What is a dominant stricture in primary sclerosing cholangitis in a 30‑ to 50‑year‑old male with ulcerative colitis?

Dominant Stricture in Primary Sclerosing Cholangitis

Definition

A dominant stricture in PSC is defined as a stenosis with a diameter of ≤1.5 mm in the common bile duct or ≤1.0 mm in a hepatic duct (within 2 cm of the main hepatic confluence). 1, 2

• This represents a focal, high-grade narrowing that stands out from the diffuse stricturing pattern typical of PSC 1
• The newer terminology "relevant stricture" refers specifically to high-grade strictures (>75% reduction in duct diameter on MRI/MRCP) that cause signs or symptoms of obstructive cholestasis and/or bacterial cholangitis 2
• These strictures are common, occurring in 45-58% of PSC patients during follow-up 1, 3

Clinical Significance

Dominant strictures should always raise suspicion for cholangiocarcinoma (CCA), as this malignancy frequently presents as a stenotic ductal lesion in the perihilar region. 1, 2

Key Clinical Features:

• Patients with dominant strictures have significantly worse survival (mean 13.7 years) compared to those without dominant strictures (23 years) 4
• The 26% risk of cholangiocarcinoma develops exclusively in patients with dominant strictures 4
• Half of cholangiocarcinoma cases present within 4 months of PSC diagnosis, emphasizing the critical importance of thorough evaluation of new dominant strictures 4
• Patients with dominant strictures demonstrate higher alkaline phosphatase and bilirubin levels, along with higher PSC Mayo risk scores 1

Symptomatic Presentation:

• Cholangitis, jaundice, pruritus, right upper quadrant pain, or worsening biochemical indices indicate the need for intervention 1
• Recent data shows patients with the new definition of dominant stricture are more symptomatic, have higher cholestatic liver enzymes, and more advanced bile duct disease 3

Diagnostic Approach

Before any therapeutic intervention, brush cytology and/or endoscopic biopsy must be obtained to exclude superimposed malignancy. 1, 2, 5

• ERCP should be performed promptly in patients with increases in serum bilirubin, worsening pruritus, progressive bile duct dilatation on imaging, and/or cholangitis 1
• The ERCP-based diameter definition does not apply to MR cholangiography due to insufficient spatial resolution, particularly for extrahepatic ducts 2
• The decision for intervention must be a compound clinical decision considering symptoms, biochemistry, and imaging findings together, not diameter criteria alone 2

Management Strategy

Endoscopic balloon dilatation alone is the preferred first-line treatment for dominant strictures in PSC. 5

Endoscopic Therapy Algorithm:

First-Line: Balloon Dilatation

• Select balloon caliber up to the maximum caliber of the ducts delimiting the stricture (typically 6-8 mm for hepatic ducts, up to 8 mm for common bile duct) 5
• Repeat dilations at intervals of 1-4 weeks until technical success, typically requiring 2-3 sessions with 80-90% success rate 5
• Technical success is defined as complete balloon inflation with no waist observed fluoroscopically, followed by unobstructed passage of contrast 5
• This approach has significantly lower complication rates (15% vs 54%) compared to stenting 5

Second-Line: Stenting

• Reserved for strictures refractory to dilatation alone 5
• Short-term stenting is preferred over long-term stenting to reduce complications 5
• Long-term stenting carries higher risk of stent clogging and cholangitis 5
• The European DILSTENT trial was prematurely stopped due to significantly higher serious adverse event rates in the stent group 5

Biliary Sphincterotomy

• Not performed routinely but considered case-by-case, particularly after difficult cannulation in patients likely to require multiple ERCPs 5

Surgical Management:

• Extrahepatic bile duct resection and Roux-Y hepaticojejunostomy is reserved for selected non-cirrhotic patients with dominant strictures refractory to endoscopic and percutaneous management 1
• Selected non-cirrhotic PSC patients have overall survival of 83% at 5 years and 60% at 10 years with surgical approach 1
• Bilirubin levels ≥2 mg/dL and cirrhosis are associated with decreased survival 1

Management of Complications

Prophylactic antibiotics should be administered routinely before ERCP in PSC patients. 5

• Bacterial cholangitis requires antimicrobial therapy with correction of bile duct obstruction 1
• Recurrent bacterial cholangitis warrants prophylactic long-term antibiotics 1
• Refractory bacterial cholangitis is an indication for liver transplantation evaluation 1

Critical Pitfalls

• The distinction between benign dominant stricture and cholangiocarcinoma is difficult; stenotic lesions are far more often benign than malignant despite the 10-15% lifetime CCA risk 1
• Dysplasia in brush cytology is more common in patients with dominant strictures (5-9%) compared to those without (3%) 3
• 15-20% of PSC patients will experience obstruction from discrete areas of narrowing within the extrahepatic biliary tree requiring intervention 1