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The OASI Care Bundle

What is an OASI?

An OASI is an obstetric anal sphincter injury that can occur during vaginal birth, also referred to as severe perineal tearing or third- and fourth-degree tears. Most women and birthing people who have an OASI detected and repaired at birth recover well, although it can take some time.

The long-term consequences of OASI include increased risk of chronic pain, sexual dysfunction and difficulty or inability to control the bladder, bowels or the passing of wind. These consequences can significantly affect mental health, the ability to carry out everyday activities and personal relationships.

If an OASI is not diagnosed and repaired immediately following childbirth, women are at greater risk of experiencing these symptoms and miss their best opportunity for improved long-term outcomes.

For more information about OASI, please visit the Tears Hub. To find out more about the impact that OASI can have on women and birthing people please visit the OASI Videos page, which provides a collection of real life experiences.


Between 2000 and 2012, OASI rates increased three-fold in England (1.8-5.9%).

This trend towards an increasing incidence of OASI did not necessarily indicate poor-quality care.

Tearing is a complex issue influenced by a range of factors including increased use of forceps during birth, advanced maternal age at first birth, and increased birth weight. Furthermore, as clinicians improve their detection of OASI, it can make it appear as if rates are increasing.

However, OASI can dramatically affect the short- and long-term health of women and birthing people. As it also affects decisions about future births, prevention and management of OASI is a priority in maternity care.

Experiences in some maternity units in England highlighted that some of the underlying problems related to this rise in OASI include:

  • Inconsistencies in approaches to preventing OASI
  • Inconsistencies in training and skills
  • Lack of awareness of risk factors and long-term impact of OASI
  • Variation in practice between health professionals

The OASI Care Bundle

In light of this, a multidisciplinary team of national UK experts, supported by national professional organisations and women’s groups, developed a ‘care bundle’, which is a set of interventions likely to improve outcomes when implemented together. The team selected the elements of the care bundle based on recommendations from existing UK guidelines.

The elements of the OASI Care Bundle included:

Good communication with the woman before, during and after birth underpins all elements of the care bundle.

The team developed and piloted an intervention package in two NHS maternity units that brought together the care bundle, a skills development module for clinicians and campaign materials to raise awareness among clinicians and women. The team subsequently received funding from the Health Foundation to implement this intervention in 16 maternity units across England, Scotland and Wales, in what became the OASI Care Bundle Project, or “OASI1” (2016-2018).