Decreased adherence and spontaneous separation of fetal membrane layers – amnion and choriodecidua – a possible part of the normal weakening process

Strohl, A.; Kumar, D.; Novince, R.; Shaniuk, P.; Smith, J.; Bryant, K.; Moore, R.M.; Novak, J.; Stetzer, B.; Mercer, B.M.; Mansour, J.M.; Moore, J.J.

doi:10.1016/j.placenta.2009.10.012

« Previous Next »Placenta
Volume 31, Issue 1 , Pages 18-24, January 2010

Decreased adherence and spontaneous separation of fetal membrane layers – amnion and choriodecidua – a possible part of the normal weakening process☆

A. Strohl
- Departments of Pediatrics, Case Western Reserve University (CWRU), MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, USA
D. Kumar
- Departments of Pediatrics, Case Western Reserve University (CWRU), MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, USA
R. Novince
- Departments of Pediatrics, Case Western Reserve University (CWRU), MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, USA
P. Shaniuk
- Departments of Pediatrics, Case Western Reserve University (CWRU), MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, USA
J. Smith
- Departments of Pediatrics, Case Western Reserve University (CWRU), MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, USA
K. Bryant
- Departments of Pediatrics, Case Western Reserve University (CWRU), MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, USA
R.M. Moore
- Departments of Pediatrics, Case Western Reserve University (CWRU), MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, USA
J. Novak
- Departments of Pediatrics, Case Western Reserve University (CWRU), MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, USA
B. Stetzer
- Reproductive Biology, Case Western Reserve University (CWRU), MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, USA
B.M. Mercer
- Reproductive Biology, Case Western Reserve University (CWRU), MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, USA
J.M. Mansour
- Mechanical and Aerospace Engineering, Case Western Reserve University (CWRU), 10900 Euclid Avenue, Cleveland, OH, USA
J.J. Moore
- Departments of Pediatrics, Case Western Reserve University (CWRU), MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, USA
- Reproductive Biology, Case Western Reserve University (CWRU), MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, USA
- Corresponding author and reprint requests: John J. Moore, MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, Ohio 44109, USA. Tel.: +1 216 778 5909(W); fax: +1 216 778 3252.

Accepted 27 October 2009. published online 18 November 2009.

Abstract

Introduction

The fetal membrane (FM) layers, amnion and choriodecidua, are frequently noted to have varying degrees of separation following delivery. FM layers normally separate prior to rupture during in vitro biomechanical testing. We hypothesized that the adherence between amnion and choriodecidua decreases prior to delivery resulting in separation of the FM layers and facilitating FM rupture.

Methods

FM from 232 consecutively delivered patients were examined to determine the extent of spontaneous separation of the FM layers at delivery. Percent separation was determined by the weight of separated FM tissue divided by the total FM weight. Separately, the adherence between intact FM layers was determined. FM adherence was tested following term vaginal delivery (13), term unlabored cesarean section (10), and preterm delivery (6).

Results

Subjects enrolled in the two studies had similar demographic and clinical characteristics. FM separation was present in 92.1% of membranes. Only 4.3% of FM delivered following spontaneous rupture of the fetal membranes (SROM) had no detectable separation. 64.7% of FM had greater than 10% separation. FM from term vaginal deliveries had significantly more separation and were less adherent than FM of term unlabored, elective cesarean section (39.0±34.4% vs 22.5±30.9%, p=.046 and 0.041±0.018N/cm vs 0.048±0.019N/cm, p<.005). Preterm FM had less separation and were more adherent than term FM (9.95±17.7% vs 37.5±34.4% and 0.070±0.040N/cm vs 0.044±0.020N/cm; both p<.001).

Conclusions

Separation of the amnion from choriodecidua at delivery is almost universal. Increased separation is associated with decreased adherence as measured in vitro. Increased separation and decreased adherence are seen both with increasing gestation and with labor suggesting both biochemical and mechanical etiologies. The data are consistent with the hypothesis that FM layer separation is part of the FM weakening process during normal parturition.

Keywords: Fetal membranes, Biomechanics, Amnion, Choriodecidua, T-peel test

Abbreviations: FM, Fetal Membranes, ROM, Rupture of Membranes, PROM, Premature Rupture of Membranes, SROM, Spontaneous Rupture of Membranes, AROM, Artificial Rupture of Membranes, SVD, Spontaneous Vaginal Delivery