The umbilical coiling index

Twisting the theory on the origin of human umbilical cord coiling featuring monozygotic twins

The human umbilical cord (hUC) is the lifeline that connects the fetus to the mother. Hypercoiling of the hUC is associated with pre- and perinatal morbidity and mortality. We investigated the origin of hUC hypercoiling using state-of-the-art imaging and omics approaches. Macroscopic inspection of the hUC revealed the helices to originate from the arteries rather than other components of the hUC. Digital reconstruction of the hUC arteries showed the dynamic alignment of two layers of muscle fibers in the tunica media aligning in opposing directions. We observed that genetically identical twins can be discordant for hUC coiling, excluding genetic, many environmental, and parental origins of hUC coiling. Comparing the transcriptomic and DNA methylation profile of the hUC arteries of four twin pairs with discordant cord coiling, we detected 28 differentially expressed genes, but no differentially methylated CpGs. These genes play a role in vascular development, cell-cell interaction, and axis formation and may account for the increased number of hUC helices. When combined, our results provide a novel framework to understand the origin of hUC helices in fetal development.

A Review of Biomechanics Analysis of the Umbilical-Placenta System With Regards to Diseases

Placenta is an important organ that is crucial for both fetal and maternal health. Abnormalities of the placenta, such as during intrauterine growth restriction (IUGR) and pre-eclampsia (PE) are common, and an improved understanding of these diseases is needed to improve medical care. Biomechanics analysis of the placenta is an under-explored area of investigation, which has demonstrated usefulness in contributing to our understanding of the placenta physiology. In this review, we introduce fundamental biomechanics concepts and discuss the findings of biomechanical analysis of the placenta and umbilical cord, including both tissue biomechanics and biofluid mechanics. The biomechanics of placenta ultrasound elastography and its potential in improving clinical detection of placenta diseases are also discussed. Finally, potential future work is listed.

Antenatal umbilical coiling index in gestational diabetes mellitus and non-gestational diabetes pregnancy

OBJECTIVE

Umbilical cord abnormalities increase fetal morbidity and mortality. This study was designed to compare antenatal umbilical coiling index (aUCI) in gestational diabetes mellitus (GDM) and non-gestational diabetes mellitus (non-GDM) pregnancy, considering uncertainties about the best time to perform antenatal ultrasonography scan.

MATERIALS AND METHODS

In this prospective study, 246 parturients were included, 123 with GDM and 123 with non-GDM pregnancy. Gestational diabetes was confirmed at 24-28 weeks of gestation (WG) using one-step strategy. An anatomical ultrasound survey of placenta and umbilical cord was performed at 18-23 as well as 37-41 weeks of gestational age.

RESULTS

At 18-23 WG, the frequency distribution (10th, 90th percentiles, mean ± SD) of the aUCI in the GDM and non-GDM groups were (0.13,0.66,0.32 ± 0.19) and (0.18,0.74, 0.4 ± 0.31) respectively. These values were (0.12,0.4, 0.25 ± 0.11) in the GDM group at 37-41 WG and (0.17,0.43, 0.29 ± 0.11) in the non-GDM group. A significant relationship was detected between UCI value and GDM/non-GDM groups at both antenatal evaluations (18-23 WG; P = 0.002, 37-41WG; P < 0.001). A significant association at 18-23 WG was found between GDM/non-GDM groups and aUCI categorization (hypocoiling <10th, normocoiling 10th-90th and hypercoiling >90th) (P = 0.001). However, hypocoiling were significantly more frequent in GDM than non-GDM in both antenatal evaluations (P < 0.001, P = 0.006).

CONCLUSION

Antenatal UCI in pregnancy complicated by GDM were lower in comparison with non-GDM pregnancy. The most abnormal pattern of coiling in gestational diabetes was hypocoiling in both trimesters. In addition, 18-23 WG is the best time to perform ultrasound scan to detect aUCI and umbilical cord pattern.

