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Normal Spontaneous Delivery (NSD) - Based on Williams Obstetrics

Note: Williams Obstetrics is the canonical reference for NSD. The content below is drawn from Williams Obstetrics principles as reflected in Rosen's Emergency Medicine and Creasy & Resnik's Maternal-Fetal Medicine (both authoritative obstetric texts in the library), which extensively cite Williams.

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Definition

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True Labor vs. False Labor

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The Stages of Labor

Stage 1 - Cervical Dilation

• From onset of regular contractions to onset of active labor (approximately 6 cm dilation)
• Average duration: ~8 hours in nulliparous women, ~5 hours in multiparous women
• May be prolonged (>20 hours in nulliparas, >14 hours in multiparas)

• From ~6 cm to full cervical dilation (10 cm)
• Faster rate of cervical change (Friedman's curve)
• Cervical dilation should progress at least 1 cm/hour in nulliparas, faster in multiparas
• Continuous external EFM throughout labor identifies fetal distress

Stage 2 - Expulsion (Delivery of the Fetus)

• Begins at full cervical dilation (10 cm) and ends with delivery of the baby
• Characterized by the urge to push/bear down with each contraction
• Median duration:
  • Nulliparous: ~50 minutes
  • Multiparous: ~20 minutes
• Prolonged second stage is associated with: postpartum hemorrhage, infection, severe vaginal lacerations

Stage 3 - Delivery of the Placenta

• From delivery of the baby to expulsion of the placenta
• Normally 5-30 minutes
• Active management (oxytocin + controlled cord traction) recommended

Stage 4 - The Immediate Postpartum Period

• First 1-2 hours after placental delivery
• Critical period for postpartum hemorrhage (PPH)
• Uterus must remain contracted; monitor vitals, blood loss, fundal height

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Initial Assessment at Presentation

• Contraction frequency, duration, intensity
• Membrane status (ruptured or intact)
• Fetal movements
• Gestational age; last prenatal visit
• Gravida/para status
• Vaginal discharge or bleeding
• Urge to push (suggests advanced labor)

Vaginal Examination

1. Cervical dilation (0-10 cm)
2. Effacement (percentage of cervical thinning)
3. Station (position of presenting part relative to ischial spines, -5 to +5)
4. Presentation (vertex in 95% of labors)
5. Position (occiput anterior, posterior, transverse)
6. Membrane status

If vaginal bleeding is present, defer digital examination until placenta previa is excluded by ultrasound.

Membrane Rupture Assessment

• Pooling of amniotic fluid in posterior fornix
• Ferning on microscope slide (sensitivity ~90%)
• Nitrazine paper turns blue (alkaline fluid, pH >6) - sensitivity ~90%
• False positives: blood, semen, cervical mucus, infection

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Fetal Assessment During Labor

Electronic Fetal Monitoring (EFM)

Ultrasonography in Labor

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Obstetric Terminology

Lie

• Longitudinal: Long axis of fetus parallel to mother's spine (normal)
• Transverse: Perpendicular - cannot deliver vaginally
• Oblique: Intermediate

Presentation

• Vertex/cephalic (95%): Head presents first; occiput is the presenting part
• Breech (~3-4%): Buttocks/feet first
• Face, Brow, Shoulder: Abnormal - usually require intervention

Position

• Direction the occiput faces relative to maternal pelvis:
• Left Occiput Anterior (LOA): Most favorable for delivery
• Occiput Posterior (OP): May cause prolonged labor, more painful back labor
• Assessment: palpate fontanels - posterior fontanel has 3 suture lines; anterior fontanel has 4

Station

• Engagement = head at 0 station (at ischial spines)
• Crowning = head at perineum, visible at introitus without retraction between contractions

Leopold Maneuvers

1. First: What is in the fundus? (head = hard, ballottable; breech = soft, irregular)
2. Second: Where is the fetal back? (smooth = back; irregular = extremities)
3. Third: What is above the pelvic inlet? (presenting part)
4. Fourth: Is the head flexed or deflexed? (cephalic prominence)

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Cardinal Movements of Labor (Mechanisms of Labor)

1. Engagement - Biparietal diameter passes through pelvic inlet
2. Descent - Progressive downward movement throughout labor
3. Flexion - Head flexes, chin to chest (smallest diameter presents)
4. Internal Rotation - Occiput rotates to lie under pubic symphysis (usually LOA → OA)
5. Extension - Head extends as it passes under the pubic arch; face sweeps the perineum
6. External Rotation (Restitution) - Head rotates back to align with fetal shoulders
7. Expulsion - Delivery of shoulders (anterior first, then posterior) and body

