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Obstetric Perineal & Vaginal Lacerations

Perineal lacerations or episiotomy affect up to 90% of nulliparous and 70% of multiparous women after vaginal delivery.[1] The sequelae of birth-related perineal and deeper pelvic-floor injury vary by structure and severity and may include persistent pain, dyspareunia, fecal or urinary incontinence, prolapse, and depression.[1][6]

Anatomy at Risk​

  • Perineal body. The most common laceration site, a mass of dense connective tissue into which the superficial and deep transverse perineal muscles and the bulbospongiosus (bulbocavernosus) insert.[2] It is the keystone of Level III distal support; its disruption widens the genital hiatus and destabilizes the posterior compartment. See Perineum anatomy.
  • Anal sphincter complex. The external anal sphincter (EAS) (striated, voluntary, generates squeeze pressure) overlaps for 1–2 cm with the internal anal sphincter (IAS) (smooth muscle, autonomic, contributes up to 80% of resting anal-canal pressure); the whole complex extends about 4 cm up the anal canal.[2] IAS integrity is the chief determinant of passive continence, which is why OASIS subclassification turns on whether the IAS is involved.
  • Levator ani. Not lacerated at the perineum but avulsed from its pubic insertion by overstretch; it is the silent injury that drives later prolapse (below).

Classification​

Lacerations are graded by depth; the third-degree tier is subclassified by anal-sphincter involvement (the Sultan classification adopted by ACOG and RCOG — OASIS = obstetric anal sphincter injury).[1][2][26]

DegreeStructures involvedRepair
FirstVaginal mucosa or perineal skin only; no muscleMay be left unrepaired if hemostatic and anatomy undistorted; ACOG (Level B) permits adhesive for hemostatic first-degree tears, while 2025 VVOG guidance recommends against adhesive for first-degree tears after higher wound complication and dehiscence rates than sutures .[2][63]
SecondInto the perineal muscles (bulbospongiosus, transverse perineal)Layered suture repair
Third (OASIS)Anal sphincter complex — subclassified:Technique depends on EAS thickness and IAS involvement; see primary repair below
  3aLess than 50% of EAS thickness torn[2]
  3bMore than 50% of EAS thickness torn[2]
  3cEAS and IAS torn
FourthAnal sphincter complex and anorectal epitheliumSphincter + epithelial repair

Obstetric perineal injury gradesOriginal schematic · v2026-09-11 · Clinical review pending

Schematic classification, not a literal scale drawing of surgical planes. Grades 3a and 3b describe the proportion of EAS thickness torn; 3c includes IAS injury; fourth degree includes anorectal epithelium. An isolated rectal buttonhole tear with an intact sphincter complex is a separate injury.[1][2]

The 2015 RCOG Green-top Guideline No. 29 uses the same classification. It advises classifying a tear of uncertain depth to the higher grade, and grading a tear as 3b when it is unclear whether more than 50% of the EAS is torn. A rectal buttonhole tear with an intact anal sphincter complex is by definition not a fourth-degree tear; if it is not recognized and repaired, it may lead to a rectovaginal fistula.[20]

Lacerations occur in 53–79% of vaginal deliveries; most are first- or second-degree.[2] Third- and fourth-degree repair is detailed on the Anal Sphincteroplasty and Episioproctotomy pages.

Mechanism of Injury​

Visible levator ani tears are most consistent with overstretch during the second stage of labor; childbirth-related neural changes may also contribute to later pelvic-floor dysfunction.[6] As the fetal head descends and crowns, the levator ani and birth-canal tissues must elongate to more than three times their resting length.[6] Biomechanical modeling localizes the peak strain to the superior perineal body and its junction with the urogenital hiatus and anal sphincter: the perineal body reaches a stretch ratio of about 1.95 (greatest near the urogenital hiatus) and the EAS transverse diameter narrows by about 51% at delivery, identifying the tissues most likely to fail.[7]

Levator ani avulsion is the consequential occult injury: visible on imaging in up to 19% of primiparous women, present in 55% of women who later develop prolapse, and carrying an odds ratio of 7.3 for prolapse versus intact support.[6] Levator avulsion is associated with a larger urogenital hiatus; hiatal enlargement can precede prolapse by years, and other support structures also contribute.[6]

Risk Factors​

Obstetric anal sphincter injury (OASI) complicates about 3% of vaginal births overall, roughly 6% in primiparas versus 2% in multiparas, and about 10% of women report anal incontinence within a year.[10] Pooled analyses and a large Kaiser cohort identify the dominant predictors:[8][9][17]

Risk factorEffect size (95% CI)Source
Instrumental deliveryRR 3.38 (2.21–5.18)Pergialiotis 2020[17]
Vacuum-assisted deliveryaOR 4.23 (3.59–4.98)Ramm 2018[9]
Midline episiotomyRR 2.88 (1.79–4.65)Pergialiotis 2020[17]
Second stage ≥180 min (vs <60 min)aOR 3.20 (2.62–3.89)Ramm 2018[9]
Persistent occiput posteriorRR 2.73 (2.08–3.58)Pergialiotis 2020[17]
Nulliparity, occiput transverse or posterior position, prior cesarean, Asian ethnicity, epidural, shoulder dystocia, birthweight over 4,000 gIndependent risk factors; effect sizes vary by cohortHu 2023, Ramm 2018, Okeahialam 2024[8][9][10]