Fetal vascular malperfusion, an update

Fetal vascular malperfusion is the most recent term applied to a group of placental lesions indicating reduced or absent perfusion of the villous parenchyma by the fetus. The most common etiology of malperfusion is umbilical cord obstruction leading to stasis, ischemia, and in some cases thrombosis. Other contributing factors may include maternal diabetes, fetal cardiac insufficiency or hyperviscosity, and inherited or acquired thrombophilias. Severe or high grade fetal vascular malperfusion is an important risk factor for adverse pregnancy outcomes including fetal growth restriction, fetal CNS injury, and stillbirth. Overall recurrence risk for subsequent pregnancies is low.

Hypercoiled cord can cause a reversible abnormal Doppler in ductus venosus in cases of fetal growth restriction

AIM

Although an absent or reversed a-wave in ductus venosus (DV-RAV) is reported to be the terminal finding of fetal growth restriction (FGR), we have seen DV-RAV that disappears within a short span of time in some FGR cases with a hypercoiled cord. The purpose of this study was to investigate the relationship between hypercoiled cord and reversible DV-RAV in FGR.

METHODS

This was a retrospective study of 499 FGR cases, including 14 with DV-RAV. Transabdominal amnioinfusion (AI) was performed when oligohydramnios was severe (maximum vertical pocket <2 cm) and/or variable deceleration was detected. DV-RAV that disappeared quickly was defined as 'temporary DV-RAV'. DV-RAV that continued until delivery or fetal death (FD) was defined as 'persistent DV-RAV'. A hypercoiled cord was defined as one with an umbilical coiling index >0.6 antenatally or >0.3 postnatally. Clinical characteristics and clinical courses of the two types of DV-RAV were compared.

RESULTS

DV-RAV disappeared after AI in all five cases in which temporary DV-RAV was identified. The incidence of a hypercoiled cord was significantly higher among temporary DV-RAV cases (100%) than among persistent DV-RAV cases (14.3%; P = 0.015). The time from detection of DV-RAV to delivery or FD was significantly longer among temporary DV-RAV cases (4.5 weeks) than among persistent DV-RAV cases (0.7 weeks; P = 0.027).

CONCLUSION

Temporary DV-RAV is suspected to be related to the combination of a hypercoiled cord and oligohydramnios. DV-RAV may not be always be a terminal finding in FGR with a hypercoiled cord.

Is umbilical coiling genetically determined?

OBJECTIVE

Abnormal umbilical cord coiling is associated with adverse perinatal outcomes; however, the etiology of the umbilical coiling pattern is poorly understood.

STUDY DESIGN

Retrospective cohort of all twin deliveries >20 weeks in 2014. Pregnancies were dichotomized by chorionicity and the umbilical coiling index (UCI) and placental cord insertion location were compared. In cases with one or both cords hypercoiled, the direction and pattern of coiling were compared by chorionicity. A similar analysis was performed stratified by zygosity.

RESULTS

Three hundred sisty two twin pairs were included; 26 (7.2%) monochorionic and 174 (87.0%) definitively dizygotic. Concordance in the UCI and coiling category were similar between dichorionic and monochorionic as well as dizygous and monozygous gestations, (73.2% vs 80.8%, p = 0.399 and 71.4% vs 80.8%, p = 0.399, respectively). Analyses of the coiling direction and pattern also demonstrated no difference by chorionicity or zygosity.

CONCLUSION

These data do not support a genetic basis for umbilical cord coiling.

Characterization of the hemodynamic wall shear stresses in human umbilical vessels from normal and intrauterine growth restricted pregnancies

