Primary Causes and Pathophysiology of Rectal Varices

Pathophysiology and Causes

Portal hypertension is the primary cause of rectal varices, which develop as portosystemic collaterals when portal pressure increases above a threshold 1, 2
Portal pressure increases due to increased resistance to flow, primarily from architectural distortion of the liver caused by fibrous tissue and regenerative nodules in cirrhosis 1, 3
Active intrahepatic vasoconstriction accounts for 20-30% of the increased intrahepatic resistance, largely due to decreased endogenous nitric oxide production 1
When portal pressure rises above the threshold (hepatic venous pressure gradient >10-12 mmHg), portosystemic collaterals develop at sites of communication between portal and systemic circulation 1, 4
Cirrhosis (most common cause) leads to portal hypertension and rectal varices 1, 4
Advanced fibrosis without cirrhosis can also lead to portal hypertension and rectal varices 3

Severity of liver disease (Child-Pugh class B/C) is a risk factor for bleeding from rectal varices 1, 5
Size of varices (larger varices have higher bleeding risk) is a risk factor for bleeding from rectal varices 6
Higher portal pressure gradient (HVPG >20 mmHg) is a risk factor for bleeding from rectal varices 3
Presence of red spots on varices (endoscopic finding) is a risk factor for bleeding from rectal varices 6, 5

Mortality is significantly higher in patients with bleeding rectal varices compared to other sources of lower gastrointestinal bleeding (80% vs 13% within 2 months in one study) 5
Rectal variceal hemorrhage often occurs in patients with liver cirrhosis at the final stage during progression of portal hypertension 5