Gallbladder Mucocele

Mucocele (hydrops) of the gallbladder is a term denoting an overdistended gallbladder filled with mucoid or clear and watery content.[1] The condition can result from gallstone disease, the most common affliction of the biliary system. Gallstone disease affects 15-20% of the US population, with nearly 1 million new cases reported annually.[2, 3, 4]

The gallbladder mucocele distention, which is usually noninflammatory, results from an outlet obstruction of the gallbladder and is commonly caused by an impacted stone in the neck of the gallbladder or in the cystic duct.[2, 3, 5, 6]

No single laboratory test is diagnostic of a gallbladder mucocele. However, laboratory workup should include all tests performed for acute cholecystitis. Ultrasonography (US) is extremely sensitive in detecting stones in the gallbladder; other imaging modalities may be helpful in certain circumstances (see Workup).

Cholecystectomy is the definitive treatment for an obstructed gallbladder. Medical approaches may be considered in specific circumstances (see Treatment).

For patient education resources, see the Digestive Disorders Center and the Cholesterol Center, as well as Gallstones.

Long-standing obstruction to the gallbladder’s outflow results in overdistention of the gallbladder; occasionally, the gallbladder assumes massive proportions, and its volume may reach 1.5 L. The bile or bile pigment is slowly resorbed, and continuing secretion from the mucosa of the gallbladder results in clear and watery or mucoid content (white bile).

The gallbladder wall may be of normal thickness, though in long-standing cases, the mucosa atrophies and the wall becomes thin, sometimes even transparent. Wall thickening can occur with recurrent attacks of cholecystitis (see the image below). The contents are usually sterile, and any bacterial contamination ends in empyema of the gallbladder.

Distended gallbladder with evidence of adhesions on its wall. Irregular surface indicates recurrent attacks of cholecystitis.

Gross overdistention may result in gangrene or perforation of the gallbladder, with ensuing pericholecystic collection or peritonitis. The severity of the inflammatory episode dictates the clinical presentation.

Microscopic examination reveals a flattened mucosa lined by low columnar or cuboidal cells; the increased intraluminal pressure results in plentiful Rokitansky-Aschoff sinuses. Inflammatory cells may be present, either in small numbers or in abundance.[2, 3, 5]

Causes of gallbladder mucoceles include the following:

• Impacted stone in the gallbladder neck or cystic duct
• Spontaneously resolved acute cholecystitis
• Tumors - Polyps or malignancy of the gallbladder
• Extrinsic compression of the neck or the cystic duct by lymph nodes or inflammatory fibrosis or by adjacent malignancies in the liver, duodenum, or colon
• Prolonged total parenteral nutrition or ceftriaxone therapy
• Congenital narrowing of the cystic duct
• Parasites (eg, Ascaris)

In infants and children, acute, acalculous, noninflammatory hydrops of the gallbladder may be associated with the following:

• Kawasaki syndrome (mucocutaneous lymph node syndrome) ^[7]
• Streptococcal pharyngitis
• Mesenteric adenitis
• Typhoid
• Leptospirosis
• Hepatitis
• Familial Mediterranean fever
• Nephrotic syndrome
• Fibrocystic disease

About 3% of all pathologic gallbladders in adults are mucoceles. Because different authors use varying criteria to define the condition, the true prevalence of gallbladder mucocele may be higher.[2, 3, 8] Some reports indicate that an association could exist between mucoceles and solitary stones of the gallbladder.[9]

The prognosis is excellent if the diagnosis is correct and no complications have ensued.

Complications may develop when progressive inflammation leads to acute cholecystitis and all its attendant manifestations.

In addition, bacterial contamination of the bile can lead to empyema of the gallbladder, in which case the patient will usually have a toxic and ill appearance. Gas-producing organisms may lead to an emphysematous gallbladder; air bubbles in the wall of the gallbladder can be visualized by means of plain radiography, US, or computed tomography (CT).

Another potential complication is perforation of the gallbladder (see the first image below) with ensuing pericholecystic abscess or fluid collection and peritonitis (see the second image below); the diagnosis is usually strongly suspected on clinical grounds. Pseudomyxoma peritonei may result from the rupture of a true mucocele of the gallbladder.

