Guidelines for the management of 3rd and 4th degree tears were updated and published last month by The Royal College of Obstetricians & Gynaecologists. The purpose of the guidelines are to provide evidence-based guidelines on diagnosis, management and treatment of 3rd and 4th degree perineal tears. These types of tears are also referred to as obstetric anal sphincter injuries, or OASIS. The authors acknowledge an increased rate of reported anal sphincter injuries in England that may in part be due to increased awareness and detection of the issue. In terms of classification of anal sphincter injuries, the following is recommended (note the different levels at grade 3:
- 1st degree tear: injury to the perineal skin and/or the vaginal mucosa
- 2nd degree tear: injury to the perineum involving the perineal muscles but not involving the anal sphincter.
- 3rd degree tear: injury to the perineum involving the the anal sphincter complex
- Grade 3a tear: Less than 50% of the external anal sphincter (EAS) thickness is torn.
- Grade 3b tear: More than 50% of the EAS thickness is torn.
- Grade 3c tear: Both the EAS and the internal anal sphincter (OAS) are torn.
- 4th degree tear: Injury to the perineum involving the anal sphincter complex (EAS and IAS) and the anorectal mucosa.
Risk factors for anal injury are also outlined in the guidelines, although the authors point out that accurate prediction based on the risk factors is not reliable. The noted risk factors are as below:
- Asian ethnicity
- Birthweight greater than 4 kg (8.8 lb)
- Shoulder distocia
- Occipito-posterior position
- Prolonged 2nd stage labor
- Instrumented delivery
Recommendations worth noting include Level A evidence that warm compression during the 2nd stage of labor reduces the risk of OASIS. A noted best practice recommendation is that “Women should be advised that physiotherapy following repair of OASIS could be beneficial.” Guidelines such as these from The Royal College of Obstetricians & Gynaecologists can help in creating common language and in making recommendations that improve communication and expectations between patients and providers.