OASIS Flashcards
Classify 1st degree tear
laceration of vaginal skin or epithelium only
Classify 2nd degree tear
more than 50% involvement of vaginal perineum, epithelium, muscle and fascia but NO involvement of anal sphincter
Classify a 3rd degree tear, then further into a,b,c
involvement of perineal skin, muscle, fascia + anal sphincter
3a - partial tear of EAS involving <50% thickness
3b - more than 50% of EAS or complete EAS
3c - IAS also torn
Define a 4th degree tear
3rd degree tear + disruption of the anal +/- rectal epithelium
What are 3 conditions that are required to repair an OASIS injury?
- performed or supervised by an SMO or senior registrar
- in operating room with good lighting and equipment + aseptic technique
- performed under GA or regional (muscle relaxation required as the torn muscle ends can retract otherwise)
what material should be used for anal skin tear?
3-0 vicryl
What is the suture material used for IAS and what is the rationale?
3-0 PDS
Monofilamentous therefore less likely to precipitate infection cf braided
Why is Nylon Prolene not as good as 3-0 PDS for IAS repair?
It is effective however it is non absorbable so has higher risk of abscess/pain
Why is Nylon Prolene not as good as 3-0 PDS for IAS repair?
It is effective however it is non absorbable so has higher risk of abscess/pain
How is the EAS repaired?
The torn ends of the EAS must be identified and gasped with Allis forceps
The muscle is then mobilised and pulled to overlap in ‘double breast’ fashion
3-0 PDS is used to suture in end to end approximation
Why is important to carefully suture together the perineal body after OASIS tear
This will create the support in a future pregnancy
List 5 post operative management options following OASIS
- 12 hours IDC
- Antibiotics - IV Cef and Met initially, then oral fo 5/7
- stool softeners (lactulose) and a bulking agent (konsyl D) for 2/52
- detailed debrief
- f/u in 6/52
Which perineal muscles are cut during an episiotomy?
transverse perineal
bulbocavernosus
What are the steps of performing an episiotomy
3-5cm incision from the fourchette at a 60-80 deg angle to the midline
perform at the time of distension of the perineum by the presenting part
What are 3 methods of preventing OASIS and their level of evidence
- Mediolateral episiotomy (grade C/D or Level 2- or 3)
- Perineal protection (grade C or Level 1+ and 2+)
- warm compresses (grade A or Level 1+++)
