What Is a Third-Degree Tear? Causes, Repair, and Recovery

A third-degree tear is a childbirth injury that extends from the vaginal tissue through the perineal muscles and into the anal sphincter, the ring of muscle that controls bowel movements. It sits on a severity spectrum between a second-degree tear (which damages perineal muscle but spares the sphincter) and a fourth-degree tear (which goes all the way through the sphincter into the rectal lining). Third-degree tears require surgical repair in the delivery room, and most people who have one recover well, though the injury can affect bowel control, sexual comfort, and emotional wellbeing in the months and sometimes years that follow.

How Third-Degree Tears Are Classified

Not all third-degree tears are the same. Clinicians grade them into three subcategories based on how much of the anal sphincter is damaged:

3a: Less than half of the external anal sphincter is torn.
3b: More than half of the external anal sphincter is torn.
3c: The external sphincter is torn and the internal anal sphincter is also damaged.

The distinction matters because outcomes differ across these grades. A network meta-analysis found that the average rate of some degree of anal incontinence was about 22% for 3a tears, roughly 25% for 3b tears, and about 27% for 3c tears. The jump from 3a to 3c carried a statistically meaningful increase in risk, with 3c tears nearly doubling the odds of incontinence compared with 3a tears.¹ This grading helps clinicians decide how to repair the injury and what follow-up care to recommend.

What Increases the Risk

Third-degree tears result from a combination of factors, not a single cause. Some relate to the baby, some to the birth itself, and some to the person giving birth. Several large studies have converged on a consistent set of risk factors.

Instrumental delivery is the biggest single contributor. Forceps carry the largest risk among assisted vaginal deliveries, with one study reporting roughly three times the odds of a third-degree tear compared with spontaneous delivery.² Vacuum extraction raises the risk too, but less dramatically. Research comparing the two instruments has consistently found forceps to be the stronger risk factor, and some data suggest that combining forceps with other forms of assistance increases the risk even further.³ A large tertiary-center study of over 33,000 deliveries put the odds ratio for forceps at about 4.5, making it one of the strongest predictors of a severe tear.⁴

Being a first-time mother (nulliparity) is another major factor, with studies consistently reporting two to three times the odds compared with people who have given birth before.⁴ Larger babies increase the risk in a dose-dependent way. A population-based study found that birth weight over 4,500 grams was a clear risk factor for severe tears even after adjusting for other variables.⁵ Among mothers who had given birth before, gestational diabetes and birth weight over 4,000 grams both showed independently elevated risk.⁶

A baby facing toward the mother’s abdomen rather than her back (the occiput posterior position) is a well-replicated risk factor, roughly tripling the odds in first-time mothers.⁶ A prolonged second stage of labor, induction, use of oxytocin for augmentation, and delivery after 40 weeks have all shown up as significant contributors in large observational studies.⁷

The Role of Episiotomy

Whether an episiotomy helps or hurts depends on how it is done. A midline episiotomy, the type that cuts straight down toward the anus, has been consistently linked to a higher risk of the cut extending into a third- or fourth-degree tear.³ Mediolateral episiotomy, which angles away from the midline, appears to have the opposite effect. Research measuring the angle of episiotomy scars found that the risk of sphincter injury dropped by about half for every six degrees the cut angled away from the midline. An incision at 60 degrees from the midline, which relaxes to about 45 degrees after repair, is considered protective.⁸ This is one of the reasons many countries have moved away from routine midline episiotomy in favor of mediolateral cuts performed selectively.

How the Tear Is Repaired

Third-degree tears are repaired surgically, usually right after delivery while anesthesia is still in effect. The torn ends of the anal sphincter are stitched back together, along with the overlying perineal muscles and skin. Two main techniques exist for repairing the external sphincter itself: end-to-end approximation, where the torn edges are sewn directly together, and overlap repair, where the cut ends are overlapped and sutured like two flaps.

