Obstetric Third/Fourth-Degree Perineal Tear (OASIS) · Graded Repair

Step-by-step decision

Choose step by step as prompted; reaching an endpoint gives the management recommendation. You can go back a step or restart anytime.

🎓 Want to practice? Do a case challenge with this pathway → (get a case, choose management step by step, scored).

Full pathway

1. [Decision] Systematic exam (including rectal exam) and grading
   Sultan/RCOG grade? (Grades: 3a EAS tear <50% thickness; 3b ≥50% thickness (full-thickness); 3c both EAS and IAS torn; 4th degree involving the anal epithelium. There is also a rectal buttonhole tear (isolated rectal mucosa tear, sphincter intact). Repair must be in theatre, good lighting, regional/general anesthesia, by a trained operator. Postoperative routine: broad-spectrum antibiotics, laxative (lactulose; avoid constipating regimens), adequate analgesia, pelvic floor physiotherapy, perineal clinic follow-up, and counselling on mode of next delivery.)
   • 3a (EAS <50% thickness, partial) → 3a → end-to-end repair
   • 3b (EAS ≥50% thickness, full-thickness) → 3b → end-to-end or overlap (equivalent)
   • 3c (involving IAS) → 3c → repair IAS first, then EAS
   • 4th degree (involving anal epithelium/rectal mucosa) → 4th degree → inside-out layered repair
   • Rectal buttonhole tear (sphincter intact) → Buttonhole tear → repair the mucosa separately
2. [End] 3a → end-to-end repair
   3a (partial-thickness EAS) → end-to-end (approximation) repair of the EAS (all 3a and some 3b use end-to-end); suture PDS 3-0 or polyglactin (Vicryl) 2-0; close the perineal body and vaginal mucosa in layers.
3. [End] 3b → end-to-end or overlap (equivalent)
   3b (full-thickness EAS) → end-to-end or overlap, equivalent long-term (overlap only for full-thickness tears, needs 1–1.5 cm of free muscle ends); PDS 3-0; layered closure.
4. [End] 3c → repair IAS first, then EAS
   3c (involving IAS) → repair the IAS separately first: end-to-end interrupted/mattress sutures, no overlap; then repair the EAS (end-to-end or overlap). IAS reconstruction is critical for postoperative continence.
5. [End] 4th degree → inside-out layered repair
   4th degree (involving anal epithelium/rectal mucosa) → inside-out layered repair: first the rectal/anal mucosa (3-0 absorbable, avoid penetrating the lumen; sutures mis-placed through the anorectum should be removed), then IAS (end-to-end no overlap), then EAS (end-to-end/overlap), finally the perineal body and vagina; check for no retained sutures afterward.
6. [End] Buttonhole tear → repair the mucosa separately
   Rectal buttonhole tear (sphincter intact, isolated rectal mucosa tear communicating with the vagina) → repair the mucosal defect separately, avoid missing it and causing a rectovaginal fistula; remove any suture mistakenly placed through the anorectum.

Source guidelines & references

• Repair of third/fourth-degree perineal tears (RCOG Green-top 29; SOGC No.457 2024; Sultan classification)

This pathway is our own synthesis of the decision logic in the guidelines above (not the guideline verbatim); thresholds and workflows change as guidelines update — in practice follow the latest guideline, your institution's protocol and the individual patient.

Other pathways