Acute Cholecystitis

Etiology

The etiology of acute cholecystitis is, by definition, cystic duct blockage, which causes inflammation. Normally, bile is made in the liver and 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 the bile of the gallbladder, through the cystic duct, down the bile duct into the duodenum. This process aids in food digestion.

The gallbladder not only stores the bile, but it also can concentrate it. Concentrated bile is susceptible to precipitation forming stones when homeostasis is disrupted, which can occur due to bile stasis, supersaturation from the liver of cholesterol and lipids, disruption in the concentration process, and cholesterol crystal nucleation. 

When cystic duct blockage is caused by a stone, it is called acute calculous cholecystitis. It is important to know, one can have pain due to temporary obstruction by gallstones, and that is called biliary colic. The diagnosis of biliary colic is upgraded to acute calculous cholecystitis if the pain does not resolve in six hours. If no stone is identified, it is called acute acalculous cholecystitis.[4][5]

Regardless of the cause of the blockage, the gallbladder wall edema will eventually cause wall ischemia and become gangrenous. The gangrenous gallbladder can become infected by gas-forming organisms, causing acute emphysematous cholecystitis; all of these conditions can quickly become life-threatening, and rupture has a high rate of mortality. 

About 95% of people with acute cholecystitis have gallstones. [6] However that does not mean incidental findings of gallstone should be treated, as it is estimated that only 20% of patients with asymptomatic stones will develop symptoms within 20 years[7], and because approximately 1% of patients with asymptomatic stones develop complications of their stones before the onset of symptoms, prophylactic cholecystectomy is not warranted in asymptomatic patients. 

Epidemiology

Gallbladder disease occurs in men and women, with certain populations being more prone to it. The risk of gallbladder disease increases in women, obese patients, pregnant women, and patients in their 40s. Drastic weight loss or acute illnesses may also increase the risk. The formation of gallstones and this condition can run in families. Other conditions that cause the breakdown of blood cells, for example, sickle cell disease, also increase the incidence of gallstones.

Pathophysiology

Occlusion of the cystic duct or malfunction of the mechanics of gallbladder emptying is the pathophysiology of this disease. Cases of acute untreated cholecystitis could lead to perforation of the gallbladder, sepsis, and death. Gallstones form from various materials such as bilirubinate or cholesterol. These materials increase the likelihood of cholecystitis and cholelithiasis in conditions such as sickle cell disease where red blood cells are broken down forming excess bilirubin and forming pigmented stones. Patients with excessive calcium such as in hyperparathyroidism can form calcium stones. Patients with excessive cholesterol can form cholesterol stones. Occlusion of the common bile duct such as in neoplasms or strictures can also lead to stasis of the bile flow causing gallstone formation.[8][9]

Histopathology

During the early phase, the gallbladder will usually reveal extensive venous congestion and edema. With time, fibrosis and the presence of chronic inflammatory cells may appear. More advanced cases may present with perforation or gangrene.

History and Physical

Cases of chronic cholecystitis present with progressing right upper quadrant abdominal pain with bloating, food intolerances (especially greasy and spicy foods), increased gas, nausea, and vomiting. Pain in the midback or shoulder may also occur. This pain could be present for years until diagnosis. Cases of acute cholecystitis have similar symptoms only more severe. Often symptoms are mistaken for cardiac issues. The finding of right upper abdominal pain with deep palpation, Murphy sign, is usually classic for this disease. Often, there is a specific dietary event leading to the acute attack, e.g., "I ate pork chops and gravy last night."

Evaluation

A physical exam with a comprehensive history is paramount in making the diagnosis of cholecystitis. A complete blood count (CBC) and a comprehensive metabolic panel are also important. In cases of chronic cholecystitis, these results may be normal. In acute cholecystitis or severe disease, white blood cell count (WBC) may be elevated. Liver enzymes may also be elevated. If there is a high bilirubin level above 2, then consider a possible common bile duct stone. Note that even in the presence of severe gallbladder disease, lab values may be normal. Amylase and lipase must also be checked to rule out pancreatitis. Often a CT scan is ordered in the emergency department as the first imaging test in the workup. Findings of cholecystitis and gallstones can often be seen in this imaging. A gallbladder ultrasound is the best test to evaluate gallbladder disease initially. A thickened gallbladder wall and gallstones are common findings with this condition. In cases of acute cholecystitis, a hepatobiliary (HIDA) scan is recommended. This scan will diagnose gallbladder function or cystic duct obstruction. The addition of cholecystokinin (CCK) in cases of no gallstones may also diagnose acalculous cholecystitis. This is indicated by an ejection fracture of less than 35%.[10][11]

Treatment / Management

The most appropriate management of cholecystitis is laparoscopic cholecystectomy. There are low morbidity and mortality rates with quick recovery. This can also be done with an open technique in cases where the patient is not a good laparoscopic candidate. In situations in which the patient is acutely ill and considered a poor surgical candidate, he or she may be treated with temporizing percutaneous drainage of the gallbladder. Milder cases of chronic cholecystitis in patients considered poor surgical candidates might be managed with low-fat and low-spice diets. The results of this treatment vary. Medical treatment of gallstones with ursodiol also has been reported to have occasional success.[12][13][3]

Differential Diagnosis

• Appendicitis
• Biliary colic
• Cholangitis
• Mesenteric ischemia
• Gastritis
• Peptic ulcer disease

Complications

The complications of acute cholecystitis include:

• Biloma
• Intraabdominal abscess 
• Bile duct injury
• Hepatic injury
• Small bowel injury
• Infection
• Retained stones in the bile duct
• Bleeding