Perineal Lacerations

Anatomy and Physiology

The female external genitalia includes the mons pubis, labia minora and majora, clitoris, perineal body, and vaginal vestibule. The perineal body is the region between the anus and the vaginal vestibular fossa. The perineum typically comprises the anatomic structures within the pelvic outlet, including the superficial and deep muscles of the perineal membrane, bordered by the ischial rami, pubic symphysis, ischial tuberosities, and sacrotuberous ligaments and coccyx. The perineal membrane is the most common site of laceration during childbirth.[8][9]

Vaginal and vulvar lacerations are typically superficial and do not require repair. However, perineal lacerations can involve multiple anatomic structures; therefore, perineal lacerations are stratified according to severity, whereas vulvar and vaginal lacerations are not. Most clinicians use the Sultan classification to stratify perineal lacerations into the following 4 primary categories:

• First Degree: superficial injury to the vaginal mucosa that may involve the perineal skin
• Second Degree: first-degree laceration involving the vaginal mucosa and perineal body
• Third Degree: second-degree laceration with the involvement of the anal sphincter complex, which can be further classified into the following 3 subcategories:
  • A: Involvement of <50% of the external anal sphincter
  • B: Involvement of >50% of the external anal sphincter
  • C: External and internal anal sphincters are torn [1][7]
• Fourth Degree: Tearing of the anal sphincter complex and the rectal mucosa [1][7]

Severe perineal lacerations, which include third- and fourth-degree lacerations, are referred to as obstetric anal sphincter injuries (OASIS).[6][8]

Indications

Following vaginal delivery, 9 of 10 women experience some form of perineal trauma either spontaneously or secondary to episiotomies.[7] The incidence of perineal trauma between countries varies due to different definitions of perineal trauma classification and underdiagnosis.[2] Most perineal lacerations that occur in a vaginal delivery can be classified as first- or second-degree. Of these lacerations, 60% to 70% will require suturing.[8] The incidence of OASIS injuries occurs in approximately 4% to 11% of deliveries in the United States.[3] With each additional birth, the frequency and severity of perineal trauma decreases.[3].

For the majority of vulvar, vaginal, and first-degree lacerations, repair is unnecessary. A Cochrane review revealed that conservative management of small, hemostatic, anatomically approximated lacerations reduced pain, analgesia use, postpartum dyspareunia, and higher breastfeeding rates. However, evidence of long-term outcomes is lacking, therefore, the American College of Obstetricians and Gynecologists (ACOG) has suggested indications for the repair of these types of lacerations be based on clinical judgment.[1] The repair technique indicated is based on the degree of perineal laceration identified.[1] Generally, for lacerations noted to have persistent bleeding or anatomic distortion, repair is indicated.[1]

Risk factors for perineal lacerations include nulliparity, operative vaginal delivery, midline episiotomy, Asian race, and increased fetal weight.[6][10] Malpresentation, including persistent occiput posterior position and advancing gestational age, both contribute to perineal lacerations.[4][5][8][11] The most common risk factors for OASIS injuries are forceps or vacuum deliveries, a midline episiotomy, and/or a large fetus. 

Contraindications

Suture repair is relatively contraindicated for hemostatic perineal lacerations. Study results have demonstrated that expectant management or using a skin adhesive results in shorter repair time and reduced pain, with similar outcomes in function and appearance compared to suture perineal repairs. Therefore, conservative management is preferred for hemostatic lacerations.[3] For lacerations with persistent bleeding or anatomical distortion requiring repair, treatment should be delayed if an appropriately trained clinician is unavailable. In such cases, wound packing is recommended, with repair deferred for 8 to 12 hours until an experienced clinician can evaluate and properly address the laceration. This management recommendation is supported by results from several studies demonstrating that clinical understanding of perineal anatomy and laceration classifications and expertise in repair techniques are directly correlated to improved patient outcomes. Results from one study found surgeon inexperience, inappropriate suture choice, and misdiagnosis of the repair type required were the primary factors leading to increased postprocedural complications. Moreover, the incidence of repair failures decreased from 29% to 12% with targeted education.[3]

