Standards of the Polish Ultrasound Society – update. The liver, gallbladder and bile ducts examinations

Abstract

Ultrasonography, which usually constitutes an initial imaging method of the gallbladder, liver and bile ducts diseases, allows for final diagnosis or determines another diagnostic step. The continuously progressing technological advancement forces to broaden the indications for ultrasound diagnostics and enables easier and more precise imaging of the tested structures. Performing the examination in accordance with current standards allows for the optimization of the sensitivity and specificity parameters of ultrasound examinations in the diagnosis of the liver, gallbladder and bile ducts pathologies as well as minimizes the probability of error-making. This article presents a recommended liver, gallbladder and bile ducts ultrasound technique which indicates an optimal positioning of the patient for the exam as well as the sites of the ultrasound transducer application. Minimum technical parameters of the apparatus have been specified with respect to the requirements of modern ultrasound techniques which enable imaging with the use of contrast agents and elastography. Furthermore, the article proposes a standard exam description containing essential patient-related data and provides required ultrasound evaluation parameters for the tested organs. Attention has been drawn to the appropriate manner of preparing the patient for the examination and the features of the tested structures have been presented. The article also contains a brief description of the liver, gallbladder and bile ducts diseases which are most often diagnosed by ultrasound examinations. Moreover, the use of elastography as well as contrast-enhanced examinations in the diagnostics of fibrosis and focal changes in the liver have been discussed. This article has been prepared on the basis of the Ultrasound Examination Standards of the Polish Ultrasound Society (2011) and updated with reference to the latest findings in pertinent literature.

This article has been prepared on the basis of the latest edition of the Ultrasonound Examination Standards of the Polish Ultrasound Society (4^th edition, Warsaw – Zamość, 2011)⁽¹⁾ and updated with reference to the latest findings in pertinent literature.

Introduction

Ultrasonography (US) is a basic imaging technique used in patients with suspicions of the liver, gallbladder and bile ducts diseases⁽²⁾. In numerous cases, the US examination allows for the final recognition without the need to perform further imaging tests. Good results are obtained in the diagnostics of cholelithiasis where concretions with the diameter greater than 2 mm are recognized with the sensitivity exceeding 95% as well as in the diagnostics of acute cholecystitis where the sensitivity and specificity of the US examination are 82% and 81% respectively^{(3, 4)}. The US examination constitutes a basic diagnostic tool in the determination of the causes of obstructive jaundice, in the diagnostics of liver cirrhosis and portal hypertension. In the diagnostics of steatosis of the liver parenchyma, the sensitivity of US examination reaches 84% and the specificity – 93%⁽⁵⁾. Worse results are obtained in the US diagnosis of other chronic diseases of the liver parenchyma. Irrespective of the etiology, the disorders may result in the development of fibrosis and therefore, the development of elastography is highly promising. This technique makes use of the differences between the speed of propagation of waves in the tested tissue, which depends on its stiffness and allows for a qualitative and quantitative evaluation of the fibrosis degree^{(6, 7)}.

Ultrasound contrast agents may be applied in the differential diagnostics of focal changes in the liver. Apart from cysts, typical hemangiomas and typical presentation of metastatic lesions, the image of the focal changes in the US examinations is usually untypical⁽⁸⁾. The results concerning the sensitivity and specificity of contrast-enhanced US examinations are similar to those obtained in computer tomography and magnetic resonance imaging⁽⁹⁾.

Apparatus

According to the Polish Ultrasound Society standards, the liver, gallbladder and bile ducts ultrasound exams are performed with the equipment of so-called high and average quality with the broadband Convex transducers – from 2 to 5 MHz. Moreover, the equipment should meet the following requirements:

• minimum 128 transmit/receive channels;

• color display with the grey scale of 256;

• color and power Doppler;

• the possibility to enlarge a frozen and real-time image without much loss in the resolution;

• examination playback stored in the memory (loop playback);

• regulation of the beam focus sites;

• measurement software (distance, surface area, volume);

• ultrasound image storing system (videoprinter, HDD hard drive, DVD recorder, USB port).

