Amniotic sheets: natural history and histology.

Abstract

Eleven amniotic sheets were detected on obstetric ultrasound. Ten of these were reviewed retrospectively and one was followed prospectively throughout gestation. Amniotic sheets are single, planar reflective membranes. Evidence presented here suggests that these membranes are composed of four distinct layers: two layers of chorion sandwiched between two layers of amnion. Their mean thickness is 2.4 mm in the

Measurement of Amniochorionic Membrane Thickness Using High-Frequency Ultrasound

“…One important indication for the existence of a physiological function of the membrane apart from having a regular layer structure, in our opinion, lies in its substantive thickness: swelling of the membranes caused by amniotic sheets as shown by Stamm et al (1991) or by amniotic bands may have a negative effect of fetal outcome. A decrease in membrane thickness not only impairs the physical barrier function of the membranes, but also decreases the exchange between the paraplacental unit and the maternal organism (Burrows et aZ., 1982;Hertzberg et al, 1987).…”

“…The use of conventional transabdominal ultrasound for viewing echogenic membranes in the amniotic cavity in twin pregnancies as well as in chorionic separations was described, among other things by Stamm et al (1991). Sonographic systems with ultrasonic frequencies of 3-5-50 MHz (e.g., a vaginal scanner) allow for only a rather vague evaluation of the membrane under examination.…”

Doppler Flow Velocimetry Assisted Diagnosis of an Intrauterine Synechia During Pregnancy

“…[1][2][3][4][5] While the former have been associated with transverse reduction defects or the lethal amniotic band syndrome, 6 the latter are usually benign and consist of a preexisting uterine septation or synechiae around which the fetal membranes fold. 7 The uterine synechia is a fibrous band or scar usually resulting from previous uterine insult including curettage, spontaneous abortion, endometritis, or cesarean delivery.…”

Umbilical cord prolapse through a transverse uterine synechia

“…Hence, the fetus is exposed only to the intact amnion and is, therefore, protected from the potential disruptive effects associated with the amniotic band syndrome. 1 In this case, the intact amniochorionic membrane folded around a uterine synechia. The association between uterine synechiae and prior uterine procedures (i.e., dilatation and curettage) has been well documented for over 40 years.J .. An amniotic sheet may become compressed against the uterine wall or simply rupture owing to the increase in tensile strength placed on it by the enlarging uterus.…”