Ultrasound signs of gallbladder and biliary tract pathology

Non-visualizable gallbladder

There are several reasons why the gallbladder is not visualized on ultrasound:

1. The patient is not examined on an empty stomach: a repeat examination is required after 6 hours of abstaining from food and water.
2. Abnormal location of the gallbladder.
   • Scan down the right side of your abdomen to your pelvic area.
   • Scan to the left of the midline with the patient in the right lateral decubitus position.
   • Scan above the costal margin.
3. Congenital hypoplasia or agenesis of the gallbladder.
4. Shrinkage of the gallbladder with complete filling of the cavity with stones with an accompanying acoustic shadow.
5. The gallbladder has been surgically removed: try to find scars on the skin or question the patient (or the patient's relatives).
6. The examiner is not sufficiently trained or does not have the appropriate experience: ask a colleague to examine the patient.

There are only a few pathological conditions (other than congenital agenesis or surgical removal) that result in reproducible failure of gallbladder visualization on ultrasound.

A clinical diagnosis cannot be made without visualization of the gallbladder, even when examined in different positions.

Enlarged (stretched) gallbladder

The gallbladder is considered enlarged if its width (transverse diameter) exceeds 4 cm.

The normal gallbladder appears distended when the patient is dehydrated, on a low-fat diet or parenteral nutrition, or when the patient is immobilized for some time. If there are no clinical signs of cholecystitis and thickening of the gallbladder wall, give the patient a fatty meal and repeat the examination in 45 minutes or 1 hour.

If there is no abbreviation, look for:

1. A stone or other cause of cystic duct obstruction. In this case, the hepatic and bile ducts will be normal. If there is no internal obstruction, there may be obstruction caused by compression of the duct from the outside by lymph nodes.
2. Stone or other cause of obstruction in the common bile duct. The common hepatic duct will be dilated (>5 mm). Examine the common bile duct for roundworms: cross-sections will show a tubular structure within another tubular structure, the “target” sign. Look for roundworms in the stomach or small intestine. Obstruction may be caused by a tumor of the head of the pancreas (echoic mass) or, in endemic areas, by cystic membranes in the common bile duct if echinococcus is present. (Also examine the liver and abdomen for cysts, and take a chest X-ray.)
3. If the gallbladder is distended and filled with fluid, with walls thickened by more than 5 mm, empyema may be present: local pain will be felt when pressing. Perform a clinical examination of the patient.
4. If you have a distended gallbladder filled with fluid and thin walls, you may have a mucocele. Mucocele usually does not cause local pain when pressed.

Acute cholecystitis

Clinically, acute cholecystitis is usually accompanied by the appearance of pain in the upper right quadrant of the abdomen with localized tenderness with (careful) movement of the transducer in the projection of the gallbladder. One or more stones may be detected, and the presence of a stone in the neck of the gallbladder or in the cystic duct is possible. The walls of the gallbladder are usually thickened and edematous, although the gallbladder may not be stretched. If the gallbladder is perforated, fluid accumulation is detected near it.

Gallstones do not always give clinical symptoms: it is also necessary to exclude other diseases, even if you find stones in the gallbladder.

Internal echo structures in the gallbladder cavity

Displaceable internal echo structures with acoustic shadow

1. Gallstones are defined in the lumen as bright hyperechoic structures with acoustic shadow. Stones can be single or multiple, small or large, calcified or not. The walls of the gallbladder may or may not be thickened.
2. If stones are suspected but are not clearly visible on a routine scan, repeat the scan with the patient tilted or upright. Most stones will change position when the patient moves.
3. If there are still doubts, put the patient on all fours. The stones should move forward. This position of the patient can be useful in the presence of severe flatulence in the intestines.

Ultrasound examination allows for the detection of gallstones with high reliability.

Ultrasound examination does not always clearly reveal stones in the bile ducts.

Gallstones do not always produce clinical symptoms: it is necessary to exclude other diseases even if gallstones are detected.

