What is the approach for an undilated right-sided Percutaneous Transhepatic Biliary Drainage (PTBD) in Interventional Radiology (IR), and what should be looked for on Ultrasound (USG) and fluoroscopy?

Approach to Undilated Right-Sided PTBD in Interventional Radiology

For undilated right-sided percutaneous transhepatic biliary drainage (PTBD), a combined ultrasound and fluoroscopy-guided approach is recommended to achieve successful biliary access while minimizing complications. 1

Pre-Procedure Evaluation

• MRCP or CECT is essential prior to attempting PTBD in patients with suspected hilar obstruction to provide a roadmap of the biliary anatomy, especially when dealing with undilated ducts 2
• Assess coagulation parameters before the procedure as PTBD is contraindicated in patients with uncorrected coagulopathy due to increased bleeding risk (approximately 2.5% of cases) 2, 3
• Evaluate for the presence of ascites, as moderate to massive ascites is a relative contraindication for PTBD 2, 3
• Prophylactic antibiotics should be administered before the procedure to prevent cholangitis, septicemia, and bacteremia 2

Ultrasound Guidance Technique

• Use ultrasound to identify the portal vein branches as landmarks when bile ducts are not well visualized due to lack of dilation 1, 4
• Employ the "parallel technique" - puncturing along the course of the targeted bile duct or adjacent to portal vein when the bile duct itself is not clearly visualized 1, 5
• For right-sided approaches, fluoroscopic guidance has shown higher success rates (91.9%) compared to ultrasound-only guidance (75%) 6
• Position the patient in slight left lateral decubitus to optimize visualization of the right hepatic lobe 4

Fluoroscopic Guidance

• After initial ultrasound-guided puncture, switch to fluoroscopy for cholangiography and guidewire manipulation 1, 4
• A 19-gauge EUS-FNA needle or equivalent is recommended for duct puncture to allow passage of a 0.035-inch or 0.025-inch guidewire 2
• Use a 0.035-inch or 0.025-inch guidewire with a floppy tip to negotiate the bile duct safely 2
• Catheters, balloons, or cystotomes are recommended for tract dilation 2

Technical Considerations for Undilated Ducts

• Multiple puncture attempts may be required in undilated systems, but combining ultrasound and fluoroscopy guidance can significantly reduce the number of punctures (average 1.2 vs. 2.9 with fluoroscopy alone) 7
• Consider CT fluoroscopy-guided initial puncture in particularly challenging cases, which has shown significantly reduced puncture times compared to conventional fluoroscopic guidance 7
• T-drainage, additional CT-guided puncture, or temporary gallbladder drainage can improve technical success rates in patients with undilated bile ducts (success rate of 100% with these adjunctive techniques vs. 60% with conventional approach) 5

Imaging Findings to Look For

• On ultrasound: Identify portal vein branches as landmarks, look for subtle linear echogenic structures representing bile ducts running parallel to portal vein branches 1, 4
• On fluoroscopy: After contrast injection, look for filling defects, strictures, or leakage points in the biliary tree 1, 4
• Confirm successful biliary access by observing bile return through the needle or contrast filling the biliary tree 1, 5

Potential Complications and Management

• Common minor complications include transient hemobilia and fever (occurring in approximately 10% of cases) 1, 4
• Major complications are rare but more frequently encountered with fluoroscopy-guided approaches 6
• A multidisciplinary approach involving interventional radiologists, surgeons, and anesthesiologists is recommended to prevent and manage complications 2

Special Considerations

• In cases where PTBD fails or is complicated by the undilated system, consider alternative approaches such as EUS-guided biliary drainage when expertise is available 3, 8
• For hilar blocks, a transhepatic approach to biliary drainage is specifically recommended 2
• The technical success rate for PTBD in undilated systems is approximately 81-90% when appropriate techniques are used, comparable to success rates in dilated systems 5, 4

By following this systematic approach combining ultrasound and fluoroscopy guidance with appropriate technical modifications, successful PTBD can be achieved even in challenging cases with undilated right-sided biliary systems.