Abstract: ObjectiveTo evaluate the risk factors of clinical and ultrasound characteristics in the metastasis of lymph node posterior to right recurrent laryngeal nerve (LN-prRLN) in papillary thyroid carcinoma (PCT). MethodsA total of 158 PCT patients in the right lobe or double lobe who were operated in Suqian People′s Hospital Affiliated to Xuzhou Medical University from January 2016 to December 2019 were enrolled and their clinical data were retrospectively analyzed. According to the presence of LN-prRLN in postoperative pathological examination, the patients were divided into two groups: a metastasis group (n=34) and a control group (n=124). Both groups were compared for clinical and ultrasound characteristics. Logistic multivariable regression analysis was used to evaluate the risk factors related to LN-prRLN metastasis. ResultsIn the current study, the LN-prRLN metastasis rate in PCT patients was 21.52% (34/158). There were significant differences between the LN-prRLN metastasis group and the control group in age,tumor diameter, extracapsular invasion, multifocality, the metastasis of prelaryngeal lymph nodes and lymph nodes anterior to right recurrent laryngeal nerve (LN-arRLN), and ultrasound-determined tumor contact capsule (P< 0.05). Logistic multivariable regression analysis showed that tumor diameter in the right lobe, extracapsular invasion, the metastasis of prelaryngeal lymph nodes and LN-arRLN were significantly correlated with LN-prRLN metastasis (P< 0.05). The ROC curve showed that the optimal cut-off value of tumor diameter in the right lobe to predict the metastasis of LN-prRLN was 12.7 mm (AUC=0.72), with a sensitivity of 74.3%and a specificity of 72.9%. ConclusionsProphylactic lymph node dissection is suggested for PCT patients with a tumor diameter≥12.7 m min the right lobe, extracapsular invasion,the metastasis of prelaryngeal lymph nodes and LN-arRLN.