Severe perineal morbidity of instrumental deliveries using Thierry's spatulas and vacuum extraction: A prospective observational cohort study

To evaluate the risk of severe perineal tear following instrumental vaginal delivery (IVD) performed with spatulas and vacuum extraction. Secondary objectives were to estimate the impact of episiotomy on this risk. From December 2008 to October 2012, women who underwent spatulas or vacuum were prospectively included. Each spontaneous vaginal delivery (SVD) following each included IVD were included as control cases (1-1 ratio). Careful perineal examination was systematically performed. Severe perineal tear was defined by the occurrence of anal sphincter rupture with or without anal mucosa tear. A total of 761 patients were included in the current study: 248 (64%) spatulas, 137 (36%) vacuums and 381 (49%) SVDs. Severe perineal tear was diagnosed in 19 (2.5%) cases. Episiotomy had been performed in 276 (36.9%) patients. Only spatulas extraction was found to significantly increase the risk of severe perineal tear (AOR=7.66; 95% CI: 2.06-28; P=0.02). Although vacuum extraction seemed to increase this risk, it was not found to be significant (AOR=3.25; 95% CI: 0.65-16.24; P=0.15). No significant difference was observed between the risk of severe perineal tear following spatulas and vacuum (AOR=2.36; 95% CI: 0.63-8.82; P=0.202). Finally, neither foetal macrosomia, nor episiotomy, nor foetal extraction with the head in the deep pelvis, nor delivery at night had a significant impact on the probability of severe perineal tear. Spatulas extraction is an independent risk factor for severe perineal tear. The practice of episiotomy was not shown to have any significant impact on this risk.