Episiotomy: Types and Suture Repair

What is an Episiotomy?

• Fetal distress requiring expedited delivery
• Breech delivery
• Shoulder dystocia
• Occiput-posterior presentation
• Imminent severe perineal tear

Timing

• Early episiotomy: Made before the head crowns (head is visible with contractions but recedes between them)
• Timely episiotomy: Made after crowning, when there is maximum tension on the perineal skin - performed at the height of a contraction when the fetal head distends the perineum to 3-4 cm visible diameter

Types of Episiotomy

Broken lines depict incision sites - midline (straight down) and mediolateral (diagonal)

1. Midline (Median) Episiotomy

• Direction: Straight downward from the posterior vaginal fourchette directly toward the anus, along the median raphe
• Length: Approximately half the length of the perineum; extends 2-3 cm upward into the vaginal mucosa
• Structures divided: None of the major muscles (cuts only the median raphe)
• Common in: United States

• Easiest to perform and repair
• Least blood loss
• Heals more rapidly
• Minimal postoperative discomfort

• High risk of extension into the anal sphincter (3rd degree) or rectal mucosa (4th degree laceration) - it is paradoxically an independent risk factor for these severe tears

2. Mediolateral Episiotomy

• Direction: Oblique incision from the posterior fourchette downward and outward, directed toward the lateral margin of the anal sphincter - either right or left
• Structures divided: Bulbospongiosus muscle + superficial transverse perineal muscle
• Common in: Europe and many other countries

• Seldom extends into the anal sphincter
• Gains more room than midline
• Lower risk of 3rd/4th degree laceration

• Greater blood loss
• More difficult to repair
• More painful healing
• May cause dyspareunia

3. Lateral Episiotomy

• Direction: Lateral incision from the lower third of the vulva
• Structures divided: Bulbospongiosus + superficial transverse perineal + levator ani (puborectalis)
• Very rarely used in modern obstetrics

• Heaviest bleeding
• Greatest potential complications including anal incontinence
• Most postpartum complaints
• Most difficult healing

Summary Comparison Table

Episiotomy Suture Repair

Suture Material

• 2-0 or 3-0 absorbable suture (chromic catgut or polyglycolic acid) on a large atraumatic needle
• Minimal tension on the wound allows use of finer suture
• Bleeding vessels are ligated separately with absorbable sutures

Repair Steps (3-Layer Closure)

Closure of the vaginal mucosa - first stitch placed above apex, then run down to the introitus

Layer 1 - Vaginal Mucosa

• Place the first stitch 1 cm cephalad to the apex of the episiotomy/laceration to ensure hemostasis
• Use a continuous locked absorbable suture running down from the apex to the hymenal ring
• Reapproximate the margins of the hymenal ring

Layer 2 - Deep Perineal Tissue (Muscle and Fascia)

• Use 3-4 simple interrupted absorbable sutures to close the deep perineal fascia and underlying levator ani muscles
• This takes the tension off the skin closure and obliterates dead space
• Bring the vaginal epithelial suture below the skin into subcutaneous tissue

Layer 3 - Skin / Superficial Layer

• Continue the existing suture as a running subcuticular stitch along the perineal skin
• Run it back up to the hymenal ring and tie off - this is associated with less pain than interrupted transcutaneous sutures

• Place several interrupted sutures through the skin and subcutaneous fascia, tied loosely
• Avoids burying two full layers of suture in a single closure

Key point: Continuous subcuticular sutures (unlocked) are associated with less pain than locked or interrupted transcutaneous sutures. Deep placement leaving the wound slightly gaping (2-3 mm) significantly decreases itching during healing.

Final Step - Rectovaginal Examination

• Confirm rectal mucosa is intact
• Confirm no suture has entered or obstructed the rectum
• Confirm no sponges or instruments remain

Repair of Extensions

Complications

• Blood loss ~300 mL from an uncomplicated midline episiotomy (can be more with delays)
• Wound infection
• Hematoma
• Dehiscence
• Dyspareunia (more common with mediolateral)
• Rectovaginal fistula (if suture pierces rectal mucosa during repair)
• Extension to 3rd/4th degree tear

Mechanism of Labour - LOA (Left Occiput Anterior)

Background - What is LOA?

• The occiput (back of the fetal head) points toward the left anterior quadrant of the maternal pelvis
• This is the most common fetal position (along with OA/direct occiput anterior)
• LOA is the most favourable starting position - it leads to a straightforward normal delivery

LOA is the most common intrauterine position. It places the left hip of the fetus against the maternal lumbosacral spine. (Campbell's Operative Orthopaedics, 15th Ed.)

