The use of fentanyl or high-dose morphine along with bupivacaine has been found to increase the efficacy and duration of single-shot spinal anaesthesia (SSSA) in the active period of developing labor without encouraging side effects, as concluded from a study published in the journal- Gynecologic and Obstetric Investigation.

Due to its easy applicability and rapid onset of action, SSSA with bupivacaine is helpful for pain relief control during active labor. The study researchers examined the effectiveness of the addition of fentanyl or high-dose morphine to bupivacaine through SSSA. 

This study comprised of 90 healthy consecutive multiparous parturients in the active progressing labour (pain score >4) entreating analgesia. These parturients were divided into 3 groups as Group 1 comprising of 30 patients with hypobaric bupivacaine 2.5-mg alone; Group 2 comprising of 30 patients with a combination of hypobaric bupivacaine 2.5-mg and fentanyl 10-μg, and; Group 3 comprising of 30 patients with a combination of hypobaric bupivacaine 2.5-mg and 0.5-mg morphine. A comparison of VAS scores, duration of analgesia, side effects, and obstetric and neonatal outcomes were done. 

Main gestational age and cervical dilatation of the patients were 38.7 ± 1.5 months and 7.2 ± 2.2 cm, respectively. The main VAS score significantly decreased in all groups at 3 hours from baseline (Table 1):

Table 1: Reduction in VAS score in three groups

All groups had similar duration of the second stage of delivery. Group 3 had significantly higher total analgesia duration. Also, all 3 groups had similar Apgar scores and fetal heart rates. Other than pruritus in group 3, the side effects were comparable throughout.