Abstract
BACKGROUND: Labor pain is one of the most intense physiological pains experienced by women. Single-shot spinal analgesia (SSSA) offers rapid and reliable labor pain relief. Combining bupivacaine with adjuvants like fentanyl or dexmedetomidine has been proposed to enhance analgesic efficacy and maternal comfort. METHODS: In this randomized, double-blind clinical trial, 90 full-term parturients in active labor were randomly allocated into three equal groups: Group B: 2.5 mg intrathecal bupivacaine with 0.5 mL of saline; Group BF: 2.5 mg bupivacaine with 25 μg fentanyl; Group BD: 2.5 mg bupivacaine with 5 μg dexmedetomidine. We compared the duration and onset of analgesia, pain scores on the visual analog scale (VAS), maternal satisfaction using the short assessment of patient satisfaction (SAPS), adverse effects, and neonatal outcomes. RESULTS: Group BD demonstrated the fastest onset of analgesia (2.1 ± 0.7 min) and the longest duration (124.2 ± 15.4 min), compared to Group BF (3.6 ± 0.9 min; 106.2 ± 18.9 min) and Group B (4.2 ± 1.0 min; 80.4 ± 14.6 min) (p < 0.001). The pattern of pain reduction over time varied across treatments; Group BD showed the most rapid and sustained decrease in pain intensity, while Group B exhibited the slowest decline. A significant time × group interaction (p < 0.001, partial η (2) = 0.67, i.e., large effect size) was observed. Maternal satisfaction scores were significantly higher in Group BD (26.63 ± 2.03) than in BF (22.00 ± 3.29) or B (15.27 ± 3.68) (p < 0.01). The incidence of itching and nausea was higher in the BF group, and mild bradycardia was found in the BD group. Apgar scores at 1 and 5 min were similar in all groups. CONCLUSION: Dexmedetomidine added to intrathecal bupivacaine produced good labor analgesia with high maternal satisfaction, with low side effects, and could be used as a better substitute for fentanyl. Trial Registration: ClinicalTrials.gov: NCT06823349.