Right portal branch to ovarian vein anastomosis: An unusual portosystemic shunt secondary to pelvic venous congestion

Abstract

Spontaneous portosystemic shunts in noncirrhotic patients are rare vascular anomalies and may present a diagnostic challenge. We report a rare right-sided spontaneous porto-ovarian venous communication in a 35-year-old woman presenting with symptoms of pelvic venous congestion. Contrast-enhanced CT performed during the portal venous phase demonstrated a segmental branch of the right portal vein anastomosing with a markedly dilated and tortuous right ovarian vein, associated with parametrial and pelvic varices. The right ovarian vein was traced inferiorly and confirmed to drain into the inferior vena cava. The main portal vein and intrahepatic branches were patent, with normal hepatic enhancement and no imaging evidence of cirrhosis, portal thrombosis, or portal hypertension. To our knowledge, only 1 similar case involving the left ovarian vein has been reported in indexed literature. Recognition of this rare porto-ovarian communication is essential to avoid diagnostic pitfalls and to guide appropriate management strategies in patients presenting with pelvic venous congestion.

Introduction

Spontaneous portosystemic shunts (SPSS) are rare vascular communications between the portal and systemic venous systems that may occur in noncirrhotic patients and often present a diagnostic challenge [1,2]. Although most portosystemic shunts are associated with cirrhosis or portal hypertension, congenital or idiopathic variants have also been described and are considered exceptionally uncommon [1,2]. Involvement of pelvic veins—particularly the ovarian veins—in direct communication with the portal system is exceedingly rare [2].

A previously reported case described a spontaneous communication between a left portal venous branch and the left ovarian vein in a patient presenting with pelvic varices [3]. In addition, isolated reports have described the use of ovarian veins as venous conduits in surgical portal or mesenteric vein reconstruction [2], underscoring the anatomical proximity but highlighting the rarity of spontaneous porto-ovarian communications. The present case illustrates a right-sided porto-ovarian venous communication and supports the concept that such anomalous connections may involve either gonadal venous pathway and potentially contribute to pelvic venous congestion syndrome.

Case presentation

A 35-year-old multiparous woman (G2P2) presented with chronic pelvic discomfort characterized by heaviness and intermittent lower abdominal pain, exacerbated by prolonged standing. She also reported mild dyspareunia and a sensation of pelvic fullness. There was no history of lower limb edema, gastrointestinal bleeding, prior abdominal or pelvic surgery, or cesarean section.

Her medical history was otherwise unremarkable, with no known liver disease, alcohol abuse, or thromboembolic events. Laboratory investigations demonstrated normal liver function tests, normal coagulation parameters, and no hematologic abnormalities. Viral hepatitis serology (HBV and HCV) was negative. Clinical examination revealed no signs of chronic liver disease.

Imaging showed no splenomegaly, ascites, or gastroesophageal varices. Doppler ultrasound was not performed prior to CT, as the patient was directly referred for contrast-enhanced CT due to persistent symptoms.

Contrast-enhanced CT of the abdomen and pelvis was performed during arterial and portal venous phases. Imaging demonstrated an anomalous vascular communication arising from a segmental branch of the anterior division of the right portal vein and extending toward the right ovarian vein. The anastomotic vessel coursed inferiorly and laterally from the hepatic hilum. The right ovarian vein was markedly dilated and tortuous, measuring approximately 7.7 mm in diameter, and was associated with para-uterine and parametrial varices forming a plexiform pattern consistent with pelvic venous congestion.

Early opacification of the right ovarian vein during the portal venous phase confirmed active porto-ovarian flow. The right ovarian vein was traced inferiorly and visualized draining into the inferior vena cava on axial and coronal multiplanar reconstructions. The main portal vein and intrahepatic branches were patent, with normal hepatic enhancement and no imaging evidence of cirrhosis, portal hypertension, or thrombosis. No additional portosystemic collaterals were identified in the gastroesophageal, retroperitoneal, or splenic territories (Fig. 1, Fig. 2, Fig. 3).

Fig. 1.

Axial contrast-enhanced CT (portal venous phase) demonstrating the anomalous vascular communication arising from a segmental branch of the right portal vein (blue arrow) and extending toward a dilated right-sided porto-pelvic venous channel (red arrow). The orange arrows indicate the communication of this venous channel with the inferior vena cava. The green arrow highlights associated pelvic venous congestion with dilated parametrial varices.

