Abstract: Objective To explore the application effect of comprehensive assessment with "fishtail ruler" on reducing perineal injury. Methods A total of 400 cases of patients with full-term pregnancy, presenting no contraindications of vaginal delivery from July 2018 to June 2019 in Zhongshan Boai Hospital were divided into control group and observation group, with 200 cases in each group. In the control group, traditional perineal protection measures were implemented while in the observation group, comprehensive assessment with "fishtail ruler" was performed to measure the anterior and posterior diameter of perineum body and vaginal opening before perineal protection measures were implemented. Results There were 35 cases without perineal tear, 40 of lateral episiotomy, 55 of first-degree tear, 70 of second-degree tear and no case of third-degree or fourth-degree tear in the observation group and in the control group, there were 10 cases without perineal tear, 30 cases of first-degree tear, 99 of second-degree tear and 1 of third-degree tear. The case of lateral perineal incisions and deep perineal laceration in the observation group was significantly less than that in the control group, and the difference was statistically significant (P<0.05). Conclusion Comprehensive assessment with "Fishtail Ruler" is accurate and quantitative, which guides the midwife to take perineal protection measures timely, thus to reduce unnecessary episiotomy and perineal laceration during childbirth.

Key words: fishtail ruler, perineal length measurement, comprehensive assessment, perineal protection