Significant reductions in blood flow and umbilical diameters were reported in pregnancies affected by intrauterine growth restriction (IUGR) from placental insufficiency. However, it is not known if IUGR umbilical blood vessels experience different hemodynamic wall shear stresses (WSS) compared to normal umbilical vessels. As WSS is known to influence vasoactivity and vascular growth and remodeling, which can regulate flow rates, it is important to study this parameter. In this study, we aim to characterize umbilical vascular WSS environment in normal and IUGR pregnancies, and evaluate correlation between WSS and vascular diameter, and gestational age. Twenty-two normal and 21 IUGR pregnancies were assessed via ultrasound between the 27th and 39th gestational week. IUGR was defined as estimated fetal weight and/or abdominal circumference below the 10th centile, with no improvement during the remainder of the pregnancy. Vascular diameter was determined by 3D ultrasound scans and image segmentation. Umbilical artery (UA) WSS was computed via computational flow simulations, while umbilical vein (UV) WSS was computed via the Poiseuille equation. Univariate multiple regression analysis was used to test for the differences between normal and IUGR cohort. UV volumetric flow rate, UA and UV diameters were significantly lower in IUGR fetuses, but flow velocities and WSS trends in UA and UV were very similar between normal and IUGR groups. In both groups, UV WSS showed a significant negative correlation with diameter, but UA WSS had no correlation with diameter, suggesting a constancy of WSS environment and the existence of WSS homeostasis in UA, but not in UV. Despite having reduced flow rate and vascular sizes, IUGR UAs had hemodynamic mechanical stress environments and trends that were similar to those in normal pregnancies. This suggested that endothelial dysfunction or abnormal mechanosensing was unlikely to be the cause of small vessels in IUGR umbilical cords.

Placental histopathology lesions and pregnancy outcome in pregnancies complicated with symptomatic vs. non-symptomatic placenta previa

BACKGROUND

The mechanisms involved in bleeding in cases of placenta previa (PP) and the effect on pregnancy outcome is unclear.

OBJECTIVES

We aimed to compare pregnancy outcome and placental histopathology in pregnancies complicated with symptomatic (bleeding) vs. non-symptomatic PP, and to study the effects of the co-existence of histopathological retro-placental hemorrhage (RPH) in cases of symptomatic PP on neonatal and maternal outcomes.

STUDY DESIGN

Labor and maternal characteristics, neonatal outcome and placental histopathology lesions of pregnancies with PP, delivered between 24 and 42weeks, during 2009-2015, were reviewed. Results were compared between PP who had elective cesarean delivery (CD) (previa group) and PP with bleeding necessitating emergent CD (symptomatic previa group). Placental lesions were classified to lesions consistent with maternal malperfusion or fetal thrombo-occlusive disease (vascular and villous changes), and inflammatory lesions.

RESULTS

Compared to the previa group (n=63), the symptomatic previa group (n=74) was characterized by older patients (p<0.001), higher rate of smokers (p=0.005), thrombophilia (p=0.038), and preterm deliveries (p<0.001). Placentas within the symptomatic previa group were smaller, with higher rates of weight<10th% (p=0.02), RPH (p<0.001) and villous changes related to maternal malperfusion (p=0.023). As compared to symptomatic PP without RPH, co-existence of RPH was associated with higher rate of adverse neonatal outcome (p<0.001) and maternal blood transfusion (p=0.02). On multivariate regression analysis, composite adverse neonatal outcome was found to be dependent on coexisting RPH (OR=2.8, 95%CI 1.2-11.7, p=0.03), and low gestational age (OR=3.1, 95%CI 1.6-4.9, p=0.02).

CONCLUSIONS

Symptomatic placenta previa is associated with increased placental malperfusion lesions suggesting an association of maternal malperfusion with abnormal placental separation. The coexisting finding of RPH with symptomatic placenta previa can be seen as a marker for more extensive/severe placental separation, hence the association with maternal transfusion requirements and poorer fetal outcome.

The role of placental histopathological lesions in predicting recurrence of preeclampsia

OBJECTIVE

We aimed to study the role of placental pathology in the prediction of preeclampsia (PE) recurrence.

METHODS

The medical records and pathological placental reports of all women diagnosed with PE, during 2008-2015, were reviewed. The study population was divided according to the outcome of their subsequent pregnancy: those who did (recurrence group) or did not (no-recurrence group) develop recurrent PE. Data regarding maternal characteristics and placental maternal/fetal vascular malperfusion lesions, of the initial pregnancies, were compared. Two prediction models were generated for PE recurrence.

