Sonographic umbilical cord morphometry and coiling patterns in twin–twin transfusion syndrome

Impact of COVID-19 on Subclinical Placental Thrombosis and Maternal Thrombotic Factors

Background: In the context of the SARS-CoV-2 pandemic, our interest was to evaluate the effect of COVID-19 during pregnancy on placenta and coagulation factors. Methods: a prospective cohort study between January and July 2021 of 55 pregnant women stratified into: Group O, 16 patients with ongoing SARS-CoV-2 infection at delivery; Group R, 21 patients with a history of SARS-CoV-2 infection during pregnancy but who recovered prior to delivery; Group C, 18 control patients with no infection at any time. All women had nasopharyngeal SARS-CoV-2 RT-PCR tests performed within 72 h of delivery. Obstetrical complications were recorded and two physiological inhibitors of coagulation, protein Z (PZ) and dependent protease inhibitor (ZPI), were analyzed in maternal and cord blood. All placentae were analyzed by a pathologist for vascular malperfusion. Results: No patient in any group had a severe COVID-19 infection. More obstetrical complications were observed in Group O (O: n = 6/16 (37%), R: n = 2/21 (10%), C: n = 1/18 (6%), p = 0.03). The incidence of placental vascular malperfusion was similar among the groups (O: n = 9/16 (56%), R: n = 8/21 (42%), C: n = 8/18 (44%), p = 0.68). No PZ or ZPI deficiency was associated with COVID-19. However, an increased ZPI/PZ ratio was observed in neonates of Group R (O: 82.6 (min 41.3–max 743.6), R: 120.7 (29.8–203.5), C: 66.8 (28.2–2043.5), p = 0.04). Conclusion: COVID-19 was associated with more obstetrical complications, but not an increased incidence of placental lesions or PZ and ZPI abnormalities.

Sonographic evaluation of umbilical cord thickness in monochorionic diamniotic twin pregnancies

OBJECTIVE

To develop a nomogram of the thickness of the umbilical cord (UC) and its components in monochorionic diamniotic (MCDA) twin pregnancies.

METHODS

This prospective longitudinal study involved 47 MCDA twin pregnancies (94 fetuses) between 18 and 33 weeks of gestation. Ultrasound assessments of UC cross-sections and measurements of the umbilical cord area (UCA), the umbilical vein area (UVA), the umbilical artery area (UAA), and the Wharton jelly area (WJA) were made. The UC measurements were correlated with gestational ages. Reference values for the gestational ages of MCDA pregnancies were determined and compared with those of dichorionic twins and singletons. The cases which developed selective intrauterine growth restriction were contrasted with normal cases.

RESULTS

A positive correlation was found between all UC components and gestational age and fetal weight. The UCA of MCDA fetuses was significantly larger than that of DC fetuses (P < 0.001) at the expense of a larger WJA (P < 0.001) and similar to that of singleton pregnancies. The MCDA fetuses with an estimated fetal weight below the 10th percentile had a smaller UCA than fetuses with a normal estimated weight (P < 0.001).

CONCLUSION

The MCDA twins exhibited a thicker UC than that of dichorionic twins. This article is protected by copyright. All rights reserved.

Current Perspectives of Prenatal Sonography of Umbilical Cord Morphology

The umbilical cord constitutes a continuation of the fetal cardiovascular system anatomically bridging between the placenta and the fetus. This structure, critical in human development, enables mobility of the developing fetus within the gestational sac in contrast to the placenta, which is anchored to the uterine wall. The umbilical cord is protected by unique, robust anatomical features, which include: length of the umbilical cord, Wharton’s jelly, two umbilical arteries, coiling, and suspension in amniotic fluid. These features all contribute to protect and buffer this essential structure from potential detrimental twisting, shearing, torsion, and compression forces throughout gestation, and specifically during labor and delivery. The arterial components of the umbilical cord are further protected by the presence of Hyrtl’s anastomosis between the two respective umbilical arteries. Abnormalities of the umbilical cord are uncommon yet include excessively long or short cords, hyper or hypocoiling, cysts, single umbilical artery, supernumerary vessels, rarely an absent umbilical cord, stricture, furcate and velamentous insertions (including vasa previa), umbilical vein and arterial thrombosis, umbilical artery aneurysm, hematomas, and tumors (including hemangioma angiomyxoma and teratoma). This commentary will address current perspectives of prenatal sonography of the umbilical cord, including structural anomalies and the potential impact of future imaging technologies.

