Risk factors for post-caesarean nausea and vomiting: a prospective prognostic study

BACKGROUND: Postoperative Nausea and Vomiting (PONV) risk factors have not been defined for obstetric patients. In this study, our objective was to identify potential risk factors for PONV after cesarean sections performed under spinal anesthesia. METHODS: One cohort of patients submitted to cesarean under spinal anesthesia was used to investigate potential risk factors for PONV. The best numerical risk factors were dichotomized using chi-squared method. A conditional independence (incremental association method) casual network was used to select the best predictors for PONV. RESULTS: Two hundred and fifty of 260 patients remained in the study. Odds ratio for PONV of younger maternal age (< 25 years: 2.9 [1.49−5.96]), lower spinal bupivacaine dose (< 13 mg, inf [2.4-inf]), lower spinal morphine dose (< 80 mg, 0.03 [0−0.97]), history of motion sickness (2.5 [1.27−5.25]), significant nausea during the first trimester (0.3 [0.16−0.64]), intraoperative nausea and vomiting (8.2 [3.67−20.47]), and lower gestational age (< 38 weeks, 2.0 [1.01−4.08]) were statistically significant. The causal network selected absence of significant nausea during the first gestational trimester, intraoperative nausea, and gestational age < 38 weeks as the main direct risk factors for PONV. CONCLUSIONS: Intraoperative nausea and maternal age < 25 years were the main risk factors for PONV after cesareans under spinal anesthesia. Absence of self-reported nausea during the first trimester was a protective factor for post-cesarean nausea and vomiting.