Gallbladder Mucocele

Etiology

Causes of cholecystitis are numerous. Cholecystitis is fundamentally related to dysfunction of the gallbladder or biliary system. The liver makes bile, which travels down the bile duct and is stored in the gallbladder. After eating certain foods, especially spicy or greasy foods, the gallbladder is stimulated to empty bile through the cystic duct and bile duct into the duodenum. This process aids in food digestion. If the gallbladder functions improperly, bile may not empty completely, leading to gallstone formation. Gallstones can cause mechanical blockage of the cystic duct or chronic irritation and inflammation leading to chronic cholecystitis. Tortuous cystic ducts increase the risk of cholelithiasis and outlet obstruction.[2]

The gallbladder also serves to concentrate bile and reabsorb water from the bile. The gallbladder can store up to 1500 mL of bile and can distend if outlet obstruction occurs. If outlet obstruction is complete, usually due to an impacted gallstone in the cystic duct, the gallbladder mucosa reabsorbs bile salts over time, and clear, watery mucus replaces them. Other etiologies of gallbladder mucocele include conditions that cause cystic duct or distal biliary tree obstruction. Neoplasms, including gallbladder polyps and tumors, can result in hydrops. Congenital strictures, gallbladder parasites, and external compression from liver disease or tumors can also cause gallbladder mucoceles. Other factors that can lead to hydrops include conditions that increase the risk of cholecystitis, such as drastic weight loss, prolonged total parenteral nutrition, gastric surgical procedures that disrupt the vagus nerve, critical illness, diabetes, hyperlipidemia, hypercalcemia, and biliary conditions such as Caroli disease. Patients with acute acalculous cholecystitis can also form gallbladder mucoceles. The mechanism is the same as that of mechanical cystic duct obstructions. However, acute acalculous cholecystitis is a functional condition resulting in a nonemptying, distended gallbladder in which biliary mucus replaces bile salts.[3]

Epidemiology

Mucoceles can occur in any patient with acute cholecystitis, whether calculous or acalculous. Gallbladder disease occurs in men and women, though certain populations are more prone to it. The risk of gallbladder disease increases in women, patients with obesity, pregnant patients, and patients in their 40s. Drastic weight loss or acute illnesses may also increase the risk. Family history also contributes to gallbladder pathology or the formation of gallstones. Other conditions that cause red blood cell breakdown, such as sickle cell disease, also increase the risk of gallstones. Most gallstones are asymptomatic. In the United States, approximately 14 million men and 6 million women between the ages of 20 and 74 years have gallstones. The prevalence increases with age. Obesity increases the likelihood of gallstones, especially in women, due to increased biliary secretion of cholesterol. Conversely, patients with drastic weight loss or fasting have a higher chance of gallstones secondary to biliary stasis. Gallstones also have a hormonal association. Estrogen has been shown to increase bile cholesterol and decrease gallbladder contractility. Women of reproductive age or receiving birth control medication containing estrogen have a 2-fold increase in gallstone formation compared with men. People with chronic illnesses such as diabetes also have an increase in gallstone formation and reduced gallbladder wall contractility due to neuropathy.[4]

Pathophysiology

Gallbladder stasis results in the buildup of intraluminal pressure, which eventually causes ischemia of the gallbladder wall and inflammation. Gallbladder stasis can also lead to bacterial colonization, which contributes to the inflammatory response. If the pressure is not relieved, the gallbladder wall becomes progressively ischemic and eventually develops gangrenous changes and perforation, leading to sepsis and shock. These findings are referred to as acute cholecystitis.[5] Chronic acalculous cholecystitis is less severe. Symptoms are more prolonged and less severe. The mechanism is the same, but chronic acalculous cholecystitis has not progressed to the findings associated with acute acalculous cholecystitis. Symptoms can also be more intermittent and vague, although patients often can present with signs of acute biliary colic. Patients with hydrops of the gallbladder usually present with signs of more acute cholecystitis

