Oblique Scanning of the Left Hepatic Lobe and Caudate Lobe

Oblique liver section • External lobe • Oblique approach

Scanning Method

The patient should be fasted for 8–12 hours and examined in the supine position. Place the ultrasound probe obliquely in the subxiphoid region and angle it toward the left upper abdomen. Adjust the probe orientation, angle, depth, and pressure to obtain a clear oblique section of the left hepatic lobe and caudate lobe. The scan should demonstrate the relevant hepatic and vascular landmarks, including the left portal vein, inferior vena cava (IVC), caudate lobe, and adjacent hepatic structures.

Key scanning point: Begin from the subxiphoid region with the probe oriented obliquely toward the left upper abdomen. Adjust the probe angle and pressure to clearly demonstrate the left hepatic lobe and caudate lobe. Optimize the depth and gain to maintain a well-defined hepatic parenchymal view and identify the caudate lobe in relation to the IVC and portal venous structures.

Ultrasound Image

Figure 1.1 Oblique sonographic section of the left hepatic lobe and caudate lobe obtained through the subxiphoid approach, demonstrating the left portal vein (LPV), inferior vena cava (IVC), aorta (Ao), caudate lobe (CL), and adjacent hepatic vascular landmarks.

Anatomical / Scanning Diagram

Figure 1.2: Diagram showing the probe orientation, oblique scanning plane, left hepatic lobe, and caudate lobe, with the relevant labeled hepatic and vascular anatomical landmarks.

Section Structure

The principal structures demonstrated in this plane include the left hepatic lobe and caudate lobe, with the QL, LPV, IVC, VL, and Ao serving as important anatomical landmarks. The numbered structures 1, 2, and 3 are also identified according to the reference diagram.

Structures to identify

• The enternal branch of left portal vein (3)
• Quadrate lobe (QL)
• Left portal vein (LPV)
• Inferior vena cava (IVC)
• Umbilical and sagittal section of left portal vein (1)
• The external superior branch of the left portal vein (2)
• Venous ligament / ligamentum venosum (VL)
• Caudate lobe (CL)
• Aorta (Ao)
• Hepatic parenchyma

Abbreviations Used in the Figure

Short form	Full form	Identification
3	Numbered structure	The enternal branch of left portal vein
QL	Quadrate lobe	Quadrate lobe of the liver.
LPV	Left portal vein	Left portal venous branch within the hepatic parenchyma.
IVC	Inferior vena cava	Major venous landmark posterior to the liver.
1	Numbered structure	Umbilical and sagittal section of left portal vein.
2	Numbered structure	The external superior branch of the left portal vein.
VL	Venous ligament	Ligamentum venosum between the left hepatic lobe and caudate lobe.
CL	Caudate lobe	Caudate lobe located adjacent to the IVC.
Ao	Aorta	Major arterial landmark posterior to the liver.

Measuring Method and Normal

In this oblique subxiphoid plane, measurements may be obtained when clinically indicated. The IVC, Ao, and selected vascular structures should be assessed only when clearly visualized and using an appropriate standardized caliper technique.

Measurement	Caliper method	Reference / interpretation
IVC	Measure the internal diameter perpendicular to the vessel's long axis when appropriate.	Interpret according to respiratory phase and clinical context.
Ao	Measure the aortic diameter at the appropriate level with calipers positioned across the vessel.	Interpret according to the measurement site and clinical context.

Measurement note: Keep the target structure clearly visualized and avoid including adjacent structures in the measurement.

The Clinical Application Value

This oblique subxiphoid plane provides an important view of the left hepatic lobe and caudate lobe and demonstrates the QL, LPV, IVC, VL, CL, and Ao, together with the numbered structures 1, 2, and 3.

• Demonstration of the left hepatic lobe.
• Identification of the quadrate lobe (QL).
• Visualization of the left portal vein (LPV).
• Recognition of the IVC as a posterior vascular landmark.
• Identification of the venous ligament (VL).
• Identification of the caudate lobe (CL).
• Identification of the aorta (Ao).
• Recognition of numbered structures 1, 2, and 3.
• Assessment of hepatic parenchymal echogenicity and contour.

Quick Scanning Checklist

1	Fast the patient for 8–12 hours when appropriate.
2	Position the patient supine.
3	Place the probe obliquely in the subxiphoid region.
4	Obtain the oblique view of the left hepatic lobe.
5	Identify QL and CL.
6	Identify the LPV and VL.
7	Identify the IVC and Ao as posterior vascular landmarks.
8	Identify the numbered structures 1, 2, and 3.
9	Assess hepatic contour and parenchymal echogenicity.

Diagnostic Pathology

This oblique subxiphoid view can assist in evaluating hepatic and vascular abnormalities. Assess the QL, LPV, IVC, VL, CL, and Ao together with the surrounding hepatic anatomy and the numbered structures 1, 2, and 3.

Key Sonographic Findings

• Hepatomegaly: Increased hepatic size with altered contour or morphology.
• Hepatic steatosis: Increased hepatic echogenicity with reduced visualization of deeper structures.
• Cirrhotic change: Coarse echotexture, irregular contour, and altered hepatic architecture.
• Focal liver lesion: Focal abnormality differing in echogenicity or architecture from the surrounding hepatic parenchyma.
• Caudate lobe enlargement: Enlargement of the CL, particularly in chronic liver disease.
• Quadrate lobe abnormality: Altered size, contour, or echotexture involving the QL.
• Portal venous abnormality: Altered caliber, thrombosis, or abnormal Doppler flow involving the LPV.
• IVC abnormality: Altered caliber, narrowing, compression, or intraluminal abnormality involving the IVC.
• Venous ligament abnormality: Abnormal appearance or adjacent structural alteration involving the VL.
• Aortic abnormality: Abnormal caliber, wall irregularity, atherosclerotic change, or aneurysmal dilatation involving the Ao.
• Portal hypertensive changes: Enlarged venous structures or collateral vessels may be identified in the appropriate clinical setting.

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