Movable internal echo structures without shadow

Scanning should be done in different positions. Most often, such echo structures appear as a result of the presence of:

1. Gallstones. Keep in mind that if the stones are very small (smaller than the ultrasound wavelength), the acoustic shadow will not be detected.
2. Hyperechogenic bile (sediment). This is thickened bile that creates a clearly defined echostructure that moves slowly when the patient's position changes, unlike stones, which move quickly.
3. Pyogenic suspension.
4. Blood clots.
5. Daughter cells of the parasitic cyst. It is also necessary to conduct a liver examination to detect cysts.
6. Ascaris and other parasites. Rarely, worms, such as roundworms, get into the gallbladder, more often they can be seen in the bile ducts. In clonorchiasis, the hepatic ducts will be dilated, twisted, and a suspension will be determined in their lumen.

Immobile internal echo structures with acoustic shadow

The most common cause is an impacted stone: look for other stones. It can also be caused by calcification of the gallbladder wall: if there is a thickening of the wall, this can be acute or chronic cholecystitis, but it can be difficult to rule out concomitant cancer.

Immobile internal echo structures without shadow

1. The most common cause of such a structure is a polyp. Sometimes the stalk of the polyp can be detected when scanning in different projections. The acoustic shadow is not determined, a change in the patient's body position does not displace the polyp, but its shape may change. A malignant tumor may look like a polyp, but is often combined with thickening of the gallbladder wall and does not have a stalk. A malignant tumor changes its shape much less often when the patient moves.
2. Kinking or constriction of the gallbladder is usually of no clinical significance.
3. Malignant tumor.

Thickening of the gallbladder wall General thickening

The normal thickness of the gallbladder wall is less than 3 mm and rarely exceeds 5 mm. When the wall thickness is 3-5 mm, it is necessary to correlate this echographic picture with the clinical picture. General thickening of the gallbladder wall may occur in the following cases:

1. Acute cholecystitis. This may be associated with the appearance of an anechoic streak in the wall or a localized fluid collection. Stones may be present: carefully examine the neck of the gallbladder.
2. Chronic cholecystitis. Stones may also be detected.
3. Hypoalbuminemia in liver cirrhosis. Look for ascites, dilated portal vein, and splenomegaly.
4. Congestive heart failure. Look for ascites, pleural effusion, dilated inferior vena cava and hepatic vein. Examine the patient.
5. Chronic renal failure. Examine your kidneys and do urine tests.
6. Multiple myeloma. Laboratory tests are required.
7. Hyperplastic cholecystosis. Aschoff-Rokitansky sinuses are best detected by oral cholecystography, rarely by ultrasound examination.
8. Acute hepatitis.
9. Lymphoma.

Local thickening

Local thickening of the gallbladder wall may occur as a result of the following reasons:

1. Constrictions formed from the mucous layer. There may be several of them in one bladder. Scan in different positions: pathological thickening (more than 5 mm in all areas) will not disappear when the patient's position changes, and constrictions change their shape and thickness.
2. Polyp. Does not move when the patient changes position, but can change its shape.
3. Primary or secondary gallbladder cancer. Appears as a thick, irregularly contoured, solid intraluminal formation, fixed and not changing position when the patient's body position changes).

Small gall bladder

1. The patient probably ate fatty foods and the gallbladder contracted.
2. Chronic cholecystitis: check to see if the gallbladder wall is thickened and if there are any stones in the gallbladder.

If the gallbladder is small, repeat the examination in 6-8 hours (without giving the patient food or water) to differentiate between a disconnected (empty) gallbladder and a contracted gallbladder. A normal gallbladder will fill up in a few hours and will be of normal size.

Jaundice

When a patient has jaundice, ultrasound examination can usually help differentiate between non-obstructive and obstructive forms by determining the presence or absence of biliary tract obstruction. However, there are times when the exact cause of jaundice is difficult to determine.

