5.1 Intrauterine Resuscitation

Match the Intervention to the Cause

Quick Answer: Intrauterine resuscitation is not a memorized list applied to every abnormal strip. The C-EFM rewards candidates who first identify the physiologic problem the pattern reveals, then choose the measure that corrects it. A variable deceleration signals umbilical cord compression, so you reposition; a late deceleration signals uteroplacental insufficiency, so you improve perfusion.

Intrauterine resuscitation (also called fetal resuscitation) is the set of maternal interventions used during labor to improve fetal oxygenation when the fetal heart rate (FHR) tracing suggests hypoxic stress. The framework is anchored in 2008 National Institute of Child Health and Human Development (NICHD) terminology and endorsed by the American College of Obstetricians and Gynecologists (ACOG) and the Association of Women's Health, Obstetric and Neonatal Nurses (AWHONN).

These measures are organized around the oxygen pathway from the maternal lungs to the fetal tissues. The exam expects you to walk the pathway backward from the pattern: identify which link is interrupted, then correct that link.

Repositioning: Relieving Compression

Turning the patient to a lateral (side-lying) position does two physiologic jobs at once. First, it shifts the gravid uterus off the inferior vena cava and aorta, relieving aortocaval compression so maternal venous return, cardiac output, and uteroplacental blood flow all increase. Second, it changes the spatial relationship between the umbilical cord, the fetus, and the bony pelvis, often relieving the cord compression that produces variable decelerations. Either lateral side is acceptable, and trying the opposite side is reasonable if the first does not help.

Repositioning is typically the first maneuver because it is fast, noninvasive, requires no order in most settings, and addresses the two most common correctable causes. The supine position is avoided because it worsens aortocaval compression and can itself provoke decelerations.

Restoring Maternal Perfusion: Fluids and Vasopressors

When the problem is maternal hypotension (commonly after neuraxial/epidural anesthesia), the fetus is under-perfused even though the cord and uterus are normal. The correction is an intravenous (IV) fluid bolus of an isotonic crystalloid such as lactated Ringer's to expand intravascular volume. When a bolus alone does not restore blood pressure, a vasopressor is added: ephedrine or phenylephrine are first-line for post-spinal/epidural hypotension. The key exam point is that this sequence treats the hypotension, which is the actual cause, rather than treating the FHR pattern directly.

Reducing Excess Uterine Activity

Tachysystole (more than five contractions in 10 minutes, averaged over a 30-minute window) shortens the rest interval the placenta needs to reoxygenate, producing late or prolonged decelerations. The first step is to reduce or discontinue oxytocin and remove any cervical-ripening prostaglandin (misoprostol, dinoprostone).

ACOG's 2025 guidance states that tachysystole associated with a Category II or III tracing that persists despite pausing oxytocin should be treated with a rapid-acting uterine relaxant (tocolytic), most commonly terbutaline 0.25 mg subcutaneously. Note the order: pause the uterotonic first, then escalate to a tocolytic only if abnormalities continue.

Amnioinfusion and the Oxygen Question

Amnioinfusion is the instillation of warmed isotonic fluid into the amniotic cavity through an intrauterine catheter. It cushions the umbilical cord and is the targeted measure for recurrent variable decelerations caused by cord compression and oligohydramnios that do not resolve with repositioning.

The evidence on supplemental oxygen has shifted, and the exam now tests this nuance. ACOG's 2025 Clinical Practice Guideline No. 10 recommends against routine maternal oxygen for Category II or III tracings in the absence of maternal hypoxia. A systematic review of 16 trials (2,052 women) found that while maternal oxygen produced a small rise in umbilical-artery PaO2, there was no difference in umbilical-artery pH, neonatal acidemia, or NICU admission.

The correct exam answer is therefore to reserve oxygen for documented maternal hypoxemia (for example, a low pulse-oximetry reading), not to apply it reflexively to every non-reassuring strip.

Pattern to Cause to Intervention

Worked Example: A 39-week patient on an oxytocin induction is averaging 7 contractions per 10 minutes over 30 minutes, and the FHR now shows recurrent late decelerations with minimal variability (Category II). You walk the pathway: the uterus (too-frequent contractions) is the broken link, so you (1) stop the oxytocin, (2) turn her lateral, and (3) give a 1-liter LR bolus. Five minutes later tachysystole persists at 6/10, so you give terbutaline 0.25 mg SC per ACOG. You do not start oxygen, because her SpO2 is 98% with no maternal hypoxemia. The decelerations resolve and variability returns to moderate, confirming the cause-directed approach worked.