What is a suitable reference site in the liver if the right hepatic lobe is absent?

Alternative Reference Site When Right Hepatic Lobe is Absent

When the right hepatic lobe is absent or unavailable, use the left hepatic lobe (segments II-IV) as the reference site for liver biopsy or assessment. 1

Rationale for Left Lobe Selection

The left hepatic lobe serves as the primary alternative when the right lobe cannot be accessed, with specific technical considerations:

Anatomical Access Points

• The left lobe is readily accessible via an anterior epigastric subcostal approach, making it a practical alternative despite being less commonly used than the right lobe 1
• The left lobe typically weighs approximately 450g and consists of segments I-IV, with the falciform ligament marking the division between the medial (segment IV) and lateral segments (segments II-III) 1, 2

Technical Considerations for Left Lobe Biopsy

Key procedural modifications include:

• Position the patient in deep inspiration to move a small or subcostal left lobe into a more caudal location for better access 1
• Be prepared for steep needle angulation when using the subcostal approach 1
• Consider that this technique may be challenging if moderate (conscious) sedation is used, as breath-holding during deep inspiration becomes more difficult 1

Image Guidance Recommendations

• Real-time ultrasound guidance is strongly preferred when biopsying the left lobe, as it allows visualization of adequate parenchyma while avoiding major vascular structures, fissures, and the gallbladder 1
• Image guidance is particularly important in cases of right lobe agenesis or hypoplasia, as these anatomical variants may be associated with other vascular anomalies 3, 4

Clinical Context: Right Lobe Agenesis

Important considerations when right lobe is congenitally absent:

• Agenesis of the right hepatic lobe is a rare developmental defect during embryogenesis, typically discovered incidentally on imaging 3, 4
• Patients with right lobe agenesis may develop portal hypertension and esophageal varices, requiring careful assessment before any invasive procedures 3
• The left hepatic segments are typically hypertrophied to compensate for the absent right lobe 3, 4

Practical Algorithm

When right lobe is unavailable, follow this approach:

1. Confirm left lobe anatomy and size using ultrasound or cross-sectional imaging 1
2. Use real-time ultrasound guidance for needle placement 1
3. Select the anterior epigastric subcostal approach as the primary access route 1
4. Target areas with adequate parenchyma (avoiding vessels, fissures, and adjacent structures) 1
5. Have patient perform deep inspiration to optimize liver position if the left lobe is small or highly subcostal 1

Common Pitfalls to Avoid

• Do not assume standard anatomy—patients with right lobe agenesis may have other vascular or biliary anomalies requiring careful pre-procedural imaging review 3, 5, 4
• Avoid attempting the procedure without image guidance in cases of anatomical variants, as this significantly increases complication risk 1
• Be aware that steep needle angulation increases technical difficulty and may compromise specimen adequacy 1