A cohort-study meta-analysis associated mediolateral episiotomy with lower severe-laceration risk after forceps delivery (OR 0.56, 95% CI 0.42–0.74), but found no statistically significant association after spontaneous or vacuum birth; a separate meta-analysis found no overall protective association.[8][17] The later EVA trial randomized 717 nulliparas requiring vacuum extraction; clinically diagnosed OASIS occurred in 21/344 (6%) assigned standardized lateral episiotomy versus 47/358 (13%) assigned no episiotomy (modified intention-to-treat; unadjusted RR 0.46, 96% CI 0.28–0.78).[59] Wound infection (32/344 versus 17/358) and dehiscence (32/344 versus 12/358) were more frequent with episiotomy.[59] English registry data cited by RCOG 2015 report lower odds of OASIS with episiotomy at both instrumental modes: ventouse without episiotomy OR 1.89 versus 0.57 with episiotomy, and forceps without episiotomy OR 6.53 versus 1.34 with episiotomy.[20] RCOG also notes that risk factors do not allow accurate prediction of OASIS.[20] Midline episiotomy combined with forceps substantially increases the risk of third- and fourth-degree injury: ACOG Practice Bulletin 198 cites odds ratios of 5.65 for third-degree and 10.55 for fourth-degree laceration with that combination in US Nationwide Inpatient Sample data, while a separate meta-analysis it cites gives 5.50 for forceps delivery and 3.82 for midline episiotomy.[2]

Prevention​

OASIS is associated with later anal incontinence, and levator avulsion with later prolapse.[6][16]

  • Intrapartum (ACOG Level A): warm perineal compresses during pushing reduce third-/fourth-degree tears (RR 0.46 for third-/fourth-degree tears; moderate-certainty Cochrane evidence), and restrictive episiotomy use is recommended over routine episiotomy.[2][11] RCOG 2015 also gives warm compression in the second stage a grade A recommendation (Cochrane meta-analysis of two studies, 1525 women, RR 0.48 for third- and fourth-degree tears).[20] Combined warm compress plus perineal massage, compared with control, probably reduces second-degree tears (RR 0.63, one trial).[11] For massage alone, Cochrane 2024 found little or no effect on second-degree tears (RR 1.04, 95% CI 0.89–1.21; low-certainty evidence) and uncertain effects on third- and fourth-degree tears; IUGA 2026 summarizes a separate five-study meta-analysis of randomized trials reporting fewer OASIs (RR 0.49, 95% CI 0.25–0.94).[11][16]
  • When episiotomy is needed: mediolateral or lateral is preferred over midline (midline is associated with sphincter injury). ACOG states that mediolateral episiotomy may be preferred (Level B) and notes limited data linking it with more perineal pain and dyspareunia. During operative vaginal birth, mediolateral or lateral episiotomy was associated with about 43% lower OASIS incidence with vacuum and about 68% lower incidence with forceps in nulliparas.[2][10] RCOG 2015 recommends that mediolateral episiotomy be considered at instrumental delivery (grade D) and that it be cut at 60 degrees from the midline when the perineum is distended, because a 40-degree incision at crowning leaves a post-delivery angle of about 22 degrees, too close to the midline to be protective.[20] It describes the evidence that episiotomy prevents OASIS and/or anal incontinence as conflicting (grade C).[20]
  • Manual perineal protection (hands-on) is associated with lower OASIS rates (NNT ≈ 37) in quality-improvement programs; randomized data for hands-on versus hands-off are limited and show no clear difference.[11] RCOG 2015 states that perineal protection at crowning can be protective (grade C) and favors hands-on over hands-poised technique on the basis of the quality-improvement programs.[20] Structured "perineal-bundle" programs have lowered OASIS rates nationally.[10] In a stepped-wedge evaluation across 16 maternity units in England, Scotland and Wales (55,060 singleton live vaginal births), implementation of the OASI Care Bundle (antenatal information, manual perineal protection and mediolateral episiotomy when indicated) was associated with a fall in the OASIS rate from 3.3% to 3.0% (adjusted OR 0.80, 95% CI 0.65–0.98), without significant change in cesarean or episiotomy rates.[27]
  • Antenatal: digital perineal self-massage from about 34–35 weeks reduced trauma requiring suture (RR 0.91, NNT ≈ 15) and episiotomy (RR 0.84) among women without prior vaginal birth in the older Cochrane review; women with a prior vaginal birth reported less perineal pain at 3 months.[18] That review found no significant reduction in third-/fourth-degree tears, whereas a later seven-study meta-analysis (3,069 women) found fewer OASIs (RR 0.36, 95% CI 0.14–0.89), as summarized by IUGA 2026.[2][10][18][16]

A separate longitudinal cohort of 1,528 women, enrolled 5 to 10 years after their first delivery and followed annually for up to 9 years (median 5.1 years), found that cesarean delivery was associated with a lower adjusted hazard of stress urinary incontinence (aHR 0.46, 95% CI 0.32–0.67), overactive bladder (aHR 0.51, 0.34–0.76), and pelvic organ prolapse (aHR 0.28, 0.19–0.42) compared with spontaneous vaginal delivery, while operative vaginal delivery was associated with a higher adjusted hazard of anal incontinence (aHR 1.75, 1.14–2.68) and prolapse (aHR 1.88, 1.28–2.78); modeled 15-year cumulative incidence after spontaneous vaginal delivery was 34.3% for stress incontinence, 21.8% for overactive bladder, 30.6% for anal incontinence, and 30.0% for prolapse.[21]

Acute Repair (Immediate Postpartum)​

Detection. Every vaginal delivery warrants a systematic perineal, vaginal, and rectal examination to avoid missing a sphincter or buttonhole injury; the commonest cause of a "failed repair" is an under-classified one.[1] ACOG notes that a digital rectal examination improves the diagnosis of OASIS when a deep perineal laceration is seen, and that routine endoanal ultrasound immediately postpartum to detect occult OASIS is of limited value and not recommended.[2] Anal sphincter and anorectal mucosal injury cannot be excluded without a rectal examination (RCOG good practice point), increased vigilance can double detection, and routine endoanal ultrasound immediately after delivery did not significantly increase detection and is regarded as a research tool.[20]

