Prenatal diagnosis of retrorenal left-sided inferior vena cava without hepatic segment using ultrasound and spatiotemporal image correlation: a rare case description

Introduction

Congenital inferior vena cava (IVC) anomalies represent a spectrum of vascular malformations with diverse anatomical variations. Among these, the retrorenal left-sided IVC without hepatic segment is exceptionally rare, with a reported prevalence of 0.2–3% (1-3). Conventional ultrasonography, limited by field-of-view and resolution, often results in underdiagnosis of intricate vascular anomalies. This study presents a case of prenatal diagnosis confirmed by postnatal echocardiography, where two-dimensional ultrasound combined with spatiotemporal image correlation (STIC) technology enabled early identification of the anatomical features and significantly improved the prenatal detection rate of complex vascular anomalies. We systematically evaluate the clinical significance and technical advantages of this combined approach in diagnosing such vascular variants.

Case presentation

A 31-year-old woman at 22 weeks of gestation, with no family history of genetic disorders, had no abnormalities on pre-pregnancy physical or laboratory tests. An initial ultrasound at another hospital revealed a suspected IVC anomaly, prompting referral to Gansu Provincial Maternity and Child-care Hospital for further evaluation. Ultrasonography revealed that the three-vessel trachea section displayed a widening of the internal diameter of the azygos vein, which was about 4.5 mm wide and converged forward into the superior vena cava (SVC) (Figure 1A). The other intracardiac structures of the fetus did not exhibit any discernible abnormalities. Coronal section of abdominal aorta showed: below the level of the renal vein, the IVC was located on the left side of the abdominal aorta; above the level of the renal vein, the hepatic segment of the IVC was not identified. The left IVC joined the hemiazygos vein, which crossed the right side behind the descending aorta in the lower thoracic cavity and joined the azygos vein. Color Doppler flow imaging (CDFI) indicated that the blood flow in the descending aorta was in the opposite direction to that in the left IVC (Figure 1B). STIC technology revealed that the left IVC merged into the hemiazygos vein at the renal vein level, and the hemiazygos vein merged into the azygos vein behind the descending aorta, the azygos vein expanded and widened, and finally converged into the SVC (Figure 1C). Prenatal ultrasound diagnosis: absence of the hepatic segment of the IVC; ectopic drainage of retrorenal left IVC into the hemiazygos vein (dilatation of the hemiazygos vein and the azygos vein). The woman chose to continue the pregnancy, and postnatal ultrasound showed that the hemiazygos vein was dilated and that the hepatic segment of the IVC was absent (Figure 1D); the dilated azygos vein was parallel to the descending aorta on both the ipsilateral and posterior sides (Figure 1E).

Figure 1 Fetal/newborn left inferior vena cava without a hepatic segment of inferior vena cava. (A) The fetal three-vessel trachea view showed dilation of the azygos vein draining into the superior vena cava. (B) Coronal section of abdominal aorta showed the left inferior vena cava draining into the hemiazygos vein and then into the azygos vein. (C) STIC technology showed the full visualization of the whole vascular course and its spatial relationships. (D,E) Postnatal ultrasound showed that the hemiazygos vein was dilated and that the hepatic segment of the IVC was absent (D); the dilated azygos vein was parallel to the descending aorta on both the ipsilateral and posterior sides (E). AZ, azygos; DAO, descending aorta; HAZ, hemiazygos; IVC, inferior vena cava; L, left; LIVC, left inferior vena cava; R, right; STIC, spatiotemporal image correlation; SVC, superior vena cava.

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient (mother) 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

The embryonic development of the IVC is a complex process occurring primarily between the 6^th and 8^th weeks of gestation. During this period, the three pairs of cardinal veins undergo a series of processes including fusion, degeneration, anastomosis, and substitution, culminating in the formation of the four segments of the IVC: the hepatic, suprarenal, renal, and retrorenal segments (4). Abnormalities in the degenerative processes of embryonic veins can lead to a variety of IVC malformations, among which the mechanism of formation of the left IVC is particularly typical. When the degeneration of the infrarenal segment of the right supracardinal vein disappears, while the left side persists, the left IVC is formed; at the same time, the right vitelline vein fails to anastomose with the right subcardinal vein, resulting in the absence of the hepatic segment of the IVC (5). These anomalies result in venous blood from the lower body being shunted through the dilated azygos or hemiazygos venous system, ultimately returning to the right atrium via the SVC. These abnormalities are primarily associated with left atrial isomerism and are frequently accompanied by comorbidities such as visceral heterotaxy (situs ambiguus) and intracardiac structural malformations (6). Although most variants are asymptomatic, some patients are still at potential risk for lower extremity venous insufficiency, deep vein thrombosis (DVT), and pelvic congestion syndrome (3). In addition, dilated azygos and hemiazygos veins can be easily mistaken for mediastinal space-occupying lesions, such as enlarged retroaortic lymph nodes, right paratracheal masses (7). Preoperative identification of these vascular variants is essential for surgical planning and facilitates early assessment and intervention.

In conventional ultrasonography, the solitary left-sided vena cava appears as an IVC below the level of the renal hilum, located posteriorly to the left of the abdominal aorta, crossing the abdominal aorta at the level of the renal hilum to converge obliquely to the right and superiorly to the right atrium. Absence of the hepatic segment of the IVC is characterized by the lack of a demonstrable IVC segment at the hepatic level, with no connection to the hepatic veins. The infrahepatic venous flow is typically shunted through the azygos vein to drain into the SVC before returning to the right atrium (8). This fetus exhibited a combined vascular anomaly characterized by two key features: left-sided IVC and absence of the hepatic segment of the IVC. The venous drainage from the lower body was diverted through the hemiazygos-azygos venous system, ultimately reaching the right atrium via the SVC. The diagnostic challenge is further increased by this intricate spatial anatomy. Due to its small field of view and poor spatial resolution, conventional two-dimensional and color Doppler ultrasonography frequently fails to fully visualize the whole vascular course and spatial adjacency connections during prenatal examination. In this study, a three-dimensional dynamic model of the fetal aortic-venous system was constructed through the introduction of STIC, which clearly showed the connecting paths and spatial positions of the blood vessels, effectively compensated for the technical deficiencies of traditional ultrasound, and provided a key basis for accurate prenatal diagnosis (9).

