Efficacy of sterile water block with or without antispasmodics for labor analgesia: A triple-arm, randomized controlled trial

Abstract

Background: Universal provision of safe, effective, and inexpensive analgesia for labor remains a challenge. In India, antispasmodics, especially drotaverine, are widely used as an adjunct to decrease labor pain and duration. Therefore, we aimed to determine the efficacy of sterile water block (SWB), with or without drotaverine. Materials and Methods: This study was a randomized, triple arm, controlled trial on 105 patients in active labor, assigned to receive either intramuscular drotaverine (Group D), Intradermal SWB (Group B), or drotaverine with SWB (Group DB). SWB was given in Michaelis Rhomboid, in active phase of the first stage of labor. Primary outcomes were extent of pain relief, as measured by the numeric rating scale (NRS). Other outcomes included patient's satisfaction, duration of active phase of first stage of labor, APGAR scores, incidence of instrumentation or cesarean section, and any adverse effects. Results: One hundred and five patients were randomized into three groups of 35 patients each. At 30 min postintervention, mean (± standard deviation) NRS score was 7.30 (±1.03), 4.88 (±0.68), and 5.04 (±0.75) in Group D, B, and DB, respectively; (P < 0.001). Two hours' postintervention, NRS was 7.61 ± 0.89, 6.66 ± 0.91, and 6.95 ± 0.85 in Groups D, B, and DB respectively with P < 0.01. Number of patients satisfied in Group D, B, and DB were 0, 24, and 25, respectively. The duration of active phase of 1st stage of labor was 144.80 (±47.46), 198.88 (±92.16), and 142.50 (±50.77) minutes in Group D, B, and DB, respectively (P < 0.01). APGAR score was comparable in three groups. No adverse effect was seen on mother or fetus except burning sensation at the time of giving SWB. The occurrence of cesarean section was 8 in Group B, 8 in Group D, and 6 in Group DB. Conclusion: SWB is a safe modality for labor analgesia, causing a significant reduction in labor pain, both with and without drotaverine. Although not always effective as a sole modality, it may be effective in reducing the requirement of other analgesics when used in conjunction with other modalities for labor analgesia. Drotaverine may not significantly lower the labor pain alone or in conjunction with SWB. Yet, it significantly decreases the duration of active phase of first stage of labor (CTRI/2019/09/021125).