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What is OASI2?

Evaluating the sustainability and scale-up of the OASI Care Bundle

What is an "OASI"?

An OASI is an obstetric anal sphincter injury which can occur during vaginal birth, sometimes referred to as severe perineal tearing. The long-term consequences of OASI include anal incontinence and painful sexual intercourse (dyspareunia) which can result in significant emotional and medical impact on women.

OASI2 research project: Evaluation of strategies for care bundle implementation

The aim of OASI2 is to support and evaluate the sustainability of the OASI Care Bundle in maternity units that participated in the initial OASI Care Bundle project (‘OASI1’), as well as compare strategies for scaling up the care bundle in new maternity units.

Following OASI1, the project team subsequently applied for and was awarded further funding by the Health Foundation to sustain and spread the intervention.

This second project ‘OASI2’ involves 10 of the maternity units that participated in the original OASI Care Bundle Project alongside 20 new maternity units across England, Scotland and Wales. Read more about the background to OASI2.

The project team will evaluate several measures in all 30 participating maternity units over the course of the study.

  • The primary measures are OASI rates (clinical outcome) and adoption of the care bundle into routine practice (implementation outcome).
  • Secondary measures that will also be analysed include episiotomy, anterior tears and caesarean section rates, alongside women’s and healthcare professionals’ perspectives on the care bundle and the way in which it was adopted in their maternity unit.

Interventions in the OASI2 project

The OASI Care Bundle that will be implemented in maternity units as part of the OASI2 project consists of the following interventions:

  1. In the antenatal period, the midwife or doctor will discuss OASI with the woman and what can be done to reduce the risk of it occurring.
  2. At the time of birth and with the woman’s consent, the midwife or doctor will use their hands to support both the perineum and baby’s head (known as manual perineal protection, or MPP) while communicating with the woman to encourage a slow and guided birth.
    1.  For spontaneous vaginal births, MPP should be used unless the woman’s chosen birth position (i.e. water births) doesn’t enable MPP to be used or she declines this technique.
    2. For assisted vaginal births (i.e. forceps, ventouse), MPP should always be used unless the woman declines this technique.
  3. If clinically indicated and with the woman’s consent, an episiotomy (a cut made through the vaginal wall and perineum) should be performed at an angle of 60 degrees from the midline at crowning.
  4. Following all vaginal births, a systematic examination of the vagina and ano-rectum should be offered to all women even if the perineum appears intact. This is to ensure that any tears are identified immediately and that treatment options are discussed and implemented as necessary.

Project design and objectives

Watch this video below to learn more about the study’s design and objectives, which was shared at the 3rd UK Implementation Science Research Conference hosted by King’s College London and supported by NIHR ARC South London in July 2020.

Study protocol and regulatory approvals

OASI2 is a research project and as such, the project team has obtained approval from the Health Research Authority to carry out its work in the NHS. We will upload the study protocol to this section once published, but in the interim you can read more about the study via the ISRCTN Registry below: