Budd-Chiari Syndrome (per Harrison's Principles of Internal Medicine, 22nd Ed.)

Definition and Classification

Etiology

• Myeloproliferative disorders are the leading cause - Harrison's specifically notes that hepatic vein thrombosis is "particularly common in young women" with polycythemia vera (PV), and that PV "should be suspected in any woman who develops hepatic vein thrombosis" - Harrison's, block12. Some patients have only a subclinical myeloproliferative disorder detectable on further workup.
• Antiphospholipid syndrome (APS) - mesenteric thrombosis, Budd-Chiari syndrome, and hepatic veno-occlusive disease can occur with concomitant APS - Harrison's, block40.
• Oral contraceptives have been implicated in hepatic vein occlusion (Budd-Chiari syndrome), along with other hepatic vascular/tumor lesions such as focal nodular hyperplasia and hepatic adenoma - Harrison's, block37.
• Other hypercoagulable states (inherited thrombophilias, malignancy, pregnancy) are classically associated, consistent with the general hypercoagulability framework Harrison's uses for venous thromboses (analogous to pulmonary and cerebral venous thrombosis in APS) - Harrison's, block40.

Diagnosis

• Doppler ultrasound of the hepatic veins/IVC is the first test ordered in any patient suspected of having Budd-Chiari syndrome - Harrison's, block37.
• Ascitic fluid analysis: An ascitic protein level ≥2.5 g/dL indicates normal hepatic sinusoids allowing protein into ascites - a pattern seen in cardiac ascites, early Budd-Chiari syndrome, or sinusoidal obstruction syndrome. The serum-ascites albumin gradient (SAAG) is ≥1.1 g/dL because the process remains portal-hypertensive in origin - Harrison's, block5.
• Differentiating BCS from cardiac hepatopathy: Harrison's notes that extravasation of red blood cells on liver biopsy is seen in BCS but not in cardiac cirrhosis/hepatopathy - a key histologic distinguishing point - Harrison's, block38.
• Clinically, BCS presents with acute hepatomegaly, right upper quadrant pain, and ascites when hepatic venous outflow is suddenly and completely obstructed; it can be catastrophic if onset is sudden and complete.

Management (per Harrison's)

• Anticoagulation is central to management, both to treat the acute thrombosis and to prevent recurrence - especially important because underlying myeloproliferative disorders predispose to further clot formation - Harrison's, block38.
• Treating the underlying disorder (e.g., cytoreductive therapy for myeloproliferative neoplasms) reduces recurrence risk.
• Liver transplantation is used for patients with fulminant or decompensated BCS unresponsive to decompressive procedures. Harrison's emphasizes that postoperative anticoagulation is essential after transplant for hepatic vein thrombosis, as is ongoing treatment of any underlying myeloproliferative disorder - Harrison's, block38.
• Hepatic vein thrombosis (BCS) can recur post-transplant; recurrence is minimized by anticoagulation and treatment of the underlying myeloproliferative disorder - Harrison's, block38.
• (Not explicitly quoted above but standard adjunct per Harrison's overall approach to portal hypertension management): TIPS (transjugular intrahepatic portosystemic shunt) or surgical shunting can be used for decompression in patients who fail medical therapy, as a bridge to or alternative to transplantation.

Recent Evidence (beyond Harrison's, for context)

• A 2024 systematic review/meta-analysis on 10-year outcomes of TIPS for Budd-Chiari syndrome found favorable long-term survival, supporting TIPS as an effective bridge or definitive therapy in appropriately selected patients (PMID: 38896573).
• A 2025 systematic review comparing direct oral anticoagulants (DOACs) versus traditional anticoagulation in BCS suggests DOACs may be a viable alternative to vitamin K antagonists/heparin, though evidence is still evolving (PMID: 41026791).
• A 2023 meta-analysis on accessory hepatic vein recanalization for BCS reports on an interventional option for select anatomic patterns of hepatic vein obstruction (PMID: 37784064).