Histopathology

The gallbladder distends to varying degrees. Clear, watery mucus replaces the normally colored bile, and a distended gallbladder can contain over 1500 mL of this mucus. Varying degrees of acute inflammation of the gallbladder wall may be present, with possible microabscesses. Various bacterial species are present in 11% to 30% of cases. Rokitansky-Aschoff sinuses are present in 90% of cholecystitis specimens. Rokitansky-Aschoff sinuses are herniations of intraluminal sinuses due to increased pressure, possibly associated with the ducts of Luschka. Most often, an impacted gallstone is located in the cystic duct or Hartmann pouch. This stone is usually solitary, but multiple stones can also be present. Cases caused by other etiologies, such as polyps, tumors, or parasites, demonstrate these findings on pathologic examination. Extreme or prolonged cases can lead to gallbladder perforation.[6]

History and Physical

Cases of chronic cholecystitis present with progressive right upper quadrant abdominal pain with bloating, food intolerance, especially greasy and spicy foods, increased gas, nausea, and vomiting. Pain in the mid back or shoulder may also occur. This pain may be present for years until diagnosis. Cases of acute cholecystitis have similar but more severe symptoms. Often, these symptoms are mistaken for cardiac conditions. The finding of right upper quadrant abdominal pain with deep palpation, or Murphy sign, is classic for this disease. The gallbladder can often be palpated at the right costal margin, especially in thin patients. The gallbladder can sometimes be felt as low as the umbilicus due to extreme distension. Often, a specific dietary event, such as a fatty meal, triggers an acute attack. Patients usually present with a history of several days of progressive symptoms.[7]

Evaluation

A comprehensive history and physical examination are paramount for diagnosing cholecystitis. A complete blood count and a comprehensive metabolic panel are also important. In cases of chronic cholecystitis, these results may be within the reference range. In acute cholecystitis or severe disease, the white blood cell count may be elevated. Liver enzymes may also be elevated. If the bilirubin level is greater than 2 mg/dL, then consider a possible common bile duct stone. Even in the presence of severe gallbladder disease, laboratory values may be within the reference range. Amylase and lipase must also be checked to rule out pancreatitis. Often, CT is ordered in the emergency department as the first test in the workup. CT findings often show cholecystitis and gallstones. Gallbladder ultrasonography is the best initial test to evaluate gallbladder disease. A distended, edematous gallbladder with gallstones or an impacted, nonmobile stone in the cystic duct or Hartmann pouch is a common finding in this condition. MRI can help identify cases of hydrops.[8] In cases of acute cholecystitis, a HIDA scan is recommended. This scan will diagnose gallbladder function or cystic duct obstruction. The addition of cholecystokinin in cases without gallstones may also diagnose acalculous cholecystitis. This is indicated by an ejection fraction less than 35%, but hydrops results are most often 0%.[9] 

Treatment / Management

A recommended treatment for cholecystitis with hydrops is laparoscopic cholecystectomy because of its low morbidity and mortality rates and quick recovery. This procedure can also be performed with an open technique in cases where the patient is not a good laparoscopic candidate. If the patient is acutely ill and considered a poor surgical candidate, consider temporizing treatment with percutaneous gallbladder drainage.[10]

Differential Diagnosis

Many other conditions can mimic gallbladder disease. Patients who present with acute biliary colic are often evaluated for cardiac conditions. Other common conditions with similar presenting symptoms include peptic ulcer disease, irritable bowel syndrome, inflammatory bowel disease, gastroesophageal reflux disease, pulmonary embolism, and musculoskeletal disorders. The diagnosis of acute cholecystitis with possible hydrops in patients with a palpable gallbladder, Murphy sign, and positive gallbladder ultrasonography findings should not be confused with any other diagnosis.[7]

Prognosis

The prognosis of gallbladder hydrops follows that of acute or chronic cholecystitis. Patients have fewer readmissions if operative treatment is pursued, but high-risk or critically ill populations always require careful consideration.[11][12] 

Complications

Gallbladder hydrops complications are on the spectrum of complications of acute cholecystitis. Hydrops can increase the difficulty of laparoscopic cases due to distension and edema, thus increasing the likelihood of bile spillage and the possibility of lost stones during the operation.[13][14] Clinicians should also consider incidentally found gallbladder cancers and the concern for peritoneal dissemination if bile is spilled during cholecystectomy.[15] Knowing a patient has hydrops can give clinicians advanced time to prepare for the surgical procedure. Gallbladder decompression before attempting dissection can help decrease the incidence of bile spillage.