A helpful option, which allows for reducing the number of artifacts and increasing the contrast of images, is harmonic imaging. In the diagnostics of neoplastic lesions, volumetric 3D probes are more frequently used. Thanks to them, a precise measurement of size/ volume/tumor localization may be obtained⁽¹⁰⁾.

At present, as far as the evaluation of liver fibrosis is concerned, elastography is used. Transient elastography is the most widespread method. By means of FibroScan apparatus, it examines the speed of propagation of mechanical waves which come from a vibration transducer equipped with a low frequency wave generator of 50 Hz and an ultrasound analyzer with the frequency of 5 MHz. Moreover, elastography is one of the options provided by modern ultrasound equipment. The color-coded real-time elastography examines liver deformations caused by controlled compressions of the ultrasound probe. They are presented by means of a color map, on which the colors of the elastogram, i.e. red, blue and green, correspond to soft, hard and intermediate tissue stiffness respectively. By means of computer-aided analysis of an elastogram, a quantitative evaluation of fibrous tissue (hard tissue) is obtained. The disadvantages of the method comprise the dependency on the operator and repeatability of compressions on tissues. This problem is solved in shear wave elastography, where the mechanical compression is replaced by acoustic impulse which causes tissue deformation and shear waves production. The speed of wave propagation in a tested region is measured by the machine. The results provided in milliseconds reflect tissue stiffness (acoustic radiation force impulse technology and shear wave elastography).

The contrast-enhanced examinations use ultrasound scanners with high quality electronic broadband or multifrequency transducers. The scanners should have software for examination with both low and high mechanical index and full scope of Doppler measurements. The software for contrast-enhanced ultrasonography enables to use the method of pulseinversion harmonic imaging. Time measuring is essential during such an examination.

Preparation for testing

The most optimal conditions are ensured in examinations on an empty stomach. It is recommended to refrain from eating and drinking for 6–8 hours prior to the examination. This reduces the quantity of air in the GI tract lumen which prevents physiological changes in the liver vascularization as well as in the presentation of bile ducts and gallbladder after a meal. Refraining from smoking for 6 hours prior to the test is also important since some substances contained in tobacco smoke are conductive to smooth muscle contractions which may lead to the contraction of the gallbladder. Prior to the examination, obese patients with intestinal flatulence should take some preparations which reduce surface tension of gas bubbles in the intestines. Barium enemas, e.g. for purging purposes, should not be recommended prior to the planned examination.

Examination technique

The ultrasound examination of the liver, gallbladder and bile ducts is performed in the supine, left lateral and left lateral oblique positions. Elastography examination is performed in the left lateral oblique position with the right upper extremity in maximum abduction. The transducer is placed in the intercostal space in the place where the liver tissue thickness is at least 6 cm and were large vessels are not detected. The elastography examination should be conducted while the patient suspends respiration for a while. Deep breath with holding in the air may cause liver hyperemia and thus, increase its stiffness⁽¹¹⁾.

The liver is evaluated in multiple sections. Above all, in oblique cross section, longitudinal and cross sections as well as in oblique longitudinal section. Each time, the liver is examined by applying the transducer along the costal margin in order to visualize the venous drainage and the arrangement of, usually three, hepatic veins as well as the visceral surface of the liver. The hepatic vein system allows for the division of the right lobe into anterior and posterior parts and the left one into medial and lateral parts. The visceral surface structures, which form an H letter, encompass the right lobe, the lateral and medial parts of the left lobe and the caudate lobe. During each US examination, it is necessary to visualize the portal vein trunk and measure its diameter. It is also crucial to evaluate the liver through the intercostal area, especially the posterior part of the right lobe. The essential evaluation also encompasses the anterior part of the right lobe and medial part of the left lobe visualized by placing the transducer flatly on the ventral part of the abdomen in the right hypochondriac region. All standardized sections connected with the change of the patient's position ensure the visualization of all liver segments.

