Prenatal diagnosis of abdominal aorta-umbilical vein fistula using high-definition flow render mode and spatiotemporal image correlation

Introduction

Congenital arteriovenous fistula involving the abdominal aorta is very rare in prenatal ultrasonography (1). In this article, we report the ultrasound findings of a rare abdominal aorta-umbilical fistula, in which four-dimensional (4D) color Doppler combined with spatiotemporal image correlation (STIC) and high-definition (HD) blood flow rendering modes were used to show the abnormal overall spatial relationship.

Case presentation

At 24 weeks of gestation, a 26-year-old gravida was referred for further evaluation due to abnormal findings in routine ultrasound, despite having no history of congenital abnormalities or medication use during pregnancy. Fetal echocardiography revealed the dilation of the right heart chambers to a certain degree due to the presence of an arteriovenous fistula. However, no other significant structural or functional abnormalities were observed in the fetal heart. Additionally, there were no signs of heart failure, cardiac hypertrophy, or mitral valve regurgitation.

Cross-sectional imaging revealed two arteriovenous complex malformations in the fetal liver, establishing connections between the abdominal aorta and the umbilical vein (UV) (Figure 1). One of these malformations presented as a direct, short, and narrow vascular channel extending from the origin of the celiac artery to the UV (Figure 1A). The other shunt connected the aorta to the dilated UV, coursing from the cranial origin of the aortic celiac artery to the diaphragm at the base of the heart, then anteriorly to the abdominal wall, and finally curving caudally to join with the UV (Figure 1B).

Figure 1 Description of vascular abnormalities. (A) Axial upper abdomen plane showing the direct, narrow aorta-UV connection (as indicated by the solid arrow). (B) Sagittal view of the fetal abdomen showing the same vessel (as indicated by the open arrow). (C) High peak velocity of blood flow in the above-described vessel (152 cm/s). (D,E) Four-dimensional spatiotemporal image correlation reconstruction of the two abnormal communications showing: the straight narrow shunt (as indicated by the open arrow); and the long, curved and large shunt (as indicated by the solid arrow). (F,G) Serial images showing another shunt (as indicated by the solid arrow) connecting aorta, and the dilated UV, coursing from the aortic celiac artery origin cranially to the diaphragm at the base of the heart, then anteriorly to the abdominal wall, and finally curving caudally to join the UV; note the progressive caliber, similar to the dilated UV at the confluence. The ductus venosus is also visibly dilated. AO, aorta; IVC, inferior vena cava; UV, umbilical vein.

Spectral Doppler confirmed arterial flow with an extremely high peak velocity of 152 cm/s in this shunt vessel (Figure 1C). A dilated ductus venosus was observed; however, the cardiac flows were normal, as was the cardiothoracic ratio, and there was no evidence of heart failure or hydrops features. These two shunts converged confluently at the UV. The spatial relationships of these abnormal communications were vividly visualized using 4D color Doppler with STIC and HD flow render mode (Voluson E10; GE Healthcare, Zipf, Austria) (Figure 1D,1E). Further, the two-dimensional ultrasound showed that the dilation of the UV was 2.9 mm wide and had a pulsating blood flow spectrum (Figure 2A,2B).

Figure 2 Fetal aorto-umbilical vein fistula: dilated umbilical veins and their blood flow spectrum. (A) Umbilical vein width: 0.29 cm. (B) The frequency spectrum of umbilical vein blood flow showed pulsation.

Two weeks later, only a short vessel could be observed above the abdominal aortic trunk, which was not connected to the UV (Figure 1F). The ultrasound review revealed that the extensive shunt was completely undetectable (Figure 3A,3B). No extracardiac abnormalities were detected. Both fetal karyotyping and chromosomal microarray analysis yielded normal results.

Figure 3 The aortic-umbilical venous fistula disappeared after two weeks of follow-up examination. (A) Two abnormal vascular connections were observed in the aorta and umbilical vein (as indicated by the solid yellow arrows). (B) No abnormal vessels were found on follow-up ultrasound two weeks later. AO, aorta; UV, umbilical vein.

A male infant was delivered vaginally at 39+4 weeks of gestational age with a birth weight of 3,540 g. An abdominal ultrasound performed on the second day after birth confirmed that the infant had a small vessel above the abdominal trunk of the descending aorta that was not connected to any blood vessels in the abdominal cavity (Figure 1G). No symptoms manifested during the 12-month postoperative/postnatal surveillance.

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

In clinical practice, congenital arteriovenous shunts in the fetal liver are very rare, and abdominal aortic UV fistulae are even rarer (1). We report a case of two anomalous vascular connections between the abdominal aorta and UV. In such cases, the arteriovenous malformation may manifest as a low-resistance arteriovenous shunt and may lead to life-threatening congestive heart failure. Thus, early prenatal diagnosis and postnatal validation are essential to enable accurate treatment before complications occur.

Fetal aorto-umbilical venous fistula occurs as the result of an interaction of embryonic vascular development errors, genetic signaling pathway disorders, hemodynamic abnormalities, and environmental factors. The core mechanisms include: (I) degeneration failure or the incorrect branching of the primitive vascular plexus; (II) genetic mutations or genetic factors, such as some aneuploids (trisomy 17), which may be associated with abnormal vascular development, and an abnormal VEGF/Notch/TGF-β signaling pathway; and (III) an aorta-umbilical venous pressure difference that maintains an abnormal shunt (2).

Baltensperger et al. reported the presence of mosaic trisomy 17 (35%) in cultured amnion cells from an aorta-UV fistula, which is a very rare genetic abnormality (3). However, in this case report, the dilated UV might have been associated with turbulent flow in arteriovenous malformations.