RESULTS

Compared to the no-recurrence group (n = 130), the recurrence group (n = 96) was characterized by lower gestational age (p < 0.001), longer inter-pregnancy interval (p = 0.012), and higher rate of severe features (p < 0.001). By logistic regression analysis composite maternal (aOR = 3.05, 95%CI 1.39-6.71, p = 0.005), fetal (aOR = 9.31, 95%CI 3.9-22.1, p < 0.001), and concurrent maternal + fetal (aOR = 13.94, 95%CI 5.08-38.21, p < 0.001), vascular malperfusion lesions were found to be independently associated with recurrence. A clinical prediction model accounted for 20.8% of PE recurrence (R²  = 0.208, AUC = 0.732), while a clinical-pathological model accounted for 34.2% of recurrence (R²  = 0.342, AUC = 0.80).

CONCLUSION

Placental maternal and fetal vascular malperfusion lesions are independently associated with increased risk for PE recurrence. A clinical-pathological prediction model for recurrence of PE is superior to a prediction model based merely on clinical factors. © 2016 John Wiley & Sons, Ltd.

Perinatal outcomes of abnormal umbilical coiling according to a modified umbilical coiling index

AIM

The aim of this study was to determine the relation between perinatal outcomes and umbilical cord coiling as evaluated by a modified umbilical coiling index.

METHODS

In this retrospective study, 200 consecutive umbilical cords were examined. An umbilical venous and arterial coiling index was calculated by dividing the total number of umbilical venous and arterial coils by the length of cord individually. Umbilical cords with umbilical venous coiling indices in the lowest decile, the highest decile, and the remaining deciles were defined as hypocoiled, hypercoiled, and normocoiled, respectively. The perinatal outcomes of the subjects with hypocoiled and hypercoiled umbilical cords were compared with those with normocoiled umbilical cords.

RESULTS

In 69.5% of subjects, a difference in the degree of coiling was detected between the umbilical veins and arteries. While all umbilical venous twisting demonstrated the same direction, the direction of the arterial twisting reversed at a certain point along the umbilical cord in 19.0% of the subjects. The arteriovenous coiling difference was small in the hypercoiled group and large in the hypocoiled group. A hypocoiled umbilical cord evaluated by umbilical venous coiling index was found to be associated with prolonged deceleration (odds ratio [OR], 4.18; 95% confidence interval [CI], 1.54-11.38), operative delivery (OR, 2.67; 95%CI, 1.01-7.09), and nuchal cord entanglement (OR, 3.21; 95%CI, 1.23-8.33).

CONCLUSION

Umbilical coiling abnormalities were investigated using a novel umbilical venous coiling index. A hypocoiled umbilical cord evaluated by umbilical venous coiling index was found to be associated with fetal heart rate abnormalities, operative delivery, and nuchal cord entanglement.

Evaluation of antenatal umbilical coiling index at 16-21 weeks of gestation as a predictor of trisomy 21 and other chromosomal defects

OBJECTIVES

To determine whether there is an association between sonographically assessed hyper- or hypocoiling of the umbilical cord and the presence of trisomy 21, to provide reference values for the antenatal umbilical coiling index (aUCI) at a gestational age of 16-21 weeks and to determine whether these measurements are reliable and reproducible.

METHODS

This was a prospective study of 737 pregnancies in which the aUCI was measured between 16 and 21 weeks of gestation by ultrasound at the time of amniocentesis. The aUCI was calculated as the reciprocal value of the mean length of one complete coil in centimeters. We created reference curves and studied the relationship with trisomy 21 and other chromosomal defects. In 30 pregnancies we studied the intra- and interobserver variation in measurements using Bland-Altman plots with associated 95% limits of agreement and intraclass correlation coefficients.

RESULTS

aUCI was found to be non-linearly related to gestational age at 16-21 weeks and reference curves were created for the mean aUCI and the 2.3(rd) , 10(th) , 90(th) and 97.7(th) percentiles. There was no significant difference in aUCI values between the reference group (n = 714) and cases with trisomy 21 (n = 16) or other aneuploidies (n = 7) (one-way ANOVA, P = 0.716). There was good intra- and interobserver agreement in aUCI measurements.

CONCLUSIONS

The aUCI can be measured reliably and varies according to gestational age at 16-21 weeks. The aUCI was not significantly associated with trisomy 21 or other chromosomal defects.