The gallbladder testing must encompass a range of longitudinal, cross and oblique sections performed in the right midclavicular line, at the level of the costal margin and in the supine position. Other helpful positions for gallbladder evaluation are supine and left lateral oblique positions.

The intrahepatic bile ducts, which are not dilated, are not usually visible in US examinations. Their width should not exceed 2 mm. In the case of intrahepatic obstruction, the dilated bile ducts form a spoke-wheel pattern. If the obstruction is localized beyond the liver, the bile ducts are dilated irregularly (the image of so-called sea wave) and the enhancement behind their posterior wall is detected. An optimal position to visualize the bile ducts (BD) is the left lateral position. The transducer should be applied longitudinally along the midclavicular line and moved towards the epigastric region. The technique enabling to visualize the BD from the area of the hepatic hilum or the head of the pancreas requires the rotation of the transducer from the transverse to oblique longitudinal position.

Each liver US exam must include the evaluation of the following parameters:

• size;

• shape;

• margins;

• echogenicity.

The liver size is evaluated in longitudinal or anteroposterior (a-p) dimensions of the right lobe (fig. 1 A, B) with the addition of the measurements of the left lobe in a-p and longitudinal dimensions in the case of anatomical variants. The standard sizes of the organs discussed herein are specified in tab. 1. A rate expressed as the ratio of the caudate lobe transverse measurement to the right lobe transverse measurement or the longitudinal measurement of the caudate and left lobes is used in order to assess the enlargement of the caudate lobe which accompanies liver cirrhosis or Budd-Chiari syndrome.

Fig. 1.

The measurements of: A. a-p dimension of the right liver lobe; B. longitudinal dimension of the right liver lobe

Tab. 1.

The normal dimensions of the liver, gallbladder and common bile duct in adults

Dimensions [mm]
Liver	Gallbladder	Common bile duct
The right lobe anteroposterior size: <120	Width: <40	Width: <6
The right lobe longitudinal size: <140	Length: <120	Width after cholecystectomy: <9–10

An essential element of the examination is the evaluation of the liver outline, particularly its superior area and inferior margin. This is conducted with the use of high-frequency convex and linear transducers.

The liver echogenicity is assessed with reference to the echogenicity of the kidney and spleen. In adults, it is usually slightly lower than the spleen echogenicity and insignificantly larger than the echogenicity of the renal cortex.

The assessment of the hepatic parenchyma homogeneity constitutes another parameter.

The exam description must precisely determine the localization of the detected lesions. This is the function of the liver division into segments proposed by Couinaud and modified by Bismuth⁽¹²⁾. Eight segments are distinguished, each of which has its own arterial and portal venous vessels and biliary drainage (fig. 2 A–C). The liver is divided on the basis of the course of the hepatic veins and portal vein branches. They enable to isolate three vertical planes, which are parallel to the hepatic veins, and a transverse plane, which crosses the vertical ones and is parallel to the portal vein branch. Segment I constitutes the caudate lobe. The lateral part of the left lobe comprises segments II (posterolateral) and III (anterolateral) and the medial part comprises segments IVa and IVb. The anterior part of the right lobe encompasses segments V and VIII and the posterior part – segments VI and VII.

Fig. 2 A–C.

The division of the liver into segments

If any focal lesions are detected, their number, localization in given segments, dimensions, echogenicity and the presence of vascularization need to be specified. The echostructure type must be determined – solid, fluid-filled (cystic) and complex lesions. As far as solid lesions are concerned, their echogenicity must be determined in relation to the echogenicity of normal liver parenchyma – hyperechogenic, of mixed echogenicity, normoechogenic or hypoechogenic.

An essential element of the liver examination is the assessment of the subdiaphragmatic region, subhepatic region and Morison's pouch for the presence of free fluid or pathological fluid reservoirs. The region of the hepatoduodenal ligament needs to be checked for the presence of enlarged lymph nodes.