An episiotomy is a surgical procedure performed at the bedside during the second stage of labor, which causes enlargement of the posterior vagina.[12] This is done just before the delivery to decrease maternal blood loss. An episiotomy may be indicated if there is a need for expedited delivery of the fetus, soft tissue dystocia, or a need to aid an operative vaginal delivery.[6][8][12] The 2 most common types of episiotomies are midline and mediolateral.[12] The midline episiotomy is the most commonly performed type in the United States and is associated with a higher frequency of severe perineal lacerations.[6][8][12] The mediolateral episiotomy is more difficult to repair and is associated with increased postpartum pain and blood loss. The routine use of episiotomy is not supported; therefore, the World Health Organization and ACOG recommend its restricted use.[6][8] Please see StatPearls' companion resource, "Episiotomy," for more information.

Equipment

When preparing to repair a vaginal laceration, the clinician will need appropriate lighting, tissue exposure, and anesthesia for examination and repair.[6][8] For first or second-degree lacerations, local anesthetic infiltration is typically sufficient. Regional or general anesthesia may be considered for OASIS repair. Additionally, betadine or chlorhexidine solution is recommended to clean the perineal area. Surgical glue, suture, needle drivers, Allis clamps, forceps, sterile gloves, sponges, and suture scissors will also be required to complete the repair.[1] The preferred suture material used depends on the laceration type. Monofilament sutures may be associated with a reduced risk of infection. ACOG recommends 2-0 or 3-0 polyglactin or poliglecaprone for the repair of first-degree lacerations, 2-0 or 3-0 polyglactin for the repair of second-degree lacerations, 2-0 polyglactin or 3-0 polyglactin or polydioxanone for third-degree lacerations, and 3-0 or 4-0 polyglactin or poliglecaprone for fourth-degree lacerations. Depending on the severity of the laceration, access to an operating room may be required.[3]

Personnel

The following personnel may be involved in the care of patients with perineal lacerations:

• Obstetric clinicians
• Family practice clinicians
• Midwife
• Nurse practitioner
• Anesthetist

Preparation

After every vaginal delivery, the perineum, vagina, and cervix should be carefully examined.[6] A digital rectal examination should be done with any severe laceration to assess the integrity and tone of the anal sphincter.[6][8] Before an OASIS repair is performed, a Foley catheter should be placed. Additionally, preoperative antibiotics, typically a second-generation cephalosporin, should be administered to reduce infection risk and surgical instrument, sponge, and suture pre- and postoperative counts should be conducted.[3]

Technique or Treatment

Second-Degree Perineal Laceration Repair Technique

Generally, for second-degree perineal lacerations, a continuous or running suture closure should be used over interrupted suturing to decrease postpartum pain and the possibility of the patient requiring suture removal.[8][13] The suture is used to reapproximate the vaginal mucosa to the level of the hymen. Once the hymen is restored attention is turned to the perineal body and submucosal region. After these areas are properly closed, the skin is reapproximated.[8][13] The following technique is typically recommended for this type of laceration:

• Anchor the suture distal to the apex of the laceration in the vaginal epithelium.
• Close the vaginal epithelium, underlying muscularis, and rectovaginal fascia with a nonlocking suture in a running fashion to the level of the hymenal ring.
• Then, using the same suture in the same fashion, close the bulbocavernosus and transverse perineal muscles from the axial plane parallel to the perineal muscles.
• With the same suture, repair the subcuticular perineal skin in a running fashion, working back up to the hymenal ring.
• Tie the suture knot behind the hymenal ring.
• Perform a rectal exam to confirm adequate repair of the laceration and no misplaced sutures.[3]