Subserosal perforation of acute, emphysematous, acalculous cholecystitis in a 58-year-old diabetic man. Patient presented with features suggestive of ileus. He had high intrathoracic liver (and gallbladder), and clinical signs were atypical. Green color is unusual.

Yellowish aspirate from gallbladder of a 28-year-old woman who presented with features of right upper quadrant peritonitis. Slightly yellowish fluid was sterile and was rich in cholesterol.

Perforation of the gallbladder into the intestinal tract results in a cholecystenteric fistula. This occurs when the stone erodes into adjacent bowel, usually the duodenum. Gas in the biliary tree may be evident on plain radiographs of the abdomen or on ultrasonograms. If the stone is large, this may result in obstruction of the distal small bowel, leading to gallstone ileus.

Large gallbladders may compress the pylorus or duodenum, causing gastric outlet obstruction.[2, 10]

Typical symptoms of a gallbladder mucocele include the following:

• Right-upper-quadrant (RUQ) pain or epigastric pain and discomfort
• Nausea and vomiting

Continuance of pain or persistence of tenderness for longer than 6 hours indicates possible acute cholecystitis. Fever and chills suggest infected bile, with a possible empyema of the gallbladder. Jaundice is unusual, except when there is coexisting obstruction of the common bile duct (CBD), either by stones or by extrinsic compression (Mirizzi syndrome).

Typically, minimal acute inflammatory signs are present. A large, palpable, somewhat (albeit usually minimally) tender mass is usual; at times, the gallbladder may even be felt down in the pelvis.[2, 3, 4, 9, 10]

No single laboratory test is diagnostic of a mucocele. However, laboratory workup should include all tests performed for acute cholecystitis. Typical findings include the following:

• A mild leukocytosis with a shift to the left is common; higher counts indicate the possibility of acute cholecystitis or infected bile
• Bilirubin levels are usually within the reference range; they may be mildly raised in patients with Mirizzi syndrome or those with associated common bile duct (CBD) obstruction or cholangitis
• Liver enzymes are usually within the reference range, though a mild rise in alkaline phosphatase may be present; any large increase should raise the suspicion of an obstructed CBD
• Serum amylase levels are generally within the reference range; any large increase suggests the possibility of acute pancreatitis due to an obstruction close to the ampulla of Vater ^{[2, 3, 4]}

Ultrasonography (US), though entirely operator-dependent, is extremely sensitive in detecting stones in the gallbladder. A grossly distended, thin-walled gallbladder measuring more than 5 cm across anteroposteriorly, an impacted stone in the infundibulum or neck of the gallbladder or in the cystic duct, and clear fluid content indicate a possible mucocele (see the images below). The ultrasonographic Murphy sign may be positive.

Stone in neck of gallbladder, with postacoustic shadowing. Minimal wall thickening and dilated gallbladder suggest mucocele.

Transverse scan shows stone in neck of gallbladder, with postacoustic shadowing. Minimal wall thickening and dilated gallbladder are also visible.

Cluster of impacted calculi in neck of gallbladder, minimal wall thickening, and clear content; this indicates mucocele of gallbladder.

Cluster of calculi with postacoustic shadowing in neck of gallbladder, normal wall, and clear content; this indicates mucocele of gallbladder.

The wall may be thickened, and a small amount of pericholecystic fluid may be present in patients with acute cholecystitis (see the first and second images below). Gross wall thickening and murky, thick fluid with sediments and a pericholecystic collection suggest an empyema or pyocele of the gallbladder (see the third image below). US is also useful in identifying ductal obstruction and is extremely sensitive in identifying intrahepatic biliary tree dilatation.[2, 4, 7]

Image is from a 35-year-old woman who presented with recurrent episodes of right upper quadrant colic; most recent attack was 3 days before. Gross wall thickening is apparent; this is usually measured on anterior wall of gallbladder. Also apparent are clear content, stone in neck of gallbladder, and absence of pericholecystic fluid. All favor diagnosis of acute cholecystitis.

Transverse scans show layering of gallbladder wall; this suggests edema and indicates acute cholecystitis.