As far as the analysis of the gallbladder is concerned, the following factors are subject to assessment: dimensions, thickness, homogeneity of its wall outline and content. In evaluating the size, it is particularly significant to measure the gallbladder width – the width below 20 mm and above 50 mm is considered abnormal.

The longitudinal size is often impossible to determine because of numerous gallbladder variants and therefore, it is not commonly used. The wall thickness is measured at the place where the gallbladder body is attached to the liver. Simultaneously, attention needs to be paid to homogeneity of the gallbladder wall contours (for hyperplasias) and the contents of the lumen. In order to differentiate between the wall hyperplasias and lithiasis, it is recommended to change the patient's position from supine to left lateral or oblique position.

In the ultrasound testing of the bile ducts, the following are subject to evaluation: lumen width, wall thickness of the common bile duct and its echogenicity (if need be, also abnormal structures in the lumen). When interpreting the BD width, one needs to include the history of cholecystectomy (10 mm broadening is admissible) and the patient's age (in patients above 50 years of age, 1 mm for every 10 years should be added as an admissible limit broadening). Contrast-enhanced ultrasound examinations should be preceded by the evaluation of the focal lesion in question during a standard grey-scale US exam. The examination is performed after intravenous administration of the contrast medium. Directly after it has been administered, it is crucial to start counting time, archiving the examination and rinsing the cannula in 5–10 ml of saline. The test consists in the assessment of three vascular phases in real time: arterial (lasting 15–35 s), portal (35–120 s) and delayed venous phase (120–240 up to 360 s). The contrast enhancement observation in the subsequent vascular phases allows for the detection and character differentiation of focal lesions in the liver according to the guidelines contained in the references⁽¹³⁾.

Every description of the liver, gallbladder and bile ducts US examination should include the following details:

• the patient's name, surname and age;

• examination date;

• apparatus name and the type of the transducer used including its frequency.

• For the liver:

• evaluation of size, contours and echogenicity;

• description of all abnormal morphological lesions (number, echostructure, echogenicity, vascularization, character – focal or diffuse).

• For the gallbladder and bile ducts:

• evaluation of the size and shape of the gallbladder, GB diameter and an indication of intrahepatic bile ducts dilation;

• evaluation of anatomical variants of the gallbladder and bile ducts;

• assessment of the gallbladder wall thickness and regularity;

• assessment of the gallbladder and bile duct lumina (concretions, solid lesions, sludge);

• evaluation of the gallbladder chamber.

The exam description should end with diagnostic conclusions and suggestions of given complementary examinations (CEUS, CT, MRI, US-FNAB), a surgical procedure or an ultrasound check-up.

The photographic documentation of all abnormalities detected during the US exam, obtained from the videoprinter, computer printer or stored on electronic storage devices need to be attached to the description.

Selected liver, gallbladder and bile ducts diseases

Steatosis of the liver parenchyma

This constitutes the most common parenchyma pathology diagnosed in US examinations with the sensitivity of 84% and the specificity of 93%⁽⁵⁾. The sensitivity of the test depends on the degree of steatosis and its arrangement in the liver (diffuse vs. focal). In the case of diffuse steatosis, 3 degrees are distinguished based on the degree of hepatocyte saturation with triglycerides: mild, moderate and severe (tab. 2, fig. 3). As for focal steatosis (fig. 4), the lesions are usually placed in a perihilar region in segment IV as well as in the subcapsular area. The hyposteatosis areas may appear in the same localization. They are the foci of lower-intensity steatosis with decreased echogenicity and irregular contours. Another typical localization of these lesions is the region of the gallbladder chamber.

Tab. 2.

The ultrasound features of diffuse liver steatosis

Mild	Enhanced parenchyma echogenicity
Medium	Increased parenchyma echogenicity, disturbed visibility of the vascular structures in the liver and diaphragm
Severe	Increased parenchyma echogenicity, low visibility of vascular structures in the liver and diaphragm, low visibility of the posterior segments of the liver

Fig. 3.