Third- and Fourth-Degree Perineal Laceration Repair Technique

Proper repair of third- and fourth-degree lacerations is more complex; clinical expertise and correct technique are essential to improve patient outcomes. The particular focus of OASIS lacerations is the reapproximation of the anal sphincter complex and rectal mucosa, depending on the severity of the injury. Once the rectal mucosa and anal sphincter are repaired as clinically indicated, the remaining portion of the laceration is closed in the same fashion as a second-degree tear.[13] The following procedure is commonly used for OASIS repairs: 

• Using 3-0 or 4-0 delayed absorbable sutures, anchor the suture distal to the apex of the laceration, being careful to embed the knot within the anorectal lumen.
• Suture the anorectal mucosa in a running, nonlocked fashion approximately 5 mm past the anal verge. Use the overlying rectovaginal fascia to perform a second layer closure over the repaired anorectal mucosa with another 3-0 or 4-0 delayed absorbable suture. 
• Identify the internal anal sphincter
• If torn, repair the internal anal sphincter with interrupted sutures in an end-to-end fashion using a 3-0 polyglactin or polydioxanone suture.
• Identify the external anal sphincter and grasp each end with an Allis clamp.
• Reapproximate the external anal sphincter with 2-0 polyglactin or 3-0 polyglactin or polydioxanone sutures using the appropriate technique based on the severity of the laceration.
  • Partial external anal sphincter laceration: Use an end-to-end technique with interrupted sutures tied at the posterior, inferior, superior, and anterior areas of the muscle. 
  • Complete external anal sphincter laceration: Use an overlapping technique, dissecting approximately 1.5 cm of the torn ends from the surrounding tissue, overlapping about 1 cm of the ends, and suture together with full-thickness interrupted or mattress sutures.
• Bury the knots from the anal sphincter repair behind the superficial perineal muscles.
• Reapproximate the remaining tissue using the second-degree perineal laceration repair approach. 
• Perform a rectal exam to confirm adequate repair of the laceration and no perforating sutures through the rectal mucosa.[3] 
• Keep the Foley catheter in place overnight due to the increased risk of urinary retention.[3] 

Postoperative Care

Clinicians should closely monitor patients immediately after perineal laceration repair for any anesthesia or postoperative complications. The Foley catheter should be removed on postoperative day 1, and a voiding trial should be conducted to assess bladder function. Perineal cool packs, topical anesthetic sprays or ointments, sitz baths, acetaminophen, and nonsteroidal anti-inflammatory medications can be used for pain control. Avoid opiates due to possible constipation. Scheduled stool softeners and oral laxatives twice daily for 6 weeks postpartum should be administered to avoid constipation and reduce the risk of wound dehiscence.[3] 

Complications

The most common complication of a perineal laceration is bleeding. Most bleeding can be quickly controlled with pressure and surgical repair.[8] However, hematoma formation can lead to large amounts of blood loss in a very short time. Beyond bleeding, immediate complications include pain and suturing time, leading to delayed mother-child bonding.[5] The risk of wound infection and dehiscence is high in patients who have undergone OASIS repair, which can cause decreased physical, emotional, and sexual health.[8] The risk of wound complications is higher in repairs performed by clinicians with insufficient training.[3] Other risk factors for wound complications include smoking, increasing body mass index, fourth-degree laceration, operative vaginal delivery, and use of postpartum antibiotics.[3]

Long-term complications include pain, urinary or anal incontinence, and delayed return to sexual intercourse due to dyspareunia.[4][6] Some studies have demonstrated worse adverse events in women who had an episiotomy compared to those who were allowed to tear spontaneously.[5] Additionally, flatal incontinence can persist for years after an OASIS.[6] Quality of life can be greatly affected by the severity of a perineal laceration and the long-term urinary, flatal or fecal incontinence that may follow. Approximately 25% of women who suffer from an OASIS injury will experience wound dehiscence in the first 6 weeks postpartum, and 20% will suffer from a wound infection. Rectovaginal or rectoperineal fistulas may develop in women who had unidentified or poorly healed OASIS injuries.[8] The time it takes a woman to return to normal sexual function after perineal trauma varies but has been correlated to the severity of the laceration. The more severe the laceration, the longer the return to normal sexual function.[14]