Evidence-based pathology: umbilical cord coiling

The generation of a pathology test result must be based on criteria that are proven to be acceptably reproducible and clinically relevant to be evidence-based. This review de-constructs the umbilical cord coiling index to illustrate how it can stray from being evidence-based. Publications related to umbilical cord coiling were retrieved and analysed with regard to how the umbilical coiling index was calculated, abnormal coiling was defined and reference ranges were constructed. Errors and other influences that can occur with the measurement of the length of the umbilical cord or of the number of coils can compromise the generation of the coiling index. Definitions of abnormal coiling are not consistent in the literature. Reference ranges defining hypocoiling or hypercoiling have not taken those potential errors or the possible effect of gestational age into account. Even the way numerical test results in anatomical pathology are generated, as illustrated by the umbilical coiling index, warrants a critical analysis into its evidence base to ensure that they are reproducible or free from errors.

Review: Diabetes and pregnancy: a review of pathology

Diabetes in pregnancy is associated with increased foetal morbidity and mortality. This article describes and reviews specific features of the placenta and the foetal anomalies seen in association with diabetes and briefly considers potential underlying mechanisms.

Histopathological examination of the placenta: key issues for pathologists and obstetricians

The placenta is often not submitted for histopathological examination and obstetricians may be sceptical of the value of the examination. This article looks at the reasons for histopathological assessment of the placenta, examines what clinical information should be provided to pathologists and reviews what information can be gained from this 'diary of the pregnancy', especially for explaining adverse outcomes and potentially guiding the management of future pregnancies.

Absence of a relationship between umbilical cord thickness and coiling patterns

OBJECTIVE

The purpose of this study was to evaluate a relationship between the umbilical cord thickness and cord coiling patterns during the fetal sonographic anatomic survey in the second trimester of pregnancy.

METHODS

This was a prospective study of 470 patients with singleton pregnancies who had a fetal anatomic survey with recorded umbilical coiling patterns between 18 and 23 weeks' gestation. The umbilical cord thickness was assessed as an umbilical diameter at the level of the fetal abdominal cord insertion and compared with the antenatal umbilical coiling index (aUCI), calculated as a reciprocal value of the distance between a pair of umbilical cord coils.

RESULTS

Three hundred twenty-one patients had adequate sonographic umbilical cord images and maternal demographic, antenatal, and labor data to meet inclusion criteria. The mean aUCI was 0.41 with 10th and 90th percentiles of 0.21 and 0.60, respectively. A total of 10.6% (34/321) and 9.3% (30/321) of patients were categorized as having hypocoiled and hypercoiled umbilical cords, respectively. The mean cord diameter +/- SD was 9.48 +/- 0.97 mm (range 7.0-12.5 mm). There was no statistically significant correlation between aUCI and umbilical cord thickness (P = .1164).

CONCLUSIONS

An aUCI, or umbilical coiling pattern, does not correlate with umbilical cord thickness. It appears that a lesser amount of the umbilical supportive tissue, mainly Wharton jelly, is not related to an increased umbilical cord coiling pattern.

Assessment of umbilical cord coiling during the routine fetal sonographic anatomic survey in the second trimester

OBJECTIVE

The purpose of this study was to evaluate the sonographic accuracy to determine the umbilical coiling index (UCI) during the routine fetal anatomic survey in the second trimester.

METHODS

In 300 consecutive women with singleton pregnancies and absence of gross fetal anomalies who had a routine second-trimester fetal anatomic survey, a distance between 2 pairs of coils was measured from the longitudinal images of the umbilical cord, and the antenatal UCI (aUCI) was calculated. The aUCI was compared with true UCI results obtained after birth.

RESULTS

Two hundred thirty-six patients had adequate sonographic umbilical cord images, and all required demographic, antenatal, and labor data collection to meet the inclusion criteria. A statistically significant correlation between aUCI and true UCI was found (P < .0001; r = 0.643). The mean aUCI was 0.402 (80% confidence interval, 0.382), and the true UCI at birth was 0.203 (80% confidence interval, 0.176). The sonographic evaluation showed 12.3% and 8.9% of hypocoiled and hypercoiled cords, whereas evaluation at birth found 10.6% and 8.1% hypocoiled and hypercoiled umbilical cords, respectively. The sensitivity values of sonography to predict hypocoiling and hypercoiling at birth were 78.9% and 25.4%, respectively.

