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Cited by 40Pregnancy and preeclampsia studiesCongenital Anomalies and Fetal SurgeryMaternal and Perinatal Health Interventions

Pathophysiological significance of abnormal umbilical cord coiling index

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Sebire, N. J.·2007·Ultrasound in Obstetrics & Gynecology
DOI 10.1002/uog.5180
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Abstract

In this issue, Cromi et al. report that sonographic assessment of cross-sectional umbilical cord area can predict fetal macrosomia1. This is the latest of numerous recent studies that have investigated the possible relationship between umbilical cord characteristics and fetal outcome, including cord thickness, but particularly in relation to umbilical cord coiling. The phenomenon of coiling of the vessels within the umbilical cord in a regular helical pattern has long been recognized, but its precise underlying causative mechanism and presumed developmental benefit remain uncertain. In the pathology literature, focal tight twisting of the umbilical cord has been associated with a proportion of intrauterine deaths, although the clinical significance of this association has remained unclear. Some have suggested that focal coiling is a consequence, rather than a cause, of intrauterine demise, whereas others have postulated that the overcoiled cord may in itself be a contributory factor to fetal death2. Numerous investigators have recently attempted to study further the relationship between the coiling pattern of the umbilical cord and a range of pregnancy complications, with initial studies focusing on the association between undercoiled cords and adverse outcomes3, 4. Several subsequent larger pathological studies, based on examination of the delivered placenta, have confirmed these associations and, in conjunction with the recognition that umbilical cord coiling could be determined antenatally by ultrasound examination5, 6, additional reports have suggested a relationship between extremes of abnormal cord coiling and diverse adverse pregnancy outcomes3-17. This Opinion aims to place such findings in context and provide a summary of the current state of knowledge regarding cord coiling and pregnancy outcome. The generally accepted method of assessing the degree of the umbilical cord coiling is by calculation of the umbilical coiling index (UCI), defined as the number of complete coils per centimeter length of cord3. Using this criterion, studies to date have been remarkably consistent in reporting of the normal UCI, which is around 0.2 in the postpartum setting following examination of the delivered placenta and umbilical cord (pUCI) and 0.4 when determined antenatally by sonography (aUCI)18, 19. This apparent discrepancy, with increased coiling identified in utero, presumably is simply a reflection of the fact that the umbilical vessels are distended with fetal blood antenatally and this simple mechanical distension will result in a tighter apparent coiling of helical vessels. In order to compare the results of various studies, undercoiled/hypocoiled cords have been defined as those with an UCI < 10th centile, whereas overcoiled/hypercoiled cords are defined as those with an UCI > 90th centile. Such studies have determined that the degree of cord coiling can be reliably identified sonographically from the first trimester and that the UCI is related to gestation and the site of sampling (coiling being greater towards the fetal end of the cord)20. The mechanism by which physiological coiling occurs still, however, remains undetermined, with speculation that it may be related to early fetal activity and hemodynamic factors (supported by the finding of increased coiling in the recipient twin in twin-to-twin transfusion syndrome), or other anatomical issues such as the presence of Roach muscle21, 22. Although an association between the aUCI and pUCI is present, which is not surprising as both are a measure of the same phenomenon, antenatal sonographic determination of UCI has a low sensitivity (40%) for predicting the presence of undercoiling or overcoiling as determined by postnatal cord examination16. Therefore, it appears that the antenatal and postnatal coiling indices may not represent measurements of exactly the same process (see previous comment regarding vascular distension in utero); some cases that appear overcoiled or undercoiled on antenatal examination are within the normal range after delivery, and vice versa. Nevertheless, despite these findings of apparent discordance, numerous studies have reported a range of adverse outcomes in association with abnormal cord coiling, detected either prenatally or postnatally (Tables 1 and 2). Essentially, it appears that hypocoiled cords are predominantly associated with an increased frequency of intrauterine death, low Apgar score, the presence of fetal congenital anomalies such as trisomies, and other abnormalities of placental development such as velamentous insertion and presence of a single umbilical artery. Such undercoiled cords are not generally associated with intrauterine growth restriction, fetal acidosis or asphyxia. Hypercoiled cords also appear to be associated with fetal abnormalities such as trisomies and single umbilical artery. However, in contrast to undercoiled cords, they are not associated with an increased likelihood of intrauterine death

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  1. Strong TH Jr, Manriquez-Gilpin MP, Gilpin BG. Umbilical vascular coiling and nuchal entanglement. J Matern Fetal Med 1996; 5: 359-361.

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Authors
Sebire, N. J.
Affiliations
Great Ormond Street Hospital (GB)
Corresponding author
Sebire, N. J.
ORCID
Sebire, N. J.
Venue
Ultrasound in Obstetrics & Gynecology
Publisher
Wiley
Published
2007-10-25
Volume
30
Issue
6
Pages
804-806
ISSN
  • 0960-7692 (ISSN-L)
  • 1469-0705
DOI
10.1002/uog.5180
OpenAlex
W2094086451
Cited by
40
References
25
Citations by year
2026: 1 · 2025: 4 · 2024: 1 · 2023: 5 · 2022: 2 · 2021: 3 · 2020: 2 · 2019: 2 · 2018: 3 · 2017: 1 · 2016: 2 · 2014: 2 · 2013: 2 · 2012: 2
FWCI
2.73
Type
journal article
Language
en
Open access
Licence
onlinelibrary.wiley.com/termsAndConditions#vor (vor)
Locations
  • Ultrasound in Obstetrics and Gynecology (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Health Sciences › Medicine › Obstetrics and Gynecology › Pregnancy and preeclampsia studies
  • Health Sciences › Medicine › Surgery › Congenital Anomalies and Fetal Surgery
  • Health Sciences › Medicine › Obstetrics and Gynecology › Maternal and Perinatal Health Interventions
Keywords
umbilical cord coiling, umbilical coiling index, macrosomia, fetal growth restriction, fetal death, prenatal ultrasound, fetal outcomes, placental examination, fetal blood volume, fetal hypoxia, fetal acidosis, fetal hypoglycemia
MeSH terms
Female, Fetal Death, Fetal Macrosomia, Humans, Infant, Newborn, Male, Pregnancy, Pregnancy Outcome, Umbilical Cord, Ultrasonography, Prenatal

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