Pelvic floor muscle function in the third trimester of pregnancy: extensibility and muscle strength

Abstract

The function of the pelvic floor muscles (PFM) in pregnant women has always been evaluated to verify the patient´s ability to contract perineal muscles and to identify possible dysfunctions, using reproductive methods with proven validity such as vaginal palpation by Oxford Scale, perineal dynamometer and Surface Electromyography (sEMG). Currently using the Epi-no®, the perineal extensibility has also been measured in this population. This is possible, due to the characteristics of the equipment that has a silicone balloon that when positioned and inflated in the vaginal canal that stretches the PFM in a homogenous way, and after analyzing the maximum perimeter in cm, we can predict about the perineal integrity during childbirth.It is known that skeletal muscle may have a tension gradually decreased when stretched beyond its resting length because of the distance between the actin and myosin filaments. As we do not know how the PFM behave under an acute stretching, likely to interfere or not in its muscle tone or strength, the aim of this study is to investigate the role of PFM in the third trimester of pregnancy analyzing the possible correlation between electrical activity (sEMG), perineal dynamometer, vaginal palpation (Oxford) and extensibility perineal (Epi-no®).Observational and cross-sectional study with sample of 60 healthy pregnant women with no cervical dilation, single fetus with a gestational age between 35th to 40th week of pregnancy and maternal age ranged from 15 to 40 years. We excluded patients with genital bleeding of any origin, multiple pregnancy, lower urinary tract infection at the time of examination or absence of perineal contraction. For electromyographic evaluating, the patient will be positioned on her back, with flexed knee and hip, the vaginal probe with two opposing metal parts placed on the distal vaginal canal to record basal myoelectric activity, followed by three maximal contraction (MVC) in the maximum time achieved by the pregnant woman in 10 seconds (30 seconds rest between them) and resting for 60 seconds in each series. The best of three sustained contractions and voluntary (MVC) will be selected for data analysis. Then it will be positioned in the vaginal canal the perineal dynamometer, as a sensor similar to perineometer, to record the basal activity and MVC following the same protocol performed in the collection of sEMG. After, the researcher through vaginal palpation, will verify the strength of pelvic floor muscles by the Oxford Scale, grading the muscle contractility form 0 a 5. After that, the Epi-no® will introduced in the vaginal canal, which being inflated to the maximum extent of discomfort reported by the patient, was slowly withdrawn while keeping the balloon inflated and measured with a tape measure the largest part of the perimeter. For the correlation between the values observed in the circumference measurement of perineal extensibility with Epi-no®, with those found in the sEMG, perineal dynamometer and the Oxford Scale in which Pearson's correlation coefficient was used with significance level of 5% (0.05). (AU)