Gastric Emptying Velocity After Labor Analgesia Assessed by Sonography: A Prospective Controlled Observational Study

Objective: The effect of labor analgesia on gastric emptying rate will affect the management of fasting during the perinatal period. To evaluate gastric emptying after labor analgesia using the gastric antrum ultrasound examination.

Methods: From September 2022 to January 2023, a prospective controlled observational study was conducted. The Study group (epidural analgesia group) and Observation group (pharmacological and non-pharmacological interventions group) were successively enrolled and grouped using the random envelope method. However, labor analgesia was supplied according to maternal women's wishes, and intention-to-treat (ITT) and per-protocol (PP) analyses were performed to establish its effect on stomach emptying. The gastric emptying rate during the first stage of labor was considered to be the primary outcome.

Results: From September 2022 to January 2023, 120 persons were studied, 90 in the Study group and 30 in the Observation group. 33 people's analgesic selection was discordant with the grouped one. ITT analysis showed that the Study group's cross-sectional area (CSA) fell from baseline (624.19 ± 92.70 mm²) to 334.64 ± 46.32 mm² after 1 hour and to 217.26 ± 29.90 mm² after 2 hours. In the Observation group, the CSA similarly dropped from 620.10 ± 100.73 mm² to 331.30 ± 51.19 mm² and 214.70 ± 28.73 mm², p<0.001. CSA was not significantly different between groups, p>0.05. The PP analysis also indicated no significant changes in the CSA between the two groups at 3 time-points, p>0.05. At the first hour, the Study and Observation group had stomach emptying speeds of 300.05 ± 103.74 mm²/h and 259.50 ± 125.25 mm²/h, respectively, which were greater than those at the second hour (115.75 ± 43.51 mm²/h vs 124.36 ± 58.98 mm²/h), p<0.001.

Conclusion: Epidural analgesia, pharmacological, and non-pharmacological labor analgesia had little effect on gastric emptying, and gastric antrum ultrasonography can be utilized to monitor maternal gastric volume changes.