First Stage of Labor

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What happens in the First Stage of Labor?

The first stage of labor begins with regular uterine contractions and ends with complete cervical dilation at 10 cm. Divided into Latent and Active phases. Epidural block or blocking of T10-T12 used to relieve pain from uterine contractions and cervical dilation.

Management:

• Assess fetal heart rate.

• Obstetric analgesia administered if necessary.

• Amniotomy performed if necessary.

Latent Phase:

Begins with uterine contractions and ends with acceleration of cervical dilation. Complications are caused by injudicious analgesia.

Duration:

• Average for primipara is 6.4 hours.

• Average for multipara is 4.8 hours.

• Upper limit for primipara is 20 hours.

• Upper limit for multipara is 14 hours.

Prolonged Latent Phase:

• Pregnant with regular contractions.

• Cervix dilated 2 cm.

• No cervical change in 14 hours.

Management of Prolonged Latent Phase:

• Therapeutic rest and sedation.

Active Phase:

Begins with cervical dilation acceleration, usually at 3-4 cm of dilation, and ends with complete cervical dilation at 10 cm. Complications are caused by excessive fetal size, abnormal fetal orientation, bony pelvis size, and inadequate or dysfunctional uterine contractions. Intravenous agents or paracervical block may be used to relieve pain.

Rate of Dilation:

• 1.2 cm/hour for primipara.

• 1.5 cm/hour for multipara.

Prolonged Active Phase:

• Pregnant with regular uterine contractions.

• Cervix dilated 8 cm.

• 2 cm change in 4 hours.

Active Arrest Phase:

• Pregnant with regular uterine contractions.

• Cervix dilated 8 cm.

• No cervical change in 3 hours.

Management of Prolonged or Arrested Active phase:

• Contractions must occur every 2-3 minutes, last 45-60 seconds with 50 mm Hg pressure.

• For hypertonic contractions, give morphine sedation.

• For hypotonic contractions, give oxytocin.

• Do emergency C-section if necessary.

Additional Reading:

Notes on Stages of Labor:

1. Diagram of Stages of Labor
2. First Stage of Labor
3. Second Stage of Labor
4. Third Stage of Labor
5. Fourth Stage of Labor

Tests for Fetal Well-Being:

1. Notes on Non-Stress Test
2. Notes on Contraction Stress Test
3. Unresponsive Fetus Algorithm

Periodic Changes in Fetal Heart Rate:

1. Fetal Heart Rate Accelerations
2. Variable Decelerations of Fetal Heart Rate
3. Early Decelerations of Fetal Heart Rate
4. Late Decelerations of Fetal Heart Rate

Types of Spontaneous Abortion:

1. Notes on Complete Abortion
2. Notes on Incomplete Abortion
3. Notes on Threatened Abortion
4. Notes on Inevitable Abortion
5. Notes on Missed Abortion

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