Midline<unk>  - easier to heal, less painful, but can extend to anus
Mediolateral - unlikely to extend to anus
Anatomic structures - vaginal epithelium, transverse perineal muscle, bulbocavernosus muscle, perineal skin
ACOG recommends restricting<unk> es, and prefers mediolateral to median (Level A, 2006)
Current data is of poor quality in regards to benefits to mother or baby
Procedure avoids spontaneous tearing and/or aids in difficult delivery:
Shoulder dystocia (contentiously the only indication)
If possible, avoid even in these situations:
Baby is large or in breech
Labor is going too quickly
Extraction instruments needed (forceps, vacuum assisted)
Contraindications:
IBD
Perineal malformations
Shoulder dystocia (contentiously the only indication)
If possible, avoid even in these situations:
Baby is large or in breech
Labor is going too quickly
Extraction instruments needed (forceps, vacuum assisted)
Baby is large or in breech
Labor is going too quickly
Extraction instruments needed (forceps, vacuum assisted)
IBD
Perineal malformations
Episiotomy
IVF maintenance
Resuscitative hysterotomy
Massive transfusion
Massive transfusion 
Coude catheter
Emergent delivery
Betamethasone