Although different types of IVC malformations have typical ultrasound manifestations, isolated IVC malformations without hemodynamic abnormalities still have a high rate of underdiagnosis. Three factors are responsible for this: first, the overall prevalence of IVC malformations is low and clinicians are inexperienced in their practice; second, the anatomical complexity of the abdominal vasculature and the prenatal ultrasonographers’ limited knowledge of the relevant theories of embryonic development hamper accurate identification; and third, the fact that current routine prenatal ultrasonographic screening does not include mandatory examination of the IVC in long-axis view (8). It is worth noting that STIC technology not only improves diagnostic accuracy but also aids in doctor-patient communication through intuitive visualization of images, helping prospective parents understand the anatomical features of fetal vascular malformations.

Furthermore, there is no single standard for the current use of STIC technology in the detection of fetal vascular abnormalities when considering medical imaging standardization in relation to International Organization for Standardization (ISO) 13485 quality management system criteria (10) for medical equipment. To ensure consistency in diagnosis across various institutions, it will be necessary to further standardize the technology in the future. This will involve developing a unified STIC operation specification and parameter standards (11), verifying operator qualification and equipment performance regularly, and elucidating the diagnostic efficacy index of the STIC technology through multi-center cross-validation (12,13) to provide a foundation for clinical application evidence.

Conclusions

In summary, prenatal ultrasound diagnosis of IVC malformations requires the use of a multisection combined scanning strategy, combined with STIC technology to achieve three-dimensional visualization of vascular structure, which can greatly improve the ability to identify complex IVC malformations and has an important clinical application value. Accurate prenatal diagnosis not only assists in assessing fetal prognosis and guiding perinatal management but also provides a basis for postnatal intervention. The usefulness of combining multimodal imaging modalities in the diagnosis of IVC anomalies may be further investigated in future research.

Acknowledgments

None.

Footnote

Funding: This study was supported by the Natural Science Foundation 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-2024-2468/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 the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient (mother) 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. Giang do TC. Rajeesh G, Vaidyanathan B. Prenatal diagnosis of isolated interrupted inferior vena cava with azygos continuation to superior vena cava. Ann Pediatr Cardiol 2014;7:49-51. [Crossref] [PubMed]
2. Ramsaran EK, Filiberti AW, Spodick DH. Isolated anomalous inferior vena cava with azygos drainage. Cardiology 1995;86:257-8. [Crossref] [PubMed]
3. Castillo Reina CF, Valdés Hernández M, Rodriguez Reus CJ, Negreros-Osuna AA. Clinical Implications of a Missing Hepatic Segment of the Inferior Vena Cava: A Case Report. Cureus 2024;16:e62857. [Crossref] [PubMed]
4. Babaoğlu K, Doğan Y, Başar EZ, Usta E. Prenatal diagnosis of hepatic interruption of the inferior vena cava with azygos/hemiazygos continuation without structural heart defects: A case series. J Clin Ultrasound 2022;50:795-802. [Crossref] [PubMed]
5. Kabakus I, Kocher M, Agha A, Burt JR. Left-sided Inferior Vena Cava with Hemiazygos Continuation to Left Superior Vena Cava. Cureus 2019;11:e6503. [Crossref] [PubMed]
6. Bronshtein M, Khatib N, Blumenfeld Z. Prenatal diagnosis and outcome of isolated interrupted inferior vena cava. Am J Obstet Gynecol 2010;202:398.e1-4. [Crossref] [PubMed]
7. Li SJ, Lee J, Hall J, Sutherland TR. The inferior vena cava: anatomical variants and acquired pathologies. Insights Imaging 2021;12:123. [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]
9. Ito M, AboEllail MAM, Yamamoto K, Kanenishi K, Tanaka H, Masaoka H, Hata T. HDlive Flow silhouette mode and spatiotemporal image correlation for diagnosing congenital heart disease. Ultrasound Obstet Gynecol 2017;50:411-5. [Crossref] [PubMed]
10. Pacheco DAJ, Bonato SV, Linck W. Advancing quality management in the medical devices industry: strategies for effective ISO 13485 implementation. Int J Qual Health Care 2025;37:mzaf004. [Crossref] [PubMed]
11. Mihcin S, Karakitsios I, Le N, Strehlow J, Demedts D, Schwenke M, Haase S, Preusser T, Melzer A. Methodology on quantification of sonication duration for safe application of MR guided focused ultrasound for liver tumour ablation. Comput Methods Programs Biomed 2017;152:125-30. [Crossref] [PubMed]
12. Mihcin S, Strehlow J, Demedts D, Schwenke M, Levy Y, Melzer A. Evidence-based cross validation for acoustic power transmission for a novel treatment system. Minim Invasive Ther Allied Technol 2017;26:151-61. [Crossref] [PubMed]
13. Karakitsios I, Mihcin S, Saliev T, Melzer A. Feasibility study of pre-clinical Thiel embalmed human cadaver for MR-guided focused ultrasound of the spine. Minim Invasive Ther Allied Technol 2016;25:154-61. [Crossref] [PubMed]