Comparative study of umbilical cord cross-sectional area in foetuses with isolated single umbilical artery and normal umbilical artery

Single umbilical artery (SUA) is one of the most common prenatal diagnoses in cases of foetal abnormality. This prospective study evaluated 77 foetuses with isolated SUAs and 77 healthy foetuses, both at 22-39 gestational weeks. We categorised gestational age into the second and third trimesters, measured the umbilical arterial blood flow parameters and calculated the umbilical vein (UV) area, umbilical artery (UA) area and UV area/UA area ratio. In the second and third trimesters, a higher UA area was obtained in the isolated SUA group than in the control group (p < .01). Furthermore, the isolated SUA group had a lower UV area/UA area ratio than the control group (p < .01), and a positive linear correlation was found between gestational age and UV area in both groups (p < .01). The presence of isolated SUAs was associated with low birth weight and a high prevalence of small for gestational age.IMPACT STATEMENTWhat is already known on this subject? Single umbilical artery (SUA) is one of the most common prenatally diagnosed foetal abnormalities and approximately 80% foetuses with SUA have isolated SUA, which is a soft indicator of chromosome abnormalities, congenital malformations and premature birth. Umbilical cord cross-sectional area can be evaluated prenatally by ultrasound imaging. Normal values increase with gestational age and foetal size in single pregnancies. Changes in umbilical cord thickness have been associated with complications during pregnancy.What do the results of this study add? The correlation between gestational age and umbilical vein area in the isolated single umbilical artery (SUA) group and control group was better than that between gestational age and umbilical artery area. UA area increased significantly in both groups before 28 weeks but not after 28 weeks, particularly in the isolated SUA group.What are the implications of these findings for clinical practice and/or further research? The study provides a reliable basis for maternal foetal monitoring during pregnancy in the isolated SUA and control groups. Objective assessment of the occurrence and development of foetuses with isolated single umbilical artery was performed.

Discordance of umbilical coiling index between recipients and donors in twin-twin transfusion syndrome

INTRODUCTION

To compare the intertwin umbilical cord coiling in twin-twin transfusion syndrome (TTTS) before fetoscopic laser treatment and to correlate these with Doppler findings in both twins.

METHODS

We performed a prospective study using three-dimensional (3D) ultrasound with color Doppler imaging of the umbilical cord in TTTS. Coiling index was measured as a reciprocal value of one complete vascular coil. Ultrasound hypocoiling was thus defined as < 0.2 coils/cm and hypercoiling as > 0.6 coils/cm, respectively. Umbilical artery pulsatility index (PI) and peak systolic velocity, middle cerebral artery peak systolic velocity and ductus venosus PI of flow-velocity waveformes of both twins were measured.

RESULTS

We included 65 women in the study. The average gestational age was 21.1 ± 2.7 weeks. In 65 recipients and 56 donors coiling index could be quantified. The median (interquartile range) coiling index of recipient twins was significantly higher than of donors, 0.55 (0.41-0.68) vs. 0.26 (0.2-0.5); P < 0.0001. The proportions of abnormal intertwin coiling were significantly (P = 0.0015) different. Out of 65 recipient with coiling indices evaluation, 1 (1.5%) showed hypocoiled and 27 (41.5%) hypercoiled cords. In contrast, 27 donor twins (48.2%) showed hypocoiled and 5 (8.9%) hypercoiled umbilical cords. There were no significant correlations between the fetal Doppler values and coiling indices.

DISCUSSION

Evaluation of umbilical cord coiling index using 3D color Doppler in both twins complicated by TTTS is feasible in both, donors and recipients. Coiling indices differ significantly between recipient and donor twins and do not correlate with Doppler findings.

Umbilical Cord Coiling in High-risk Pregnancies: Associations With Determinants of Adverse Birth Outcomes and Iron Status

