A real and rare type of complete duplication of portal vein: a case report and literature review

doi:10.21203/rs.3.rs-2859861/v1

Download PDF

Research Article

A real and rare type of complete duplication of portal vein: a case report and literature review

https://doi.org/10.21203/rs.3.rs-2859861/v1

This work is licensed under a CC BY 4.0 License

Version 1

posted

You are reading this latest preprint version

Duplication of the portal vein is a rare type of congenital anomaly of the portal system. Herein, we present a rare type of complete portal vein duplication in a 71-year-old female patient complaining of longstanding abdominal distension and dyspepsia and illuminate the mechanism underlying severe complication in embryonic portal vein development. Interventional radiological procedures excluded other probable pathological alternations. Understanding the embryonic development of the portal vein and timely intervention are essential to manage such patients.

Portal vein duplication

Embryonic development

Congenital anomaly

Case report

Duplication of the portal vein (DPV) is an uncommon, albeit a real, developmental anomaly of the portal venous system [1]. It presents as two separated portal veins (PVs) coursing towards the porta hepatis and dividing into segmental branches morphologically. A few types of DPV have been described in previous reports due to different developmental variations of the vitelline system and umbilical vein in embryolonic development. This anomalous condition could lead to life-threatening complications, such as portal hypertension and variceal bleeding. This report described a case of DPV manifesting as two completely separated portal systems without any confluence at the porta hepatis or intrahepatic region. PV hypoplasia of segment branches and preduodenal PV were also present. Finally, we reviewed the relevant literature in English to propose the underlying mechanism of complication from the perspective of embryonic development, as hinted by this case representation.

A 71-year-old female presented to the department of digestive medicine in our institution with a complaint of longstanding abdominal distension and dyspepsia. Laboratory testing showed no abnormal results. The patient was negative for hepatitis, chronic hepatic diseases, and diabetes mellitus. She also denied a history of family genetic disease. She reported that an endoscopic submucosal dissection of stomach had been performed 10 months ago and that signet-ring cell carcinoma had been pathologically determined.

Abdominal examination revealed no abnormal findings. Vital signs at presentation were as follows: body temperature, 36.4 ℃; blood pressure, 110/72 mmHg; heart rate, 82 beats per min; respiratory rate, 19 breaths per min. Laboratory testing showed no abnormal results. A routine contrast-enhanced computed tomography (CT) of the abdomen and pelvis revealed many dilated and tortuous vessels in the portal hepatic area. In addition, the early evident enhancement of the dorsal part of the abnormal portal vessels extending from the splenic vein in the arterial phase was observed (Fig. 1). Coronal CT in the portal vein phase showed that the superior mesenteric vein and splenic vein entered separately into the liver, with no precise confluence between them in the region where the main PV originally ran. The superior mesenteric vein was found to lie anteriorly, inferiorly and ventrally to the splenic vein (Fig. 2). Notably, a “bridge”, about 2.2 cm long, seemed to connect the two portal systems at the lower level of third part of the duodenum. The maximum intensity projection on CT revealed the stenosis at the both distal portion of the “bridge” vein (Fig. 3).

Based on the findings of obvious homogeneous enhancement in the left and right anterior liver lobes as well as probable hypoplasia of portal veins of segment IV, V and VIII regarding vessel edge and shape, diffuse arterioportal fistula beyond CT density resolution was suspected in this case. However, the digital subtraction angiography demonstrated no abnormal channels between the arteries and the portal or hepatic veins. The result of hepatic venous pressure gradient was also negative (free hepatic veinous pressure 3.4 mmHg, wedge hepatic veinous pressure 6.8 mmHg). Given lack of any evidence of portal hypertension and potential puncture complications, portography was not preformed.

During regular follow-up visits in the past one year after discharge, no adverse events occurred. So far, regular follow-up visits have been scheduled in the outpatient department at digestive medicine for this patient.

DPV has been reported with a lower incidence compared to other PV abnormalities. In addition, due to this portal system anomaly developing within different fetal periods, a few heterogeneous forms have been reported. Congenital PV developmental anomalies and their secondary complications should be recognized from an embryological viewpoint.

The vitelline system and umbilical vein system lead to the development of the portal system. After the invasion of the cephalic portions of the vitelline veins by the cells of the liver bud entering the septum transversum, a figure-of-eight cross anastomosis develops between two vitelline veins; this is related to the finding of DPV [2]. These are the cranial-ventral, dorsal and caudal-ventral anastomoses, with being named according to its position relative to the primitive foregut destined to evolve into duodenum. The various parts of the figure-of-eight system obliterate sequentially, namely, (1) the left limb of the cranial ring; (2) the right limb of the caudal ring; (3) the ventral and caudal anastomosis [3]. Interestingly, in this case, none of the aforementioned normal portal embryonic developments had occurred, and the dorsal anastomosis should not have atrophied. Notably, it is the ventral and caudal anastomosis that will develop as the preduodenal portal vein (Fig. 4).

