Pre- and Postoperative Imaging of the Rex Shunt in Children: What Radiologists Should Know

Abstract

The Rex shunt is a potentially curative surgical procedure that reestablishes physiologic hepatopetal portal flow. It is typically accomplished by interposing a vascular conduit between the superior mesenteric vein to the still patent intrahepatic portal venous system. This procedure results in resolution of portal hypertension.

Sonographic Evaluation of a Unique Meso-Rex Shunt: A Case Study

“…3 The Rex shunt is meant to be a curative to the broad diagnosis of portal hypertension. 3 Portal hypertension in pediatric medicine is usually a result of an increase in intrahepatic resistance to hepatopetal portal venous flow. 1 Extrahepatic portal vein obstruction (EHPVO) is one of three different types of portal hypertension and is considered the most common cause of upper gastrointestinal bleeding in children.…”

“…2 These obstructions can happen in the venous flow at three levels: prehepatic (caused by portal or splenic vein thrombosis), intrahepatic (secondary to cirrhosis), or posthepatic (secondary to hepatic vein occlusion, congestive heart failure, or constrictive pericarditis). 3 It is possible for the thrombosis of the extrahepatic portal vein to extend into the intrahepatic portal vein as well. This thrombosis impairs the hepatopetal flow from the SMV and splenic vein, causing a development of prehepatic portal hypertension.…”

Surgical Mesoportal Bypass and Portosystemic Shunt Interventions

“…11,13,22,23 Candidacy for a meso-Rex bypass is three-fold as follows: (1) a patent intrahepatic portal tree with the left portal vein measuring at least 2 mm, (2) adequate mesenteric vein purchase for an inflow tract, and (3) no intrinsic liver disease. 24 Vascular assessment of the IVC, renal veins, and splenic vein is essential in such event where the meso-Rex is infeasible and other shunts are to be considered. Often the splenic and superior mesenteric veins are not well evaluated with the Doppler US due to the presence of bowel gas; therefore, portal venous phase computed tomography (CT) is performed.…”

Non–Catheter-related Venous Thromboembolism in Children: Imaging Review from Head to Toe

“…In older children, other causes include infection and inflammation (eg, appendicitis, inflammatory bowel disease), dehydration, sickle cell disease, congenital and acquired prothrombotic disorders, and liver transplant (73,75). Extrahepatic portal venous obstruction has also been described after splenectomy for hematologic disease (Fig 12) and after laparoscopic cholecystectomy (76)(77)(78)(79).…”

“…In extrahepatic portal venous obstruction, flow from the SVC and the splenic and coronary veins into the liver is hampered by a relative or complete occlusion of the portal vein. This occlusion eventually results in cavernous transformation of the portal vein and prehepatic portal hypertension (79).…”