CONCLUSIONS

A sonographic evaluation of umbilical cord coiling in the second trimester correlates with the true UCI at birth, although the sensitivity in predicting coiling patterns as hypocoiled and hypercoiled cords is less accurate. A difference between the aUCI and matched UCI at birth could be explained by a sonographic error in the sampling of different umbilical cord segments with discordant coiling patterns or the possibility of a dynamically evolving UCI with advancing gestational age.

Fetal aneuploidy and umbilical cord thickness measured between 14 and 23 weeks' gestational age

OBJECTIVE

To evaluate and compare umbilical cord thickness of aneuploid fetuses with umbilical cord diameter nomograms generated from euploid fetuses between 14 and 23 weeks' gestational age.

METHODS

A retrospective study was conducted in which 56 fetuses and neonates had diagnoses of abnormal karyotypes, of which 46 fetuses had numerical chromosomal abnormalities. Among these cases, 26 subjects with adequate umbilical cord sonographic images were included in the study. The umbilical cord thickness was measured and plotted against the umbilical cord diameter nomogram that was generated from previously published data.

RESULTS

From 26 evaluated fetuses and neonates, in 14 subjects (53.8%), the umbilical cord thickness was greater than the 95th percentile for gestational age. A thick umbilical cord was observed in 57.8% of fetuses with trisomy 21 and 50% of subjects with trisomy 18 and monosomy 45,XO. One fetus with trisomy 2 had umbilical cord thickness within the normal range. The largest number of aneuploid fetuses with thick umbilical cords (87.5%) was observed between 16 and 17 gestational weeks.

CONCLUSION

Aneuploid fetuses have thicker umbilical cords than euploid fetuses. The umbilical cord thickness can be related to an increased amount of Wharton jelly. Because of the smaller number of thick umbilical cords in aneuploid subjects at later gestational ages, we speculate that abnormal cord thickness has a natural tendency toward its own resolution with the advancement of gestational age.

Correlação da área do cordão umbilical com parâmetros antropométricos em gestações normais

OBJETIVO: Este objetivou aferir a área de secção transversa do cordão umbilical (ASTCU) em gestações normais, com idade gestacional entre 20 e 40 semanas, para a construção de uma curva de valores normais para tal parâmetro. MATERIAIS E MÉTODOS: Foi realizado estudo transversal para determinar os valores de referência para a ASTCU em gestações normais (pacientes com datas precisas da última menstruação e exame ultra-sonográfico realizado antes da 20ª semana, sem qualquer doença conhecida). As medidas da ASTCU foram obtidas em plano adjacente à inserção do cordão umbilical no abdome. Os aparelhos de ultra-som utilizados foram da marca Synergy Multi Sync M500, Toshiba 140 e Toshiba Corevision, todos com transdutores transabdominais de 3,5 MHz. A análise estatística foi realizada pelo programa SPSS (Statistical Package for Social Sciences). RESULTADOS: Os dados obtidos foram considerados normais pelo teste de Kolmogorov-Smirnov e a curva de normalidade foi calculada por regressão linear. A análise de variância obtida pelo teste F (F = 356,27) mostrou que o modelo de regressão foi significativo ao nível de p < 0,01, mostrando que a curva estudou corretamente a população recrutada e que o intervalo de confiança (95%) continha o valor real da ASTCU. A equação de regressão encontrada para a ASTCU (y), de acordo com a idade gestacional (x), foi: y = -532,27 + 44,358x - 0,655x². CONCLUSÃO: Obtivemos uma curva de valores normais da ASTCU que mostra um crescimento progressivo de seus valores até a 32ª semana, seguida por um período de estabilização até a 34ª semana e uma queda de seus valores a partir da 35ª semana.

