Transjugular intrahepatic portosystemic shunt (TIPS) complications: what diagnostic radiologists should know.
Giuseppe Mamone, Mariapina Milazz, Ambra Di Piazza, Settimo Caruso, Vincenzo Carollo, Giovanni Gentile, Francesca Crinò, Gianluca Marrone, Gianvincenzo Sparacia, Luigi Maruzzelli, Roberto Miraglia
Abdominal Radiology (2022) doi: 10.1007/s00261-022-03685-0
Transjugular intrahepatic portosystemic shunt (TIPS) is a recognized treatment for the complications of portal hypertension. Morbidity has been shown to be as high as 20% (1) with complications having a 2% fatality rate (2). Early identification of complications have a favorable outcome. The authors provide a review to outline the role of diagnostic radiology in identifying and assessing post-TIPS complications.
CT, MRI and Doppler US all have a role in the pre-procedural evaluation of hepatic and portal vein patency as well as important anatomical variations. Liver morphology, masses and cysts should all be documented as these may interfere with the technical success of the procedure. Obstructed bile ducts should be identified as they require pre procedure decompression.
The authors identify two categories of complications: those related to interventional technique (e.g. hepatic vein thrombosis, haemorrhage, ischaemia, vascular or biliary injury, stent malpositioning or migration) and those associated with TIPS dysfunction and the portosystemic shunting effect.
Correct stent position is of prime importance to achieve adequate function and patency. Stent malpositioning can cause perfusion and shunt outflow stenosis (1). Stent migration can lead to a myriad of cardiovascular complications (1). Covered stents have a higher tendency for migration on comparison to bare metal stents (1). Stent position can be assessed by US, CT and MRI, with the proximal end sited at the confluence of the portal vein and the liver parenchymal tract.
Accidental perforation of the hepatic artery or a branch occurs in 1 to 6% of patients (1, 3). This is usually of low clinical significance (1). Multiphase contrast enhanced CT can be utilized to detect potential complications including pseudoaneurysm, vascular dissection or occlusion and arterioportal fistula haemorrhage.
Portal vein injury on the other hand, has been considered the riskiest step in a TIPS procedure (4) as it can result in massive haemorrhage. Clear understanding of the vascular anatomy with pre-procedural imaging is of prime importance. This is treated immediately by the interventional radiologist, however post-procedure CT or MRI are useful for visualizing residual perihepatic haemorrhage. Haematoma appears as hyperdense on CT and hyperintense on T1, with no contrast enhancement. (4)
Portal and hepatic vein thrombosis appear as non-enhancing vessels on contrast enhanced CT or MRI, with absence of flow at colour doppler examination. Hepatic vein thrombosis is usually of little clinical consequence (5), however a Budd-Chiari type hepatic ischaemia and acute hepatic failure can result.
Biliary duct puncture is reported in up to 5% of cases (1, 3). The connection between biliary and vascular systems can result in infection and haemobilia (1). TIPS stents can also generate biliary occlusion (6) and rapid hepatic decompensation (7). Segmental cholestasis, with intrahepatic biliary dilatation can be seen on imaging. MRI and MRCP is the best way to evaluate cholangitis. Classic findings of a hepatic abscess are the double target sign on contrast enhanced CT: caused by a central low attenuation lesion surrounded by an enhancing rim and a low density outer ring (oedema) (8).
The incidence of liver ischaemia is thought to be underestimated imaging is only performed when complications occur. Infarcts are rare due to the dual blood supply. CT show the parenchymal ischaemic injury as a hypodense, non-enhancing area without mass effect which is often peripheral and wedge shaped.
Puncture of non-target organs, most commonly gallbladder (1), is another known complication.
TIPS dysfunction is defined as a reduction in the portal venous decompression due to occlusion or stenosis of the shunt. Follow up with doppler US is the method to identify such complications, with the initial baseline examination performed 7-14 days post-procedure.
Stenosis and occlusion are the most frequent complications, with long term patency of ePTFE covered stents having favorable outcomes on comparison to bare metal stents: dysfunction at 2 years of 20-30% as compared to 60-80% respectively (9).
Gold standard for TIPS evaluation is trans-shunt venography with portosystemic pressure gradient (PSG) measurement. TIPS dysfunction criteria include a PSG greater than 12mmHg or a luminal narrowing greater than 50%. CT can be used to identify filling defects but it does not provide functional information about flow or pressure. MRI is limited in view of a large number of susceptibility artefacts. Overall, doppler US is the best screening tool for identifying early shunt dysfunction, with reversal of flow and abnormal shunt velocities being the key criteria of assessment (2). The authors however identified that few studies have examined how to apply doppler US optimally, in particular to covered stents.
Less than 5% of TIPS result in acute shunt thrombosis (6). Diagnosis is with doppler US: neither colour nor duplex signals are present in the shunt lumen. Contrast enhanced CT or MRI show absence of lumen opacification (10).
Patients with hernias who undergo TIPS for refractory ascites are at increased risk of incarceration (6) due to the resolution of massive ascites changing the intra-abdominal configuration. CT and MRI can be used to evaluate these complications and plan for surgery
The authors conclude that although TIPS is a relatively safe procedure, the understanding of the procedure and the knowledge of potential complications helps the diagnostic radiologist reach a prompt and correct diagnosis.
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This article was prepared by Dr. Stephanie Arrigo from the Mater Dei Hospital in Msida, Malta.
Comments may be sent to: steffianastasi@gmail.com