A third-degree tear, also known as a severe perineal laceration, is a significant injury that can occur during vaginal childbirth. This tear extends beyond the skin and muscles of the perineum (the area between the vagina and the anus) to involve the anal sphincter complex. The anal sphincter is the ring of muscle that controls the ability to hold in gas and stool. Medical professionals recognize this injury quickly after birth, and effective surgical treatment is available to restore the muscle’s anatomy and function. This intervention minimizes the risk of long-term problems and supports a complete recovery.
Understanding the Classification of Perineal Lacerations
Perineal tears are categorized into four degrees based on the depth of tissue damage. First-degree tears involve only the skin and superficial tissue, while second-degree tears extend into the perineal muscles but stop short of the anal sphincter. Third and fourth-degree tears are collectively termed Obstetric Anal Sphincter Injuries (OASIS) because they involve the muscle structure controlling bowel movements.
A third-degree tear involves the partial or complete disruption of the anal sphincter muscles. It is defined by injury to the external anal sphincter (EAS) and sometimes the internal anal sphincter (IAS). If the tear extends into the rectal lining, it is classified as a fourth-degree tear. The severity of a third-degree tear is further broken down into three subtypes based on the extent of the muscle damage.
Subtypes of Third-Degree Tears
Recognizing these distinctions allows medical teams to tailor the surgical repair to the specific layers and extent of the injury.
- Grade 3a involves less than 50% of the thickness of the external anal sphincter.
- Grade 3b involves more than 50% of the external anal sphincter thickness.
- Grade 3c includes a complete tear of the external anal sphincter along with damage to the internal anal sphincter.
Identifying the Risk Factors
Several factors related to the mother, the baby, and the delivery process can increase the likelihood of a third-degree tear. A first vaginal delivery (primiparity) is a significant risk factor associated with a higher rate of these injuries. Assisted deliveries, particularly those involving forceps, carry an increased risk compared to spontaneous vaginal births. Vacuum delivery also increases the risk.
Fetal characteristics also play a role, including a large infant head diameter or high birth weight (macrosomia). The risk also rises when the baby is delivered in the occiput posterior position (“sunny-side up”). Other contributing factors include a prolonged second stage of labor (the pushing phase) or the use of a midline episiotomy.
Surgical Repair and Immediate Care
Prompt and meticulous repair of a third-degree tear is fundamental to ensuring the best possible outcome. The repair is typically performed immediately after the baby is delivered and the placenta is birthed. To ensure optimal conditions for the specialized procedure, the repair often takes place in an operating room or a dedicated labor suite.
Regional anesthesia, such as an existing epidural, spinal, or general anesthetic, is used for pain relief and muscle relaxation. The procedure involves a layer-by-layer reconstruction of the damaged tissues, starting with the anal sphincter complex. The surgeon carefully identifies the torn ends of the external and internal anal sphincters and sutures them back together.
The objective of this specialized suturing is to restore the integrity and continuity of the anal sphincter complex, which is responsible for bowel control. The external anal sphincter is repaired using either an end-to-end or an overlapping technique. After the sphincter is repaired, the surgeon closes the overlying perineal muscles and skin. A single dose of broad-spectrum antibiotics is administered before the repair to reduce the risk of infection.
The Recovery Process and Long-Term Outlook
Recovery from a third-degree tear requires focused care starting immediately after the repair. Pain management is a high priority, involving regular medication and local relief measures like ice packs or warm sitz baths. Patients are strongly advised to use stool softeners for at least two weeks to prevent straining during bowel movements, which stresses the newly repaired muscle.
Initial healing of the surgical site usually takes four to six weeks, though full internal healing can take up to 12 weeks. The stitches used for the repair are dissolvable and do not need to be removed. During this period, women are advised to avoid strenuous activity and heavy lifting.
The long-term prognosis is favorable for most women; roughly 6 to 8 out of 10 women experience no long-lasting complications after the tear has been repaired. Potential long-term issues include persistent pain, pain during sexual intercourse (dyspareunia), and problems with bowel control. Anal incontinence (difficulty controlling gas or stool) occurs in a minority of women. Pelvic floor physical therapy is an important component of recovery, as strengthening these muscles improves tone and function for long-term continence.