PONV is a common adverse reaction following surgery, including caesarean sections [1]. PONV not only increases the risk of other postoperative complications but also often causes discomfort to patients with nausea and vomiting, leading to reduced patient satisfaction and extended discharge time, imposing a substantial burden on patients [2].
In non-obstetric surgery, patient susceptibility to PONV is evaluated using the Apfel simplified risk score [7]. In the Apfel score, patient and anaesthesia factors contribute most to the risk of vomiting. For instance, the ORs for postoperative opioid use in women were reported as 4.78 and 2.44, respectively [7]. However, in patients undergoing spinal anaesthesia, these two factors generally exist by default, potentially limiting their predictive value for caesarean sections. In contrast, some maternal physiological and caesarean section-related factors may be associated with PONV risk; however, their predictive performance has not been integrated into the risk score prediction model. In addition, when evaluating the efficacy of the Apfel score, it was found that the AUC ROC of obstetric patients was 0.59, while that of non-obstetric patients was 0.753, further indicating the limited predictive performance of the Apfel score in the obstetric population [7].
To establish a specific risk prediction model for caesarean section, this study collected information on potential perioperative risk factors such as patients’ basic conditions, surgical factors, anaesthesia factors, and gastric ultrasound. In this study, a total of 32 patients developed PONV, accounting for 27.59% of the total sample size. Analysis of the collected data revealed that a history of motion sickness, gastric volume, and systolic blood pressure fall > 20% were independent risk factors for nausea and vomiting after caesarean section. Based on these three factors, a predictive model for nausea and vomiting after the caesarean section was established using R software and visualised as a nomogram. The model underwent verification and evaluation using the area under the ROC curve, calibration curve, and decision curve analysis. The model demonstrates good predictive performance and clinical application value.
Among the included indicators, a history of motion sickness has been widely confirmed to possess a high predictive value for PONV. Apfel and Koivaranta included it in their studies, constructing PONV prediction models that have found widespread use in clinical practice [7, 13]. The results highlighted that a history of motion sickness stands as an independent risk factor for PONV during caesarean section, with the incidence of PONV being 5.08 times higher in patients with this history than in those without [14]. Lee et al. further demonstrated the efficacy of prophylactic dexamethasone administration in reducing the incidence of PONV in patients with a history of motion sickness [15]. Horn et al. found that after spinal anaesthesia, hypotension caused by vasodilation, whether postural hypotension or hypotension caused by other factors, can stimulate the receptors of the central nervous system to release emetic neurochemical transmitters, resulting in nausea and vomiting. This is consistent with the results of the present study, illustrating that intraoperative hypotension is an independent risk factor for PONV during caesarean section [16]. The use of gastric ultrasound has become increasingly prevalent in obstetric anaesthesia in recent years [17, 18]. Hong et al. observed that pregnant women had larger gastric volumes than non-pregnant women, while Cozza et al. found that increased gastric volume corresponds to a higher incidence of PONV. Hamed et al. showed that preoperative metoclopramide administration could effectively reduce the incidence of PONV by decreasing gastric volume, further substantiating these findings [10, 19, 20]. The results of this study also suggest that increased stomach volume is an independent risk factor for PONV in caesarean sections.
The nomogram prediction model constructed in this study effectively foresees the risk of PONV in caesarean sections. Internal verification shows that the model exhibits good discrimination, consistency, and clinical utility. In the era of individualised precision medicine, which is gaining increasing attention, the ability to promptly identify caesarean section patients at risk of PONV and implement targeted preventive measures, such as preoperative antiemetic drugs administration, intraoperative management of blood pressure stability, adjustment of opioid dosage, auxiliary support, and other treatment measures, is invaluable. These measures can significantly enhance postoperative recovery speed and patient satisfaction.
However, this study has some limitations. First, this was conducted at a single centre with a relatively small sample size, potentially introducing selection bias. As such, further verification using larger, multicentre datasets is warranted to validate the study's results. Second, the scope of relevant factors considered in this study was limited, potentially overlooking certain risk factors associated with PONV. Follow-up studies can further expand patient data based on this study, identifying screen indicators with stronger correlations to PONV to establish a more precise prediction model. In this study, a nomogram model for predicting PONV was constructed by combining three independent risk factors identified through multivariate regression analysis. This model serves to optimise the preoperative evaluation system for caesarean sections, formulate individualised perioperative management strategies, accelerate recovery, and improve prognosis.