Diffuse liver steatosis

Fig. 4.

Focal liver steatosis

Liver cirrhosis

The accuracy of liver cirrhosis recognition in a US test in patients presenting portal hypertension signs such as ascites, splenomegaly and collateral circulation, exceeds 90% and is definitely lower in early stages of the disease. Typical ultrasound features indicating cirrhosis are as follows: lack of homogeneity of the parenchymal echostructure, uneven or nodular outline of the liver margins and surface (fig. 5), regenerative nodules, disorders of the ratio of caudate lobe and right lobe sizes, changes in hepatic vascular structure and the symptoms of portal hypertension.

Fig. 5.

Liver cirrhosis

Acute viral hepatitis

There is no typical ultrasound presentation for this disease. In the majority of cases, enlargement of local lymph nodes is diagnosed. The reduced parenchyma echogenicity with the image of so-called starlit sky is observed much less frequently.

Liver fibrosis

Fibrosis is one of the stages of liver diseases of various etiologies: infectious, metabolic, autoimmunological and toxic. A golden standard in fibrosis diagnostics is histopathological evaluation of a tissue sample. Elastography is a highly promising tool for a non-invasive diagnosis of this pathology. The method of measuring the elasticity which is the most widely used is FibroScan. The measurement results are provided in kPa in a range from 2.5 to 75 kPa. Ten measurements should be performed so as to obtain reliable results. This method is approved of in assessing the fibrosis degree in patients with chronic viral hepatitis C and B. Many studies, however, have proven its value in the diagnosis of fibrosis and portal hypertension in the course of other hepatopathies^(14–16). The upper limit for normal liver tissue stiffness is 5.3 kPa. Significant fibrosis expressed by F≥2 in METAVIR score corresponds to the range 7.2–7.6 kPa and liver cirrhosis is expressed by the values above 12.5 kPa. Liver elastography is also performed in patients suffering from cirrhosis in order to noninvasively diagnose portal hypertension⁽¹⁵⁾. Here, the values indicating portal hypertension are those between 13.6 and 21 kPa. The basic limitation in this method is the patient's obesity. Reliable results may be obtained in patients whose BMI is below 28 kg/m². Even greater range of possibilities is provided by elastography techniques in standard ultrasound machines, thanks to which the operator is able to observe the tested organ and choose a place for tissue elasticity measurements. The greatest number of available data concern color-coded real-time sonoelastography, elastography using the AFRI (acoustic radiation force impulse) technique and shear wave elastography. In the first technique mentioned above, the degree of mechanical tissue deformation, caused by the pressure applied by the ultrasound transducer, is presented as a color map where the proportion of each color, which correspond to tissue stiffness, is analyzed (fig. 6 A, B). AFRI and SWE techniques use tissue deformation caused by acoustic impulses which produce shear waves whose speed is proportional to tissue stiffness. The advantage of SWE is the possibility of obtaining images of tissue elasticity visualized on the color map. It enables to choose the most suitable localization and site from which quantitative analysis in kPa or ms will be performed (fig. 7 A, B). The studies carried out so far have shown that the values obtained in healthy persons are between 4.92 and 5.39 kPa whereas the same parameters in patients suffering from cirrhosis exceed 11.4 kPa⁽¹⁶⁾.

Fig. 6.

Color-coded sonoelastography of the liver: A. stiff tissue presentation; B. normal tissue presentation

Fig. 7.

Shear wave elastography images: A. stiff tissue presentation; B. normal tissue presentation

Focal lesions in the liver

Seldom does the presentation of the liver focal lesions, during routine US examinations, allow for final diagnosis without the necessity to verify it in another exam. Simple cysts, which appear quite frequently, i.e. in 2.5% of people, constitute an exception. In US examinations the cysts present themselves as normoechogenic, well-circumscribed lesions with thin walls behind which enhanced acoustic signal is observed (fig. 8). Thickened walls, numerous chambers or tissue structures inside the lesion comprise the image of complex lesions and constitute an indication for further examinations, usually a CT scan.