Randomized trials have compared the two methods, and the results are surprisingly similar. One trial with a year of follow-up found no significant difference in continence scores, sphincter defects on ultrasound, or anal pressure measurements between the two groups.⁹ Another trial with about 18 months of follow-up likewise reported similar improvements in continence and squeeze pressure in both groups.¹⁰ In practice, the choice often depends on the surgeon’s training and the specific anatomy of the tear. What matters more than the technique is that a clinician experienced with sphincter repair performs it and that the full extent of the injury is recognized at the time of delivery.

Why a Missed Tear Is a Problem

Sphincter injuries are sometimes not detected immediately after delivery. Tears can hide beneath intact-looking skin, or the examining clinician may underestimate the depth of the injury. When a tear goes unrepaired, outcomes are worse. A study comparing women whose sphincter injuries were detected and repaired at delivery with those whose injuries were missed found that the missed-tear group had significantly higher incontinence scores, worse urinary symptoms, and poorer physical functioning.¹¹ This is one reason many maternity units now train all birth attendants in systematic perineal examination, sometimes supplemented with ultrasound, to catch injuries before the window for primary repair closes.

Pain Management and Early Recovery

The first days and weeks after repair focus on controlling pain, keeping stools soft, and watching for infection. For pain relief, acetaminophen and anti-inflammatory medications are considered first-line treatments. For people who already have an epidural in place during labor, a small dose of epidural morphine can provide extended relief. Ice packs applied to the perineum are also recommended as a simple, low-risk measure.¹²

Laxatives are routinely prescribed to prevent straining during bowel movements, which could stress the healing repair. A review of prescribing practices found considerable variation in which laxatives were given. Bulking agents were the most commonly prescribed class, used in about two-thirds of cases, even though some trial data had previously questioned their value. Reassuringly, the type of laxative did not appear to affect continence outcomes, so the goal is simply to keep stools soft and easy to pass.¹³

Spotting Signs of Infection

A small percentage of perineal repairs develop an infection, which can compromise healing and worsen long-term outcomes. One large survey found an infection rate of about 4.5% for perineal tears overall. The strongest early warning sign was a pain score of seven or higher (on a ten-point scale) combined with redness at the wound site. That combination was by far the most reliable predictor of infection during the first week, more telling than swelling or discharge alone.¹⁴

A single dose of intravenous antibiotics given around the time of repair may reduce wound complications. One trial found that perineal wound problems at two weeks were substantially lower in the antibiotic group, though the trial was small and had high dropout, so this finding comes with a note of caution.¹⁵ Many hospitals now give prophylactic antibiotics as standard practice after sphincter repair.

Long-Term Bowel Function

The question most people ask after a third-degree tear repair is whether they will have lasting bowel control problems. The honest answer is that most people do well, but a meaningful minority experience some form of incontinence, often milder than they fear.

One follow-up study of women after primary sphincter repair found that about 57% reported some symptoms. The most common issue was difficulty controlling gas, reported by about a third of the group, with a smaller proportion experiencing leakage of liquid or solid stool.¹⁶ A larger study of 114 women found that at short-term follow-up, about one in five was incontinent, with the vast majority having only mild symptoms. At medium-term follow-up, those numbers stayed roughly stable, and severe incontinence was rare.¹⁷

The severity of the original tear matters. As noted earlier, the network meta-analysis showed that anal incontinence rates rose with each subgrade, from about 22% for 3a tears up to nearly 29% for fourth-degree tears. The odds of incontinence were significantly higher for 3c and fourth-degree tears compared with 3a injuries.¹ This is why accurate grading at the time of delivery, and appropriately skilled repair, can make a real difference in long-term function.

Effects on Sexual Health

Sexual recovery after a severe perineal tear takes longer and can be more complicated than after a minor tear or intact perineum. A study examining the relationship between tear severity and sexual outcomes found that women who had a severe tear reported more complications overall, including pain during intercourse (dyspareunia), urinary incontinence, and constipation. They also reported lower quality of sexual activity and were more hesitant about future pregnancies.¹⁸ These effects tend to improve over time, and pelvic floor rehabilitation can help, but they are worth knowing about so you can seek support rather than assume something is wrong with your recovery.

