Sinusoidal fetal heart rate pattern during labor

Area of Science:

• Perinatology
• Fetal Monitoring
• Obstetrics

Background:

• The sinusoidal heart rate (SHR) pattern is a rare fetal heart rate (FHR) abnormality.
• Understanding its causes and implications is crucial for intrapartum fetal assessment.

Purpose of the Study:

• To investigate the incidence and characteristics of the SHR pattern during labor.
• To identify factors associated with the development of SHR.
• To evaluate the impact of SHR on fetal outcomes.

Main Methods:

• Retrospective analysis of 1280 fetuses monitored with internal scalp electrodes during labor.
• Identification and characterization of fetuses exhibiting the SHR pattern.
• Comparison of SHR and non-SHR (NSHR) groups regarding clinical data and fetal outcomes.

Main Results:

• The SHR pattern was observed in 4.2% of fetuses.
• Prolonged SHR (>90 minutes) occurred in seven cases, predominantly during oxytocin administration.
• No significant differences were found in Apgar scores, other FHR abnormalities, or meconium passage between SHR and NSHR groups.
• Alphaprodine administration was associated with SHR, while other narcotics were not.
• Fetal scalp pH remained above 7.30 in the few cases tested.

Conclusions:

• The SHR pattern is uncommon and often transient.
• Oxytocin and alphaprodine may be associated with SHR development.
• The SHR pattern, when meeting strict definitions and with normal scalp pH, does not appear to be indicative of fetal distress or adverse outcomes.