Purpose The primary aim of this study was to observe the change in obstetric anal sphincter tear rates in instrumental deliveries during one decade. Secondly, the changes in non-instrumental deliveries were followed. Methods Data from all deliveries at Hudiksvall Hospital, Sweden 2010–2011 and 2016–2017 were collected. The change of OASIS rate during instrumental deliveries was the most important. Statistical significances were calculated by using chi-square test, test for relative proportions, and Students t-test, where appropriate. Results The total incidence of OASIS decreased significantly (from 2.54% to 0.73%, p < .001). Even the OASIS rate in instrumental deliveries decreased substantially from 15.1% to 3.0% (p = .002) but the decrease was statistically insignificant in spontaneous deliveries (from 1.22% to 0.60%, p = .065). Conclusion Based on the results of our study the manual protection of the perineum reduces the risk of OASIS in instrumental delivery significantly.
Read full abstract