What UA Monitors on Fetal Monitoring
UA stands for Uterine Activity, not Umbilical Artery, and it monitors maternal uterine contractions during labor and antepartum surveillance. 1
Primary Function
- UA measures the frequency, duration, and relative strength of uterine contractions during labor and fetal monitoring 1
- The UA tracing provides essential information about contraction patterns that must be interpreted alongside fetal heart rate (FHR) to assess fetal well-being 1
- Obstetricians evaluate both FHR and UA recordings together when assessing fetal status, as the relationship between these two parameters reveals how the fetus tolerates labor stress 1
Clinical Significance
- UA monitoring reveals the temporal relationship between uterine contractions and FHR changes, which is critical for identifying concerning patterns such as late decelerations that may indicate uteroplacental insufficiency 1
- Research demonstrates that FHR and UA signals are causally related, meaning changes in uterine activity directly influence fetal heart rate patterns 1
- The interaction between FHR and UA signals helps characterize fetal response to the stress of contractions, allowing clinicians to distinguish reassuring from non-reassuring patterns 1, 2
Common Pitfall
Do not confuse UA (Uterine Activity) with umbilical artery Doppler assessment. Umbilical artery Doppler is a separate ultrasound-based evaluation that measures blood flow resistance in the fetal-placental circulation and is used primarily for assessing growth-restricted fetuses 3. UA on the cardiotocography monitor specifically tracks maternal uterine contractions, not fetal umbilical blood flow.