OASIS repair (IUGA 2026; RCOG 2015). Identify the injury grade before repair. RCOG advises OASIS repair in an operating theatre under regional or general anesthesia by a trained clinician or supervised trainee (good practice point); IUGA considers this setting desirable but allows another setting with adequate analgesia, lighting, equipment and asepsis.[16][20] If a suitably trained repairer is unavailable and bleeding is not significant, IUGA permits a short delay to obtain expertise; a randomized trial of 165 women found no detected difference in 12-month anal incontinence after immediate versus 8–12-hour repair.[16]

  • Anorectal mucosa. IUGA 2026 recommends full-thickness continuous nonlocking closure with 3-0 polyglactin or poliglecaprone, with knots on the vaginal side (Grade D). RCOG 2015 permits continuous or interrupted 3-0 polyglactin rather than PDS (grade D).[16][20]
  • Internal anal sphincter. Repair separately with interrupted or mattress sutures, without overlap (RCOG grade C; IUGA agrees that IAS injury is repaired separately).[16][20]
  • External anal sphincter. Partial-thickness tears (all 3a and some 3b) are repaired end-to-end. Full-thickness tears permit overlap or end-to-end repair with equivalent outcomes (Grade A in both guidelines; ACOG Level A, which adds that overlap needs a full-thickness tear and is not used for 3a or partial-thickness 3b injuries).[2][16][20] Use 3-0 PDS or 2-0 polyglactin for the muscle (Grade B), and bury the knots beneath the superficial perineal muscles to reduce knot and suture migration to the skin (RCOG grade B).[20] See Anal Sphincteroplasty.[2][16][20]
  • Complete the perineal repair. Reconstruct the perineal muscles after sphincter repair to avoid a deficient perineum .[16]
  • Avoid figure-of-eight sutures in the sphincters or anorectal epithelium because they are hemostatic and may cause ischemia; a rectal examination after repair confirms that no suture has passed through the anorectal mucosa.[16][20]
  • Antibiotics. Give intravenous broad-spectrum antibiotics, within an hour before repair per IUGA (Grade B in both guidelines).[16][20] ACOG considers a single dose at the time of repair reasonable (Level B); its 2018 interim update, aligning with Practice Bulletin 199, withdrew an earlier Level A wording that called it recommended.[2]

Isolated rectal buttonhole tear. An isolated rectal buttonhole tear has an intact sphincter complex. If a separate OASI coexists, document the buttonhole tear and the OASI grade, then repair both injuries.[16] Roper and colleagues' three cases used interrupted 2-0 polyglactin for rectal mucosal repair, but their proposed protocol specifies continuous nonlocking 3-0 polyglactin for the rectal mucosa, interrupted 2-0 or 3-0 PDS for the rectovaginal fascia, and continuous 2-0 polyglactin for the vaginal epithelium. Visualize both ends of the rectal tear before closure. IUGA 2026 recommends the same transvaginal three-layer sequence, also allowing continuous fascial closure, with rectal-mucosal knots on the vaginal side (Grade D for mucosa and fascia; Grade A for vaginal closure). For a large tear (about 7 cm) extending above the pelvic floor or gross fecal contamination, discuss diversion with a colorectal surgeon.[16][22] In a review of nine published case reports (four with a two-layer closure, five with three layers), all had an uneventful recovery; follow-up at 6 weeks or 3 months was specified for four cases; in the same authors' own three-patient series, one patient later required a defunctioning stoma after a second breakdown of the rectovaginal repair.[22]

Counseling for a future birth. Mode-of-delivery counseling after OASI, including recurrence risk and the role of EAUS and manometry, is covered under Mode of Delivery After OASI.

First-degree: a tear that is not bleeding and does not distort anatomy may not need repair; standard suture or tissue adhesive may be used for a hemostatic first-degree tear or for the perineal skin of a second-degree tear (ACOG Level B).[2] For second-degree tears and episiotomy, adhesive reduces pain and repair time but raises dehiscence, so suture remains standard.[5]

Second-degree. A layered, deep-to-superficial repair in three stages:[1][3]

  1. Vaginal mucosa. Anchor about 1 cm above the apex, then run a continuous (optionally locked-for-hemostasis) closure of mucosa and underlying rectovaginal fascia down to the hymenal ring.
  2. Perineal muscle. Reapproximate the bulbospongiosus and transverse perineal muscle ends with one or two running, non-locked sutures, rebuilding the perineal body.
  3. Skin. A running subcuticular closure back toward the hymen, the final knot buried behind the hymen. A separate skin layer is often unnecessary: leaving the skin apposed but unsutured reduces dyspareunia and perineal pain (at the cost of more gaping wounds at 48 h).[1][3]

The "crown stitch"​

The crown stitch is a teaching term (not a standardized entity in ACOG, Cochrane, or AAFP guidance) for the transition stitch at the hymenal ring or posterior fourchette where the running vaginal closure hands off to the perineal-body repair.[1][3] It takes a bite of each side of the fourchette and the underlying perineal-body muscle to reconstruct the posterior fourchette and restore the introitus-to-perineal-body relationship. Tension determines the result: too tight creates a constricting ridge and dyspareunia; too loose leaves the fourchette splayed and the introitus patulous. It is best understood as the same anatomic checkpoint a urogynecologist re-creates, deliberately and under tension control, during an elective perineorrhaphy.