If the patient has jaundice, ultrasound examination provides information about the condition of the gallbladder and bile ducts and usually helps differentiate between obstructive and non-obstructive jaundice, but does not always accurately identify the cause of jaundice.

Every patient with jaundice should have the liver, bile ducts, and both halves of the upper abdomen examined.

Technique

The patient should be lying on their back with their right side slightly elevated. Ask the patient to take a deep breath and hold it during the scan.

For adults, use the 3.5 MHz sensor. For children and thin adults, use the 5 MHz sensor.

Start with sagittal or slightly oblique views: locate the inferior vena cava and the main trunk of the portal vein lying anteriorly. This will facilitate the identification of the common hepatic and common bile ducts, which will be visualized descending at an angle to the liver anteriorly from the portal vein to the pancreas.

In one third of patients, the common bile duct will be visualized lateral to the portal vein and will be better seen on oblique-longitudinal sections.

Normal bile ducts

1. Extrahepatic Ducts. It may be difficult to visualize the extrahepatic bile ducts, especially with a linear transducer. Use a convex or sector transducer if possible. In cases where extrahepatic bile ducts must be visualized, try to vary the scanning technique as much as possible by performing the examination in different patient positions.
2. Intrahepatic ducts. The intrahepatic bile ducts are best visualized in the left half of the liver during deep inspiration. Normal intrahepatic ducts are difficult to visualize using ultrasound because they are very small and thin-walled. However, if the ducts are dilated, they are easily visualized and appear as multiple branching tortuous structures against the background of the liver parenchyma (there is a “branching tree” effect) near the portal vein and its branches.

Gallbladder in jaundice

1. If the gallbladder is distended, there is more likely to be obstruction of the common bile duct (eg, by a calculus, roundworm, pancreatic tumor, or acute pancreatitis). The hepatic ducts will also be dilated.
2. If the gallbladder is not distended or is small, obstruction is unlikely or occurs above the level of the cystic duct (eg, enlarged lymph nodes or a tumor near the porta hepatis).

Bile ducts in jaundice

Maximum diameter of normal common bile duct: less than 5 mm

Maximum diameter of normal common bile duct: less than 9 mm

Small diameter of normal common bile duct after cholecystectomy: 10-12 mm

Sometimes after surgery and in patients over 70 years of age, the common bile duct may be a few millimeters wider (i.e. 12-14 mm). Add 1 mm to all measurements for each subsequent decade in patients over 70 years of age.

1. If the intrahepatic ducts are moderately dilated, biliary obstruction may be suspected before clinical manifestations of jaundice appear.

If bile duct dilation is not detected in the early stages of jaundice, repeat the test after 24 hours.

2. If the extrahepatic ducts are dilated but the intrahepatic ducts are not, perform an ultrasound examination of the liver. If jaundice is present, this may be due to cirrhosis. However, it is also necessary to exclude obstruction of the lower parts of the common bile duct.

Dilated intrahepatic ducts are best visualized by scanning under the xiphoid process in the left lobe of the liver. They will be defined as tubular structures parallel to the portal vein, located centrally and extending to the peripheral parts of the liver.

If, during scanning, two vessels are detected running parallel, extending throughout the liver, and the diameter of which is approximately equal to the diameter of the portal vein, then it is most likely that one of them is a dilated bile duct.

Clonorchiasis

In clonorchiasis, the common hepatic and common bile ducts are dilated, tortuous, and present saccular structures, while in obstructive jaundice without cholangitis, they will be uniformly dilated without saccular formations. In clonorchiasis, sediment can be visualized within the ducts, but the parasite itself is too small to be visualized by ultrasound.

If both the intra- and extrahepatic bile ducts are dilated and there are large cystic formations in the liver parenchyma, the presence of echinococcosis rather than clonorchiasis is most likely.

Ultrasound will help to detect gallstones, but not always common bile duct stones. Clinical evaluation should be given, especially in a patient with jaundice.