Longitudinal scan shows layering, with fluid in wall of gallbladder and impacted stone in neck of gallbladder. Intraluminal shadowing indicates sediments in fluid; image indicates acute cholecystitis with possible pyocele of gallbladder.

Plain radiography of the abdomen may show a soft-tissue–density shadow with an intraluminal calcific shadow in the subhepatic region. By itself, this finding is nonspecific; it should be used only as a guideline in the differential diagnosis.

Scintigraphy (hepato-iminodiacetic acid [HIDA] scanning) may be indicated in obscure cases, though it can offer only indirect evidence. Nonvisualization of the gallbladder indicates an obstructed gallbladder and possible acute cholecystitis; nonvisualization in the small intestine indicates CBD obstruction.

Computed tomography (CT) may be indicated in cases where the diagnosis is unclear or where there are other associated conditions or complications that must be assessed. The gallbladder is well visualized on CT scanning, and the wall and contents are readily assessed; however, stones may be difficult to identify. The best use of CT may lie in the evaluation of associated hepatic conditions, pancreatitis, and complications such as abscess formation or perforation of the gallbladder.

Magnetic resonance cholangiopancreatography (MRCP) clearly shows the biliary-pancreatic tree, and it is increasingly being used in place of diagnostic endoscopic retrograde cholangiopancreatography (ERCP) to assess the biliary tree. Cholecystokinin (CCK)-enhanced studies are more specific.

Occasionally, percutaneous injection of contrast into the mass may be carried out to identify anatomic details.

Contraindications for surgical treatment of gallbladder mucocele would obviously include any associated medical conditions or illnesses that preclude surgery. No absolute contraindication for surgical treatment exists.

Laboratory research suggests that chemical ablation of the gallbladder mucosa may be an alternative in patients who are medically unfit, elderly, or critically ill. A combination of ethanol, sodium tetradecyl sulfate, and mucosal exfoliant has been successfully tried in rats.[2, 3, 4, 11]

A medical line of management with oral dissolution therapy should not be considered in patients with obstructed gallbladders. In acalculous hydrops observed in children as a part of a wider spectrum, expectant management may be considered.

Cholecystectomy is the definitive treatment for an obstructed gallbladder. Laparoscopic cholecystectomy (see the images below) is the criterion standard procedure.[12, 13, 14] A 2009 study derived from database information and a literature review found evidence that even when gallstones are absent in patients with right-upper-quadrant (RUQ) pain and a positive hepato-iminodiacetic acid (HIDA) scan, symptom relief is more likely to occur after cholecystectomy than it is after medical treatment.[15]

Laparoscopic view of distended gallbladder in woman aged 70 years with sudden onset of severe right upper abdominal pain.

Stone being extracted from cystic duct through small ductotomy.

Open cholecystectomy may be performed in patients who have a very large gallbladder, greatly thickened gallbladder walls, or an obliterated triangle of Calot. In such cases, laparoscopic dissection may be difficult and time-consuming.

In patients with systemic signs and symptoms, preoperative management should include correction of hydration, nasogastric drainage (if necessary), and appropriate broad-spectrum antibiotic therapy. Preferably, cholecystectomy is carried out during the same admission.

Intraoperative aspiration of the large gallbladder helps facilitate grasping the gallbladder for dissection. The aspirate is clear and watery or mucoid (white bile). Intraoperative cholangiography may be indicated, depending on clinical and investigative features that may suggest obstruction of the common bile duct.

Upon being opened, the gallbladder shows a white wall, clear and watery or mucoid content, a stone or stones impacted in the neck or cystic duct, a narrowed cystic duct, or a tumor or polyp causing obstruction of the neck of the gallbladder.

In some patients, percutaneous cholecystostomy (guided by ultrasonography [US]) or open cholecystostomy may be used as a temporary measure. Cholecystostomy is usually performed in cases where the patient is very sick or the dissection is technically very difficult; in such instances, if the surgeon is an expert, laparoscopic subtotal cholecystectomy also can be performed. A subsequent completion cholecystectomy may be carried out once the patient’s initial condition improves.[2]

Endoscopic US (EUS)-guided endoluminal approaches to gallbladder drainage have been described.[16]