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OBJECTIVE: This study describes the frequency of obstetric anal sphincter injuries (OASIS) in patients after instrumental delivery according to the type of forceps used. METHODS: A retrospective comparative cohort study was conducted on patients who underwent instrumental delivery from January 2017 to April 2022. The primary outcome was the presence of OASIS following delivery. Patients were categorized into Cohort A if only rotation forceps were used, Cohort B for only traction forceps, and Cohort C if both types were used sequentially. Statistical analysis was performed with SPSS (IBM, New York, NY) with χ2, Fisher's exact, and analysis of variance testing. A P-value <0.05 was considered significant. RESULTS: OASIS occurred in 45 of 328 instrumental deliveries. OASIS after rotation forceps occurred in 12.9% (n = 8) of cases, after traction forceps in 13.2% (n = 34), and after sequential use of rotation and traction forceps in 37.5% (n = 3) of cases (p = 0.141). An odds ratio (OR) of 0.91 (95% confidence interval [CI] 0.40-2.08) for OASIS was obtained with the use of rotation forceps, 0.81 (95% CI 0.38-1.70) for traction forceps, and 3.97 (95% CI 0.91-17.2) for the sequential use of rotation and traction forceps. CONCLUSION: There were no significant differences in the presence of OASIS comparing traction and rotation forceps. A non-significant trend of higher OASIS following the sequential use of traction and rotation forceps was observed.
RESUMEN
OBJECTIVE: We aimed to determine whether a threshold number of forceps deliveries in residency predicts use of forceps in independent practice. STUDY DESIGN: We surveyed obstetrics and gynecology residency graduates of 2 academic programs from 2008 through 2012 regarding the use of operative vaginal delivery in practice. At these programs, residents are trained in both forceps and vacuums. Individual case log data were obtained with the number of forceps deliveries performed by each respondent during residency. Respondents were grouped as currently using any forceps or vacuums alone. A logistic regression model estimated the probability of forceps use, predicted by the number of residency forceps deliveries. From the resulting receiver-operating characteristic curve, we assessed sensitivity, specificity, positive predictive value, and area under the curve. RESULTS: The response rate was 85% (n = 58) and 90% (n = 52) practice obstetrics. Seventy-nine percent (n = 41) use forceps in practice. The mean number of forceps performed during residency was 22.3 ± 1.3 (mean ± SE) in the any-forceps group and 18.5 ± 2.1 in the vacuums-only group (P = .14). Although the model performed only moderately (area under the curve, 0.61, 95% confidence interval [CI], 0.42-0.81), more than 13 residency forceps deliveries corresponded to a 95% sensitivity (95% CI, 84-99) and a positive predictive value of 83% (95% CI, 69-92) for using forceps in practice. The specificity of this threshold is 27% (95% CI, 6-61). CONCLUSION: Although exceeding 13 forceps deliveries made it highly likely that obstetricians would use them in practice, further study is necessary to set goals for a number of resident forceps deliveries that translate into use in practice.