Umbilical coiling index in normal and complicated pregnancies

First trimester umbilical cord and vitelline duct measurements using virtual reality

BACKGROUND

the umbilical cord and vitelline duct are of vital importance to the fetus, but they are rarely the subject of first trimester two-dimensional (2D) ultrasound evaluation due to the complexity of their shape and morphology. Virtual reality (VR) allows efficient visualisation and measurement of complex structures like the umbilical cord and vitelline duct.

AIM

to measure normal first trimester human growth of the umbilical cord length (UCL) and vitelline duct length (VDL) using a VR system; and to correlate both measurements with the gestational age (GA) and crown-rump length (CRL) and the VDL with the yolk sac volume (YSV).

STUDY DESIGN

prospective cohort study. Serial three-dimensional (3D) ultrasound measurements were performed from six to 14weeks GA, resulting in 125 3D volumes. These volumes were analysed using an I-Space VR system.

SUBJECTS

Thirty-two healthy pregnant women with an ongoing, normal pregnancy.

OUTCOME MEASURES

the UCL, VDL, YSV and other related structures were measured.

RESULTS

The UCL, measurable in 55% of cases, was positively correlated to advancing GA and CRL (p<0.001). The VDL could be measured in 42% of cases and showed a positive relationship with GA and CRL (p<0.001). There was a significant (p<0.001) relationship between YSV and VDL.

CONCLUSIONS

the present study, facilitated by a VR system, is the first to provide an in-vivo longitudinal description of normal first trimester growth of the human umbilical cord and vitelline duct. Further studies will reveal whether these parameters can be used in detection of abnormal fetal development.

Cord coiling, umbilical cord insertion and placental shape in an unselected cohort delivering at term: relationship with common obstetric outcomes

BACKGROUND

The position of the placental cord insertion, its shape and cord coiling are thought to be associated with perinatal outcome. This study derives indices describing the relationship of cord insertion to the placental centre, the shape of the placenta and cord coiling in placentas from unselected term pregnancies. Further, we investigate these indices in pregnancies affected by pre-eclampsia (PET), pregnancy induced hypertension (PIH), gestational diabetes mellitus (GDM) and delivery of a small for gestational age (SGA) baby.

DESIGN/METHODOLOGY

Eight hundred and sixty one unselected women with singleton pregnancy delivering at 37-42 weeks were prospectively recruited to this study. Placental axes and their relationship with the cord insertion were measured using digital photography and proprietary software. From these, the cord centrality (distance of umbilical cord insertion from the centre) and placental eccentricity (deviation of the placental shape from circular) were derived. The cord coiling index (number of coils in the cord divided by the length of cord in cm) was also calculated from manual measurements.

RESULTS

The mean value of cord centrality index was 0.36 (SD = 0.21) and of placental eccentricity 0.49 (SD = 0.17). Left direction of umbilical cord coiling was more common than right (79% vs 16.4%) The mean cord coiling index was 0.20 (SD = 0.09) coils/cm. The indices were constant between 37 and 42 weeks and were no different in the non-affected population compared to women with pre-eclampsia (n = 17), PIH, (n = 27), GDM (n = 38) or delivery of an SGA baby (n = 54).

CONCLUSION

The cord centrality index that we derive suggests that the cord insertion is most commonly 'off centre', and eccentricity index that the placental shape is elliptical. Therefore, contrary to widely held belief, the cord does not normally insert centrally nor is the placenta normally round in shape. There is a preponderance of left sided coiling. There was no difference for any of the indices between the non-affected pregnancies and pregnancies affected by pre-eclampsia, PIH, GDM and SGA.

Detection of umbilical venous constriction by Doppler flow measurement at midgestation

OBJECTIVES

To investigate whether umbilical venous velocity and venous velocity pulsation are associated with umbilical vein diameter, umbilical ring diameter and umbilical cord coiling index at midgestation.