Doppler ultrasonography is a rapid, non-ionizing, reliable, and secure imaging modality for diagnostic purposes. In congenital aorto-umbilical fistulae cases, color Doppler imaging typically reveals dilation of the UV segment at the fistula site, accompanied by turbulent, high-velocity arterialized flow directed away from the liver (4). Associated clinical features often include splenomegaly and varices. Aortic tapering near the celiac trunk is frequently observed, stemming from reduced blood flow distal to the fistula in the abdominal aorta.

The key objective of the diagnosis of prenatal arteriovenous fistula is to identify whether there are abnormal blood vessels between the aorta or its branches and veins. On Doppler sonography, vascular mapping and Doppler waveforms can be seen. An ultrasound image of an aorto-umbilical venous fistula should show one or more tortuous enlarged vessels connecting the aorta and UV with high-peak Doppler shifts, low arterial resistance index, and increased venous pulsation (5).

Sonographers should be aware that arteriovenous fistulas may involve different vascular sites and morphology, that structural abnormalities and genetic associations are uncertain, and that congenital malformations leading to secondary cardiac hemodynamic changes do not necessarily reflect the direct diameter or number of fistulas or the caliber of the involved vessels. If a fistula persists or appears abnormal on follow-up, surgery may be necessary.

Although most aorta-UV fistulas require postnatal intervention, a minority may close spontaneously. The mechanisms of occurrence of the aorta-UV fistula include: (I) increased placental resistance or redistribution of cardiac output to reduce shunting; (II) a local endothelin-1 increase or thrombosis contributing to lumen occlusion; and (III) the upregulation of anti-angiogenic factors such as TSP-1, inhibiting fistula maintenance (2). In this case report, spontaneous closure of the aorto-umbilical venous fistula was diagnosed, and abnormal vessels were detected by ultrasound after two weeks. Kesrouani et al. reported a related case in 2022 in which the abdominal aorta-umbilical venous fistula closed spontaneously, and the infant outcome was satisfactory (6).

For fetuses with abnormal vascular connections between the UV and aorta, 4D color Doppler combined with STIC and HD flow rendering modes can be very effective in tracking the flow of abnormal blood vessels between the arteriovenous and the overall spatial relationship. 4D color Doppler combined with STIC and HD flow rendering modes can also be used to determine whether there is a normal connection between the fetal portal vein and the umbilical cord system, and whether the fetal UV is directly connected to the right atrium (7).

Early fetal ultrasound detection can be used in the clinic to: (I) show the spatio-anatomical correlation of the abdominal aorta-UV fistula using 4D color Doppler and STIC HD flow modes; (II) perform fetal karyotyping and genetic testing in the case of related malformations; (III) immediately perform a detailed fetal morphological scan if a suspicious arteriovenous fistula is found during the scanning process to dynamically monitor the development of abdominal organs, and the presence or absence of ascites throughout the fetal period; and (IV) perform long-term follow up (8).

In conclusion, we present an extremely rare case of UV fistula involving the abdominal aorta. The prognosis of the fetus after birth was good. Antenatal screening was instrumental in achieving a timely diagnostic evaluation through clinical and radiological means. In this case, prenatal ultrasonography using 4D color Doppler with STIC and HD flow modes helped to visualize the spatio-anatomical correlation of the abdominal aorta-UV fistula. Although the progression of fetal arteriovenous malformation depends on the size of the lesion, associated arteries, and associated abnormalities, the majority of published isolated cases have shown favorable outcomes, including natural closure and surgical success.

Acknowledgments

None.

Footnote

Funding: This work was supported by the Science and Technology Program of Gansu Province (No. 23JRRA1383).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-24-2353/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for publication of this article and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Iliescu DG, Ruican D, Nagy R, Burada F. Aorta-umbilical vein fistulae in fetus with trisomy-17 mosaicism. Ultrasound Obstet Gynecol 2020;55:419-21. [Crossref] [PubMed]
2. Hartung J, Chaoui R, Kalache K, Tennstedt C, Bollmann R. Prenatal diagnosis of intrahepatic communications of the umbilical vein with atypical arteries (A-V fistulae) in two cases of trisomy 21 using color Doppler ultrasound. Ultrasound Obstet Gynecol 2000;16:271-4. [Crossref] [PubMed]
3. Baltensperger A, Haischer G, Rohena L. Rare case of live born with confirmed mosaic trisomy 17 and review of the literature. Clin Case Rep 2016;4:420-4. [Crossref] [PubMed]
4. Beraud E, Rozel C, Milon J, Darnault P. Umbilical vein varix: Importance of ante- and post-natal monitoring by ultrasound. Diagn Interv Imaging 2015;96:21-6. [Crossref] [PubMed]
5. Yang BZ, Li Z, Wang ZG. Nutcracker syndrome due to left-sided inferior vena cava compression and treated with superior mesenteric artery transposition. J Vasc Surg 2012;56:816-8. [Crossref] [PubMed]
6. Kesrouani A, Obeid R, Daou L, Fakih C, Choueiry E, Chalouhy G. Characteristics and outcome in prenatally diagnosed vascular aorta-umbilical vein malformation. J Matern Fetal Neonatal Med 2022;35:6687-90. [Crossref] [PubMed]
7. Hata T, Kawahara T, Konishi M, Bouno S, Yamanishi T, Koyanagi A, Miyake T. Isolated tortuous ductus arteriosus in a fetus: HDlive Flow with spatiotemporal image correlation (STIC) study. J Perinat Med 2023;51:798-804. [Crossref] [PubMed]
8. Tie HX, Ma B, Zhang DC, Li TG. Prenatal diagnosis of fetal inferior vena cava malformation using HDlive flow combined with spatiotemporal image correlation. Echocardiography 2022;39:685-90. [Crossref] [PubMed]