From the Guidelines
The prevalence of vaginal tears after vaginal birth varies by degree, with first-degree tears affecting 5.5% to 16.4% of women, second-degree tears affecting 29.0% to 35.1%, third-degree tears affecting 1.8% to 7.1%, and fourth-degree tears affecting 0% to 0.3% of women, as reported in a prospective study published in the American Journal of Obstetrics and Gynecology 1.
Prevalence of Vaginal Tears by Degree
The prevalence of vaginal tears after vaginal birth is a significant concern, as it can impact a woman's quality of life and morbidity. The prevalence rates of perineal lacerations vary by degree, with:
- First-degree tears: 5.5% to 16.4% of women
- Second-degree tears: 29.0% to 35.1% of women
- Third-degree tears: 1.8% to 7.1% of women
- Fourth-degree tears: 0% to 0.3% of women These rates are based on a prospective study conducted in the United Kingdom, which looked at births that occurred in a hospital, free-standing midwifery-led units, or at home 1.
Risk Factors and Preventive Measures
Risk factors that increase the likelihood of more severe tears include first vaginal delivery, large baby size (macrosomia), instrumental delivery (forceps or vacuum), prolonged second stage of labor, occiput posterior position, and episiotomy. Preventive measures such as perineal massage during pregnancy, warm compresses during labor, controlled pushing during delivery, and proper perineal support by the birth attendant may help reduce the risk of severe tears.
Importance of Proper Repair and Care
Proper repair and care of perineal trauma are crucial to optimize short- and long-term outcomes. The birth attendant should be well-versed in how to appropriately identify and repair different types of perineal trauma. If the primary surgeon is inexperienced or unfamiliar with repair techniques, or there is uncertainty at delivery, it is best practice for another trained provider to reexamine the tear 1.
From the Research
Prevalence of Vaginal Tears After Vaginal Birth
The prevalence of vaginal tears after vaginal birth varies by degree of tear.
- First-degree tears: The study 2 found that 191 out of 554 primiparous women (34.5%) had no, labia, or first-degree tears.
- Second-degree tears: The study 2 found that 189 out of 554 primiparous women (34.1%) had second-degree tears.
- Third- and fourth-degree tears: The study 3 found that 96 out of 38,252 women (0.25%) sustained third- or fourth-degree perineal tears.
- Episiotomy: The study 4 found that episiotomy was performed in 15.2% of women with spontaneous births and 58.5% of women with vacuum-assisted births.
Risk Factors for Vaginal Tears
Several risk factors for vaginal tears have been identified, including:
- Asian ethnicity 3
- Primiparity 3
- Persistent occipito posterior 3
- Vacuum delivery 3
- Heavier birthweight 3
- Operative vaginal delivery 2
Distribution of Tear Types
The distribution of tear types varies by mode of delivery.
- Spontaneous births: The study 4 found that any kind of perineal tear was seen in 45.7% of women with spontaneous births.
- Vacuum-assisted births: The study 4 found that any kind of perineal tear was seen in 32.7% of women with vacuum-assisted births.
- High-grade obstetric anal sphincter injuries (OASIS): The study 4 found that OASIS appeared in 1.1% of women with spontaneous births and 3.1% of women with vacuum-assisted births.