Suture technique and material​

  • Continuous beats interrupted. A Cochrane meta-analysis (16 trials, 8,184 women) found continuous repair associated with less pain to 10 days (RR 0.76), less analgesia use with continuous subcuticular skin repair (RR 0.70), and less suture removal (RR 0.56); a 2025 systematic review of 55 RCTs confirmed superiority for pain, repair time, and healing with no significant difference in dehiscence, and found no pain difference by suture material.[4][5] ACOG prefers continuous over interrupted suturing of a second-degree laceration (Level B).[2]
  • Absorbable synthetic suture (e.g., polyglactin) is recommended over catgut for first- and second-degree repair: less pain and fewer resuturing events, although unabsorbed suture more often needs removal.[2]
  • Lock selectively, not by default. A running locked vaginal-mucosal closure can aid hemostasis and was traditionally thought to limit vaginal shortening. For episiotomy or second-degree tear repair, trials favor continuous over interrupted suturing for short-term pain and analgesic use; locking muscle or skin can overtighten tissue as it swells and add pain, so reserve locking for bleeding mucosa.[2][4]

Postoperative care​

For OASI repair, give postoperative laxatives to maintain soft formed stools (RCOG grade C), with a stool softener such as lactulose for about 10 days; routinely adding bulking agents is not advised (RCOG grade B; incontinence in the immediate postpartum period was 32.86% versus 18.18% with lactulose plus ispaghula husk versus lactulose alone).[20] Continue antibiotics per local protocol to reduce dehiscence (RCOG grade B) and provide bladder drainage until recovery from anesthesia and mobility permit a voiding assessment; then observe bladder filling and emptying and use postvoid bladder scans to assess emptying .[16][20] SOGC 2026 recommends pelvic-health physiotherapy referral after every clinically diagnosed OASI, with care starting as early as 2–6 weeks postpartum .[52] Follow-up timing and content are covered under Postpartum Perineal Clinic. Women can be told that 60% to 80% are asymptomatic 12 months after delivery and EAS repair (grade B); suture migration occurs in about 7%.[20]

After second-degree tear or episiotomy repair, prophylactic antibiotics may be considered: in the single-center REPAIR randomized trial, three oral doses of amoxicillin–clavulanate 500/125 mg starting within six hours postpartum did not significantly reduce overall wound complications at 4–14 days (47/218 versus 62/215), the primary outcome, but reduced clinically relevant wound complications (19/218 versus 36/215), a secondary outcome.[62] Multimodal acetaminophen and NSAIDs, osmotic laxatives to prevent constipation, and monitoring for urinary retention. Arnold and colleagues advise avoiding opiates because of constipation, and treat a new opioid requirement as a prompt to suspect infection or repair breakdown rather than escalate.[3] ACOG allows NSAIDs or opiates if they are paired with oral laxatives and stool softeners, and advises caution with rectal suppositories after a fourth-degree laceration.[2]

Perineal wound dehiscence​

Management of a dehisced second-degree tear or episiotomy is not standardized. A Cochrane review of two small, methodologically weak trials (52 women total) found insufficient evidence to support or refute secondary suturing over healing by secondary intention.[23] In the pilot PREVIEW trial (34 women randomized), wound healing at 2 weeks favored re-suturing, but at 6 weeks, 13/14 assessed re-sutured wounds and 16/16 assessed expectancy wounds had healed, and women who were re-sutured reported greater satisfaction at 3 months.[24] A retrospective series of 72 women re-sutured at a tertiary urogynecology unit, after debridement and once the wound was judged clean, reported complete healing among the 63 women with full healing follow-up in 31/63 (49.2%) at 4 weeks, 40/63 (63.5%) at 6 weeks, and 48/63 (76.2%) at 8 weeks, using continuous vaginal mucosal and perineal-muscle closure followed by interrupted mattress skin sutures.[25] For a dehisced second-degree tear or episiotomy, base the choice between early re-suturing and expectant management on tissue condition (clean, non-infected, viable edges) and patient preference rather than a fixed interval. Dehiscence of a primary OASIS repair requires specialist gynecologic or colorectal assessment, including EAUS; early secondary sphincter repair may be offered with counseling about recurrent dehiscence, infection and fistula, and should be avoided during obvious active infection.[16]

The Urogynecologist's Role​

The urogynecologist meets birth injury at two moments: the complex acute repair (OASIS, extended or vaginal-sulcus tears, the referral the delivering team escalates) and the delayed reconstruction of what didn't heal or what attenuated over years. The mental model that separates the two is the contrast between acute obstetric repair and elective perineorrhaphy — same territory, opposite tissue and goals.

FeatureAcute obstetric repairElective perineorrhaphy
Timing / settingImmediately postpartum; minor tears may be repaired in the delivery room, while OASIS requires a trained repairer and an appropriately equipped setting[16][20]Months–years later, OR under anesthesia
GoalReapproximate fresh torn layers; hemostasis, healingReduce an enlarged genital hiatus; rebuild perineal body for Level III support
TissueFresh edges, edematous, vascularChronic, attenuated, scarred; thinned perineal body
DissectionMinimal — the laceration provides the planesExtensive — sharp dissection of epithelium off rectovaginal fascia
Key stepLayered reapproximation; the fourchette transition ("crown") stitchPerineal-body reconstruction; surgeons may use midline fascial plication or excise attenuated tissue according to the defect and technique[13][14]
Suture patternContinuous running (less pain)Interrupted, heterogeneous between surgeons
Combined withRepair of associated vaginal, perineal, sphincter or rectal injury when present[16]Posterior colporrhaphy ± apical suspension

An enlarged genital hiatus is the single most influential factor urogynecologists cite when deciding to add perineorrhaphy, yet the procedure remains non-standardized; a 2024 survey of 114 responding IUGA urogynecologists found that 98% sometimes perform perineoplasty during prolapse surgery but with wide variation in indication and technique; ACOG and AUGS advise that posterior repair avoid tension on the levator ani because this may cause dyspareunia, and that perineorrhaphy reattaching the perineal muscles to the rectovaginal septum can be performed as needed when a perineal defect is present.[12][13][14][15]

