Labor & Delivery
Reading the tracing, calling arrest, and handling the delivery-room emergencies
Normal labor: stages and cardinal movements
| Stage | From → to | Key points |
|---|---|---|
| 1 | Onset of labor → full dilation (10 cm) | Latent phase 0–6 cm (slow); active phase 6–10 cm (about 1.2–1.5 cm/hr) |
| 2 | Full dilation → delivery of the fetus | Pushing and descent |
| 3 | Delivery of the fetus → delivery of the placenta | Normally <30 minutes |
| 4 | The first hours postpartum | Watch bleeding and uterine tone |
Cardinal movements. The fetal head negotiates the pelvis in a fixed order:
- Engagementwidest diameter of the head enters the pelvic inlet
- Descentcontinues throughout labor
- Flexionchin to chest, presenting the smallest diameter
- Internal rotationocciput turns anteriorly
- Extensionhead delivers under the pubic symphysis
- External rotation (restitution)head realigns with the shoulders
- Expulsionanterior, then posterior shoulder and body
Third stage. Signs of placental separation are cord lengthening, a gush of blood, and a firm, globular fundus that rises. Active management—oxytocin after delivery, controlled cord traction, and uterine massage—reduces postpartum hemorrhage; a placenta retained beyond 30 minutes may need manual removal.
Fetal heart rate monitoring
Reassuring features. The normal baseline is 110–160 bpm. Accelerations (≥15 bpm above baseline for ≥15 seconds) reflect fetal well-being. Moderate variability (6–25 bpm) is the single best sign of adequate fetal oxygenation—an intact, non-acidemic fetal CNS. Minimal (≤5 bpm) or absent variability is concerning; fetal tachycardia >160 bpm most often reflects maternal fever or chorioamnionitis.
| Type | Shape and timing | Cause | Significance |
|---|---|---|---|
| Early | Gradual; mirrors the contraction, nadir at its peak | Head compression | Benign |
| Variable | Abrupt drop and recovery, variable timing | Cord compression | Recurrent → amnioinfusion, reposition |
| Late | Gradual; nadir after the contraction peak | Uteroplacental insufficiency | Worrisome, especially recurrent |
- Category I (normal): baseline 110–160, moderate variability, no late or variable decelerations; early decelerations may be present.
- Category II (indeterminate): everything in between; resuscitate and reassess.
- Category III (abnormal): absent variability with recurrent late or variable decelerations or bradycardia, or a sinusoidal pattern (think fetal anemia); expedite delivery.
Intrauterine resuscitation and abnormal labor
- Repositionleft lateral, relieving cord and aortocaval compression
- IV fluids and oxygenimprove placental perfusion; correct maternal hypotension (e.g., after an epidural)
- Stop oxytocinreduce uterine activity; consider a tocolytic (terbutaline) for tachysystole
- Amnioinfusionfor repetitive variable decelerations
- No improvement → deliveroperative vaginal delivery if fully dilated, otherwise cesarean
| Diagnosis | Definition | Management |
|---|---|---|
| Prolonged latent phase | >20 hours (nulliparous) or >14 hours (multiparous) | Therapeutic rest or oxytocin/amniotomy—not a cesarean indication |
| Active-phase arrest | ≥6 cm, ruptured membranes, no cervical change for ≥4 hours of adequate contractions (≥200 Montevideo units) or ≥6 hours of inadequate contractions | Cesarean |
| Second-stage arrest | No descent or rotation after ≥3 hours of pushing (nulliparous) or ≥2 hours (multiparous); longer with an epidural | Operative vaginal delivery or cesarean |
Never diagnose active-phase arrest before 6 cm. For slow labor, assess the three P's—Power (contractions; augment with oxytocin), Passenger (size, position), and Passage (pelvis).
Induction: Bishop score and cervical ripening
Bishop score grades cervical dilation, effacement, station, consistency, and position. A score ≥8 is favorable—induction behaves like spontaneous labor—while a score of 6 or less is unfavorable and calls for cervical ripening before oxytocin.
Ripening. Use prostaglandins—misoprostol (PGE1) or dinoprostone (PGE2)—or a mechanical Foley balloon, then augment with oxytocin (and amniotomy). Avoid misoprostol with a prior cesarean because of uterine rupture risk. Oxytocin can cause tachysystole (more than 5 contractions in 10 minutes) and, because it resembles ADH, water intoxication with hyponatremia.
Delivery emergencies and operative delivery
Shoulder dystocia. The turtle sign—the delivered head retracts against the perineum—signals an impacted anterior shoulder. Risk factors include macrosomia, maternal diabetes, obesity, and a prior dystocia. Start with McRoberts (hyperflex the maternal hips onto the abdomen) plus suprapubic pressure to dislodge the anterior shoulder, then rotational maneuvers (Woods, Rubin) or delivery of the posterior arm.
Never apply fundal pressure—it worsens impaction. Complications include brachial plexus injury (Erb palsy, C5–C6, "waiter's tip" arm), clavicle fracture, and maternal hemorrhage and perineal lacerations.
Cord prolapse. Fetal bradycardia after membrane rupture with a palpable cord: manually elevate the presenting part off the cord, place the mother in knee-chest or Trendelenburg position, and proceed to emergency cesarean.
Operative vaginal delivery (forceps or vacuum) requires a fully dilated cervix, ruptured membranes, an engaged head of known position, adequate anesthesia, and an empty bladder. Indications are a prolonged second stage, a nonreassuring tracing, or maternal exhaustion. Vacuum is linked to cephalohematoma and subgaleal hemorrhage; forceps to facial nerve injury and severe perineal lacerations.
Cesarean indications include nonreassuring fetal status, arrest of labor, malpresentation, placenta previa, cord prolapse, active genital herpes, and a prior classical (vertical) uterine incision, which carries a high rupture risk and mandates repeat cesarean. A prior low-transverse incision permits a trial of labor after cesarean (TOLAC); uterine rupture then presents with fetal bradycardia, pain, and loss of station.
Breech. For persistent breech near term, offer external cephalic version at about 37 weeks (with anti-D if Rh-negative); if unsuccessful, planned cesarean is usually chosen. Footling breech and cord prolapse are indications for cesarean.