Hypercoiling of the umbilical cord in uncomplicated singleton pregnancies

Umbilical cord coiling index for the prediction of adverse pregnancy outcomes: a meta-analysis and sequential analysis

Purpose: To evaluate the potential association of abnormal cord coiling with adverse pregnancy outcomes.Materials and methods: We used the Medline (1966-2018), Scopus (2004-2018), Clinicaltrials.gov (2008-2018), Embase (1980-2018), Cochrane Central Register of Controlled Trials CENTRAL (1999-2018), and Google Scholar (2004-2018) databases. The date of last search was set on 31 May 2018. Language, country, or date restrictions were not applied during the literature research to prevent bias. All observational (both prospective and retrospective) studies that reported maternal and neonatal antenatal and perinatal outcomes based on the umbilical coiling index (UCI) status were considered as eligible for inclusion. Meta-analysis of the risk ratio (RR) and mean differences (MD) among hypocoiled/hypercoiled and normocoiled cases was performed with RevMan 5.3 software. Univariate metaregression and leave-one-out meta-analysis was performed with Open Meta-Analyst statistical software. Trial sequential analysis was performed with the trial sequential analysis (TSA) software.Results: Twenty four studies were finally included that involved 9553 pregnant women. Umbilical cord coiling was evaluated with the use of the umbilical coiling index (UCI). Values of the UCI below the 10th percentile were evaluated as hypocoiled and above the 90th percentile as hypercoiled. Hypocoiled cords were significantly associated with increased prevalence of preterm birth < 37 weeks, need for interventional delivery due to fetal distress, meconium stained liquor, Apgar scores < 7 at 5 min, small for gestational age (SGA) neonates, fetal anomalies, need for admission in the neonatal intensive care unit (NICU), fetal heart rate abnormalities, and fetal death. Hypercoiled cords were significantly associated with increased prevalence of preterm birth < 37 weeks, need for interventional delivery due to fetal distress, meconium stained liquor, Apgar scores < 7 at 5 min, small for gestational age (SGA) neonates, fetal anomalies, fetal growth restriction fetal heart rate abnormalities, fetal acidosis, and fetal death.Conclusions: The findings of our meta-analysis underline the correlation of UCI abnormalities with antenatal and perinatal pathology. More studies are needed, however, to elucidate whether antenatal assessment of the UCI can be used as routine in clinical practice as well as its value in uncomplicated pregnancies.

Umbilical cord characteristics and their association with adverse pregnancy outcomes: A systematic review and meta-analysis

Objective

Current data on the role of the umbilical cord in pregnancy complications are conflicting; estimates of the proportion of stillbirths due to cord problems range from 3.4 to 26.7%. A systematic review and meta-analysis were undertaken to determine which umbilical cord abnormalities are associated with stillbirth and related adverse pregnancy outcomes.

Methods

MEDLINE, EMBASE, CINAHL and Google Scholar were searched from 1960 to present day. Reference lists of included studies and grey literature were also searched. Cohort, cross-sectional, or case-control studies of singleton pregnancies after 20 weeks’ gestation that reported the frequency of umbilical cord characteristics or cord abnormalities and their relationship to stillbirth or other adverse outcomes were included. Quality of included studies was assessed using NIH quality assessment tools. Analyses were performed in STATA.

Results

This review included 145 studies. Nuchal cords were present in 22% of births (95% CI 19, 25); multiple loops of cord were present in 4% (95% CI 3, 5) and true knots of the cord in 1% (95% CI 0, 1) of births. There was no evidence for an association between stillbirth and any nuchal cord (OR 1.11, 95% CI 0.62, 1.98). Comparing multiple loops of nuchal cord to single loops or no loop gave an OR of 2.36 (95% CI 0.99, 5.62). We were not able to look at the effect of tight or loose nuchal loops. The likelihood of stillbirth was significantly higher with a true cord knot (OR 4.65, 95% CI 2.09, 10.37).

Conclusions

True umbilical cord knots are associated with increased risk of stillbirth; the incidence of stillbirth is higher with multiple nuchal loops compared to single nuchal cords. No studies reported the combined effects of multiple umbilical cord abnormalities. Our analyses suggest specific avenues for future research.

Umbilical Cord Abnormalities and Stillbirth

OBJECTIVE

Umbilical cord abnormalities are commonly cited as a cause of stillbirth, but details regarding these stillbirths are rare. Our objective was to characterize stillbirths associated with umbilical cord abnormalities using rigorous criteria and to examine associated risk factors.

METHODS

The Stillbirth Collaborative Research Network conducted a case-control study of stillbirth and live births from 2006 to 2008. We analyzed stillbirths that underwent complete fetal and placental evaluations and cause of death analysis using the INCODE (Initial Causes of Fetal Death) classification system. Umbilical cord abnormality was defined as cord entrapment (defined as nuchal, body, shoulder cord accompanied by evidence of cord occlusion on pathologic examination); knots, torsions, or strictures with thrombi, or other obstruction by pathologic examination; cord prolapse; vasa previa; and compromised fetal microcirculation, which is defined as a histopathologic finding that represents objective evidence of vascular obstruction and can be used to indirectly confirm umbilical cord abnormalities when suspected as a cause for stillbirth. We compared demographic and clinical factors between women with stillbirths associated with umbilical cord abnormalities and those associated with other causes, as well as with live births. Secondarily, we analyzed the subset of pregnancies with a low umbilical cord index.

RESULTS

Of 496 stillbirths with complete cause of death analysis by INCODE, 94 (19%, 95% CI 16-23%) were associated with umbilical cord abnormality. Forty-five (48%) had compromised fetal microcirculation, 27 (29%) had cord entrapment, 26 (27%) knots, torsions, or stricture, and five (5%) had cord prolapse. No cases of vasa previa occurred. With few exceptions, maternal characteristics were similar between umbilical cord abnormality stillbirths and non-umbilical cord abnormality stillbirths and between umbilical cord abnormality stillbirths and live births, including among a subanalysis of those with hypo-coiled umbilical cords.

CONCLUSION

Umbilical cord abnormalities are an important risk factor for stillbirth, accounting for 19% of cases, even when using rigorous criteria. Few specific maternal and clinical characteristics were associated with risk.