A New Methodology to Measure Strength of Adherence of the Fetal Membrane Components, Amnion and the Choriodecidua

Abstract

We have previously shown that separation of the amnion from choriodecidua occurs as an integral part of the fetal membranes (FM) rupture process. We have also reported that spontaneous separation of FM is nearly universal with term vaginal delivery. The etiology of this spontaneous FM separation is unknown. If biochemical degradation at the amnion-choriodecidua interface is a factor, decreased adhesive force between the FM components prior to their complete separation would be expected. The purpose of this project was to develop and validate machinery and procedures to measure the adhesive force between amnion and choriodecidua. Commercial tensile testing equipment was adapted to perform a standard T-peel test, per the American Society for Testing and Materials (ASTM) guidelines. FM test strip dimensions, peel speed, and peel force data measurements from force versus displacement curves were optimized for reproducibility. Test system validation was performed using Shurtape CP 60 (slow release painter's masking tape) as the standard. Equipment and procedures for a standard T-peel test on FM were developed. Shurtape CP 60 of decreasing widths showed reproducible, linear changes in the adhesive force range for FM (r 2 = 0.96). The adhesive force between FM components ranged from 0.017-0.262 N/cm. Reproducibility was optimal with FM test strips of 4x6 cm and a peel speed of 25.4 cm/min. FM showed greater adhesive force adjacent to the placental disc than distal from the disc (p<0.05). We have developed equipment and procedures to accurately and reproducibly measure adhesive force between the FM amnion and choriodecidua.

Weakening and Rupture of Human Fetal Membranes – Biochemistry and Biomechanics

“…Discovery that FM (amnion and choriodecidua) separate during the process of rupture led to development of equipment to measure their adherence and allowed us demonstrate that FM peel apart and become less adherent with increasing gestation (Kumar et al, 2009;Strohl et al, 2010). Commercial industrial tensile testing equipment (Com-Ten) was adapted to perform a standard engineering T-peel test to measure the adhesive force of FM (Fig.…”

“…) [R.M. Moore et al, 2009]. The mechanism of Lipoic acid action is unclear but this effect on FM is not isolated.…”

Biomechanics of fetal membranes – relation with newborn and maternal anthropometric data

“…The machine has a wide speed range (1 -100 mm/min). Our samples were stretched at the speed of 25.4 mm/min which was also used in previous studies (8,9). The data from the machine was collected and analyzed via software that was provided with digital sensor.…”

“…The membranes tend to twist and break quite easily. For uniaxial test, we wrapped the strip's ends with filter paper to prevent the strip from twisting (4,9,11). Furthermore, such handling alleviated the problems with sample fixation between clamps.…”

Neurosurgical patties: adhesion and damage mitigation

“…Previous studies have adopted a wide range of peel rates, from 0.04 mm/sec 11 to 166.6 mm/sec. 9 Without an established standard for biomaterial-on-tissue peel tests, we considered 5 mm/sec to be the most appropriate rate, similar to rates used by Bundy et al 3 and Kumar et al 10 The quicker peel rate condition (speed) was 20 mm/sec because this rate was visually quicker than rates observed in neurosurgical practice. Each patty was placed onto the white matter of its corresponding brain slice.…”