Psychological and Emotional Impact

Physical healing is only part of recovery. A growing body of research shows that severe perineal tears are associated with psychological effects that deserve attention. A population-based survey found that women who experienced perineal trauma reported more physical symptoms after birth, and each increase in physical symptoms was associated with substantially higher odds of adverse psychological symptoms, including post-traumatic stress.¹⁹

Women with sphincter injuries were more likely to experience their birth as traumatic and to report avoidance symptoms of post-traumatic stress, as well as a greater negative impact on parenting tasks compared with those who had less severe injuries.²⁰ A prospective cohort study following women from pregnancy through two years postpartum found that the degree of perineal tear was significantly associated with childbirth-related post-traumatic stress symptoms at both eight weeks and two years after delivery, suggesting a dose-response relationship between tear severity and psychological distress.²¹ These findings argue for routine mental health screening as part of postpartum follow-up after a severe tear, not just pelvic exams and continence questionnaires.

Can Third-Degree Tears Be Prevented

No method eliminates the risk entirely, but several approaches can reduce it. One of the more promising and low-tech interventions is applying a warm compress to the perineum during the second stage of labor. A systematic review with meta-analysis pooling multiple trials found that warm compresses significantly reduced the rate of third-degree tears, cutting the risk to roughly a third of what it was in control groups. The rate of intact perineums tripled in the warm-compress group.²² Individual randomized trials have confirmed these findings, showing fewer severe tears and less pain in women who received warm compresses during pushing.²³²⁴

Beyond warm compresses, selective use of mediolateral episiotomy (rather than midline or routine episiotomy) during instrumental deliveries is a widely recommended protective strategy, as discussed earlier. Choosing vacuum extraction over forceps when an assisted delivery is needed, supporting the perineum with a hands-on technique during crowning, and avoiding unnecessary induction or prolonged pushing when alternatives exist are all part of the clinical toolkit. None of these guarantees prevention, but layering several evidence-based approaches together reduces the overall risk substantially.

Planning a Future Pregnancy

Many people who have had a third-degree tear worry about whether it will happen again. The reassuring news is that recurrence is uncommon. A Finnish cohort study found that after a sphincter injury, about 78% of women planned a vaginal delivery for their next birth, and among those who delivered vaginally, only about 2% had a recurrent sphincter injury.²⁵ About one in five opted for a planned cesarean section instead. The decision between vaginal birth and cesarean typically depends on how well the sphincter healed, whether you have ongoing continence symptoms, and personal preference. Clinicians often recommend an assessment of sphincter integrity (sometimes with ultrasound) before making a birth plan for the next pregnancy.

If you had a 3a tear with a good repair and no lingering symptoms, vaginal birth is generally considered safe and the recurrence rate is low. If you had a 3c tear or have persistent incontinence, the conversation shifts toward whether a cesarean section might better protect long-term bowel function. There is no one-size-fits-all answer, which is why a dedicated postnatal review with a knowledgeable provider matters before making plans.

Pelvic Floor Rehabilitation

Pelvic floor muscle exercises, often called Kegel exercises, are a standard part of recovery recommendations. The study examining quality of life after severe tears found that women who had experienced a severe tear were significantly more likely to be performing Kegel exercises systematically at home.¹⁸ In practice, many maternity units refer women with third- or fourth-degree tears to a pelvic floor physiotherapist for supervised rehabilitation. The therapist can assess muscle strength, guide exercise progression, and address any urinary symptoms alongside bowel concerns. While the evidence base for exactly which rehabilitation protocol works best after sphincter injury is still evolving, regular pelvic floor work is widely considered part of standard care, and most women who engage with it report improvement over time in both continence and sexual comfort.