Sharma AM, Zhu D, Henry Z. Portal vein thrombosis: When to treat and how? Vasc Med. 2016 Feb;21(1):61-9. doi: 10.1177/1358863X15611224. Epub 2015 Nov 19. Review. PubMed PMID: 26584887.
European Association for the Study of the Liver. EASL Clinical Practice Guidelines: Vascular diseases of the liver. J Hepatol. 2016 Jan;64(1):179-202. doi: 10.1016/j.jhep.2015.07.040. Epub 2015 Oct 26. PubMed PMID: 26516032.
Definition, Etiology, PathogenesisTop
Thrombosis of the portal vein (PVT) or its intrahepatic branches results in the impairment of blood outflow from the portal venous system and the development of portal hypertension.
Causes: In up to ~50% of cases the cause cannot be determined (idiopathic thrombosis). Possible causes include cirrhosis (the most common known etiology; PVT occurs in <1% of patients with compensated cirrhosis and 8%-25% of those with decompensated cirrhosis), acquired hypercoagulable states (liver or pancreatic cancer, myeloproliferative neoplasms, trauma, inflammatory bowel disease, pancreatitis), inherited prothrombotic states (factor V Leiden; deficiency in protein C, S, or antithrombin protein), and portal vein compression (pancreatic cysts, tumors of the adjacent organs, purulent intra-abdominal lesions).
1. Acute PVT: Clinical presentations range from asymptomatic (presenting later as chronic PVT) to severe abdominal pain, abdominal distention secondary to ileus, and bloody diarrhea if complicated by small bowel infarction. A symptomatic patient with acute PVT often presents within days of the initial thrombotic event. PVT must be differentiated from ischemic colitis and other causes of “acute abdomen.”
2. Chronic PVT develops over several weeks and may be identified by the development of collateral circulation, splenomegaly, and worsening portal hypertension on imaging. Patients often present due to complications of portal hypertension (eg, ascites and variceal bleeding). However, chronic PVT may also be initially clinically silent (no signs or symptoms) and identified incidentally on imaging studies obtained for other indications.
1. Doppler ultrasonography visualizes portal vein flow. In patients with acute thrombosis the portal vein may be dilated, but no collateral circulation is seen. In patients with acute or subacute thrombosis, collateral circulation with flow reversal and splenomegaly are observed.
2. Contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI) can visualize the portal venous system and identify thrombi and collateral circulation. These techniques have superseded classical angiography, which is now performed only in exceptional cases before surgical treatment or liver transplantation.
Other causes of “acute abdomen” and portal hypertension (see Cirrhosis).
1. Management of bleeding esophageal varices: see Gastrointestinal Bleeding.
2. Uncomplicated acute PVT: Antithrombotic treatment (low-molecular-weight heparin [LMWH] followed by a vitamin K antagonist [VKA]) for ≥6 months, or for life in patients with risk factors for thrombosis that cannot be eliminated. Direct oral anticoagulants (DOACs) have not been adequately studied in this population but would be a reasonable option for patients in whom VKA treatment is undesirable.
3. Complicated acute PVT: Antithrombotic treatment (LMWH followed by a VKA) alone or with prior thrombolysis. Indications for local catheter-directed thrombolysis may include thrombus extension with worsening symptoms in patients receiving anticoagulant treatment or threatening bowel infarction related to venous stasis. Intestinal necrosis is an indication for surgical referral and treatment.
4. PVT in patients with cirrhosis: The evidence for treatment of acute PVT in the setting of cirrhosis is predominantly based on observational and case-series studies (no randomized controlled trials are currently available). The outcomes of these studies suggest that treatment with anticoagulant agents and subsequent recanalization may decrease portal hypertension and associated complications. Guidelines from the American Association for the Study of Liver Diseases (AASLD) state that there is insufficient evidence to recommend for or against routine anticoagulation in patients with compensated cirrhosis or incidental PVT awaiting liver transplantation. The European Association for the Study of the Liver (EASL) does not differentiate the efficacy of anticoagulation based on the presence or absence of cirrhosis.
5. Chronic PVT: Long-term antithrombotic treatment is very rarely needed and used. Treat complications of portal hypertension. Prevention of bleeding esophageal varices: see Cirrhosis. In patients with thrombosis limited to the splenic vein (SVT), observation alone may be appropriate. However, splenectomy can be considered in the context of bleeding gastric varices secondary to SVT.