Abstract
During certain clinical situations, some parturients require instruments for operative vaginal delivery, and various designs of vacuum extractors may affect the fetal head. To investigate the biomechanical effects of divergent sizes of silicone rubber vacuum extractors, we employed finite element analysis in this study. First, we constructed computer models for different vacuum extractor sizes (diameters: 40 mm, 50 mm, 60 mm, and 70 mm), flat surface, hemispherical ball, and fetal head shape. A hemispherical ball was the main design for the vacuum extractor model, and the material used for the vacuum extractor was silicone rubber. Next, the settings of 1 mm vacuum extractor displacement and vacuum cap pressure of 60 cmHg were applied. The main observation markers of this study were the respective von Mises stresses on the vacuum extractor and skull by the reaction force on the fixed end. The concluded results revealed that vacuum extractors with larger diameters lead to greater reaction force, stress, and strain on fetal heads. Therefore, this study’s biomechanical analytic consequences suggest that clinicians avoid selecting larger vacuum extractors during operative instrumental delivery so that fetal heads will experience less external force, deformation, and resultant complications. It could also provide a practical reference for obstetricians for instrumental vaginal delivery with the vacuum extractor made of silicone rubber.
Highlights
Introduction12% of deliveries require instrumental aid under special circumstances for a successful delivery
The American College of Obstetricians and Gynecologists (ACOG) published guidelines on the use of operative vaginal delivery, which included a list of indications for its use such as prolonged second stage of labor, nonreassuring fetal status, elective shortening of the second stage of labor, and maternal exhaustion [2]
This study employed finite element analysis to examine the biomechanics of different diameters of silicone rubber vacuum extractors
Summary
12% of deliveries require instrumental aid under special circumstances for a successful delivery. Such deliveries can be classified as forceps-assisted and vacuum extractor suction deliveries [1]. In. 2017, 3.1% of all deliveries were accomplished by an operative vaginal approach [3]. The most significant disadvantage of using instruments for operative vaginal approach is that there is a higher chance of having a vaginal tear that involves the muscle or wall of the anus or rectum, known as a third- or fourth-degree perineal laceration; the overall risk of complications due to the use of obstetrical forceps is higher than the use of vacuum extractors; the use of vacuum extractors has a lower risk of vaginal tearing and many clinicians employ vacuum extractors to perform operative vaginal deliveries at present [4–7]
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