Copyright 2008
Introduction
The normal gallbladder in the fasting state contains about 50-70mls of bile and measures 8-10 cms in length, by 3-4cms in diameter using ultrasound. Because of its ellipsoid shape the approximation for gallbladder volume can be estimated by using the formula of length X width X depth X .5cms.
Normal Size Fasting State |
| The normal gallbladder in the fasting state measures 8-10cms in longitudial view by 3-4cms int transverse dimension, and has a volume of 50-70ccs.
04766b05b04.60k gallbladder size length width volume normal anatomy Davidoff art copyright 2008 |
Normal Size of the Fasting Gallbladder on Ultrasound |
| In this instance it measures 10 by 3.5cms.
82021.8s gallbladder normal anatomy size shape position character width 3.5cms length = 10cms pear shape pyriform shape fundus body neck fundus anterior neck posterior USscan ultrasound Courtesy Ashley Davidoff MD copyright 2008 pear shape |
The wall is normally 2-3mm thick in the fasting state. It is only about 1mm thick in the neonate.
Wall Thickness by Ultrasound |
| The wall on this sagittal view of the gallbladder measures 1.00mms in this instance. From a technical view it is best measured at the liver surface as shown above.
82427.8s gallbladder wall normal size thickness USscan ultrasound Courtesy Ashley DAvidoff MD Copyright 2008 |
Normal Variations
The gallbladder contracts following a fatty meal. Patients are therefore required to fast for 6-8hours before the examination, for optimal evaluation. Examples of contracted gallbladders are shown below.
Contracted Gallbladder Following a Fatty Meal |
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Following a fatty meal, the gallbladder in this instance measures 6.5cms by 1.3cms. 25902c.8s gallbladder small normal post fatty meal normal physiology USscan ultrasound copyright 2008 Courtesy Ashley Davidoff MD |
Normal but Small Fasting Gallbladder |
| 83033c.8s 25 F normal gallbladder gracile small common hepatic duct CBD common bile duct normal pancreas anatomy USscan ultrasound Courtesy Ashley Davidoff MD copyright 2008 25 F normal gallbladder gracile small common hepatic duct CBD common bile duct normal pancreas anatomy USscan ultrasound Courtesy Ashley Davidoff MD copyright 2008 |
The fundus has the largest diameter, the body the largest volume while the the neck is the smallest part of the gallbladder proper.
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Oral Cholecstogram post Fatty MEal |
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The oral cholecystogram shows a contracted gallbladder following a fatty meal. 04751 gallbladder contracted gallbladder oral cholecystogram cystic duct normal anatomy oral cholecystogram Davidoff MD |
Applied Biology
The size of the gallbladder is one of the more important determinants of the presence of disease in the evaluation of gallbladder.
The size of the gallbladder cannot be assessed by clinical examination since the gallbladder lies under the liver and only a small portion of the fundus is exposed. Therefore under normal circumstances it cannot be palpated and is only palpable when it is significantly enlarged. For this reason, assessment of the size of the gallbladder requires the use of an imaging technique. This is best accomplished by ultrasound, since the true long axis and short axis can be defined by the ultrasonographer who is able to angle the transducer along the appropriate axis. The gallbladder is normally positioned at an angle that is off the horizontal, sagittal and coronal planes. The fundus is located relatively inferiorly, while the neck is positioned more medially and superiorly. Thus by the nature of the transverse imaging of CT and usual orthogonal imaging of MRI, the true axis is not routinely defined by these methods. Although nuclear imaging can also assess the size of the gallbladder accurately, other factors such as wall thickness and probe tenderness cannot be evaluated. Thus when assessment of the size of the gallbladder, and associated features of wall thickness and probe tenderness is required, ultrasound becomes the procedure of choice.
From a practical and clinical standpoint, the clinician who suspects an enlarged gallbladder is really asking whether there is increased pressure in the gallbladder. The imaging technology uses size as an indirect measure of the intraluminal pressure since we would otherwise have to use invasive techniques to assesss the pressure directly. Since there are situations where the gallbladder loses its tone (atonic or hypotonic gallbladder as a result of aging process or diabetes) it can enlarge without an increase in pressure. On the other hand there are situations when the gallbladder wall is fibrotic (chronic cholecystitis) and this results in a small contracted gallbladder which cannot dilate when the luminal pressure rises.
Multiple factors therefore have to be taken into consideration when assessing the size of the gallbladder.
The Large Gallbladder
The large galllbladder is defined as a gallbladder that exceeds 4cms in the short axis.
The shape of the gallbladder becomes more rotund when it is enlarged. The gallbladder is normally ovoid in shape in the transverse plane.
Gallbladder enlargement is not necessarily pathological. In aymptomatic patients, enlargement can occur as a variant in people with asthenic builds, in older patients and in diabetics (atonic). It is suggestive of cholestasis in patients who are on a prolonged fast, and those on hyperalimentation. An atonic or hypotonic ileus of the gallbladder is seen in patients following abdominal surgery, patients with GI infections, hepatitis, pancreatitis, and bowel ileus, all of which can cause asymptomatic enlargement. In these patients there is no gallbladder tenderness, the wall is normal , but there may be thickened bile (sludge) in the lumen.
Pathological gallbladder enlargement is most often caused by mechanical abnormalities and usually by a stone that is impacted in the infundibulum, or cystic duct. If the obstruction results in inflammation then acute cholecystitis results.