METHODS

Two hundred and eighty pregnant women were enrolled in the study at between 18 and 24 weeks of gestation. The diameter of the umbilical cord and internal diameter of the umbilical vein in a free loop and at the ring, and the umbilical coiling index, were measured using ultrasonography. Umbilical venous velocities were measured by Doppler ultrasonography at the umbilical ring and a free loop of the cord.

RESULTS

All variables were successfully measured in 92% of the patients. There were negative correlations between the diameters of the umbilical ring and of the umbilical vein at the ring and the venous velocity at the umbilical ring. The venous velocity at the umbilical ring was significantly higher and the umbilical ring diameter was significantly lower in fetuses with umbilical venous pulsation at the free loop. Significant correlations were observed between the venous velocity and amplitude of pulsation. Venous pulsations at the free loop were frequently observed in fetuses with a hypercoiled cord.

CONCLUSION

High venous velocity and increased venous pulsation at the umbilical ring may be associated with umbilical cord constriction.

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.

Do fetal heart rate deceleration patterns during labor differ between various umbilical cord abnormalities?

OBJECTIVE

To examine differences in intrapartum fetal heart rate (FHR) patterns among cases with various cord abnormalities.

METHODS

Vertex singleton cases with nuchal cord (226 cases), velamentous (12 cases), marginal cord insertion (53 cases) or hyper-coiled cord (39 cases) and without them (466) that were delivered at our hospital were examined. The relationship between cord abnormalities and intrapartum FHR patterns were retrospectively investigated. Deceleration patterns were analyzed for the presence of variable, early, late and prolonged decelerations. The frequencies of each FHR pattern per uterine contraction were assessed during 30 uterine contractions at the end of the first stage and throughout the entire second stage of labor.

RESULTS

In the first stage of labor, frequencies of variable decelerations were 34.5+/-23.8% and 27.3+/-25.5% in cases with velamentous insertion and hyper-coiled cord, respectively. These were significantly higher than in controls (11.7+/-17.3%, P<0.0001). In the second stage of labor, however, frequencies of each deceleration were not different among various cord abnormalities.

CONCLUSION

Fetal heart rate tracing from the first stage of labor is indicated in cases with the prenatal diagnosis of velamentous insertion or hyper-coiling of the cord.

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.

Prenatal ultrasonographic prediction of the umbilical coiling index at birth and adverse pregnancy outcome

OBJECTIVES

To evaluate whether the antenatal umbilical coiling index (aUCI) as measured by ultrasonography predicts the postnatal umbilical coiling index (pUCI) and adverse pregnancy outcome.

METHODS

In a prospective study in 117 pregnancies, the aUCI was measured between 28 weeks and term by ultrasonography. The aUCI was calculated as the reciprocal value of the mean pitch of one complete coil. The pUCI was calculated as the number of coils divided by the cord length in cm. The correlation between aUCI and pUCI was assessed and likelihood ratios for adverse pregnancy outcome were calculated.

RESULTS

We had complete data on 81 subjects. Mean aUCI +/- SD was 0.30 +/- 0.09 and mean pUCI +/- SD was 0.17 +/- 0.08. The correlation coefficient between aUCI and pUCI was 0.66, P < 0.001. Limits of agreement were 0-0.28 coils/cm. The positive likelihood ratio for small-for-gestational-age infants was 2.6 (95% confidence interval (CI) 0.6-11.6) for ultrasound hypocoiling, and 5.7 (95% CI 1.3-24.8) for ultrasound hypercoiling. The positive likelihood ratio for interventional delivery for non-reassuring fetal status was 1.2 (95% CI 0.2-9.0) for ultrasound hypocoiling, and 10.3 (95% CI 2.1-50.2) for ultrasound hypercoiling.

CONCLUSIONS

Strong correlation coefficients comparing the aUCI and pUCI do not reflect agreement. Since the limits of agreement were almost as wide as the full range for the pUCI, the aUCI does not predict the pUCI with sufficient precision. Larger prospective studies are required to confirm the predictive potential of the aUCI for adverse pregnancy outcome.