Purpose: To investigate if early epidural analgesia can influence fetal head engagement into the pelvis and if it can increase the rate of transverse and asynclitic position during labour.
Materials and methods: 195 women with combined spinal-epidural analgesia (CSE) or without neuraxial analgesia were studied. CSE was performed using a mixture of ropivacaine 0.02% with 0.3 microg/ml of sufentanil administered in the spinal space. Maintenance of analgesia was managed with intermittent epidural administration of 10-15 ml of ropivacaine (0.07%-0.10%) mixed with 0.5 microg/ml of sufentanil, based on the stage of labour and the degree of pain. 2D transabdominal ultrasound (US) was used. Serial transabdominal US examinations were performed at 45-90 min intervals to detect transverse and asynclitic positions, using the following signs: squint sign, sunset thalamus and cerebellum signs that best details the fetal head station. After delivery, the complete set of clinical and US data obtained by each examination were recorded and compared in women with and without labour analgesia. Data were examined by independent reviewers.
Results: There was no difference in obstetric outcome between women in whom CSE had been used and those who did not request analgesia during labour (p > 0.05).
Conclusions: Epidural analgesia initiated early during labour and using low doses does not increase the rate of dystocic labors. Transverse fetal head positioning with anterior or posterior asynclitism does not seem to be promoted by drug or technique-related mechanisms, but rather should be the consequence of cephalopelvic disproportion.