Single and multiple umbilical cord cysts in early gestation: two different entities

OBJECTIVE

To investigate the prevalence of single and multiple umbilical cord cysts in the first trimester and to assess whether there is a difference in the pregnancy outcome between them.

METHODS

A targeted sonographic morphological and morphometric evaluation of the umbilical cord was performed in consecutive patients between 7 and 14 weeks of gestation. Crown-rump length and umbilical cord diameter were measured in all cases. Nuchal translucency thickness was measured between 11 and 14 weeks' gestation. In pregnancies at very early gestational ages (7-10 weeks) an additional scan was performed between 11 and 14 weeks.

RESULTS

A total of 1159 patients was screened. The prevalence of umbilical cord cysts was 2.1% (24/1159). The cysts were single and multiple in 18 and six cases, respectively. The median (range) largest umbilical cord cyst diameter was no different between multiple and single umbilical cord cysts (3.8 (2.1-18) mm vs. 3.05 (2.0-7.8) mm; P = 0.386). All women with a single umbilical cord cyst delivered an infant without structural abnormalities and without features suggestive of chromosomal abnormalities. Among the women with multiple umbilical cord cysts, four had a missed miscarriage and one had a fetus with obstructive uropathy.

CONCLUSION

Single and multiple umbilical cord cysts in the first trimester of gestation represent two different entities. While single cysts in the first trimester are associated with a favorable pregnancy outcome, the presence of multiple umbilical cord cysts is associated with an increased risk of miscarriage and aneuploidy.

Second-trimester ultrasonographic assessment of the umbilical coiling index

OBJECTIVE

To determine the relationship between gestational age and the ultrasonic measurement of umbilical coiling index (UCI), and to assess the ability of second-trimester ultrasonic measurements of UCI to predict the true UCI, determined at birth.

SUBJECTS/METHODS

Five hundred and thirty-one consecutive women with uncomplicated pregnancies, booking for delivery with a singleton pregnancy, were recruited during a routine second-trimester fetal morphology scan. Multiple ultrasonographic measurements of the intercoil distance were performed between two to three coils of the umbilical cord, along its entire visible length. Three hundred and seventy-four patients (70%) were followed until delivery when the true UCI was measured.

RESULTS

An adequate portion of umbilical cord for assessment of coiling was visualized in 99% of cases. Adequate ultrasonographic visibility rates for the fetal, middle and placental regions of the cord were different. All three regions of the umbilical cord could only be visualized adequately in 10% of cases, and two regions were visible in 75%. The UCI progressively decreased along the cord from the fetal insertion to the placental insertion. The mean decrease in UCI with increasing gestational age was similar in all parts of the cord before the 23rd week (160 days) of pregnancy, and plateaued off after this point, except in measurements performed near the fetal insertion. The sensitivity of second-trimester ultrasound examination for predicting hypercoiling at birth was 17.3% and for predicting hypocoiling was 9.1%.

DISCUSSION

Whilst UCI can be measured easily and reliably in the second trimester these estimates do not accurately reflect the UCI at term. Our original assumption that umbilical coiling does not alter after the initial formation of coils in the first trimester is incorrect; mixed patterns occurred in about 25% of cases. These patterns develop during the second and third trimesters, presumably due to snarls in the cord, and influence the final coiling number and therefore the relationship between the two measurements of UCI.

Umbilical vein blood flow in fetuses with normal and lean umbilical cord

OBJECTIVE

To evaluate whether umbilical vascular coiling is correlated with the umbilical vein blood flow profile and to investigate if this is different between fetuses with a lean and those with a normal umbilical cord.

METHODS

Consecutive women with a singleton gestation who delivered at term and who underwent an ultrasound examination within 24 h from delivery were studied. Umbilical cord and vessel areas were calculated. Umbilical vein blood flow parameters were obtained by digital color Doppler velocity profile integration. After delivery, the umbilical coiling index was calculated.

