Helical structure of the human umbilical cord

Abstract

The helical structure of the human umbilical cord has been studied on 528 full-term cords from normal deliveries, 18 cords from aborted and developmentally normal fetuses with a CR length of 1.2–19.5 cm, and 10 cords from monozygotic twins. In order to resolve the discrepancy in the nomenclature of the twist direction, a method has been suggested which takes into account the direction to which the fetus must have rotated to produce the twist. The incidence of the right helical pattern was 64.58%, of the left helical pattern 15.15%, and of the mixed patterns 17.43%; the twists were indeterminate in 1.89% and absent in 0.95% of the cords. Details of the mixed patterns are listed. The number of the uniform right twists ranged from 1 to 29 (7.5) and that of the left twists from 1 to 19 (6.7). There exists an exponential relation between the number of the twists and the ratio between length and thickness of the cords. The twists begin to appear during the early part of the 8th week, and their final number is possibly attained soon after the 9th week of development. In view of the absence of concordance in monozygotic twins, the helical nature of the cord is possibly controlled by factors which may be partly genetic and partly environmental.

Morphometry of Umbilical Cord and Its Relation With Umbilical Arteries- A Foetal Study

“…According to Chaurasia (1979) the true aetiology of umbilical cord coiling is unclear, but it is thought to result from foetal movements as well as unequal vascular growth. 11 According to Percy Malpas (1966), helical structure of the cord results from the reciprocal action between the intrinsic structures of the vessel walls on the one hand and the pressure, volume and flow rate of foetal blood on the other. 12 Number of complete twists present in these undistorted cords ranged between 8 and 16.…”

Natural and artificial helical structures

“…Normal human umbilical cords have two small arteries and one large vein. Typically, the two arteries are spiraled around the vein, running a helical course through the umbilical cord [13][14][15], as shown in fig. 4.…”

“…It has been reported that the helical nature of the cord is possibly controlled by factors which may be partly genetic and partly environmental [15]. However, this configuration can vary, implying alterations to the blood supply.…”

Sonographic assessment of the umbilical cord

“…The true etiology of umbilical coiling is unclear, but it is thought to result from fetal movement as well as unequal vascular growth. 37,38 It appears that umbilical coiling pattern is established in the first trimester, although the presence of a mixed coiling pattern and even reversal of coiling direction in third trimester has been demonstrated. 39 The normal umbilical cord coiling is approximately one coil per 5 cm of umbilical cord length, or 0.20-0.24 coils per cm.…”