172 Intrapartum Emergencies for the PANCE

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The water breaks and the heart rate drops. The head delivers and pulls back. A scarred uterus loses station. Three of today’s four emergencies announce themselves the same way, with the fetal heart rate falling, and what separates them is what happened right before. This episode is the tracing going bad, the cord coming first, the shoulders getting stuck, and the ways out.

Fetal Distress (Nonreassuring Fetal Status)

• A fetal heart rate tracing suggesting the fetus isn’t getting enough oxygen. The American College of Obstetricians and Gynecologists (ACOG) prefers “nonreassuring fetal status.” Same thing, older name.
• Reassuring = the tracing tells you the fetus is well oxygenated. Category I: baseline 110 to 160, moderate variability, no late or variable decelerations.
• Nonreassuring = any of these on the tracing:
  • Minimal or absent variability. Variability is the beat-to-beat wiggle in the baseline. A well-oxygenated fetal brain keeps adjusting the heart rate, so a flat line means the brain isn’t getting enough oxygen.
    • The benign explanations: the fetus is asleep, or mom got opioids or magnesium.
  • Recurrent late decelerations.
  • Recurrent variable decelerations.
  • Prolonged deceleration: 2 to 10 minutes below baseline.
  • Bradycardia under 110 or tachycardia over 160 (usually maternal fever).
  • Sinusoidal pattern.

Causes

• Uteroplacental insufficiency → late decelerations.
  • Not enough oxygenated blood getting across the placenta.
  • Maternal hypotension (often epidural), tachysystole, preeclampsia, abruption, post-dates, growth restriction.
• Cord compression → variable decelerations.
  • Oligohydramnios: too little amniotic fluid, so less cushion around the cord.
  • Cord prolapse.
• Maternal fever or chorioamnionitis → fetal tachycardia.
  • Chorioamnionitis: infection of the amniotic fluid, membranes, and placenta. Maternal fever, uterine tenderness, foul-smelling fluid.

Category III and the Sinusoidal Pattern

• Category III (act now): absent variability with recurrent late or variable decelerations or bradycardia, or a sinusoidal pattern.
• Sinusoidal pattern: smooth, regular sine wave with no variability → fetal anemia.
  • Rh alloimmunization: maternal antibodies destroying fetal red cells.
  • Ruptured vasa previa: bare fetal vessels crossing the cervix. In velamentous cord insertion, the cord plugs into the thin part of the amniotic sac instead of directly into the placenta, and its vessels run bare across the membranes to reach it. If that stretch lies over the cervix, the vessels tear when the water breaks, and the blood being lost is the baby’s.
  • Fetomaternal hemorrhage: fetal blood crossing into the mother’s circulation.
• The question stem will likely describe a tracing in words and ask for the next step, not the name of the pattern.
  • Example: a woman at 6 cm on oxytocin has decelerations that start after each contraction peaks and recover after it ends, with minimal variability. Next step? Reposition, fluid bolus, stop the oxytocin.

Diagnostics

• Fetal scalp stimulation: rub the fetal scalp during a cervical exam. An acceleration in response means fetal pH is >7.20. Reassuring.
• Umbilical cord arterial gas after delivery, sent after a bad tracing or a depressed newborn to document whether the baby was actually hypoxic during labor.
  • pH <7.0 with a base deficit ≥12 mmol/L = significant metabolic acidemia.
  • That newborn gets evaluated for hypoxic-ischemic encephalopathy and may be a candidate for therapeutic hypothermia.

Treatment

• Intrauterine resuscitation first, all at once. Every move is about getting more oxygen to the fetus.
  • Left lateral positioning, takes the uterus off the vena cava.
  • Stop the oxytocin.
  • IV fluid bolus. Epidural hypotension gets ephedrine or phenylephrine.
  • Terbutaline for tachysystole: a beta-2 agonist (same class as albuterol) given subcutaneously to relax the uterus.
  • Cervical exam to check for cord prolapse or rapid descent.
  • No routine maternal oxygen. ACOG recommends against it for the tracing alone. Trials showed it doesn’t improve newborn outcomes, and extra oxygen may do harm. Give it only if the mother is hypoxic.
• Amnioinfusion: saline into the uterus through an intrauterine pressure catheter (IUPC) for recurrent variable decelerations. Cushions the cord.
• Category III that doesn’t resolve → deliver now. Fully dilated with the head low → operative vaginal delivery. Otherwise → emergency cesarean.