Downstream sequelae the urogynecologist manages:

  • Prolapse. Levator avulsion and an enlarged genital hiatus are associated with later prolapse (see Posterior Compartment Prolapse and POP overview). Perineorrhaphy reconstructs a deficient perineal body; posterior repair addresses a symptomatic posterior vaginal wall defect, with apical support assessed separately.[6][15]
  • Fecal incontinence. May follow occult or persistent sphincter injury after OASIS (see Fecal Incontinence). Assess stool consistency, other causes of leakage, and sphincter anatomy and function. Begin dietary and bowel management; consider pelvic-floor rehabilitation when symptoms persist. Anal Sphincteroplasty may be considered for a repairable EAS defect, though functional benefit often wanes; sacral neuromodulation may be considered as a first-line surgical option with or without a defect.[16][60] Episioproctotomy may be used for a coexisting obstetric rectovaginal fistula with a sphincter defect.[61]
  • Dyspareunia and introital narrowing or splaying. From an over- or under-tightened fourchette, managed by revision perineoplasty.
  • Rectovaginal fistula. May follow breakdown of a fourth-degree repair or an unrecognized or failed rectal buttonhole repair (see Rectovaginal Fistula).[16][22]

Postpartum Perineal Clinic​

A postpartum perineal clinic is a dedicated outpatient service for women after OASI and other complicated perineal trauma that brings symptom assessment, examination, anorectal investigation, wound care, physiotherapy referral and counseling about future births into one pathway.[16][28] The 2026 IUGA guideline states that subspecialty OASI clinics provide an opportunity for streamlined early, comprehensive care (Grade C) and that EAUS and anorectal manometry (ARM) can both be used to characterize laceration sequelae and inform discussion of future births (Grade C).[16] The case for structured testing rests on the weak link between symptoms and sphincter status. In a Liverpool perineal-clinic cohort of 1,348 women seen over 13 years, with anorectal studies at 6 weeks and 6 months, 894 (66.3%) were asymptomatic; of these, only 221 (24.7%) had normal EAUS and manometry, 274 (31%) had abnormal manometry alone and 313 (35%) had both studies abnormal.[29][30] In a retrospective series of 69 women after primary repair of 3a tears, 38% of asymptomatic and 52% of symptomatic women had a defect on EAUS, a difference that was not significant.[31]

Referral and Timing​

Referral criteria vary by unit. The Croydon one-stop clinic accepted all women with OASI (postnatally, and antenatally in a later pregnancy), perineal wound complications within 16 weeks of delivery, female genital mutilation, and peripartum urinary or anal incontinence or prolapse.[28] In a survey of 86 obstetric providers at the Cleveland Clinic after a peripartum pelvic floor disorder clinic opened, the referral indications most often reported were third- and fourth-degree lacerations (94.9%), complex lacerations (70.5%), wound breakdown (57.7%) and urinary retention (53.8%); among 78 referring providers, 77 (98.7%) agreed that evaluations were useful for patients; 84.6% of respondents agreed that the clinic increased their awareness of OASI.[32]

The timing of the first visit is not standardized. RCOG Green-top Guideline No. 29 advises review at a convenient time, usually 6 to 12 weeks postpartum and where possible by clinicians with a special interest in OASIS, referral to a specialist gynecologist or colorectal surgeon for incontinence or pain at follow-up, and advice that physiotherapy could be beneficial (good practice points).[20] If facilities and resources allow, it places follow-up in a dedicated perineal clinic with access to EAUS and anal manometry.[20] The IUGA guideline describes an early consultation with a pelvic floor specialist as ideal, noting that wound breakdown after OASI (up to 25% in the literature it cites) often occurs within 2 weeks of birth; in its counseling algorithms, assessment is typically at 6 to 8 weeks, and EAUS and ARM are performed at least 6 weeks postpartum.[16] A 2024 systematic review of nine national guidelines found that postpartum follow-up varied, particularly in physiotherapy and the timing of specialist consultation.[33]

GuidelineFirst review after OASISphincter imaging and manometry
ACOG PB 198 (2018)[2]No interval set; expert opinion recommends early and consistent follow-up because of short-term wound complications (IUGA separately describes assessment within 1–2 weeks as reasonable[16])Routine EAUS immediately postpartum not recommended; no postpartum EAUS or manometry recommendation; ask women with OASIS about anal incontinence and refer if symptomatic
Australian guidelines1–2 weeks after birthEAUS for symptomatic women (Queensland guideline)
RCOG GTG 29 (2015)Usually 6–12 weeks, by a clinician with a special interest in OASISDedicated perineal clinic with EAUS and anal manometry if resources allow
German guideline12 weeksEAUS for symptomatic women
SOGC 465 (2026)[52]No first-review interval specified; refer postpartum women with diagnosed OASI and pregnant women with previous OASI to a dedicated clinic, or arrange review by an experienced provider where no clinic is available (conditional, moderate). Pelvic-health physiotherapy care may begin as early as 2–6 weeks postpartum (strong, high).EAUS for structure and ARM for function (strong, high); where EAUS is unavailable after primary repair, 2D/3D transperineal ultrasound may screen for residual defects, with EAUS confirmation after a positive screen (strong, moderate).
IUGA (2026)Early specialist consultation; algorithm assessment typically 6–8 weeksEAUS and ARM (Grade C), at least 6 weeks postpartum; 2D or 3D transperineal ultrasound as a screen where EAUS is unavailable[16]

Australian and German entries are as summarized in the IUGA guideline.[16][20]

