Abstract
Abstract Introduction and hypothesis We compared hands-on manual perineal protection (MPP) and hands-off delivery techniques using the basic principles of mechanics and assessed the tension of perineal structures using a novel biomechanical model of the perineum. We also measured the effect of the thumb and index finger of the accoucheur’s dominantposterior hand on perineal tissue tension when a modified Viennese method of MPP is performed.
Methods Hands-off and two variations of hands-on manual perineal protection during vaginal delivery were simulated using a biomechanical model, with the main outcome measure being strain/tension throughout the perineal body during vaginal delivery. Results Stress distribution with the hands-on model shows that when usingMPP, the value of highest stress was decreased by 39 % (model B) and by 30 % (model C) compared with the hands-off model A.
On the cross section there is a significant decrease in areas of equal tension throughout the perineal body in both hands-on models. Simulation of the modified Viennese MPP significantly reduces the maximum tension on the inner surface of the perineummeasured at intervals of 2mmfromthe posterior fourchette.
Conclusions In a biomechanical assessment with a finite element model of vaginal delivery, appropriate application of the thumb and index finger of the accoucheur’s dominant-posterior hand to the surface of the perineum during the second stage of delivery significantly reduces tissue tension throughout the entire thickness of the perineum; thus, this intervention might help reduce obstetric perineal trauma.