Abnormal umbilical cord coiling has been associated with adverse neonatal outcomes, but the etiology of these findings remains poorly characterized. This study was undertaken to examine associations between cord coiling and maternal iron (Fe) status and to identify potential determinants of hypo- and hypercoiling in 2 higher risk obstetric groups: pregnant adolescents (≤18 years, n = 92) and adult women carrying twins (n = 49), triplets (n = 11), or quadruplets (n = 1). Umbilical cords were classified as hypo-, normo-, or hypercoiled using digital photographs to assess gross appearance. Hypocoiling and hypercoiling were observed in 44% (n = 86/195) and 13% (n = 26/195) of the combined study population. The prevalence of hypocoiling among women carrying multiples was over 3-fold higher than the prevalence in singleton pregnancies based on the published data. Within the entire study population, hypocoiling was associated with a lower gestational age at birth when compared to normocoiling and hypercoiling (36.3 ± 3.6 weeks [n = 86] vs 37.8 ± 2.7 [n = 83], P < .01, and 38.2 ± 2.6 [n = 26], P < .01, respectively), whereas hypercoiling was associated with significantly lower serum ferritin when compared to normocoiling ( P < .01) and hypocoiling ( P < .001). In the multiples cohort only, hypercoiling was significantly associated with multiparity ( P < .01) and lower birth weight ( P < .05). Further studies are needed to identify the determinants and consequences of cord coiling.

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.

Recipient umbilical artery elongation (redundancy) in twin-twin transfusion syndrome

BACKGROUND

Chronic hypertension in adults causes arterial lengthening in major arteries, but the effects of early fetal hypertension on the twin-twin transfusion syndrome recipient's vascular architecture remains unknown.

OBJECTIVE

We hypothesize that arterial cord redundancy is related to recipient hypertension and subsequent heart failure. Our objectives were to: (1) establish a 3-dimensional color Doppler ultrasound method of measuring umbilical arterial length relative to its corresponding venous segment in the umbilical cord using artery vein angle; (2) compare recipient artery vein angle to gestational age-matched controls; and (3) test the association of artery vein angle with recipient heart failure.

STUDY DESIGN

We compared 3 groups prospectively: twin-twin transfusion syndrome pregnancies undergoing fetoscopic laser surgery (preoperatively) and 2 groups of gestational age-matched controls: uncomplicated monochorionic-diamniotic twin pregnancies and healthy singletons. Using a 3-dimensional color-Doppler volume image of 5 cm of cord near the placental insertion, we traced the umbilical artery and vein producing umbilical artery:vein length, (artery vein index) and measured the artery vein angle between umbilical artery and vein. Correlation of artery vein angle to twin-twin transfusion syndrome stage, maximum vertical pocket, umbilical arterial indices, ductus venosus Doppler, and brain natriuretic peptide were performed. We used pulsed-wave and tissue Doppler to measure tissue Doppler velocities and indexed cardiac output and correlated these with artery vein angle. Comparative statistics, including multivariable linear regression, examined the relationship between umbilical arterial Doppler indices and artery vein angle.

RESULTS

Artery vein angle and artery vein index correlated significantly (R², 0.86; P < .0001), hence, artery vein angle was used for analysis. Mean artery vein angle was 33.1 ± 31.5 degrees in recipients (n = 44), 9.5 ± 6 degrees in monochorionic-diamniotic (n = 11; 22 fetuses), and 8.9 ± 8.3 degrees in singleton controls (n = 16) (P < .001). An artery vein angle ≥26 degrees (>95th percentile for controls) was measured in 52% recipients. Artery vein angle was higher in twin-twin transfusion syndrome stage 3R vs 1 (P = .001). Artery vein angle increased with increasing umbilical arterial pulsatility index (P < .001), and decreased with increasing resistance index (P = .02) after adjusting for gestational age. Interrater agreements to categorize abnormal artery vein angle values was 95% (P < .001). Abnormal ductus venosus Doppler and elevated recipient amniotic fluid N-terminal pro-brain natriuretic peptide/protein levels correlated significantly with artery vein angle. Abnormal artery vein angles were associated with decreased indexed cardiac output, lower tissue Doppler velocities, higher right-sided Tei indices, and severe tricuspid regurgitation.

CONCLUSION

Umbilical arterial lengthening occurs in 52% of recipients and is associated with abnormal Doppler flows, low systolic tissue Doppler velocities, reduced cardiac output, and elevated markers of cardiac failure. This may reflect chronicity and severity of hypertension in the recipient fetus. Further research is needed to explore the mechanisms of elongation and long-term implications.

Longitudinal reference range for umbilical cord cross-sectional area in twin pregnancies at 18-32 weeks of gestation

OBJECTIVES

The objectives of this study were to establish gestational age-specific reference ranges for cross-sectional area of the umbilical cord, and its components, in twin pregnancies and to compare them with previously reported singleton reference ranges.