Fig. 8.

Simple cyst of the liver

Another frequent focal lesion in the liver is cavernous hemangioma which, usually by chance, is detected in 4% of people. The typical presentation of a single, well-circumscribed and hyperechogenic homogeneous lesion with the diameter of <3 cm (fig. 9) is detected in 67–79% of cases during US examinations. If such a lesion is visualized incidentally in a patient with no symptoms indicating a neoplasm, it is enough to schedule a US check-up in 3–6 months in order to document the lack of dynamics in the US image. Otherwise, further diagnostic steps are recommended.

Fig. 9.

Liver hemangioma

Contrast-enhanced US examinations improve the sensitivity and specificity of the classic ultrasound in relation to the differential diagnostics. The typical features of selected lesions in contrast-enhanced examinations, based on the opinions of the experts from EFSUMB (European Federation of Societies for Ultrasound in Medicine and Biology), are presented in tab. 3 ⁽¹³⁾.

Tab. 3.

The typical features of enhancement in contrast-enhanced US of the most common focal liver changes

Focal lesion	Arterial phase	Portal phase	Delayed phase
Hemangioma	Irregular peripheral enhancement in the form of nodules without central enhancement; in the case of slight lesions, the enhancement of the whole lesion, more intense on the periphery	Partial enhancement medially intensified or complete	Complete enhancement of the lesion, non-enhanced areas are possible
Focal nodular hyperplasia (FNH)	Hyperintense, fast, medial and complete lesion enhancement, arterial vessels are arranged radially and form so-called spoke-wheel image	Hyperintense enhancement, central scar may be visible as a hypoechogenic area inside the tumor	Isointense or hyperintense lesion, central scar may be visible as a hypoechogenic area inside the tumor
Adenoma	Hyperintense enhancement of the whole lesion, non-enhanced areas are possible	Isointense or discreetly hyperintense enhancement, non-enhanced areas are possible	Isointense or discreetly hyperintense enhancement, non-enhanced areas are possible
Focal steatosis	Isointense enhancement as the surrounding liver parenchyma	Isointense enhancement as the surrounding liver parenchyma	Isointense enhancement as the surrounding liver parenchyma
Focal lack of steatosis	Isointense enhancement as the surrounding liver parenchyma	Isointense enhancement as the surrounding liver parenchyma	Isointense enhancement as the surrounding liver parenchyma
Hepatocellular carcinoma (HCC)	Hyperintense, fast, and complete lesion enhancement with visible chaotic arterial vascularization, “basket-like” presentation	Isointense enhancement non-enhanced areas are possible	Hypointense, sometimes isointense enhancement
Non-vascularized metastasis	Peripheral enhancement	Hypointense enhancement of the lesion or the lack of enhancement	Hypointense enhancement of the lesion or the lack of enhancement
Vascularized metastasis	Hyperintense, fast enhancement of the lesion with visible chaotic arterial vascularization	Hypointense enhancement of the lesion	Hypointense enhancement of the lesion or the lack of enhancement

Selected gallbladder and bile ducts diseases

Ultrasound examinations constitute the first choice tests in the diagnostics of gallbladder and bile ducts diseases. The suspicion of cholelithiasis is the basic indication for gallbladder tests. Concretions present themselves in the US image as hyperechogenic echoes of various sizes localized in the gallbladder lumen, which give acoustic shadows and are mobile when the patient changes position (fig. 10). The concretions with the diameter below 1 mm as well as pigment stones may not present acoustic shadows, which is conductive to diagnostic errors. The gallbladder filled with concretions gives the image of so-called WES triad (wall-echo-shadow complex) (fig. 11), which needs to be distinguished from porcelain gallbladder. Gallbladder polyps are lesions in the wall of the gallbladder which remain immobile while the patient changes position. Their number, size and possible stalks should be determined during the examination. The most common, however, are cholesterol polyps. They are characterized by various echogenicity and thin stalk. Usually, they are of benign nature and do not exceed 5 mm in diameter. The ultrasound check-up is required every 6 months (fig. 12). Due to the fact that determining the malignant character of polyps in imaging tests is limited, it is assumed that cholecystectomy is performed in the case of polyps with the diameter >10 mm in patients above 50 years of age as well as in the event of lesion enlargement detected during check-ups⁽¹⁷⁾.

