Background: Inadequately treated postoperative pain can contribute significantly to morbidity in women undergoing cesarean section.  Recent studies showed that nalbuphine and fentanyl has promising result as neuraxial adjuvants in terms of postoperative analgesia and with lower incidents of adverse effect when use in cesarean section. 

Objective: To determine the effectiveness of postoperative analgesia with intrathecal nalbuphine versus intrathecal fentanyl as neuraxial adjuvants in cesarean section. 

Methods:  A meta-analysis following the PRISMA guidelines was performed.  Articles were searched through the Cochrane Library, PubMed.Gov and Pubmed Central, Google Scholar, HERDIN, WPRIM and ProQuest Guideline Central using different search strategies such as keywords and MeSH term.  Cochrane version 2 risk-of-bias tool for randomized trials (RoB 2) was used to assess for quality.  Quantitative data were pooled and analyzed using Review Manager 5.4. 

Results: A total of four trials, involving 425 full term pregnant women were analyzed. The pooled mean difference showed significantly longer duration of postoperative analgesia (MD=21.12 minutes, 95%CI=11.13,31.11, I2=73%), pooled risk ratio showed lesser risk for pruritus (RR=0.09, 95%CI=0.02,0.50, I2 = 0%) and postoperative nausea and vomiting (RR=0.38, 95%CI= 0.19,0.78, I2 = 11%) who received intrathecal nalbuphine compared to intrathecal fentanyl. 

Conclusions: The results of this meta-analysis demonstrates that the use of intrathecal nalbuphine appears to have a better outcome in increasing the duration of postoperative analgesia and with lesser incidence of PONV and pruritus than fentanyl.  However, due to the presence of heterogeneity it warrants that the results should be treated with caution especially with the possibility of publication bias. 

Recommendations: Better literature search through inclusion of high-quality studies from relevant databases and strict adherence on the uniformity of the dosage and methods used are very crucial to achieve the target clinical outcomes and minimize the publication bias.