Transverse Scanning of the Middle Segment of the Common Bile Duct at the Level of the Lower Part of the Pancreatic Head by the Right Subcostal

Transverse biliary section • Middle CBD • Lower pancreatic head • 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 adjust the transducer to obtain a transverse section at the level of the lower part of the pancreatic head. Optimize probe rotation, angulation, depth, and compression to demonstrate the middle segment of the common bile duct (CBD) and its relationship to the adjacent pancreatic, vascular, renal, and gastrointestinal structures.

Key scanning point: Use the right subcostal window to obtain a transverse section through the lower pancreatic-head region. The supplied image demonstrates the labeled RL, Gb, PH, Du, RK, SMV, SMA, CBD, IVC, and Ao.

Ultrasound Image

Figure 1.1: Transverse right-subcostal sonographic view at the level of the lower part of the pancreatic head. The supplied image labels the right lobe of liver (RL), gallbladder (Gb), pylorus (PH), duodenum (Du), right kidney (RK), superior mesenteric vein (SMV), superior mesenteric artery (SMA), common bile duct (CBD), inferior vena cava (IVC), and aorta (Ao).

Anatomical / Scanning Diagram

Figure 1.2: Reference sonographic image demonstrating the transverse scanning plane and the anatomical relationship of the middle CBD to the pancreatic-head region, mesenteric vessels, IVC, aorta, duodenum, and right kidney.

Section Structure

The principal structures demonstrated in the supplied image are the right lobe of the liver (RL), gallbladder (Gb), pylorus (PH), duodenum (Du), right kidney (RK), superior mesenteric vein (SMV), superior mesenteric artery (SMA), common bile duct (CBD), inferior vena cava (IVC), and aorta (Ao). These structures provide useful landmarks for identifying and assessing the middle segment of the CBD.

Structures to identify

• Right lobe of liver (RL)
• Gallbladder (Gb)
• Pylorus (PH)
• Duodenum (Du)
• Right kidney (RK)
• Superior mesenteric vein (SMV)
• Superior mesenteric artery (SMA)
• Common bile duct (CBD)
• Inferior vena cava (IVC)
• Aorta (Ao)

Abbreviations Used in the Figure

Abbreviation	Full form	Identification
RL	Right Lobe of Liver	Right hepatic lobe/parenchyma demonstrated in the scanning field.
Gb	Gallbladder	Gallbladder visualized adjacent to the right hepatic lobe.
PH	Pylorus	Pyloric portion of the stomach shown near the hepatobiliary region.
Du	Duodenum	Duodenal structure adjacent to the pancreatic-head and distal biliary region.
RK	Right Kidney	Right renal structure visible inferior/posterior to the scanning field.
SMV	Superior Mesenteric Vein	Major mesenteric venous landmark in the pancreatic region.
SMA	Superior Mesenteric Artery	Major arterial landmark adjacent to the SMV.
CBD	Common Bile Duct	Principal biliary structure and target of this scanning view.
IVC	Inferior Vena Cava	Major venous landmark posterior to the pancreatic-head region.
Ao	Aorta	Major arterial landmark posterior to the pancreatic region.

Abbreviation note: The abbreviations are taken directly from the labels visible in the supplied ultrasound image: RL, Gb, PH, Du, RK, SMV, SMA, CBD, IVC, and Ao.

Measuring Method and Normal

When clinically indicated, assess the middle segment of the CBD in the transverse plane at the level of the lower pancreatic head. Place the calipers across the duct lumen at an appropriate point and avoid including adjacent vessels, pancreatic tissue, or bowel structures. Interpretation should consider the proximal biliary tree and the clinical context.

Measurement	Caliper method	Reference / interpretation
Middle Segment of CBD	Measure the visible duct lumen across its short axis in the transverse plane, with the calipers placed across the duct and not through adjacent structures.	Document the measured caliber together with the sonographic appearance and clinical context.

Measurement note: Confirm the CBD lumen before placing calipers and differentiate it from the adjacent SMV, SMA, IVC, and surrounding pancreatic/duodenal structures.

The Clinical Application Value

This transverse right-subcostal approach provides a useful section for evaluating the middle segment of the common bile duct at the level of the lower pancreatic head. The SMV, SMA, IVC, and Ao provide important vascular landmarks, while the Du and RK help define the surrounding anatomy.

• Demonstration and assessment of the middle segment of the CBD.
• Assessment of CBD caliber at the lower pancreatic-head level.
• Identification of the SMV and SMA as mesenteric vascular landmarks.
• Identification of the IVC and Ao as major posterior vascular landmarks.
• Recognition of the duodenum (Du) adjacent to the pancreatic region.
• Recognition of the right kidney (RK) when included in the field.
• Assessment for ductal dilatation or focal narrowing.
• Evaluation for intraluminal echogenic material when visible.

Quick Scanning Checklist

1	Fast the patient for 8–12 hours when appropriate.
2	Position the patient supine.
3	Place the probe at the right subcostal region.
4	Rotate and angle the probe to obtain a transverse section through the lower pancreatic head.
5	Identify the RL and Gb when visualized.
6	Identify the SMV and SMA as vascular landmarks.
7	Identify and optimize the CBD.
8	Assess the CBD caliber in the transverse plane.
9	Identify the IVC and Ao as posterior vascular landmarks.
10	Identify the Du, PH, and RK when visualized.
11	Assess for CBD dilatation, narrowing, intraluminal material, or other abnormalities.
12	Complete the examination with additional hepatobiliary and pancreatic views when clinically indicated.

Diagnostic Pathology

The transverse right-subcostal view at the level of the lower pancreatic head can assist in evaluating the middle segment of the CBD and its surrounding anatomy. Findings should be correlated with the complete hepatobiliary and pancreatic ultrasound examination.

Key Sonographic Findings

• Common bile duct dilatation: Increased CBD caliber requiring correlation with the proximal biliary tree and clinical context.
• CBD narrowing: Focal reduction in duct caliber that may require further assessment.
• Intraductal calculus: Echogenic intraluminal focus that may demonstrate posterior acoustic shadowing.
• Biliary sludge: Low-level or echogenic intraluminal material when adequately visualized.
• Obstructive pattern: CBD dilatation associated with upstream biliary dilatation or a possible obstructing process.
• Pancreatic-head abnormality: Altered surrounding tissue or mass effect that may affect the course or caliber of the CBD.
• Mesenteric vascular abnormality: Altered appearance of the visualized SMV or SMA requiring correlation with the complete examination.
• Limited visualization: Bowel gas, patient habitus, or an unfavorable scanning window may limit demonstration of the CBD.

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

Image labeling note: The supplied image labels are preserved as: RL, Gb, PH, Du, RK, SMV, SMA, CBD, IVC, and Ao.

Hepatobiliary Ultrasound • Right Subcostal Approach

Diagnostic Sonography Reference