Exam Keys

• Late decels = placenta. Left side, fluids, stop the oxytocin.
• Recurrent variable decels = cord. Amnioinfusion.
• Sinusoidal pattern = fetal anemia.
• Acceleration with scalp stimulation = pH >7.20. Reassuring.
• Category III that won’t resolve = deliver.

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Umbilical Cord Prolapse

• The cord slips down ahead of the presenting part after the membranes rupture and gets compressed against the pelvis. An obstetric emergency.
• Overt: cord seen or felt in the vagina. Occult: cord beside the presenting part, not palpable.

Risk Factors

• Anything that leaves room in the pelvis for the cord to slip past:
  • Malpresentation, especially footling breech and transverse lie.
  • Prematurity, low birth weight.
  • Polyhydramnios.
  • Multiple gestation, especially the second twin.
• Amniotomy with an unengaged head. The one we cause ourselves.

Clinical Presentation

• Sudden fetal bradycardia or severe variable decelerations right after the membranes rupture.
• Pulsating cord felt on cervical exam, or seen at the introitus.
• The question stem will likely describe membranes rupturing, then the fetal heart rate dropping within minutes.

Diagnostics

• Clinical. A cervical exam finds it. Don’t wait on an ultrasound.

Treatment

• Call for help and go to emergency cesarean.
• Elevate the presenting part with a gloved hand in the vagina, lifting it off the cord. The hand stays until the baby is out.
• Knee-chest or steep Trendelenburg position.
  • Knee-chest: mom on her knees, chest down on the bed, hips up. Gravity pulls the baby back out of the pelvis and off the cord.
• Stop the oxytocin.
• Never push the cord back into the uterus. Minimize handling, it causes cord vasospasm.
• Vaginal delivery only if fully dilated and delivery is imminent.

Exam Keys

• Membranes rupture + sudden bradycardia = cord prolapse until proven otherwise.
• Hand in the vagina lifts the head off the cord and stays until cesarean.
• Knee-chest or Trendelenburg. Never push the cord back.
• Unengaged head + amniotomy = the setup.

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Shoulder Dystocia

• The head delivers, then the anterior shoulder catches behind the pubic symphysis and gentle downward traction won’t deliver the body.
• Hard to predict. Most cases happen in babies of normal weight, so every delivery team drills for it.

Risk Factors

• Fetal macrosomia, the strongest risk factor: birth weight over 4,000 to 4,500 g.
• Maternal diabetes → fat deposits across the shoulders and trunk, so the body outgrows the head.
• Prior shoulder dystocia: recurs in roughly 10% of later deliveries.
• Maternal obesity, post-dates.
• Operative vaginal delivery, prolonged second stage.

Clinical Presentation

• Turtle sign: the head delivers, then retracts back against the perineum.
• The question stem will likely describe a diabetic mother with a large baby whose head delivers and pulls back.
• Prevention: consider planned cesarean for estimated fetal weight ≥5,000 g without diabetes or ≥4,500 g with diabetes.

Treatment: HELPERR

• Help: call for it.
• Evaluate for episiotomy. Makes room for your hands, doesn’t fix the bony obstruction.
• Legs: McRoberts maneuver, hyperflex the thighs onto the abdomen. Flattens the sacrum and rotates the symphysis up.
• Pressure: suprapubic, pushing the anterior shoulder down and under the symphysis.
• Enter: internal rotation maneuvers (Rubin, Woods corkscrew).
• Remove the posterior arm.
• Roll to all fours (Gaskin maneuver).

• McRoberts plus suprapubic pressure first. They resolve most cases.
• Never fundal pressure. It drives the shoulder harder into the symphysis.
• Avoid excessive lateral traction on the head.
• Last resort: Zavanelli maneuver, pushing the head back up and delivering by cesarean.

Complications

• Brachial plexus injury:
  • Erb-Duchenne palsy (C5-C6): upper trunk injury. The shoulder and elbow muscles are weak, the hand works. The arm hangs at the side, rotated in, elbow straight, palm facing back: the “waiter’s tip.” The most common, and most recover.
  • Klumpke palsy (C8-T1): lower trunk injury. The small muscles of the hand are weak, the shoulder works. Claw hand: knuckles extended, fingers curled, weak grip. Can come with Horner syndrome, since T1 carries the sympathetic fibers to the eye. Rarer, and a worse prognosis than Erb.
• Clavicle or humerus fracture, hypoxic injury.
• Maternal: postpartum hemorrhage, third and fourth degree lacerations.