METHODS

This was a prospective longitudinal study involving uncomplicated dichorionic twin pregnancies. Sonographic measurements of the cross-sectional area of the umbilical cord, umbilical vein and arteries and Wharton's jelly were obtained in a plane adjacent to the fetal abdomen, every 3 weeks, between 18 and 32 weeks of gestations. Multilevel regression analysis was used to determine gestational age-specific reference ranges for each parameter, and these were plotted against singleton pregnancy references.

RESULTS

Three hundred and thirty four ultrasound scans were performed in 44 twin pregnancies, between 18 and 32.9 weeks (mean: 3.8 ± 0.7 scans/pregnancy and mean interval between scans: 3.3 ± 0.9 weeks). All umbilical cord cross-sectional areas (total, vein, artery and Wharton's jelly) showed a significant increase with gestational age. Compared with singleton pregnancy ranges, mean values were considerably lower in twin pregnancies and resemble the lower limits observed in singletons.

CONCLUSION

In twin pregnancies, cross-sectional area of the umbilical cord, and its components, increases between 18 and 32 weeks, and mean values are substantially lower compared with singleton pregnancies.

Placental vascular pathology and increased thrombin generation as mechanisms of disease in obstetrical syndromes

Obstetrical complications including preeclampsia, fetal growth restriction, preterm labor, preterm prelabor rupture of membranes and fetal demise are all the clinical endpoint of several underlying mechanisms (i.e., infection, inflammation, thrombosis, endocrine disorder, immunologic rejection, genetic, and environmental), therefore, they may be regarded as syndromes. Placental vascular pathology and increased thrombin generation were reported in all of these obstetrical syndromes. Moreover, elevated concentrations of thrombin-anti thrombin III complexes and changes in the coagulation as well as anticoagulation factors can be detected in the maternal circulation prior to the clinical development of the disease in some of these syndromes. In this review, we will assess the changes in the hemostatic system during normal and complicated pregnancy in maternal blood, maternal–fetal interface and amniotic fluid, and describe the contribution of thrombosis and vascular pathology to the development of the great obstetrical syndromes.

Pentalogy or hexalogy of Cantrell?

Pentalogy of Cantrell (PC) is a rare congenital syndrome involving the abdominal wall, sternum, diaphragm, pericardium, and heart. The embryonic period in which PC develops coincides with that of umbilical cord (UC) formation. The aim of the following study was to address the question of whether PC is associated with UC pathologies. Four cases, prenatally identified between 2002 and 2008, were enrolled in this study. Umbilical cord pathologies defined as single umbilical artery, short cord, or UC with atypical coiling pattern were retrospectively assessed on stored ultrasound images and from autopsy reports. The literature regarding PC and UC pathologies was reviewed. Three singleton pregnancies and 1 monoamniotic twin pregnancy with twin reversed arterial perfusion sequence were reviewed. All had a normal karyotype. Three showed the classical PC stigmata, with ectopia cordis. One fetus had no ectopia cordis; this case had a normal UC, whereas all others fetuses showed a short UC with atypical coiling pattern. Of 26 publications dealing with PC, the UC was described in only 8 cases, 7 of which were abnormal. There seems to be a strong correlation between the PC and UC abnormalities, in particular in cases with ectopia cordis. We speculate that the insult leading to the classical malformations of PC and UC abnormalities is the same or the sequence of malformations itself may alter the early fetoplacental blood flow and therefore the normal development of the UC angioarchitecture.

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.

Coiling characteristics of umbilical cords in breech vs. vertex presentation

OBJECTIVE

To compare selected umbilical cord parameters, especially cord coiling, between breech and vertex presentations.

METHODS

We prospectively collected umbilical cords from uncomplicated breech and vertex obtained during elective term cesarean deliveries. We compared various cord parameters between the two groups as well as data regarding obstetric history and pregnancy outcome.

RESULTS

We evaluated 55 umbilical cords from breech and 55 from vertex deliveries. Umbilical cord length (56.93 cm vs. 63.95 cm, P=0.05), number of coils (5.1+/-0.4 vs. 11.7+/-0.6, P<0.0001) and umbilical cord index (UCI) (0.09 coils/cm vs. 0.18 coils/cm, P<0.0001) were all significantly lower for breech presentations and remained significant following multivariate analysis.

CONCLUSION

We document significant differences in umbilical coiling and the UCI between breech and vertex presentation. The precise reason for these differences is still unclear.