The Denominator & Presenting Diameter

Cardinal Movements of Labour

1. ENGAGEMENT

• Fetus is engaged when the presenting part is at 0 station (ischial spine level)
• In LOA, the head enters the pelvic inlet with the sagittal suture in the left oblique diameter of the pelvis (the widest available diameter)
• The occiput points toward the left iliopectineal eminence, the sinciput toward the right sacroiliac joint
• Primigravida: engagement usually occurs in the last 2 weeks of pregnancy
• Multigravida: may only occur at onset of labour

The mechanism is determined by the pelvic dimensions and configuration, the size of the fetus, and the strength of uterine contractions. The fetus follows the path of least resistance by adapting the smallest achievable diameter to the most favourable dimensions of the birth canal. (Roberts and Hedges, p. 1351)

2. FLEXION

• Converts the presenting diameter from occipitofrontal (11.5 cm) to suboccipitobregmatic (9.5 cm)
• This smaller diameter allows easier passage through the pelvic brim and midcavity
• Occurs passively - no muscle action required
• Necessary for both engagement and descent

Flexion of the fetal head is necessary to minimize the presenting cross-sectional diameter of the head during passage through the smallest diameter of the bony pelvis. (Roberts and Hedges, p. 1351)

3. DESCENT

• Occurs throughout labour but most rapid in the second stage
• Forces producing descent:
  1. Uterine contractions
  2. Abdominal muscle contractions (bearing down / pushing)
  3. Straightening and extension of the fetal body
  4. Amniotic fluid pressure
• Descent is gradual and progressive but not necessarily continuous
• In LOA, the head descends with the occiput leading in the left oblique diameter

4. INTERNAL ROTATION

• In LOA, the occiput rotates 45° to the right (anteriorly) to reach the direct occiput anterior (OA) position
• Now the sagittal suture lies in the anteroposterior diameter of the pelvic outlet
• The occiput slides under the pubic arch
• This movement is necessary for the head to traverse the ischial spines (the narrowest part of the pelvis at the midcavity)
• Caused by the gutter-shaped levator ani muscle guiding the head anteriorly
• The smallest presenting diameter (suboccipitobregmatic) now aligns with the largest pelvic outlet diameter (AP diameter = 13.5 cm in gynaecoid pelvis)

Internal rotation occurs with descent and is necessary for the head or presenting part to traverse the ischial spines. The occiput gradually moves from its original, more transverse position anteriorly toward the symphysis pubis. (Roberts and Hedges, p. 1351)

5. EXTENSION (Delivery of the Head)

• The suboccipital region (nape of neck) becomes the pivot point under the symphysis pubis
• The following parts are delivered in sequence over the perineum:
  1. Occiput (already under symphysis)
  2. Bregma (anterior fontanelle)
  3. Forehead
  4. Nose
  5. Mouth
  6. Chin - last to pass over the perineum
• Immediately after delivery, the head drops downward so the chin lies over the maternal anal region

Extension occurs as the flexed head reaches the anteriorly directed vaginal introitus. The head is born by further extension as it rotates around the pubic symphysis and the occiput, bregma, forehead, nose, mouth, and finally, the chin pass successively over the anterior margin of the perineum. (Roberts and Hedges, p. 1351)

6. RESTITUTION (External Rotation - Part 1)

• The head had been twisted on the neck during internal rotation
• Restitution "undoes" this twist - a passive, elastic recoil movement
• In LOA: the occiput rotates back 45° to the left (to the original LOA position)
• The sagittal suture returns to the left oblique diameter

7. EXTERNAL ROTATION (Restitution continued)

• The shoulders, which entered the pelvis in the oblique diameter, now rotate to the AP diameter of the pelvic outlet
• In LOA: the occiput rotates a total of 90° to the left (ending up pointing toward the left maternal thigh)
• The head is now in the transverse position that it occupied at engagement
• The face turns to look at the mother's right inner thigh

External rotation or restitution is the return of the head to the correct anatomic position with respect to the fetal torso. It follows delivery of the head as it rotates to the transverse position that it occupied at engagement. This is also a passive movement. (Roberts and Hedges, p. 1351)

8. EXPULSION (Delivery of Shoulders and Body)

• Anterior shoulder is delivered first - beneath the symphysis pubis (with gentle downward traction)
• Posterior shoulder - delivered across the perineum (with gentle upward traction)
• Remainder of the body follows easily
• In LOA: anterior shoulder (fetal right) delivers from under the symphysis; posterior shoulder (fetal left) over the perineum

The shoulders descend in a path similar to that traced by the head - rotating anteroposteriorly for delivery. First, the anterior shoulder is delivered beneath the symphysis pubis followed by the posterior shoulder across the perineum. (Roberts and Hedges, p. 1351)

OSCE Summary Table - All 7 Movements in LOA

Key OSCE Points to Remember

• LOA is the most common fetal position - most favourable for normal vaginal delivery
• The fetus follows the path of least resistance, adapting its smallest diameter to the widest pelvic dimension at each level
• Flexion is the most important movement - without it, a larger diameter is presented and descent is impeded
• Internal rotation is the critical movement at the midcavity - failure leads to deep transverse arrest
• The total internal rotation in LOA = 45° (from left oblique → direct anterior)
• The total external rotation in LOA = 90° (45° restitution + 45° further rotation)
• Movements are not strictly sequential - descent occurs throughout; flexion and engagement often occur together
• Internal rotation is caused by the gutter shape of the levator ani directing the head anteriorly