Oblique Scanning of the Liver Through the Gallbladder and Inferior Vena Cava by the Right Subcostal Margin

Oblique liver section • Gallbladder • Inferior Vena Cava by the Right Subcostal Margin

Scanning Method

The patient should be fasted for 8–12 hours and examined in the supine position. Place the ultrasound probe along the right subcostal margin with the transducer oriented obliquely toward the left shoulder. Use the liver as an acoustic window and angle the probe superiorly and medially to obtain an oblique longitudinal view of the right and central portions of the liver. The scanning plane should demonstrate the gallbladder, right hepatic lobe, caudate lobe, inferior vena cava (IVC), and adjacent hepatic vessels as appropriate. Gentle respiratory maneuvers may be used to bring the liver and gallbladder into a favorable position. Optimize depth, gain, focal position, and probe angulation to clearly demonstrate the gallbladder and IVC in relation to the hepatic parenchyma.

Key scanning point: Begin at the right subcostal margin with the probe placed obliquely between the costal margins. Direct the transducer superomedially toward the left shoulder and use gentle cranial and medial angulation to obtain an oblique view through the liver. The gallbladder serves as an important anterior landmark, while the inferior vena cava (IVC) provides a deep posterior vascular landmark. Adjust the probe position and respiratory phase to demonstrate the gallbladder, hepatic parenchyma, caudate lobe, IVC, and adjacent vascular structures within the same scanning plane. Maintain adequate depth and gain to clearly define the hepatic parenchyma and the anatomical relationship between the gallbladder and IVC.

Ultrasound Image

Figure 1.1 Oblique sonographic section of the liver obtained through the right subcostal approach, demonstrating the gallbladder (GB) and inferior vena cava (IVC) within the hepatic scanning plane, along with the right hepatic lobe (RL), left hepatic lobe (LL), right portal vein (RPV), left portal vein (LPV), caudate lobe (CL), and vascular landmarks.

Anatomical / Scanning Diagram

Figure 1.2: Diagram showing the right subcostal probe orientation and oblique scanning plane directed superomedially toward the left shoulder, demonstrating the right hepatic lobe, gallbladder (GB), caudate lobe, and inferior vena cava (IVC), with relevant hepatic and vascular anatomical landmarks including the right portal vein (RPV), left portal vein (LPV), and adjacent hepatic vessels.

Section Structure

The principal structures demonstrated in this oblique right subcostal plane include the gallbladder (GB), left hepatic lobe (LL), right portal vein (RPV), left portal vein (LPV), ligamentum venosum (VL), inferior vena cava (IVC), right hepatic lobe (RL), and caudate lobe (CL). These structures provide important anatomical landmarks for orientation of the liver and hepatic vascular anatomy.

Structures to Identify

• Gallbladder (GB)
• Left hepatic lobe (LL)
• Right portal vein (RPV)
• Left portal vein (LPV)
• Ligamentum venosum (VL)
• Inferior vena cava (IVC)
• Right hepatic lobe (RL)
• Caudate lobe (CL)
• Hepatic parenchyma

Abbreviations Used in the Figure

Short form	Full form	Identification
GB	Gallbladder	Fluid-filled gallbladder identified anteriorly within the hepatic parenchyma and serving as an important sonographic landmark.
LL	Left hepatic lobe	Hepatic parenchyma of the left hepatic lobe demonstrated within the upper portion of the scanning field.
RPV	Right portal vein	Portal venous branch coursing within the right hepatic lobe and providing an important vascular landmark.
LPV	Left portal vein	Portal venous branch coursing toward the left hepatic lobe and forming an important landmark for hepatic orientation.
VL	Ligamentum venosum	Fibrous remnant of the fetal ductus venosus located in the fissure between the left hepatic lobe and caudate lobe.
IVC	Inferior vena cava	Major retrohepatic venous structure serving as an important posterior vascular landmark.
RL	Right hepatic lobe	Hepatic parenchyma of the right hepatic lobe demonstrated in the main portion of the scanning field.
CL	Caudate lobe	Posterior hepatic lobe located between the inferior vena cava and the fissure containing the ligamentum venosum.

