Chapter 7

Ultrasound (US) plays a critical role in the evaluation and management of patients with hepatobiliary disorders. Diagnostically, US is able to identify common illnesses related to cholelithiasis, including acute cholecystitis and choledocholithiasis. It is the optimal test for detection of biliary dilation, and is also a mainstay of screening for hepatobiliary malignancies and other liver masses (eg, cystic vs. solid lesions). US also plays a vital role in therapy for hepatic disorders, particularly in guiding surgical resection and ablational therapies. Because of its widespread applicability, facility and familiarity with US are important to all physicians involved in the management of hepatobiliary disease. Indications, technique, normal and abnormal findings, and therapeutic maneuvers applicable to US will be discussed in the following pages.

1. Investigation of right upper quadrant pain, particularly when there is suspicion for symptomatic cholelithiasis

2. Investigation of abnormal liver function tests. Specifically, US may demonstrate dilation of the bile ducts in the setting of extrahepatic biliary obstruction, or can identify the stigmata of chronic liver disease

3. Screening for hepatocellular carcinoma in cirrhotic patients

4. Assessment of hepatic vasculature to aid in the planning of liver resection

5. Guidance (either transcutaneous or intraoperative) for ablative therapy or biopsy

6. Intraoperative assessment of tumor anatomy with respect to vasculature

7. Detection of venous or hepatic arterial thrombosis after liver transplantation

8. Identification of intraperitoneal hemorrhage in cases of suspected hepatic trauma (Focused Assessment with Sonography in Trauma, FAST)

9. Assessment of portal hypertension

### Segmental Anatomy of the Hepatic Parenchyma

An understanding of the segmental anatomy of the liver is fundamental to modern radiological investigation and surgical management of hepatic malignancy (Figure 7-1). The classification was first described in 1957 by the French surgical anatomist Couinaud, and later popularized by Bismuth and is globally recognized.1 The eight hepatic segments are divided into those constituting the right hemiliver (segments V–VIII), the left hemiliver (segments II–IV), and the caudate lobe (segment I). The right and left hemilivers are separated in the functional midline by the plane of the principal fissure between the gallbladder fossa and the inferior vena cava (IVC) (Cantlie Line). This plane is defined by the course of the middle hepatic vein, and has no external markings. In the left lobe of the liver, the plane formed by the umbilical fissure divides the left lateral sector (segments II and III) from the left medial sector (segment IV). The medial sector is divided into segments IVA superiorly and IVB inferiorly. In the right lobe of the liver the plane formed by the right hepatic vein and the IVC divides the right anterior sector (segments V and VIII) from the right posterior sector (segments VI and VII).

###### Figure 7-1.

The segmental anatomy of the liver with the tributaries of the portal vein. (Ellis H. Anatomy of the liver. Surgery (Oxford). 2011;29(12):589–592.)

### Vascular Anatomy

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