Episiotomy and Perineal Tears
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Direct answer
Episiotomy is a surgical perineal incision made to enlarge the vulval outlet during delivery, and perineal tears are the lacerations that may follow. When an incision is needed, the mediolateral cut is preferred because it carries a lower risk of anal sphincter extension than the midline cut, though it bleeds more. Tears are graded from first to fourth degree, and third and fourth degree injuries involve the anal sphincter.
What you must remember
- Indications: operative vaginal delivery, shoulder dystocia, breech delivery, fetal distress needing rapid delivery and a rigid perineum that threatens a severe tear.
- Midline episiotomy: a cut in the midline that bleeds less and repairs easily, but carries a higher risk of extension into the anal sphincter.
- Mediolateral episiotomy: angled away from the midline, which lowers the risk of sphincter injury but increases blood loss.
- First degree: a tear of the vaginal mucosa or perineal skin without muscle involvement, often needing no repair if superficial.
- Second degree: involves the perineal muscles and perineal body but not the anal sphincter, and is the commonest grade needing sutures.
- Third degree: involves the anal sphincter complex, subdivided into 3a (under 50 per cent of the external sphincter), 3b (over 50 per cent) and 3c (internal sphincter also torn).
- Fourth degree: extends through the anal sphincter into the rectal mucosa.
Repair layers and the sphincter rule
Good repair restores the layers in order, and the anal sphincter is checked first whenever a tear extends beyond the vagina. The steps below set out a standard repair sequence.
- Confirm the extent. Inspect the perineum under good light and examine the rectum digitally to confirm sphincter integrity when a tear may be third degree.
- Give analgesia and antibiotics. Adequate anaesthesia is given, and prophylactic antibiotics are commonly used for third and fourth degree tears and operative vaginal delivery.
- Repair the sphincter. Torn ends of the anal sphincter are approximated with delayed absorbable sutures, using an overlapping technique by an experienced clinician.
- Repair the rectal mucosa. In a fourth degree tear, the anal mucosa is closed with fine absorbable sutures before the sphincter layers are covered.
- Close the vaginal mucosa. The vaginal mucosa is closed with continuous or interrupted absorbable sutures, starting at the apex of the tear.
- Repair the perineal body and skin. The perineal muscles are approximated to restore the perineal body, and the skin is closed with a subcuticular suture.
Where the exam tries to catch you
The questions usually test which episiotomy is chosen, how a tear is graded and what is missed when a sphincter injury is not recognised.
- Trap: choosing a midline episiotomy because it heals well Correct: midline heals well but raises the risk of anal sphincter extension, so mediolateral is the textbook choice when an episiotomy is needed.
- Trap: repairing a third degree tear as a second degree tear Correct: any sphincter involvement makes it third degree or more, and missing it leads to faecal incontinence later.
- Trap: performing routine episiotomy in every primigravida Correct: routine episiotomy is no longer recommended, and it is reserved for specific indications.
Frequently asked questions
What is the difference between midline and mediolateral episiotomy?
A midline episiotomy is a cut in the midline, which heals well and bleeds less, but it carries a higher risk of anal sphincter extension. A mediolateral episiotomy is angled away from the midline, which lowers the risk of sphincter injury but increases blood loss. Mediolateral is the usual choice when episiotomy is needed.
What defines a third degree perineal tear?
A third degree perineal tear involves the anal sphincter complex, meaning the external anal sphincter is torn, with or without the internal sphincter. It is subdivided into 3a, 3b and 3c according to the extent of the sphincter injury. A rectal examination helps confirm the diagnosis before repair.
How is a second degree perineal tear repaired?
A second degree perineal tear is repaired by closing the vaginal mucosa first, then the perineal muscles and perineal body, and finally the skin. Absorbable sutures are used for each layer. The anal sphincter is checked to confirm it is intact before the repair is completed.
What are the indications for episiotomy in current practice?
Episiotomy is indicated for operative vaginal delivery, shoulder dystocia, breech delivery and fetal distress needing rapid delivery. It is also used when the perineum is rigid and threatens a severe tear. Routine episiotomy is not recommended in current practice.
Why are antibiotics given after third degree perineal tears?
Antibiotics are given after third degree perineal tears to reduce the risk of wound infection and sepsis. The anal sphincter lies close to the rectum, so contamination is a real risk. Prophylaxis is usually given at the time of repair.