Perineal tears
These are classified by the degree of damage caused. Tears are most likely to occur with big babies, precipitant labours, babies with poorly flexed heads, shoulder dystocia, when forceps are used, or if there is a narrow suprapubic arch. Perineal massage in pregnancy helps prevent perineal trauma but may be uncomfortable at first.
Labial tears
Common, these heal quickly and suturing is rarely helpful.
First degree tears
These tears are superficial and do not damage muscle. They may not need suturing unless blood loss is marked.
Second degree tears
These lacerations involve perineal muscle. They are repaired in a similar fashion to repair of episiotomy (see below).
Third degree tears
Damage involves the anal sphincter. If rectal mucosa is involved it is a fourth degree tear. See p 91. Repair by an experienced surgeon, under epidural or GA in theatre with intra-operative antibiotic cover. Rectal mucosa is repaired first using absorbable suture from above the tear's apex to the mucocutaneous junction. Muscle is interposed. Vaginal mucosa is then sutured. Severed ends of the anal sphincter are apposed using figure-of-eight stitches. Finally skin is repaired. Avoid constipation postoperatively by using a high-fibre diet and faecal softeners for 10 days.
Episiotomy
This is performed to enlarge the outlet, eg to hasten birth of a distressed baby, for instrumental or breech delivery, to protect a premature head, and to try to prevent tears (but anal tears are not reduced by more episiotomies in normal deliveries). Rates: 8% Holland, 12% England, 50% USA.
The tissues which are incised are vaginal epithelium, perineal skin, bulbo-cavernous muscle, superficial, and deep transverse perineal muscles. With large episiotomies, the external anal sphincter or levator ani may be partially cut, and ischiorectal fat exposed.1
Technique
Hold the perineal skin away from the presenting part of the fetus (2 fingers in vagina). Infiltrate area to be cut with local anaesthetic, eg 1% lidocaine (=lignocaine). Still keeping the fingers in the introitus, cut mediolaterally towards the ischial tuberosity, starting medially (6 o'clock), so avoiding the Bartholin's glands. (Midline episiotomy is ineffective at protecting perineum and sphincters and may impair anal continence).2
Repair
(See diagrams.) NB: use resorbable suture polyglactin 910 recommended.3 In lithotomy, and using good illumination, repair the vaginal mucosa first. Traditional method: start above the apex using interlocking stitches 1cm apart, 1cm from wound edges. Tie off at mucocutaneous junction of fourchette. Then repair muscles with interrupted stitches to obliterate any dead spaces. Finally close the skin (subcutaneous stitch is more comfortable than interrupted stitches). A loose continuous non-locking suturing technique to appose each layer is associated with less short-term pain compared with traditional interrupted method.
Advertisements
