Portal Anastomoses: Anatomy, Clinical Significance, and Management in Portal Hypertension
Anatomic Sites of Portosystemic Anastomoses
Portal-systemic anastomoses are critical collateral pathways that develop when portal pressure exceeds normal values, creating connections between the high-pressure portal venous system and the low-pressure systemic circulation. The major anatomic sites include:
Gastroesophageal junction: Portal blood from the left gastric and short gastric veins anastomoses with systemic azygos veins, forming esophageal and gastric varices that represent the most clinically significant collateral pathway due to high bleeding risk 1
Rectum and anal canal: Superior rectal veins (portal) connect with middle and inferior rectal veins (systemic), forming anorectal varices 2
Umbilical region: Paraumbilical veins recanalize to connect portal circulation with superficial abdominal wall veins, creating caput medusae 2
Retroperitoneum: Splenic, colic, and mesenteric veins form collaterals with retroperitoneal systemic veins 2
Stomal sites: In patients with ileostomies (particularly PSC patients post-colectomy), peristomal varices develop in up to 26% of cases, representing a unique and challenging anastomotic complication 1
Clinical Significance and Complications
Variceal Bleeding
Clinically significant portal hypertension (CSPH) is defined as hepatic venous pressure gradient (HVPG) ≥10 mmHg, which drives the formation of varices and risk of decompensation 2
Bleeding risk becomes substantial when HVPG exceeds 12 mmHg, making this the therapeutic target for pressure reduction 1, 3
Esophageal varices represent the most life-threatening manifestation, with acute bleeding episodes carrying significant mortality 4, 5
Other Manifestations
Ascites develops as the most common first decompensation event in compensated cirrhosis with CSPH 2
Portal hypertensive gastropathy and gastric antral vascular ectasia syndrome cause chronic blood loss 4
Hepatic encephalopathy occurs in approximately one-third of patients, particularly after portosystemic shunt procedures 6, 7
Management Algorithm for Portal Hypertension
Stage 1: Compensated Cirrhosis Without CSPH (HVPG <10 mmHg)
Focus exclusively on etiological treatment (antiviral therapy for hepatitis C, alcohol abstinence, treatment of metabolic dysfunction) and healthy lifestyle modifications 1, 2
Initiate hepatocellular carcinoma surveillance 2
No pharmacologic portal pressure reduction indicated at this stage 2
Stage 2: Compensated Cirrhosis With CSPH (HVPG ≥10 mmHg)
Non-selective beta-blockers (NSBBs) including propranolol or carvedilol should be considered to prevent clinical decompensation 1, 2
Perform variceal screening via endoscopy if liver stiffness measurement (LSM) by vibration-controlled transient elastography (VCTE) is >20 kPa or platelet count <150×10⁹/L 1
NSBBs become mandatory if moderate or large varices are present 2
Consider statin therapy (simvastatin), which reduces portal pressure and decreases liver-related mortality including variceal bleeding deaths 1
Stage 3: Acute Variceal Bleeding
Acute bleeding requires immediate triple therapy: 4, 5
Vasoactive drugs (terlipressin as first-line agent) to reduce splanchnic blood flow 4
Prophylactic antibiotics to prevent bacterial infections and reduce rebleeding 1, 4
Endoscopic therapy (band ligation for esophageal varices, cyanoacrylate injection for gastric varices) 4
Refractory Bleeding Management
Self-expandable metal stents provide bridging to definitive therapy when initial measures fail 4
Early or "pre-emptive" TIPS within 72 hours should be considered in high-risk patients (Child-Pugh B with active bleeding or Child-Pugh C <14 points), though patient selection remains debated 1, 6
Portal pressure gradient should be reduced to <12 mmHg or by ≥20% of baseline during TIPS placement 1
Stage 4: Secondary Prevention of Rebleeding
Combination therapy with NSBBs plus endoscopic band ligation represents the standard approach for preventing recurrent variceal bleeding 2, 4
Add simvastatin 20-40 mg daily in Child-Pugh A/B patients (10-20 mg in Child-Pugh C) 2
TIPS should be deployed for recurrent bleeding despite optimal medical and endoscopic therapy 1, 2
Stage 5: Refractory Ascites
TIPS is recommended for refractory ascites when fluid accumulation persists despite diuretics and repeated paracentesis 1, 6
Note that patients with difficult ascites are not optimal candidates for NSBBs 2