Fig. 10.

Concretion in the gallbladder lumen

Fig. 11.

The image of so-called WES triad (wall-echo-shadow complex)

Fig. 12.

Gallbladder polyp

Ultrasound tests constitute a useful tool in the diagnosis of acute cholecystitis with sensitivity and specificity of 88% and 80% respectively⁽¹⁸⁾. The ultrasound features of acute cholecystitis encompass:

• thickening of the gallbladder wall >3 mm;

• concretions in the gallbladder;

• gallbladder enlargement;

• blocking of the concretions in the neck of gallbladder or cystic duct;

• inflammatory infiltration/fluid areas around the gallbladder;

• increased blood supply to the gallbladder wall in Doppler test;

• positive ultrasound Murphy's sign;

The bile ducts diseases usually manifest themselves with patency disorders which result in the lumen dilation of the intra- and/or extrahepatic ductal fragments. Due to the high sensitivity obtained in the diagnosis of bile ducts dilation, ultrasonography constitutes a good tool to evaluate the localization and cause of this pathology. The width of the common bile duct lumen, which in healthy persons should not exceed 6 mm, is measured at the crossing with the right hepatic artery. The history of cholecystectomy and the age of the patient should be taken into account while performing the measurements (fig. 13). The width of the BD may be slightly larger in the distal part of the common bile duct (the difference may reach as much as 2 mm). The diameter of the intrahepatic bile ducts may amount to 2 mm or constitute not more than 40% of the diameter of the accompanying portal vein branches. In the case of intrahepatic obstruction, the dilated ducts form a “spoke-wheel” pattern. When, however, the obstacle is situated beyond the parenchyma, the bile ducts are dilated irregularly and the enhancement behind their posterior wall is observed presenting an image of so-called sea wave.

Fig. 13.

Common bile duct dilation

The reasons for patency disorders are presented in tab. 4⁽¹⁹⁾.

Tab. 4.

The reasons for patency disorders of the bile ducts

Non-neoplastic reasons	Neoplastic reasons	External pressure/Mass effect
Choledocholithiasis	Cholangiocarcinoma	Mirizzi's syndrome
Hemobilia	Gallbladder cancer	Pancreatitis
Congenital diseases of the bile ducts (Caroli's disease, inborn bile duct cysts)	Pancreatic cancer	Lymphadenopathy
Purulent cholangitis	Ampulla of Vater carcinoma
Parasitic diseases	Metastases
HIV-related cholangiopathy
Primary sclerosing cholangitis (PSC)

Based on: Rumack CM, Wilson SR, Charboneau JW, Levine D (eds.): Diagnostic Ultrasound. 4^th ed., vol. 1, Mosby Inc., Philadelphia 2011⁽¹⁹⁾.

Conclusion

The ultrasound examination of the liver, gallbladder and bile ducts is the first imaging test conducted in patients reporting problems in these regions. Carrying out ultrasound examinations on the basis of the proposed standards enables to optimize the test results, make final diagnosis based on the US examination or recommend further tests. The classic US examination, which is supplemented with the evaluation of the vascularization in the parenchyma or changes in Doppler tests as well as using ultrasound contrast agents, remains the standard examination. Elastography is a promising and widely used method. Nevertheless, as of today, it is not considered a standard US examination.

Conflict of interest

Authors do not report any financial or personal links with other persons or organizations, which might affect negatively the content of this publication and/or claim authorship rights to this publication.