Fig. 2.

Coronal reformatted image demonstrating the tortuous, dilated right ovarian vein (red arrow).

Fig. 3.

3D reconstruction showing the markedly tortuous and dilated right ovarian vein (red arrow).

Based on these findings, a diagnosis of a right portal branch to the right ovarian vein portosystemic shunt secondary to pelvic venous congestion was established. Given the patient’s symptomatic pelvic discomfort, she was managed conservatively with regular clinical and imaging follow-up. Treatment options for symptomatic portosystemic shunts include endovascular embolization or surgical ligation, depending on the patient’s symptoms and hemodynamic impact. In this case, conservative management was preferred, and the patient remained clinically stable without progression of pelvic symptoms during follow-up.

Discussion

Several entities should be considered in the differential diagnosis of anomalous porto-systemic communications involving the pelvic venous territory. Congenital extrahepatic portosystemic shunts, classically described as Abernethy malformations, are characterized by partial or complete diversion of portal blood into the systemic circulation and are frequently associated with hypoplastic or absent intrahepatic portal branches [4,5]. In the present case, the main portal vein and intrahepatic branches were normally developed and patent, with preserved hepatic perfusion, effectively excluding this entity.

Acquired portosystemic collaterals secondary to portal hypertension must also be considered. These are typically associated with imaging findings of chronic liver disease, including cirrhosis, splenomegaly, ascites, and gastroesophageal varices. None of these features were present in our patient, making portal hypertension an unlikely underlying mechanism.

Isolated pelvic congestion syndrome without portal communication represents another important differential diagnosis. In classic pelvic congestion syndrome, ovarian vein dilatation results from gonadal venous reflux rather than portal inflow. In this case, early opacification of the right ovarian vein during the portal venous phase strongly supports a porto-systemic contribution rather than isolated gonadal reflux.

Retroperitoneal or lumbar venous collaterals may mimic the anatomical course of the gonadal veins. However, careful multiplanar evaluation confirmed the characteristic anatomical trajectory and inferior vena cava drainage pattern of the right ovarian vein, supporting its correct identification [6].

Spontaneous porto-systemic shunts (SPSS) in noncirrhotic patients are exceptionally rare [1,2], and their recognition remains essential for accurate diagnosis and appropriate management. Most documented shunts occur intrahepatically or involve splenic, mesenteric, or systemic venous pathways, whereas pelvic veins—particularly the ovarian veins—are almost never implicated as spontaneous drainage routes.

The embryologic basis of this anomaly likely involves persistence of a fetal vascular connection between the vitelline venous system and the subcardinal venous system [7]. Failure of regression may result in a persistent porto-systemic communication [7], supporting a congenital mechanism in this patient, who demonstrated no cirrhosis, portal thrombosis, or additional collateral pathways.

Hemodynamic factors may also contribute to the persistence of such channels. Chronic pelvic venous congestion could theoretically maintain anomalous flow within a pre-existing embryologic conduit. From a radiologic perspective, early opacification of the ovarian vein during the portal venous phase represents a key diagnostic clue [2,8]. Dilated ovarian veins may function as low-resistance pathways between the portal and systemic venous systems [8,9].

Clinically, SPSS involving the ovarian veins may mimic classical pelvic congestion syndrome, presenting with chronic pelvic pain, heaviness, dyspareunia, or venous engorgement. Awareness of these rare communications is therefore essential to avoid misdiagnosis and to guide appropriate therapeutic decision-making. The right-sided location in this case further illustrates that such porto-ovarian communications may occur on either side, emphasizing the importance of comprehensive vascular mapping of both the portal and pelvic venous systems in patients with unexplained pelvic venous congestion.

This case expands the understanding of spontaneous porto-ovarian venous communications and highlights the importance of integrating clinical findings, laboratory results, and detailed cross-sectional imaging to accurately identify rare vascular anomalies and optimize patient management.

Conclusion

We report a rare right-sided spontaneous porto-ovarian venous communication arising from a segmental branch of the right portal vein and draining into the right ovarian vein. To our knowledge, only 1 similar case involving the left ovarian vein has been described in indexed literature. Awareness of this uncommon vascular anomaly is essential for accurate diagnosis, appropriate interventional planning, and optimal management of patients presenting with pelvic venous congestion.

Patient consent

Written informed consent was obtained from the patient for the publication of this case report.