TIPS Procedure: Technical Considerations
Pre-Procedure Requirements
All elective TIPS cases must be discussed in multidisciplinary team including hepatology and interventional radiology 1
Cross-sectional imaging is mandatory to assess vascular anatomy 1, 6
Evaluate liver function, renal function, coagulation status (using thromboelastography rather than INR), cardiac function, nutritional status, and encephalopathy risk 1, 6
Technical Standards
PTFE-covered stents (8-10 mm diameter) should be used as they reduce stenosis rates compared to bare metal stents and are cost-effective 1
General anesthesia or deep sedation with propofol is recommended 1
Target portal pressure gradient <12 mmHg or ≥20% reduction from baseline for variceal bleeding; individualize targets for other indications balancing efficacy against encephalopathy risk 1
Stent placement must not compromise future liver transplantation options—avoid extending toward splenic/superior mesenteric vein confluence or into the right atrium 1
Volume Requirements
- Centers should perform minimum 10 TIPS cases annually, with complex cases (thrombosed vessels, transplant recipients) reserved for centers performing ≥20 cases yearly 6
Post-TIPS Monitoring and Complications
Surveillance Protocol
Doppler ultrasound at 1 week post-procedure in patients with prothrombotic conditions or suspected dysfunction 1, 7
Routine Doppler ultrasound at 6-12 month intervals (6-monthly if undergoing HCC surveillance) 1
No indication for routine venography except in prothrombotic conditions like Budd-Chiari syndrome 1
Hepatic Encephalopathy Management
Lactulose titrated to 2-3 soft bowel movements daily serves as first-line therapy for post-TIPS hyperammonemia and encephalopathy 7
Add rifaximin if lactulose alone fails to control symptoms, or use as replacement in lactulose-intolerant patients 7
For patients with pre-TIPS encephalopathy history, combination lactulose plus rifaximin is strongly recommended 7
In the 8% with refractory encephalopathy despite optimal medical therapy, consider shunt reduction or occlusion (improves encephalopathy in 48-100% but may cause recurrence of original indication) 7
Prophylactic lactulose or rifaximin is NOT recommended for preventing post-TIPS encephalopathy 7
Transaminitis Management
Mild-to-moderate transaminase elevation post-TIPS is typically self-limited and requires only monitoring with serial liver function tests 8
Perform Doppler ultrasound to exclude shunt dysfunction or thrombosis as cause of enzyme elevation 8
For severe transaminitis with liver failure signs, consider TIPS reduction or occlusion 8
Special Clinical Scenarios
Peristomal Varices in PSC Patients
Patients requiring colectomy should preferably undergo ileal pouch-anal anastomosis rather than terminal ileostomy to prevent peristomal varix development 1
Bleeding peristomal varices can be managed with local sclerotherapy, cyanoacrylate injection, microcoil embolization, or TIPS 1
TIPS appears more effective than sclerotherapy alone, though sclerotherapy serves as effective bridging in critically ill patients 1
Some patients require liver transplantation for definitive control 1
Gastric Varices
Treatment depends on vasoactive drugs and cyanoacrylate injection 4
The role of variceal embolization during TIPS remains unclear; decisions should be individualized based on cross-sectional imaging and portography showing large varices where pressure reduction alone may be insufficient 1
Common Pitfalls and Caveats
Avoid using INR to guide coagulopathy correction in cirrhotic patients—thromboelastography provides more reliable assessment 1
Do not perform premature TIPS reduction for transient transaminitis alone without other liver dysfunction signs, as this risks recurrence of the original TIPS indication 8
Recognize that transaminitis degree does not correlate with TIPS function or predict long-term outcomes 8
Smaller diameter TIPS stents (8 mm) were associated with less adequate portal pressure control when compared to 10 mm stents in randomized trials, though they may reduce encephalopathy risk 1
Patients with sarcopenia face increased post-TIPS encephalopathy risk and require careful nutritional assessment 7
TIPS complications (bleeding, infection, heart/liver/kidney failure) occur in <5% of patients, but hepatic encephalopathy affects approximately one-third long-term 1, 6