding after the procedure. If this happens you can phone the number on the back of this leaflet, or out of hours phone 111.
How long will my appointment be?
Your appointment will take around 30 minutes, and we will try to get all your tests done in one visit. Sometimes you may have to return on another day for the tests, particularly if you are in pain at the time of your appointment.
The tests in the OASI clinic are considered ‘mobile’ and are generally quick. Some patients may benefit from more thorough assessments so you may be referred for further tests either at Southmead Hospital or Bristol Royal Infirmary. These will be done on another day, and we will see you again in the clinic for a follow-up appointment after the tests. Sometimes we will offer you a follow-up in the Colorectal Clinic with Miss McCarthy if you have ongoing bowel issues.
Where can I find more information?
MASIC Foundation
Home - Aiming to change the lives of women injured during childbirth. (masic.org.uk)
Royal College of Obstetricians and Gynaecologists
Perineal tears and episiotomies in childbirth | RCOG
© North Bristol NHS Trust. This edition published September 2024. Review due September 2027. NBT003413
Contact the Gynaecology Secretaries
Emma-Rose Thompson/Gynaecology Secretaries
Women and Children's Division
The Chilterns
0117 414 6749
