Oblique Scanning of the Left and Right Hepatic Ducts by the Right Subcostal Approach
Scanning Method
The patient should preferably be fasted for 8–12 hours and examined in the supine position. Place the ultrasound probe in the right subcostal region and direct the transducer obliquely toward the porta hepatis. Adjust the probe angle, rotation, and depth to obtain an appropriate oblique section demonstrating the right hepatic duct (RHD), left hepatic duct (LHD), and their relationship to the common hepatic duct (CHD) and adjacent portal structures.
Ultrasound Image
Figure 1.1: Oblique section of the hepatic ducts obtained through the right subcostal approach. The image should demonstrate the right hepatic duct (RHD), left hepatic duct (LHD), common hepatic duct (CHD), portal vein (PV), and adjacent hepatic parenchyma when adequately visualized.
Anatomical / Scanning Diagram
Figure 1.2: Diagram space showing the probe orientation and oblique scanning plane directed toward the porta hepatis, with labeling of the hepatic ducts and adjacent anatomical landmarks.
Section Structure
The principal structures demonstrated in this scanning plane include the right hepatic duct (RHD), left hepatic duct (LHD), common hepatic duct (CHD), portal vein (PV), porta hepatis, and adjacent hepatic parenchyma. Depending on the exact probe position and patient anatomy, the gallbladder, common bile duct, hepatic artery, and additional vascular structures may also be visualized.
Structures to identify
- Right hepatic duct (RHD)
- Left hepatic duct (LHD)
- Common hepatic duct (CHD)
- Portal vein (PV)
- Porta hepatis
- Hepatic parenchyma
- Gallbladder, when included in the scanning field
- Common bile duct (CBD), when adequately visualized
- Hepatic artery, when identifiable
- Adjacent upper abdominal structures
Abbreviations Used in the Figure
| Abbreviation | Full form | Identification |
|---|---|---|
| RHD | Right Hepatic Duct | Biliary duct draining the right hepatic lobe. |
| LHD | Left Hepatic Duct | Biliary duct draining the left hepatic lobe. |
| CHD | Common Hepatic Duct | Duct formed by the union of the right and left hepatic ducts. |
| PV | Portal Vein | Major vascular landmark within the porta hepatis. |
| CBD | Common Bile Duct | Extrahepatic biliary duct distal to the common hepatic duct. |
| HA | Hepatic Artery | Arterial structure associated with the porta hepatis. |
| GB | Gallbladder | Biliary reservoir that may be visualized depending on the scanning plane. |
| PH | Porta Hepatis | Region containing the major hepatic ducts and accompanying vascular structures. |
Measuring Method and Normal
When clinically indicated, assess the visible portions of the right hepatic duct, left hepatic duct, and common hepatic duct. Measurements should be obtained with the duct clearly visualized and the calipers positioned appropriately across the duct lumen. The sonographic appearance should be interpreted together with the patient's age, clinical findings, laboratory results, and the remainder of the hepatobiliary examination.
| Structure | Caliper method | Reference / interpretation |
|---|---|---|
| Right Hepatic Duct (RHD) | Measure the visible duct lumen at an appropriate transverse point, avoiding the duct wall and adjacent vascular structures. | Document the measured caliber together with the sonographic appearance and clinical context. |
| Left Hepatic Duct (LHD) | Measure the visible duct lumen perpendicular to its course when adequately demonstrated. | Assess for normal caliber, focal dilatation, irregularity, or nonvisualization. |
| Common Hepatic Duct (CHD) | Measure the duct lumen at a clearly visualized segment, avoiding oblique caliper placement. | Interpret the caliber in conjunction with the intrahepatic ducts and distal biliary tree. |
Measurement note: Avoid measuring a duct obliquely because an oblique section may overestimate its apparent diameter. Confirm the duct lumen and differentiate it from the adjacent portal vein and hepatic artery before placing calipers.
The Clinical Application Value
The right subcostal oblique approach provides a useful sonographic plane for evaluating the right and left hepatic ducts and their relationship to the common hepatic duct and structures of the porta hepatis. The plane can be used as part of a systematic hepatobiliary examination and may assist in evaluating the biliary tree for ductal dilatation or other abnormalities.
- Demonstration of the right hepatic duct (RHD).
- Demonstration of the left hepatic duct (LHD).
- Identification of the confluence of the right and left hepatic ducts when adequately visualized.
- Visualization of the common hepatic duct (CHD).
- Assessment of the porta hepatis.
- Assessment of the relationship between the bile ducts and portal vein.
- Evaluation for intrahepatic biliary ductal dilatation.
- Assessment for focal ductal abnormalities.
- Evaluation of associated gallbladder and extrahepatic biliary structures when included in the examination.
Quick Scanning Checklist
| 1 | Fast the patient for 8–12 hours when appropriate. |
| 2 | Position the patient supine. |
| 3 | Place the probe in the right subcostal region. |
| 4 | Direct the probe obliquely toward the porta hepatis. |
| 5 | Adjust probe rotation and angulation to optimize the biliary ducts. |
| 6 | Identify the right hepatic duct (RHD). |
| 7 | Identify the left hepatic duct (LHD) and follow it toward the ductal confluence when possible. |
| 8 | Identify the common hepatic duct (CHD). |
| 9 | Identify the portal vein (PV) as an important anatomical landmark. |
| 10 | Assess the visible ducts for dilatation, irregularity, intraluminal echoes, or other abnormalities. |
| 11 | If a duct is measured, place the calipers appropriately across the duct lumen rather than along an oblique diameter. |
| 12 | Complete the assessment with the remaining hepatobiliary views and Doppler evaluation when clinically indicated. |
Diagnostic Pathology
The oblique right-subcostal view can assist in identifying abnormalities involving the right hepatic duct, left hepatic duct, common hepatic duct, and porta hepatis. Findings should be assessed together with the remainder of the hepatobiliary ultrasound examination.
Key Sonographic Findings
- Intrahepatic biliary ductal dilatation: Dilatation of visible intrahepatic ducts may indicate obstruction or other biliary pathology and should be assessed in relation to the extrahepatic biliary tree.
- Right hepatic duct dilatation: Increased caliber of the RHD compared with the expected appearance, particularly when associated with upstream ductal dilatation.
- Left hepatic duct dilatation: Increased caliber of the LHD or its visualized branches.
- Common hepatic duct dilatation: Increased caliber of the CHD requiring correlation with the intrahepatic and distal extrahepatic ducts.
- Biliary obstruction: Ductal dilatation proximal to an obstructing process, with the level and cause requiring further assessment.
- Intraductal calculus: Echogenic intraluminal focus that may demonstrate posterior acoustic shadowing, depending on its size and composition.
- Biliary sludge: Low-level or echogenic material within the biliary lumen that may demonstrate dependent distribution.
- Biliary stricture: Focal narrowing of a duct with possible upstream dilatation.
- Duct wall abnormality: Irregularity or thickening of the visible duct wall, requiring correlation with clinical and laboratory findings.
- Focal biliary lesion: Focal abnormality involving the duct lumen or duct wall when adequately visualized.
- Portal-region abnormality: Abnormal tissue or mass effect within the porta hepatis that may alter the appearance or course of the ducts.
- Nonvisualization of a hepatic duct: Failure to adequately demonstrate a duct should be interpreted in relation to patient habitus, bowel gas, scanning plane, and the remainder of the examination.
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