As far as we know, no literature or case reports have described a complete DPV which courses separately without any confluence to form a main trunk and supply the liver without traffic branches. Several types of DPV have been reported presenting with confluence or portal main trunk between the splenic and superior mesenteric veins [4–6]. Additionally, stenosis located in the distal potion of the residual ventral anastomosis, along with transient inhomogeneous perfusion and hypoplasia of segmental PV, were observed in this case.

The abnormal configuration of DPV does not directly give rise to life-threatening complications. Snavely and Breakell [7] reported a 24-year-old patient suffering a fatal hemorrhage from esophageal varices. It was eventually determined that stenosis at the points of junction of the primitive portal system branches was responsible for it. Similarly, in this case, CT revealed two slits situated in the both distal portion of the “bridge” vein. However, only dyspepsia was found in this patient, probably because of anomalous course and hemodynamic disorders. Generally, inexplainable mild gastrointestinal symptoms are more frequently presented in the patients with DPV, as Dighe reported [6].

Portal vein hypoplasia was also suspected in this case because of slender and tortuous vessels supplying to the segment IV, V and VIII of the liver. On the basis of angiography and hepatic venous pressure gradient measurement, the arteriovenous or arterioportal malformation and elevated portal pressure were excluded in this case, implying that abnormal communication with other vessel systems seems not to be involved in the setting of DPV.

In summary, we encountered a patient with a complete DPV that coursed separately without any confluence to form a main trunk. Stenosis situated in the junction of portal system and residual anastomosis was observed. Fortunately, no severe complications occurred. However, the underlying regional portal hypertension and secondary variceal hemorrhage resulting from the potential stenosis should be noted. Interventional radiological treatment like percutaneous transluminal angioplasty is preferred in this dangerous situation. Understanding the fundamental developmental details of portal vein embryogenesis is essential to manage such patients properly.

Author contributions

Jianan Yu, Siwei Yang: Concept development. Jianan Yu, Siwei Yang: Drafting of the manuscript. Tianhao Su: Manuscript editing. Long Jin: administrative, technical, or material support, study supervision.

Funding Not applicable.

Data or materials sharing statement

The data or materials regarding this case are available from the corresponding author on reasonable request.

Informed consent

Written informed consent was obtained from the patient for publication of this Case Report and any accompanying images.

Conflict of interest statement

The authors have no conflict of interests related to this publication. And the manuscript has been read and approved by all the authors.

Marks C (1974) Surgical implications of portal venous system malformation. Annals of The Royal College of Surgeons of England 55(6): 299-306.
Marks C (1969) Developmental basis of the portal venous system. The American Journal of Surgery 117(5): 671-81. https://doi.org/10.1016/0002-9610(69)90404-8
Corness JA, McHugh K, Roebuck DJ, Taylor AM (2006) The portal vein in children: radiological review of congenital anomalies and acquired abnormalities. Pediatric Radiology 36(2): 87-96, quiz 170-1. https://doi.org/10.1007/s00247-005-0010-4
Yang Q, Li J, Wang H, Wang S (2021) A rare variation of duplicated portal vein: left branch derived from splenic vein mimicking cavernous transformation. BMC Gastroenterol 21(1): 404. https://doi.org/10.1186/s12876-021-01970-8
Yang DM, Kim HC, Kim SW (2014) Hepatic fat accumulation with sparing associated with portal vein duplication. Clinical Imaging 38(4): 550-552. https://doi.org/10.1016/j.clinimag.2014.01.011
Dighe M, Vaidya S (2009) Case report. Duplication of the portal vein: a rare congenital anomaly. The British Journal of Radiology 82(974): e32-4. https://doi.org/10.1259/bjr/81921288
Snavely JG, Breakell ES (1954) Fatal hemorrhage from esophageal varices, due to malformations and congenital stenoses in portal venous system. American Journal Medicine 16(3): 459-64. https://doi.org/10.1016/0002-9343(54)90361-7

No competing interests reported.

Download PDF

Version 1

posted

You are reading this latest preprint version

A real and rare type of complete duplication of portal vein: a case report and literature review

Status:

Version 1

Abstract

Figures

Introduction

Case report

Discussion

Conclusion

Declarations

References

Additional Declarations

Status:

Version 1