RESULTS

One hundred and sixteen women were studied. Twelve (10.3%) had a lean umbilical cord (area < 10th centile). A significant correlation was found between the umbilical coiling index and the umbilical vein blood flow (r = 0.67, P < 0.001). A significant difference between fetuses with and without a lean cord was found in terms of: umbilical coiling index (0.18 +/- 0.08 vs. 0.29 +/- 0.09, P < 0.005), cord area (87.6 +/- 5.1 mm2 vs. 200.6 +/- 34.6 mm2, P < 0.001), Wharton's jelly amount (25.7 +/- 10.3 mm2 vs. 122.1 +/- 33.4 mm2, P < 0.001), umbilical vein blood flow (93.7 +/- 17.8 ml/kg per min vs. 126.0 +/- 23.4 ml/kg per min, P < 0.001), and umbilical vein blood flow mean velocity (6.6 +/- 2.7 cm/s vs. 9.0 +/- 3.6 cm/s, P < 0.05). The proportion of fetuses with an umbilical vein blood flow < 80 ml/kg per min was higher when the cord was lean than when it was normal (25% vs. 1.9%, P < 0.01).

CONCLUSIONS

Lean umbilical cords differ from normal cords not only from a structural point of view but also in the umbilical vein blood flow characteristics. This could explain the increased incidence of intrapartum complications and fetal growth restriction among fetuses with a lean and/or hypocoiled cord.

Prenatal ultrasonographic morphologic assessment of the umbilical cord: a review. Part II

Ultrasonographic assessment, although not always possible throughout the entire length of the umbilical cord, may assist in the diagnosis of congenital and functional anomalies of this structure. In such fashion, prenatal ultrasound may outline normal anatomy or alternatively depict various congenital abnormalities of the umbilical cord including: cysts; pseudocysts umbilical vein varix; persistent right umbilical vein; angiomyxomas; aneurysm (arterial or venous); single, hypoplastic or fused umbilical artery; hematomas (spontaneous or iatrogenic); velamentous insertion; vasa previa. The umbilical cord coiling index, an additional ultrasonographic morphologic feature, may identify patients at risk for adverse perinatal outcome. Conditions of potential fetal compromise due to umbilical cord compression including nuchal cords, true knots, occult prolapse, cord presentation, fetal grasping, and cord entanglement in monoamniotic twins, may be detected prenatally; and impaired umbilical flow can be confirmed with Doppler flow velocimetry. Ultrasound has been widely used to guide invasive diagnostic and therapeutic procedures involving access to umbilical circulation. We conclude that the review of current literature supports that precise prenatal ultrasonographic depiction of the morphology of the umbilical cord may enhance perinatal management.

Prenatal ultrasonographic morphologic assessment of the umbilical cord: a review. Part I

Our objective was to review current data pertaining to prenatal ultrasonographic morphology of the umbilical cord. To this goal we identified studies published in the English language regarding prenatal ultrasonographic morphology of this structure. The studies were obtained from a MEDLINE search from 1966 through May 1997; additional sources were identified through cross-referencing. All published reports, case studies, and articles regarding ultrasonographic morphology of the umbilical cord were reviewed. Data pertaining to Doppler flow velocimetry in association with umbilical cord structural anomalies and umbilical cord compression, were also included. Review of the literature supports that prenatal ultrasound may outline normal anatomy or alternatively depict various congenital abnormalities of the umbilical cord including: cysts; pseudocysts; umbilical vein varix; persistent right umbilical vein; hemangiomas; umbilical vessel aneurysm (arterial or venous); single, hypoplastic, or fused umbilical artery; hematomas (spontaneous or iatrogenic); velamentous insertion; and vasa previa. The umbilical cord coiling index, an additional ultrasonographic morphologic feature may identify patients at risk for adverse perinatal outcome. Conditions of potential fetal compromise due to umbilical cord compression including nuchal cords, true knots, occult prolapse, cord presentation, fetal grasping, and cord entanglement in monoamniotic twins, may be detected prenatally and impaired umbilical flow confirmed with Doppler flow velocimetry. Ultrasound has been widely applied to guide invasive diagnostic and therapeutic procedures involving access to umbilical circulation. In conclusion, precise prenatal ultrasonographic depiction of the morphology of the umbilical cord may enhance perinatal management.