Acute Cholecystitis |
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In this artistic rendition, a small stone has become impacted in the neck of the gallbladder, resulting in obstruction and acute cholecystitis. 04766b08.8s gallbladder stones cholelithiasis acute cholecystitis distended enlarged bile ducts Davidoff art copyright 2008 |
The stone can also lodge in the common bile duc (CBD) resulting in an enlarged gallbladder. In this instance the patient presents with obstructive and if inflammation ensues, cholangits results.
Choledocholithiasis |
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The MRCP performed using T2 weighted FSE technique shows a CBD stone associated with dilatation of the CBD, cystic duct and the gallbladder. 17083c02.3k.8s 82 female presents with obstructive jaundice gallbladder duct enlarged distended distension dilated dilatation choledocholithiasis stone obstruction obstructive jaundice MRI T2 weighted Courtesy Ashley Davidoff MD copyright 2008 |
Another common cause of an enlarged gallbladder is acalculous cholecystitis. It is an advanced form of cholestasis where inflammatory changes supervene as a complication. Patients who have prolonged course in the ICU become cholestatic and with increased distension, inflammation ensues.
 
Acalculous Cholecystitis |
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Acalculous cholecystitis is an inflammatory condition of the gallbladder that is caused by prolonged fasting. Absent stimulation by CCK is most commonly seen in patients in the ICU setting. The gallbladder enlarges, becomes rounded and the bile becomes black and thickened – (sludge) The drawing on the left depicts the condition with a distended gallbladder, a thick slurry of bile, and inflammation in the walls. The photograph on the right is bile taken from a patient with acalculous cholecystitis. The bile which is usually a pale orange becomes as “black as crankcase oil”. 11921.8b05b043.8s gallbladder distended tumefactive bile thick sludge enlarged dilated fluid fluid level gravity specific gravity sediment sludge cholestasis stasis inflammation acalculous cholecystitis Davidoff art copyright 2008 26067 bile black crankcase oil dx acalculous cholecystitis body fluid Laboratory Test Courtesy Ashley DAvidoff MD |
Obstruction by pancreatic cancer, or less commonly by an ampullary tumor will result in an enlarged gallbladder as well. This results in a Courvoisier sign which is a palpable gallbladder in the presence of painless jaundice.
Courvoisier Gallbladder |
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The patient presented with painless jaundice and a palpable gallbladder. (Courvoisier sign) The epicentre of the collage of images is in image c where the arrow points to a mass in the head of the pancreas that has caused obstruction of the pancreatic duct (seen upstream from the mass in c ), gallbladder distension (a) and bile duct dilatation (a,b, &d) A percutaneous biliary drainage catheter has traversed the obstruction and is in the duodenum that will allow for decompression. (d) 44005c01.8s elderly patient presents with painless jaundice Courvoisier gallbladder distended enlarged dilated pancreatic duct pancreas mass pancreatic carcinoma CTscan percutaneous cholangiogram PTC Courtsy Ashley DAvidoff MD copyright 2008 bile duct |
The Small Gallbladder
The small gallbladder usually is of lesser clinical significance than the enlarged gallbladder. The most common cause of a small gallbladder is recent ingestion of a meal. In chronic cholecystitis, the development of fibrosis results in a chronically contracted gallbladder. In HIV cholangiopathies or hepattis, significant edema of the wall results in impingement on the lumen and the gallbladder which will appear relatively small.
Hypercontractile Gallbladder |
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The gallbladder in this patient is unusually small. (white arrows b,c,d) There is some fluid and minimal solid content in the stomach that could have been the stimulus. We suspected a hypercontractile gallbladder. 82264c01.8s gallbladder hypercontractile contracted predisposition to adenomyomatosis hyperplastic cholesterolosis small stomach filled with fluid and food particles CTscan Courtesy Ashley Davidoff MD copyright 2008 |
Chronic Cholecystitis, Hyperemic Wall, Small Contracted Gallbladder |
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The CTscan shows a gallbladder that is small, contains a calcified stone and a hyperemic wall consistent with a fibrotic gallbladder of chronic cholecystitis. these patient are usually not symptomatic. 30701.8s stone cholelithiasis hyperemic wall small contracted chronic cholecytitis stomach gastrostomy redundant mucosa CTscan Courtesy Ashley Davidoff MD copyright 2008 chronic cholecytitis |
Thick Wall Normal Lumen – Hepatitis |
| 48008c01 gallbladder thick wall non distended dx hepatitis USscan Davidoff MD |
Animals Aristotle and Shakespeare
There has been interest in the presence absence and size of the gallbladder in animals. It appears that the presence and size mostly relates to diet so that carnivores tend to have larger gallbladders, omnivores intermediate size and herbivores small or even absent gallbladders. (Hobart) The Petromyzon is a sea lamprey that is an eel like jawless fish that parasitises on healthy fish by attaching to them. They are born with a biliary system which subsequently degenerates. In the pigeon the gallbladder also develops and then disappears. In the rat horse, zebra, camels, rhinos, elephants, dolphins, and deer the gallbladder never develops(Mann) (Robinson) Aristotle discussed this in his treatise on animal anatomy in 350BC.
Shakespeare seemed to have been familiar with the absence of gallbladders in pigeons “But I am pigeon-liver’d and lack gall ” Hamlet: II, ii
References
Dodds, Wylie