Exam Keys

• Turtle sign = shoulder dystocia.
• McRoberts + suprapubic pressure first. Never fundal pressure.
• Diabetes + macrosomia = the setup.
• Erb palsy (C5-C6) = waiter’s tip. Klumpke (C8-T1) = claw hand.

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Operative Delivery

Operative Vaginal Delivery

• Forceps or vacuum on the fetal head to finish the second stage.
• Indications: prolonged second stage, maternal exhaustion, maternal conditions where pushing is dangerous (cardiac or cerebrovascular disease), nonreassuring tracing in the second stage.
• Prerequisites:
  • Fully dilated.
  • Membranes ruptured.
  • Head engaged, station 0 or lower.
  • Position known.
  • Adequate analgesia, empty bladder, consent, and a plan for cesarean if it fails.
• Vacuum → more cephalohematoma and subgaleal hemorrhage. Fewer maternal lacerations. Not before 34 weeks.
• Forceps → more third and fourth degree lacerations and facial nerve palsy. Higher success rate.
• Subgaleal hemorrhage: bleeding under the scalp aponeurosis that crosses suture lines and can hold enough blood to cause neonatal shock. Cephalohematoma stops at the sutures.

Cesarean Delivery

• Most common indications: prior cesarean, labor arrest, nonreassuring fetal status, malpresentation (mostly breech).
• Cesarean required:
  • Placenta previa: the placenta covers the cervical opening. Painless bright red bleeding in the third trimester. Labor would tear right through it.
  • Vasa previa: bare fetal vessels over the cervix. Planned cesarean at 34 to 37 weeks.
  • Transverse lie.
  • Prior classical incision.
  • Active genital herpes lesions.
  • HIV viral load >1,000 copies/mL or unknown near delivery.
• Cefazolin within 60 minutes before the incision.
• Complications: infection, mostly endometritis, the most common. Hemorrhage, venous thromboembolism, bladder or bowel injury. Each cesarean raises the risk of placenta previa and accreta next pregnancy.

Incision Type and TOLAC

• Low transverse: the standard. Allows a trial of labor after cesarean (TOLAC).
  • Candidates: one or two prior low transverse incisions.
  • Vaginal birth after cesarean (VBAC) succeeds in about 60 to 80%.
  • Uterine rupture risk about 0.5 to 1%.
• Classical (vertical): cuts the contractile upper segment. No labor, ever. Repeat cesarean at 36 to 37 weeks.
• Uterine rupture:
  • Sudden fetal bradycardia, the most common sign.
  • Loss of fetal station.
  • Abdominal pain, vaginal bleeding, contractions stopping.
  • Emergency laparotomy.

Exam Keys

• Forceps or vacuum = fully dilated, ruptured membranes, head engaged, position known.
• Vacuum → cephalohematoma and subgaleal hemorrhage. Forceps → maternal lacerations and facial nerve palsy.
• Subgaleal crosses suture lines. Cephalohematoma doesn’t.
• Low transverse = TOLAC candidate. Classical = cesarean at 36 to 37 weeks, never labor.
• Sudden bradycardia + loss of station during TOLAC = uterine rupture.

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Putting It Together: The Tracing Drops in Labor

• Three of the four show up the same way, with the heart rate dropping during labor. The fourth you see. When it happened tells you which one.
• Recurrent late decels tied to contractions = uteroplacental insufficiency. Resuscitate in place.
• Sudden bradycardia right after the membranes rupture = cord prolapse. Hand in the vagina, go to cesarean.
• Sudden bradycardia + loss of station in a scarred uterus = uterine rupture. Laparotomy.
• Head out, body stuck, head pulls back = shoulder dystocia. McRoberts and suprapubic pressure.
• The filter: after the contraction = placenta. After the water breaks = cord. On a scar = rupture. After the head = shoulders.
• The trap: the stem lists all four plus “continue monitoring.” Find the trigger event before you commit.

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Study Tip: Underline the Trigger Event

On this block, the question is almost never “what is it.” It’s “what happened right before.” Water broke, then the heart rate dropped. Head came out, then pulled back. Prior cesarean, then the station disappeared. When you read a stem, underline the trigger event before you look at the answers. That’s a test-taking skill, not a content problem.

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