What does a sinusoidal fetal heart rate pattern indicate?

A sinusoidal fetal heart rate pattern is characterized by a smooth, wave-like oscillation of the heart rate, often seen as a distinct pattern on a fetal monitor. This pattern is associated with fetal anemia. The sinusoidal pattern indicates that there is likely a reduction in the fetal blood volume or an unhealthy fetal environment, often resulting from conditions like Rh disease or other causes of significant fetal blood loss.

In contrast, the other options relate to different conditions and are not typically associated with a sinusoidal pattern. Maternal hypertension can cause variable or late decelerations due to placental insufficiency but would not produce a sinusoidal pattern. Fetal distress usually presents with more chaotic heart rate patterns that fluctuate rather than the smooth oscillations seen in a sinusoidal trace. Similarly, intrauterine growth restriction is often indicated by decreased variability and may also present with late decelerations due to hypoxia but does not specifically indicate a sinusoidal pattern. Thus, the presence of a sinusoidal fetal heart rate pattern is a critical sign leading to suspicion of fetal anemia and warrants further investigation and management.