Radiofrequency driven cord occlusion for selective termination of pregnancy: evaluation in the fetal sheep

OBJECTIVE

This study was designed to assess the ability of an ultrasound-guided radiofrequency (RF)-driven procedure to induce complete and irreversible cord occlusion using a 90 days fetal sheep model.

STUDY DESIGN

Twenty 90 days gestation sheep underwent general anesthesia. The first ten fetuses were exposed under hysterotomy, and RF electrode was inserted visually in the middle of the umbilical cord and deployed. Fetuses were then replaced into the amniotic fluid and RF procedure (average target temperature of 100 degrees C during 10 minutes) was applied. For the next ten fetuses, RF electrode was inserted into the cords under trans-parietal ultrasound guidance and the same RF procedure was applied. Cord occlusion was assessed by Doppler examination (absence of cordonal flows at the end of the procedure and until fetal heart failure occurred) and by subsequent histopathological analysis.

RESULTS

Cord occlusion was always complete at Doppler examination at the end of RF procedure for the ten experiments realized under hysterotomy. No cordonal reperfusion was observed until fetal heart failure. Histopathological analysis confirmed cordonal occlusion at the site of impact. Neither cordonal rupture nor cordonal bleeding was observed for any of the ten experiments. When RF electrode was inserted under ultrasound guidance, complete occlusion could be obtained only for 6 of the ten experiments.

CONCLUSION

Our results suggest that RF might be an appropriate method for selective termination of pregnancy. Yet, optimal insertion of the electrode is required to engender a complete and irreversible cord occlusion, and ultrasound-guidance training seems necessary before current human application.

Reference intervals for the cross sectional area of the umbilical cord during gestation

OBJECTIVE

To establish reference values for the sonographic cross-sectional area of the umbilical cord during gestation and to correlate them with fetal anthropometric parameters.

METHODS

A cross-sectional study was performed involving 312 normal pregnant women at gestational ages 24-39 weeks. Measurement of the cross-sectional area of umbilical cord was performed on a plane adjacent to the insertion of the cord into fetal abdomen. The following anthropometric parameters were calculated: biparietal diameter, head circumference, abdominal circumference and femur length. A polynomial regression analysis identified the curves that were better adjusted to the average and standard deviation according to gestational age. Spearman correlation was used to evaluate the correlation of the cross-sectional area of umbilical cord with fetal anthropometric parameters.

RESULTS

A statistically significant correlation was observed between the cord cross-sectional area and gestational age (r=0.376, P<0.001, CI 95%[0.276; 0.467]).

CONCLUSIONS

The reference values of the cross-sectional area of umbilical cord increased according to gestational age until the 33rd week and are related to parameters of fetal growth.

Investigation of normal organ development with fetal MRI

The understanding of the presentation of normal organ development on fetal MRI forms the basis for recognition of pathological states. During the second and third trimesters, maturational processes include changes in size, shape and signal intensities of organs. Visualization of these developmental processes requires tailored MR protocols. Further prerequisites for recognition of normal maturational states are unequivocal intrauterine orientation with respect to left and right body halves, fetal proportions, and knowledge about the MR presentation of extrafetal/intrauterine organs. Emphasis is laid on the demonstration of normal MR appearance of organs that are frequently involved in malformation syndromes. In addition, examples of time-dependent contrast enhancement of intrauterine structures are given.

The cross-sectional area of umbilical cord components in normal pregnancy

OBJECTIVE

To determine the normal cross-sectional areas of the umbilical vein, umbilical artery, and Wharton jelly in healthy pregnancies, and correlate the obtained values with fetal anthropometric parameters.

METHODS

A cross-sectional study was performed with 312 women between the 24th and 39th weeks of a normal pregnancy. The cross-sectional areas of umbilical cord vessels were measured at the junction of the cord and fetal abdomen, and the values were subtracted from the total cord cross-sectional area to assess the cross-sectional area of the Wharton jelly. The anthropometric parameters analyzed were biparietal diameter, head circumference, femur length, and estimated fetal weight, and the Spearman correlation was used to assess the correlation between the cross-sectional areas of umbilical cord components and fetal anthropometric parameters. A polynomial regression analysis was performed to identify the curves that best adjusted to mean and standard deviation according to gestational age.

RESULTS

A statistically significant correlation was observed between the cross-sectional areas of cord components and fetal anthropometric parameters (P<0.001) as well as gestational age (P<0.001).

CONCLUSIONS

Reference measurements of the cross-sectional areas of umbilical cord components are important tools in the assessment of fetal growth.