Saturday, August 13, 2011

Ultrasound of Gallbladder



Ultrasonic anatomy Located inferior to rt. Lobe of liver
Long axis 6-12 cm , short axis 3-5 cm (4*10cm usually at fasting )
Contracted < 5 cm
Distended > 12 cm when the patient is fasting
Max normal diameter of CBD=4 to 7 mm
Wall Thickness:
Measured in the side in contact with the liver.usually < 3 mm.
From 3-5 mm >>> suspect thick wall
More than 5 mm >>> It is a thick wall gall bladder which is seen in:
Cholecystitis (acute-chronic).
Hepatitis ( viral).
Common Bile Duct is anterior to portal vein.this is the position of porta hapatis

Imaging technique
-overnight fast(6-12hr) to distent GB and remove gas shadow
Short focal length transducer is better as GB is anteriorly located organ.
Supine ,LPO position for imaging
Ganarally dilated bile duct seen in longitudional scan.portal vein ant. To IVC
Contents

Stones:

seen inside, mobile except at the neck they appear white with posterior shadow.
Thick bile.
Called sludge.Change with changing position. The picture occurs in the presence of thick bile in patients on IV fluids for 3-4 days and in inflammation.

Parasite:

Fasciola appears pearl shape.
Move as a whole.

Cancer & polyps:

Polypoidal or heterogeneous mass.


Pathologies

CHOLELITHIASIS-gall stone have high reflictive echo with prominent acoustic posterior shadow
Gravity dependent movement confirms diagnosis
Wall thickening as a hypoechoeic region b/n two echoeic lines,suggest chr.cholecystitis,alcoholism.

Sludge

No acoustic shadow
Low to mild level echoes
Moves very sluggishly
Acute cholecystitis

Associated with cholelithiasis in most cases
Gall stone with focal GB tenderness,usg MURPHY s sign

Pericholecystic edema
Wall edema or wall hypoechoeic
Sometime stone may not be present ,called acalculus cholecystitis eg.burns,old age,after major trauma,and fasting patient

Intrahepatic bile duct

If bile duct are >2mm dia
Second ultrasonic feature of bile duct dilatation is irregularity of bile duct dilatation

Extrahapatic bile duct

Normally 4mm at age 40,5mm at 50
Common site at head of pancrease when double duct sign may be seen
Cbd seen by parasagittal scan

Other facts

Fluid filled colon may appear like GB,wait and watch peristalsis.
In bed ridden ,numerous mass,sludge is not pathological
Polyps donot produce posterior shadow
In obese,difficult to see GB from subcostal approach

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