Clinical Significance

Perineal trauma can have long-term effects on a woman's life and well-being. Results from multiple studies have found that some women who experience severe perineal lacerations suffer long-term psychological trauma and social isolation.[14] Women may be embarrassed by their symptoms and, therefore, do not discuss them with their clinicians. Practicing clinicians must take care to properly diagnose and repair lacerations in childbirth as well as address concerns in the postpartum period.

Preventive Measures

Multiple strategies have been proposed for the prevention of perineal trauma at the time of vaginal delivery; however, a consensus on the most effective prevention measures to avoid or reduce the severity of perineal lacerations has not been established.[5] Perineal massage has been shown to decrease the incidence of lacerations requiring sutures, although the reduction was minor.[8] Additional studies have shown a decrease in third- and fourth-degree lacerations when massage was performed during the second stage of labor. However, no consistently proven benefit was observed.[5][8] Perineal massage may promote perineal relaxation, increasing perineal blood flow, and stretching the vaginal tissue before delivery, leading to less severe lacerations. This relaxation may decrease the number of episiotomies cut.[4][15] Massage can be started after 34 weeks and be performed daily until delivery.[4][5]

Perineal support, or a "hands-on" approach, can protect the perineum and decrease the severity of perineal lacerations at the time of delivery.[5] However, studies are conflicting on the significant benefit of this measure.[16] Delayed or immediate pushing after a woman reached 10 cm of dilation showed no difference in the incidence of perineal lacerations. However, there was a higher incidence of delivery with intact perineum in women who delivered in the lateral position with delayed pushing compared to immediate pushing in the lithotomy position.[8] Warm compresses can be used during the second stage of labor to decrease the risk of third- and fourth-degree lacerations.[8] Warm compresses and perineal massage are the only interventions shown to reduce the frequency of third- or fourth-degree lacerations.[6]

Enhancing Healthcare Team Outcomes

Managing perineal lacerations during childbirth requires a collaborative, interprofessional approach to enhance patient-centered care, outcomes, patient safety, and team performance. Physicians, midwives, and advanced practitioners must be skilled in diagnosing and repairing lacerations, employing strategies to prevent severe injuries, and ensuring timely intervention. Nurses are critical in assessing lacerations, providing immediate care, and supporting patients throughout healing. Pharmacists contribute by managing pain relief and recommending appropriate medication regimens to prevent infections. Clear and continuous interprofessional communication is essential to coordinate care effectively, ensuring that each team member is informed about the patient's condition and treatment plan. This cohesive teamwork promotes a holistic approach to care, addressing the physical and emotional needs of the patient, ultimately improving recovery and quality of life.

Nursing, Allied Health, and Interprofessional Team Interventions

Postpartum care clinicians must ensure they are addressing and validating any concerns a woman may have about her perineal trauma experienced during childbirth. A woman's physical and psychological health should be discussed. Severe perineal trauma can have long-term effects on a woman's sexuality, overall well-being, and relationship with her partner.[14]

Women who have had an OASIS injury in a previous pregnancy need to be counseled about the risk of recurrence of injury with subsequent pregnancies. Elective cesarean section can be discussed as an option, but the low risk of another OASIS injury should be carefully weighed against the risk of cesarean delivery.[6][8] Women with a history of an OASIS injury who are currently asymptomatic and show no symptoms of sphincter injury can be encouraged to have a vaginal delivery.[8]

The healthcare team should be prepared and willing to ask about and treat any complications a woman may have after childbirth. Some women feel embarrassed and ashamed about the problems they encounter and will not bring up concerns to their clinicians.[14] By asking questions at the postpartum visit and understanding the details of her delivery and any perineal trauma encountered, clinicians can provide complete and compassionate care for their patients.