Measuring Method and Normal

In this oblique right subcostal plane, measurements may be obtained when clinically indicated. The IVC should be measured only when it is clearly visualized in an appropriate standardized imaging plane. Calipers should be placed perpendicular to the vessel wall and measurements should be interpreted according to the imaging plane, respiratory phase, patient position, and clinical context.

Measurement	Caliper Method	Reference / Interpretation
IVC	Measure the internal diameter perpendicular to the long axis of the IVC when an appropriate standardized view is obtained.	Interpret according to respiratory phase, measurement level, patient position, and clinical context.
Portal vein	When clinically indicated, measure the portal venous caliber in an appropriate imaging plane with clear visualization of the vessel walls.	Interpret according to the measurement site, Doppler findings, respiratory variation, and clinical context.

Measurement note: Obtain measurements only when the target structure is clearly defined. Avoid oblique measurements and inclusion of adjacent hepatic tissue or vessels.

The Clinical Application Value

This oblique right subcostal plane provides an anatomical overview of the hepatic parenchyma and demonstrates important landmarks including the GB, LL, RPV, LPV, VL, IVC, RL, and CL. Recognition of these structures assists in hepatic orientation and assessment of the relationship between the gallbladder, portal venous system, caudate lobe, and retrohepatic IVC.

• Demonstration of the gallbladder (GB).
• Demonstration of the left hepatic lobe (LL).
• Identification of the right portal vein (RPV).
• Identification of the left portal vein (LPV).
• Recognition of the ligamentum venosum (VL).
• Recognition of the IVC as an important posterior vascular landmark.
• Demonstration of the right hepatic lobe (RL).
• Identification of the caudate lobe (CL).
• Assessment of the surrounding hepatic parenchyma.

Quick Scanning Checklist

1	Fast the patient for 8–12 hours when appropriate.
2	Position the patient in the supine position.
3	Place the probe along the right subcostal margin.
4	Orient the probe obliquely toward the left shoulder.
5	Use gentle cranial and medial angulation to obtain an oblique hepatic view.
6	Identify the GB and RL.
7	Identify the RPV and LPV.
8	Identify the VL, CL, and IVC.
9	Optimize depth, gain, focus, and probe pressure for clear visualization.
10	Assess hepatic contour and parenchymal echogenicity.

Diagnostic Pathology

This oblique right subcostal view can assist in the assessment of hepatic, gallbladder, portal venous, and retrohepatic vascular abnormalities. The GB, LL, RPV, LPV, VL, IVC, RL, and CL should be evaluated together with the complete abdominal sonographic examination.

Key Sonographic Findings

• Gallbladder abnormality: Gallbladder wall thickening, distension, calculi, sludge, intraluminal lesion, or pericholecystic abnormality should be documented when identified.
• Hepatic steatosis: Increased hepatic echogenicity with variable posterior attenuation and reduced visualization of deeper structures.
• Hepatomegaly: Increased hepatic size with alteration of normal hepatic contour or morphology.
• Cirrhotic change: Coarse hepatic echotexture, irregular contour, and altered hepatic architecture.
• Focal hepatic lesion: Focal abnormality differing in echogenicity or architecture from the surrounding hepatic parenchyma.
• Portal venous abnormality: Altered caliber, intraluminal thrombus, abnormal flow, or other abnormality involving the RPV or LPV.
• Ligamentum venosum region abnormality: Focal alteration or abnormal soft-tissue appearance along the expected course of the VL should be documented.
• Caudate lobe abnormality: Enlargement, focal lesion, altered echotexture, or architectural distortion involving the CL.
• IVC abnormality: Altered caliber, narrowing, compression, thrombus, or other intraluminal abnormality involving the IVC.
• Hepatic parenchymal abnormality: Altered echogenicity, coarse echotexture, focal lesions, or architectural distortion should be documented when present.
• Portal hypertension: Abnormal portal venous caliber, altered flow, or collateral venous vessels may be identified in the appropriate clinical setting.

Diagnostic note: Sonographic findings should be interpreted together with the complete abdominal ultrasound examination, Doppler assessment, clinical history, and relevant laboratory findings. A single sonographic finding should not be used in isolation to establish a diagnosis.