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.

Fetal brain hemodynamic changes in intrauterine transfusion: influence of needle puncture site.

OBJECTIVES: Previous research has suggested that hemodynamic changes after in utero transfusion may be related to fetal stress. We tested the hypothesis that these hemodynamic changes are more pronounced when the needle is inserted in the fetal abdomen compared with the umbilical cord root. METHODS: Most intrauterine transfusions are performed by inserting a needle either in the umbilical cord root at the placental surface (PCI) or in the intrahepatic portion of the umbilical vein (IHV). We analyzed prospectively collected data of all intrauterine blood transfusions (IUT) for fetal alloimmune anemia (from 2000 to 2003), for which complete data were available on needling site and middle cerebral artery (MCA) Doppler flow velocity measurements before and immediately after the procedure. RESULTS: Data of 57 IUTs were included. In 32 patients, the transfusion was performed through the PCI and in 25 patients through the IHV. Mean pulsatility index (PI) in the PCI group was 2.0 before and 1.7 after IUT (p = 0.011), and in the IHV group 1.9 before and 1.5 after IUT (p = 0.001). In both groups, MCA PI decreased significantly, but there was no difference in decrease between the two groups (p = 0.99). CONCLUSIONS: In anemic fetuses undergoing transfusion, the observed fetal brain hemodynamic changes were independent of the site of needle insertion. The decrease in fetal MCA PI is therefore likely to be caused by the volume expansion.

On the origin of amniotic fluid bilirubin.

We studied the relationship between bilirubin concentrations in amniotic fluid and fetal blood in 68 non-hydropic rhesus d-alloimmunized anemic fetuses at first blood sampling. In these alloimmunized fetuses, the amniotic fluid/fetal blood ratio for bilirubin decreased from 0.09 at 28 weeks to 0.05 at 33 weeks. In normal fetuses, amniotic fluid/fetal blood ratios for bilirubin, and for albumin, are in the same range and show a similar decrease during gestation. We conclude that amniotic fluid bilirubin concentration is determined, firstly, by fetal blood bilirubin concentration and, secondly, by the amniotic fluid/fetal blood ratio of albumin. Among five possible pathways bilirubin could take to build up a concentration in amniotic fluid (fetal kidneys, lungs, skin, bowel, membranes), the intramembranous pathway is the only one that is compatible with the amniotic fluid/fetal blood ratios for bilirubin that we found and must therefore be the most important.

Non-invasive tests to predict fetal anemia in Kell-alloimmunized pregnancies.

OBJECTIVES: To compare test characteristics of ultrasound and Doppler parameters in the prediction of fetal anemia in Kell-alloimmunized pregnancies. METHODS: In this prospective study, 27 fetuses at risk for anemia due to Kell alloimmunization were evaluated with ultrasound and Doppler imaging. Spleen perimeter, liver length, middle cerebral artery (MCA) peak systolic velocity and intrahepatic umbilical venous (IHUV) maximum velocity were measured. Results were compared with fetal hemoglobin values at first intrauterine blood sampling or delivery. Severe fetal anemia was defined as a hemoglobin deficit of at least 5 SD below the mean for gestational age. RESULTS: Eighteen fetuses were anemic and required intrauterine transfusions. In the other nine pregnancies no transfusions were performed; one of these fetuses was severely anemic at birth. MCA and IHUV flow velocities were the best predictors of fetal anemia in Kell alloimmunized fetuses (sensitivity 89% for each test). Sensitivities for spleen perimeter (15%) and liver length (14%) were disappointing. CONCLUSIONS: Doppler evaluation of MCA peak systolic velocity and IHUV maximum velocity can be used to reliably predict severe fetal anemia in Kell alloimmunization.

Fetal cardiac contractility before and after intrauterine transfusion.

OBJECTIVE: To evaluate the effect of fetal anemia and intrauterine transfusion on ventricular shortening fraction. METHODS: The end-diastolic and end-systolic transverse dimensions of the left and right ventricles were obtained using M-mode ultrasonography. The shortening fractions of both ventricles were calculated at three time points: before, immediately after and one day after intrauterine transfusion. The blood volume given at intrauterine transfusion was expressed as a percentage of estimated fetoplacental blood volume. RESULTS: Complete measurements were obtained from 49 transfusions in 23 fetuses. Intrauterine transfusion was performed at a median gestational age of 31 (range, 19-35) weeks. Median hemoglobin concentration before and after intrauterine transfusion was 7.9 (range, 2.7-13.7) g/dL and 14.3 (range, 12.7-16.1) g/dL, respectively. Both left and right ventricular shortening fractions differed significantly between the three time points. Left ventricular shortening fraction decreased immediately after transfusion in 43 (88%) of the 49 procedures. Right ventricular shortening fraction decreased immediately after transfusion in 42 (86%) of the 49 procedures. At the first intrauterine transfusion, there was only a weak correlation between the decrease in shortening fraction of both ventricles and the transfused volume (left: R(2) = 0.15; P = 0.20/right: R(2) = 0.005; P = 0.81). CONCLUSION: Transfusion significantly decreases the shortening fraction of both ventricles of the fetal heart. There is, however, little correlation between the decrease in shortening fraction and the volume of red cells given at intrauterine transfusion. Published by John Wiley & Sons, Ltd.