Practice lags behind these positions. In a 2025 UK survey of 126 consultants (estimated response rate about 2.5%), 81.7% routinely examined women at the postpartum visit and 57.6% performed a rectal examination, but only 36.5% used an objective incontinence screening tool; 72.6% referred symptomatic and 34.2% asymptomatic women for anorectal studies, EAUS was the modality of choice (70%) and no respondent chose manometry, and almost 80% discharged asymptomatic women within 3 months.[34] Earlier contact is achievable: in a US quality-improvement project (185 OASI cases), a care bundle of education and standardized electronic orders raised follow-up within 2 weeks from 16.3% to 52.8% and shortened mean time to follow-up from 33 to 18 days.[35] In 81 women scanned with 4D introital ultrasound before discharge and at 3 months, residual EAS defects were seen in 17.3% and 13.6%, respectively; early scans were unassessable in 9.9%, showed an apparent defect absent at 3 months in 9.9%, and missed a defect found at 3 months in 4.9%.[36]

The Clinic Visit​

  • History and symptom scores. Bowel, bladder, pain and sexual symptoms, quantified with a validated score; the St Mark's (Vaizey) Incontinence Score is used by the Croydon, Liverpool and Toronto clinics, and the IUGA algorithms grade it as mild (0–4), moderate (5–8) or severe (9–24).[16] IUGA also recommends assessing sexual function at the perineal clinic (good practice point).[16][28][30][37]
  • Examination. Perineal inspection, wound review and rectal examination. IUGA advises against digital rectal examination alone for assessing sphincter structure (sensitivity 12–82% and specificity 32–55% for EAS defects seen on EAUS); in a Dublin cohort of 437 women seen 4 to 12 months postpartum, EAUS and digital examination were complementary.[16][38]
  • Anorectal investigation. EAUS with or without ARM, or transperineal ultrasound as a screen (below).
  • Mental health. In the Michigan clinic, 15.6% of 294 women screened positive on the Edinburgh Postnatal Depression Scale; urinary incontinence during and after pregnancy (adjusted OR 3.81) and referral for pain (adjusted OR 2.61) were independently associated with a positive screen.[39]
  • Wound complications, physiotherapy and counseling. In the Croydon series, more than 42% of women referred with perineal wound complications needed further intervention, including secondary re-suturing (8.4%) and scar refashioning (5.4%).[28] Dehiscence management is covered under Perineal wound dehiscence; counseling under Mode of Delivery After OASI.

Endoanal Ultrasound, Manometry and Transperineal Ultrasound​

Three-dimensional EAUS is the reference standard for sphincter integrity.[16][40] IUGA defines a residual defect on EAUS as EAS discontinuity of at least 30° (more than 1 hour on the clock face) over at least two-thirds of the sphincter length, and on four-dimensional transperineal ultrasound as a defect of at least 30° on at least 4 of 6 tomographic slices.[16] Residual defects after primary repair are common. In a Toronto clinic cohort of 247 women, a residual defect wider than 30° was present in 64.3% after third-degree and 86.7% after fourth-degree tears, the clinical diagnosis of OASIS was not confirmed in 36.8%, and defect size correlated only weakly with the St Mark's score (EAS r = 0.37; IAS r = 0.31).[37] Among 74 women after fourth-degree tears at Croydon, EAUS showed an IAS defect in 77% and an EAS defect in 49%, and only 18% had no defect; 61% were asymptomatic, and symptoms alone predicted abnormal investigations poorly.[41] EAUS also corrects overdiagnosis: 1,135 women attended the London clinic 12 weeks after a clinically diagnosed OASIS; among the 1,112 who underwent EAUS, sphincter injury was confirmed in 876 (78.8%), while 236 (21.2%) had no sonographic sphincter injury.[42]

ARM measures maximum resting and squeeze pressures; the incremental maximum squeeze pressure (iMSP) reflects EAS function, and the IUGA algorithms treat an iMSP below 20 mmHg as abnormal. In the IUGA expert-consensus algorithm, repeat abnormal postpartum ARM during a subsequent pregnancy; EAUS need not be repeated unless its original findings are uncertain. Where ARM is unavailable postpartum, it may be deferred to a subsequent pregnancy or the work-up before surgery for anorectal symptoms.[16] In the London cohort, 45.6% of women who had anorectal physiology had a resting pressure below the normal range and 68.8% a subnormal incremental squeeze pressure.[42] In the Liverpool cohort, manometry identified more women with impaired sphincter function than EAUS alone; without it, almost a third of asymptomatic women would not have been identified, and the authors recommend manometry alongside EAUS for all women with OASI.[30] In a Norwich series of 233 women, by contrast, internal sphincter defects and low resting pressures added little to counseling.[43]

Transperineal and introital ultrasound use the probe already present in obstetric units and cause less discomfort than EAUS. In a cross-sectional study of 250 women who had all three modalities, transperineal imaging detected EAS defects with a sensitivity of 0.70 and specificity of 0.69 against EAUS; across introital and transperineal imaging, positive predictive values were 0.37 to 0.63 and negative predictive values 0.85 to 0.93, and only EAUS defects correlated with symptoms.[40] The authors and IUGA recommend exoanal ultrasound as a screen for an intact sphincter, with referral for EAUS when a defect is detected.[16][40] Agreement on the presence of a defect is high (κ = 0.87 for EAS and 1.00 for IAS in 250 paired scans), but agreement on EAS defect angle is poor, and the authors advise that the 30° EAUS cut-off should not be transferred to transperineal imaging.[44]

Published Clinic Models​

The longest-running published services are the Croydon perineal clinic of Abdul Sultan and Ranee Thakar, a weekly one-stop clinic run by a consultant urogynecologist with a perineal wound clinic staffed by a specialist perineal midwife, and the Michigan Healthy Healing After Delivery (MHHAD) clinic at the University of Michigan, reported by Dee Fenner and colleagues, which identified nurse-led triage, patient education and follow-up as the factors behind its sustainability.[28][45][46] IUGA describes the models in use as differing in provider specialty, consolidated versus staged assessment, telehealth versus in-person review, patient population and management protocol.[16] All series below are single-center and observational.

