Aorta–umbilical vein fistulae in fetus with trisomy‐17 mosaicism

Arteriovenous shunts in the fetal liver are very rare vascular malformations, especially when there is more than one or it is related to the aorta and umbilical vein (UV)1, 2. To the best of our knowledge, there is only one prenatal report of an arteriovenous shunt involving the abdominal aorta, which was an aorta–portal vein–UV fistula3. We report the case of a fetus with aorta–UV communications emerging from celiac and superior mesenteric sites, and describe their features and associations. A 24-year-old woman, gravida 2 para 1, presented to our center for a routine anomaly scan. She had had no previous ultrasound examinations in her current pregnancy and she had a negative history for congenital abnormalities or medication use during pregnancy. Serial fetal scans between 19 and 22 weeks revealed an intrahepatic arteriovenous complex malformation (Figure 1, Videoclips S1–S3) with two intrahepatic high-peak velocity fistulae (275 cm/s) connecting the abdominal aorta to the UV. One presented as a direct, short and narrow vessel (Videoclip S3) between the origin of the superior mesenteric artery and the UV. The other shunt emerged from the celiac artery site with an unusual wide curvilinear course that became gradually wider, similar to the dilated UV at the confluence. We noted that the openings of the two shunts in the UV were almost facing each other (Videoclips S2 and S3). Doppler determination of the blood-flow direction was useful to differentiate the latter fistula from an abnormal umbilical-cardiac shunt. A dilated ductus venosus and right-heart enlargement were noted (Figure 2, Videoclip S4), with normal ductal/cardiac flows, normal cardiothoracic ratio and absence of heart failure or hydrops features. In addition, vermian malrotation, partial agenesis of the corpus callosum, frontal bossing and a low nasal bridge were noted (Figure 2, Videoclip S4). Conventional cytogenetic analysis of cultured amniocytes using G-banding revealed mosaic trisomy 17 (35% affected cells), which is a very rare genetic anomaly, with only nine cases reported prenatally, all of which had abnormal ultrasound findings. The previously reported clinical features4, 5 are consistent with some of the extravascular findings of our case, such as facial dysmorphism and cerebral and heart defects. The pregnancy was terminated at 22 weeks following counseling provided by a multidisciplinary team including a maternal-fetal specialist, geneticist and pediatric cardiologist. Pathology confirmed the ultrasound features, and fibroblast culture analysis from skin biopsy showed 7.5% trisomy-17 mosaicism (Figure 2). This report presents a prenatally diagnosed case of multiple aorta–UV fistulae which originated and terminated close together but which were very different in terms of course and caliber. Interestingly, in our case, cardiohemodynamic implications were mild, although the supposed determinants for the 'steal phenomenon' (number and size of the shunts and the caliber of the artery involved) were significant. There have been several previously reported cases of intrahepatic shunts in association with hydrops, trisomy 21 and other malformations (left-sided inferior vena cava, duodenal atresia)1, 3, but our case presented anomalies consistent with the underlying chromosomal syndrome. Healthcare professionals should keep in mind that intrahepatic shunts may involve various vascular sites and patterns, and aorta–UV communications are not an exception. Abnormal structural and genetic associations are also variable, while the secondary cardiac and hemodynamic determinations may not always reflect the caliber/number of fistulae or the size of the vessels involved. Videoclips S1–S5 may be found in the online version of this article. Videoclip S1 Grayscale and directional power Doppler ultrasound in axial view of fetal abdomen, showing direct, short and narrow vascular communication between abdominal aorta and umbilical vein. Videoclip S2 Longitudinal sweep of fetal abdomen on directional power Doppler ultrasound, showing intrahepatic arteriovenous complex malformation, with two fistulae connecting abdominal aorta to umbilical vein. One straight and narrow vessel originates from superior mesenteric artery site and other fistula emerges from celiac artery site with wide curvilinear course and increasingly greater caliber. At confluence with intrahepatic segment of umbilical vein, the two fistulae are almost facing each other. Videoclip S3 Longitudinal sweep of fetal abdomen on grayscale and directional power Doppler ultrasound. Doppler determination of blood-flow direction was useful to differentiate fistula that courses close to heart from abnormal umbilical-cardiac shunt. Dilated ductus venosus was noted. Videoclip S4 Axial cardiac sweep on grayscale and directional power Doppler ultrasound, showing mild enlargement of right heart, with normal cardiothoracic ratio and cardiac flows. Videoclip S5 Four-dimensional rendering of fetal face, showing frontal bossing and low nasal brid Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.