Modeling manual perineal protection during vaginal delivery.

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 dominant-posterior 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 using MPP, 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 perineum measured at intervals of 2 mm from the 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.

Stereophotogrammetry of the perineum during vaginal delivery.

OBJECTIVE: To analyze deformation of the perineum during normal vaginal delivery in order to identify clinical steps that might be beneficial when executing manual perineal protection. METHODS: The present prospective study at Charles University Hospital, Pilsen, Czech Republic, enrolled 10 primiparous women at term undergoing non-instrumental vaginal delivery assisted by the same obstetrician between September 2009 and September 2010. A modified hands-poised technique performed concurrently with stereophotogrammetry was used to analyze and quantify perineal deformation and strain at the final stage of delivery. RESULTS: The highest tissue strain (mean, 177%; 95% confidence interval [CI], 106.3-248.5) was in a transverse direction and occurred at the level of the fourchette (i.e. 1cm was transversely stretched and deformed to 2.77 cm during the final stage of vaginal delivery). This strain was more than 4 times higher than the maximum anteroposterior strain (mean, 43%; 95% CI, 28.6-57.4). CONCLUSION: On the basis of these stereophotogrammetry data, a technique of perineal protection executed by fingers of the posterior (right) hand can be proposed. Further experimental and clinical studies are needed to evaluate whether this technique might assist in reducing obstetric perineal trauma.

Importancia del ángulo de la episiotomía / Significance of the angle of episiotomy

La metodología de los estudios que evalúan el papel de la episiotomía mediolateral carece de la calidad necesaria y no puede extraerse actualmente de ellos conclusión alguna acerca del traumatismo perineal grave y la incontinencia anal. Se identificaron cuatro problemas: la definición y la ejecución práctica de la episiotomía mediolateral, y el diagnóstico y clasificación del traumatismo perineal. La definición y ejecución de la episiotomía mediolateral difieren ampliamente entre las distintas instituciones y los distintos individuos. El problema principal es la precisión de la dirección elegida. Se introdujeron tres términos: ángulo de incisión, de sutura y de cicatrización de episiotomía. Anteriormente, la episiotomía mediolateral se definía por un ángulo de incisión mínimo de 40°. Sin embargo,cuando se incide a 40°, el ángulo mediano luego de la reparación era de 20°, mientras que el ángulo de cicatrización era de 30° en los casos de desgarros de tercer grado frente a 38° en los controles. Al usar un ángulo de incisión de 60°, el ángulo mediano de sutura fue de 45° y el de cicatrización de 48°. Actualmente se propone que la episiotomía mediolateral se defina como “una incisión en el perineo durante la última parte de la segunda etapa del trabajo de parto, que comienza en el perineo medial pero se dirige lateralmente en un ángulo de al menos 60° en dirección de la tuberosidad isquial”. Se requieren más investigaciones para evaluar la seguridad de este ángulo de incisión.