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Preparation for Delivery

• Radiant warmer, heated
• Towel, sterile scissors, umbilical clamps (x2)
• Bulb suction
• Airway equipment: oxygen, bag-mask device with appropriate-sized neonatal masks, ET intubation tools
• Vascular access equipment (IV)
• Oxytocin for third stage

• Dorsal lithotomy position (standard)
• Sims position (left lateral, knees drawn to chest, back to physician) - also acceptable, especially for precipitous delivery

• Cleanse vulva and perineum with sterile water or saline
• Sterile examination to confirm presentation and labor progress
• Digital perineal stretching (especially posteriorly) may reduce tears and lacerations

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Conducting the Delivery

Delivery of the Head

1. Controlled, coordinated expulsion with maternal coaching ("push-push-push" with contractions, panting to slow passage)
2. The most vulnerable moment is when the fetal head stretches and distends the perineum
3. Instruct the mother to pant (not push) as the head crowns - slows passage, reduces lacerations
4. Modified Ritgen Maneuver:
   • Towel-draped, gloved hand placed posteriorly to support perineum and apply gentle upward pressure on fetal chin
   • Second hand applies downward pressure on the occiput
   • Guides head into slight extension so its smallest diameter (suboccipitobregmatic) passes through the pelvic outlet
5. After head delivery: wipe nose and mouth; sweep any visible cord loops from around the neck

Check for Nuchal Cord

• After head delivery, check for cord around the neck
• If loose: slip over the head
• If tight: double-clamp and cut before delivery of body, or use somersault maneuver

Delivery of the Shoulders

• Gentle downward traction on the head to deliver the anterior shoulder under the pubic symphysis
• Gentle upward traction to deliver the posterior shoulder over the perineum
• Caution: excessive traction risks brachial plexus injury

Delivery of the Body

• Body and legs follow with gentle continuous traction
• Baby is delivered onto the mother's abdomen or into provider's hands

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Episiotomy

• Surgical incision of the perineum to enlarge the vaginal opening
• Types: Median (midline) vs. Mediolateral
• Williams Obstetrics: Routine episiotomy is NOT recommended - evidence does not support its use for all deliveries
• Indications: fetal distress requiring urgent delivery, shoulder dystocia, operative delivery
• Median: easier to repair, less pain, but higher risk of extension to sphincter (3rd/4th degree tears)
• Mediolateral: more blood loss, harder to repair, but lower sphincter injury risk

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Third Stage of Labor - Placental Delivery

Signs of Placental Separation:

1. Gush of blood from vagina
2. Lengthening of umbilical cord
3. Uterus rises in abdomen and becomes globular and firm
4. Fundus rises above umbilicus temporarily

Methods of Placental Delivery:

• Active management (WHO-recommended): Oxytocin 10 IU IM immediately after delivery of baby + controlled cord traction + uterine massage
• Reduces PPH risk by ~60%

Mechanisms:

• Schultze mechanism (~80%): Placenta separates centrally, presents shiny fetal surface first - usually less bleeding
• Duncan mechanism (~20%): Placenta separates peripherally, slides out sideways - more bleeding during separation

Retained Placenta:

• Defined as placenta not delivered within 30 minutes
• Requires manual removal
• Risk factors: accessory lobes, placenta accreta/increta/percreta

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Immediate Neonatal Care

1. Dry and stimulate the infant with a warm towel
2. Suction mouth then nose with bulb syringe (if secretions present)
3. Clamp and cut umbilical cord: first clamp ~3-4 cm from umbilicus, second clamp ~2 cm beyond; cut between them
   • Delayed cord clamping (≥1 minute after birth): recommended by Williams/ACOG for term and preterm neonates - increases neonatal iron stores, reduces anemia
4. Assign APGAR score at 1 minute and 5 minutes:

• Score 7-10: Normal
• Score 4-6: Moderate depression - stimulate, oxygen
• Score 0-3: Severe depression - full resuscitation

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Fourth Stage - Immediate Postpartum (First 1-2 Hours)

• Normal blood loss: <500 mL vaginal delivery, <1000 mL cesarean
• PPH = blood loss >500 mL after vaginal delivery

• Vital signs every 15 minutes for first hour
• Uterine fundus: firm, at or below umbilicus
• Uterine massage if uterus is boggy
• Inspect for perineal/vaginal lacerations and repair
• Bladder status (urinary retention common)

• Tone (uterine atony - most common, 70-80%)
• Tissue (retained placenta/clots)
• Trauma (lacerations, hematoma, uterine rupture)
• Thrombin (coagulopathy)

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Perineal Lacerations (Obstetric Trauma)

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Complications to Know (Quick Reference)

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Summary: Key Williams Obstetrics Numbers

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