ClinicCohortAssessmentReported outcomes
Croydon University Hospital, UK[28]3,254 first attendances, 2006–2016; 58.1% for OASIOne-stop visit: questionnaires, examination, AM and EAUS for all OASI regardless of symptoms; median follow-up 10 weeks after deliverySecondary sphincter repair in 11/1,147 (1.0%) and wound re-suturing in 10/1,147 (0.9%) postnatal OASI patients; of 742 seen in a later pregnancy, 11.3% advised cesarean
Croydon, 3-year follow-up[47]344 three-year questionnaire respondents initially seen 9 weeks after primary repairSt Mark's score, Manchester Health Questionnaire, EAUSOf 31 with FI at 9 weeks, 28 asymptomatic at 3 years; 33 de novo cases; fecal urgency at 9 weeks predicted FI at 3 years (OR 4.65)
Liverpool Women's Hospital, UK[29]1,348 women, 2007–2020Symptoms, EAUS and AM at 6 weeks and 6 months66.3% asymptomatic; 24.7% of asymptomatic women had normal studies
Guy's and St Thomas', London[42]1,135 clinic attendees, 2008–2019; 1,112 underwent EAUSEAUS at 12 weeks; anorectal physiology in a subsetSphincter injury confirmed in 876/1,112 imaged (78.8%); bowel symptoms in 34.8%
University of Michigan MHHAD, USA[45][46]247 in the first 4 years (2007–2011); 1,138 over 11 yearsNurse-led triage, education and follow-up; 62.3% referred for third- or fourth-degree laceration21.5% needed a procedure and 8.1% surgery (first 4 years); 9.1% had surgery within 1 year (11 years); 15.8% referred for physical therapy
Cleveland Clinic, USA[48]483 women in the first 36 months (2018–2020); 318 with OASIPeripartum pelvic floor disorder clinicMedian 17 days (IQR 11–34) from delivery to evaluation; minor office procedures in 141, surgery in 26 (5.4%)
National Maternity Hospital, Dublin[38][49]437 seen 4–12 months postpartum; 557 assessed in a later pregnancyEAUS, digital examination and symptom score; antenatal EAUS and manometry70% delivered vaginally, recurrent OASI in 20/393 vaginal births (5.1%), no significant change in continence (35% returned for follow-up)
Albert Schweitzer Hospital, Dordrecht[50]265 women, 2010–20163D transperineal ultrasound-based recommendation for mode of birth5.6% did not follow the recommendation; recurrent OASI 4.3% after vaginal birth; anal incontinence 48% at 2–5 years
Kaplan Medical Center, Israel[51]55 clinic patients versus 68 historical controls4D transperineal ultrasound-based algorithmSubsequent vaginal birth 53.3% vs 19.6%; recurrent OASI among subsequent vaginal births 0% vs 10% (p = 0.22)

Reoperation in Clinic Cohorts​

Clinic cohorts also report how often early secondary surgery follows birth injury. In the Michigan cohort of 1,138 new patients (2007–2019), 103 (9.1%) had surgery within 1 year of the first visit; among these 103 surgical patients, anal sphincter defect and/or anal incontinence was a primary or secondary indication in 53 (51.5%).[46] The commonest operations were anal sphincteroplasty (37.9%, n = 39), perineal laceration revision (33.0%, n = 34) and rectovaginal fistula repair or fistulotomy (19.4%, n = 20); 61.5% of the women who had sphincteroplasty had sustained a fourth-degree laceration.[46] Other clinics, with different case mix and follow-up windows, report surgery in 5.4% at the Cleveland Clinic over 36 months; among 1,147 postnatal OASI patients at Croydon, 11 (1.0%) underwent secondary sphincter repair and 10 (0.9%) wound re-suturing. Compared with 3a/3b tears, 3c tears were associated with secondary sphincter repair (OR 9.0, 95% CI 2.1–38.2); fourth-degree tears were associated with fistula compared with third-degree tears (OR 6.0, 95% CI 1.2–30.3).[48][28] IUGA cites a 9% surgical intervention rate from a mixed postpartum pelvic floor clinic cohort (103/1,138 within one year of first visit) and notes that dedicated follow-up can identify candidates for surgery within 2 to 3 weeks of birth; for persistent anorectal symptoms it lists secondary anal sphincter repair, sacral neuromodulation, an artificial anal sphincter or gracilis neosphincter reconstruction after postpartum recovery or completion of childbearing.[16] The operations are covered on the Anal Sphincteroplasty, Perineorrhaphy and Rectovaginal Fistula pages.

Mode of Delivery After OASI​

RCOG advises that every woman with a previous OASIS is counseled about mode of delivery, with the discussion documented, and that women who are symptomatic or have abnormal EAUS or manometry are counseled about the option of elective cesarean (good practice points). It reports a 5% to 7% risk of a further third- or fourth-degree tear, notes that 17% of women with a prior third-degree tear had worsening fecal symptoms after a second vaginal delivery in the studies it reviewed, and finds no evidence that prophylactic episiotomy at the next delivery prevents OASIS.[20] IUGA recommends individualized, documented counseling (Grade B), advises quoting an overall recurrent OASI risk of 6.1% for a subsequent vaginal birth (Grade B), and notes that elective cesarean may not completely protect against de novo or worsening anorectal symptoms (Grade C).[16] It does not endorse routine elective cesarean after OASI, but its expert-consensus algorithm recommends cesarean for a subsequent birth after secondary anal sphincter repair of a clinically diagnosed OASI.[16] Published protocols combining symptoms, EAUS and ARM can guide counseling (Grade B); where EAUS and ARM are unavailable, symptoms, rectal examination findings and a history of fourth-degree tear can be used (Grade C).[16] ACOG advises counseling that the absolute risk of recurrent OASIS with a subsequent vaginal delivery is low (it cites about 3%, OR 4.2) and that cesarean on request is reasonable after advising of its risks (Level C).[2] By expert opinion, it lists anal incontinence after the delivery, wound infection or repeat repair, and psychological trauma with a request for cesarean as grounds to offer cesarean, and it notes that EAUS and anal manometry have been used to guide the decision; in the study it cites, fecal urgency, anal incontinence and bowel-related quality of life did not change after either vaginal or cesarean delivery compared with before the birth.[2] SOGC Guideline No. 465 (Part II) adds algorithms for shared decision-making about the subsequent mode of delivery and describes the role of dedicated clinics and access to pelvic health physiotherapy; IUGA adapts these algorithms for centers with and without access to EAUS, transperineal ultrasound and ARM.[52][16]

