Yolanda BW.indd

Objective To assess the ultrasonographic appearance of the jugular lymphatic sacs (JLS) in fi rst-trimester fetuses with a normal nuchal translucency (NT). Methods Seventy-fi ve fetuses with a normal NT thickness (< 95th percentile) were examined weekly between 11 and 17 weeks of gestation. After measurement of the NT thickness, the neck region was examined using both transvaginal and transabdominal ultrasound for the presence of the JLS. If present, their diameters were measured in three axial planes and the volume was calculated using the formula of a spheroid. Data were analyzed using multilevel analysis. Results Seventy-fi ve fetuses were evaluated and a total of 243 ultrasound examinations of the neck region were performed. In 25 (33%) of the 75 fetuses, the JLS could be observed once or more than once. In 19 fetuses JLS were visualized once, in fi ve fetuses two times and in one fetus three times. In total, the JLS were visualized 32 times (n= 15 bilaterally, n = 15 only the left JLS and n = 2 only the right JLS). Relatively greater NT thickness was associated with a higher probability of the presence of JLS, although this was not statistically signifi cant (NT <1mm: probability 0.03; NT 1–2mm probability 0.15 P = 0.10; NT >2mm probability 0.20 P = 0.08). Gestational age was predictive for the presence of JLS, with the highest probability between 13 to 15 weeks of gestation (P < 0.01). No relationship was found between gestational age and the volumes of the left and right JLS. Conclusion The JLS can be visualized on ultrasound examination in a signifi cant proportion of fetuses with normal NT, most often between 13 and 15 weeks of gestation, and this does not seem to represent any abnormality in these fetuses. Yolanda BW.indd 24 21-12-10 13:52