Obstetric Lacerations

Introduction

• Description: Obstetric lacerations of the vaginal wall or introitus are common in vaginal deliveries. Laceration of the cervix, labia, and periurethral and periclitoral (prepuce) tissues is also possible.

• Prevalence: Common; 50%–80% of vaginal deliveries; third- and fourth-degree lacerations occur in less than 5% of deliveries.

• Predominant Age: Reproductive age (most common in females younger than 25 years).

• Genetics: No genetic pattern.

Etiology and Pathogenesis

• Causes: Tissue laxity induced by the hormonal changes of pregnancy, combined with the large diameter of the fetal head and shoulders, often result in vaginal wall or introital lacerations, in even the most controlled spontaneous delivery. The use of instrumentation (forceps or vacuum) to augment or expedite vaginal delivery increases these chances. Fetal malpresentation, such as occiput posterior, can also increase the risk to maternal tissues due to the altered geometry of these deliveries.

• Risk Factors: Nulliparity, fetal macrosomia, precipitous birth, operative delivery, episiotomy, epidural anesthesia, occiput posterior delivery.

Signs and Symptoms

• Vaginal bleeding (may be profuse and prolonged)

• Visible tissue damage on inspection

• Lacerations are classified as follows:

  • First-degree lacerations —Injury to the skin and subcutaneous tissue only.

  • Second-degree lacerations —Extends into the fascia and musculature of the perineal body, the deep and superficial transverse perineal muscles, and the pubococcygeus and/or bulbocavernosus muscles.

  • Third-degree lacerations —Involve some or all of the fibers of the external anal sphincter (EAS) and/or the internal anal sphincter (IAS). Subclassified as follows:

    • 3a—<50% of EAS thickness is torn

    • 3b—>50% of EAS thickness is torn

    • 3c—Both EAS and IAS are torn

  • Fourth-degree lacerations —Involves both the anal sphincter complex (EAS and IAS) and anal mucosa.

Diagnostic Approach