A 38-year-old primigravida at 39+2 weeks is admitted for induction of labor. After 6 hours of oxytocin infusion, the cardiotocograph shows a pattern marked **C** — a gradual decrease in fetal heart rate with the nadir occurring 15–20 seconds AFTER the peak of each uterine contraction, with symmetric shallow decelerations (drop of ~25 bpm) and return to baseline between contractions. The baseline FHR variability remains normal. Which of the following is the MOST appropriate FIRST step in intrauterine resuscitation?

Explanation

## Why option 1 is correct The pattern marked **C** (late deceleration) is the most ominous CTG finding, indicating uteroplacental insufficiency and fetal hypoxia. The key diagnostic feature is the gradual FHR decrease with nadir AFTER the contraction peak (lag time 10–30 seconds), reflecting chemoreceptor-mediated response to transient placental hypoperfusion during contractions. The FIRST-LINE management is intrauterine resuscitation: (1) LEFT LATERAL DECUBITUS positioning to relieve aortocaval compression and restore placental perfusion, (2) DISCONTINUE oxytocin (which is driving excessive contractions and worsening hypoxia), (3) IV fluid bolus to increase maternal intravascular volume and uterine perfusion, and (4) supplemental O₂ to maximize fetal oxygenation. These measures address the underlying mechanism (uteroplacental insufficiency) and allow reassessment before escalating to operative delivery. [Williams Obstetrics 26e; ACOG/FIGO Intrapartum Surveillance Guidelines] ## Why each distractor is wrong - **Option 2 (fetal scalp blood sampling)**: While pH/lactate assessment may be considered if late decelerations persist despite resuscitation, it is NOT the first step. Resuscitation measures must be attempted first to improve placental perfusion and fetal oxygenation. Invasive fetal assessment is reserved for cases unresponsive to conservative management. - **Option 3 (emergency cesarean without intervention)**: Although persistent late decelerations unresponsive to resuscitation do warrant operative delivery, immediate cesarean without attempting intrauterine resuscitation is premature and increases maternal morbidity. The pattern here is not yet categorized as "persistent" or "severe," so resuscitation is the standard of care first. - **Option 4 (scalp stimulation + continue oxytocin)**: Fetal scalp stimulation is appropriate for variable decelerations (cord compression) to assess fetal well-being, NOT for late decelerations. Continuing oxytocin in the face of late decelerations is contraindicated—it perpetuates the mechanism of hypoxia by maintaining excessive uterine contractions and further reducing placental blood flow. **High-Yield:** Late decelerations = uteroplacental insufficiency = STOP oxytocin, LEFT LATERAL position, IV fluids, O₂; escalate to delivery only if unresponsive. [cite: Williams Obstetrics 26e; ACOG/FIGO Intrapartum Surveillance]