The Croydon protocol recommends elective cesarean when an EAS defect is combined with an iMSP below 20 mmHg. RCOG cites a prospective cohort of 73 women in which an EAS defect greater than 30 degrees with an incremental squeeze pressure below 20 mmHg prompted an offer of cesarean; the women who delivered vaginally had no significant deterioration in anal sphincter function or quality of life at short-term follow-up.[20][53] In Jordan's prospective cohort of 122 women, vaginal birth was recommended for absent or minor symptoms, an EAS scar <30°, and iMSP >20 mmHg; 99 delivered vaginally and 10/99 (10%) sustained recurrent OASI.[54] At 8–12 weeks postpartum, bowel symptom scores did not worsen significantly and no new EAUS defects appeared, although squeeze pressure fell.[54] In a 20-year review of 607 women assessed in a later pregnancy, symptoms and clinical tear grade identified that clinic's combined cesarean trigger (EAS defect plus iMSP <20 mmHg) with accuracy ranging from 75.4% after 3a to 43.6% after fourth-degree tears.[53] Among asymptomatic women with prior 3a tears, negative predictive value was 100% for that combined trigger, but 97.1% for EAS defect alone and 93.5% for iMSP <20 mmHg alone; the authors cautioned that symptoms and grade alone should not generally guide delivery recommendations, while suggesting vaginal birth may be recommended for asymptomatic 3a tears.[53] After fourth-degree tears, only 7% of 74 women were asymptomatic with normal EAUS and manometry and so would not have been offered cesarean under RCOG guidance, and the Croydon authors suggest offering cesarean to all such women where EAUS and manometry are unavailable.[41] Algorithms diverge widely: applied to the same 233 women in Norwich who underwent EAUS and manometry (excluding asymptomatic 3a tears), they would have advised cesarean for 40.3% (local protocol), 81.5% (any one abnormal investigation) or 85.0% (symptoms or any abnormal investigation).[43]

A 2025 meta-analysis (13 studies, 3,020,897 women) found that, among subsequent vaginal births, women with prior OASI had higher odds of OASI at the second delivery than women without prior OASI (OR 4.9, 95% CI 4.0–5.9; absolute recurrence risk 6.1%); among women with prior OASI, anal incontinence after a second vaginal delivery did not differ significantly from cesarean delivery (OR 1.1, 0.9–1.4; 5 studies, 2,330 women), while recurrent OASI was associated with higher odds of anal incontinence than a subsequent delivery without recurrent OASI (OR 1.6, 1.3–2.0).[19] A second meta-analysis (9 studies, 2,104 participants) found no difference in adjusted anal incontinence between subsequent vaginal birth and cesarean (OR 0.92, 95% CI 0.72–1.20) and rated the evidence too low in quality to determine whether planned cesarean is protective.[55] The only randomized trial cited by IUGA, EPIC, enrolled 434 women at high risk of sphincter injury but without anal incontinence in six Paris maternity units; 264 had a sonographic sphincter lesion, of whom 222 were randomized to planned cesarean or vaginal delivery, and anal continence did not differ at 6 to 8 weeks or 6 months (median Vaizey score 1 in both arms at 6 months).[56] IUGA questions its relevance to clinically diagnosed OASI: 91.0% of index births were forceps deliveries, 71.1% of randomized women had no perineal laceration, 14.7% had a third-degree and none a fourth-degree tear, and ARM was not performed.[16]

Most women choose a further vaginal birth. In a Michigan survey (50 of 115 eligible women responded), 82% had a subsequent vaginal delivery; 54% reported no regret about their choice, 36% mild and 10% moderate or severe regret, and regret was associated with older age and with fecal incontinence after the index delivery. Among respondents to the counseling question, 15 (34.9%) said the counseling they received had influenced their decision.[57]

Evidence Gaps​

  • No study has compared outcomes between units with and without a standardized post-OASI pathway; the authors of the UK survey propose a prospective multicenter audit to do so.[34] The clinic cohorts above are single-center, mostly retrospective and incompletely followed.
  • The single randomized trial of planned cesarean enrolled mainly women with sonographic lesions after forceps delivery rather than clinically diagnosed OASI, and followed them for 6 months.[56][16]
  • Long-term outcome data are sparse. At a mean of 6.6 years after OASI, 51% of 146 women (of 372 contactable) reported anal incontinence in a Sydney cohort, with residual IAS defects and levator avulsion as independent risk factors; IUGA cites a 25-year cohort of 171 women in which symptom prevalence rose from 38% to 61%.[58][16]
  • Defect thresholds for transperineal ultrasound, the timing of investigations and the counseling algorithm itself are not standardized, and national guidelines disagree on follow-up.[44][43][33]

See Also​

Podcasts​

Season 1, Episode 3: The OASIS podcast
IUGA Podcast, Season 1 Episode 3 (2023)
open.spotify.com

References​

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