Diagnostics

Disease

 Cholecystitis

General

Cholecystitis is inflammation of the gallbladder, and commonly occurs secondary to obstruction of the cystic duct by cholelithiasis (or gallstones).  In fact, upwards of 90% of cases presenting as cholecystitis are due to stone blockage, while the remaining 10% or so are due to acalculous cholecystitis.  Risk factors for developing cholecystitis are similar to those of developing cholelithiasis and include increasing age, female gender, obesity and rapid weight loss, drugs, pregnancy, and being of certain ethnic descents.

The process of calculous cholecystitis results when the a stone obstructs the cystic duct, leading to distension of the gallbladder.  As the gallbladder distends, blood flow and lymphatic drainage become compromised, leading to mucosal ischemia and necrosis.  Inflammation ensues, leading to cholecystitis.  The exact mechanism of acalculous cholecystitis is less clear, but is thought to be related to conditions associated with bile stasis, including debilitation, major surgery, long-term TPN, and prolonged fasting.

Of the 10-20% of Americans with gallstones, up to one third will develop acute cholecystitis, and as such, cholelithiasis is the major risk factor for disease.  Most patient's symptoms will resolve with 1-4 days, however 25-30% will require surgery or develop some form of complication.  Perforation occurs in approximately 10-15% of cases. 

Clinical Presentation and Diagnosis

Patient's with cholecystitis have symptoms similar to those seen in cholelithiasis.  Upper abdominal pain and biliary colic is the most common complaint and this pain often radiates to the right scapula.  Unlike true biliary colic, the pain often becomes constant in the majority of patients, after a period of colicky pain and tenderness.  In fact, the two are often distinguished by the persistence of constant, severe pain lasting longer than 6 hours.  Nausea and vomiting are often present and due to the nature of the inflammatory process, fever is common as is a leukocytosis with left shift.

Physical exam may reveal fever, tachycardia, and RUQ tenderness, often with guarding or rebound.  Murphy's sign (tenderness and an inspiratory pause elicited during palpation of the RUQ) is often present.  Importantly, the absence of physical findings does not rule out the diagnosis of cholecystitis.  Many patients may present with diffuse epigastric pain, without localization to the RUQ.  Additionally, diabetic patients may have atypical presentations including vague symptoms and absence of fever.

Although laboratory studies are not 100% reliable in making the diagnosis of cholecystitis, certain findings may be helpful in arriving at the diagnosis.  A leukocytosis with a left shift may be observed.  The liver enzymes ALT and AST may be elevated when there is obstruction of the common bile duct, owing to a combined cholecystitis and hepatitis.  Common duct obstruction ban also be investigated with bilirubin and alkaline phosphatase assays and an alkaline phosphatase is elevated in about a quarter of patients with cholecystitis.  Amylase and lipase are commonly ordered to rule out pancreatitis, one of the complications of gallstone disease.

In addition to lab studies, radiography, ultrasound, and even CT/MRI can be used to assess the biliary system, with ultrasound giving high sensitivity and specificity for diagnosing both stones and cholecystitis.  CT and MRI also provide high sensitivity and specificity for predicting acute cholecystitis, with findings of wall thickening, pericholecystic fluid, subserosal edema, and sloughed mucosa being the most commonly seen features.  CT and MRI are also useful for examining surrounding structures, when the diagnosis is not entirely clear.

Treatment

For acute cholecystitis, initial (medical) treatment includes bowel rest, IV hydration, analgesia, and IV antibiotics.  For mild cases of acute cholecystitis, antibiotic therapy with a single broad-spectrum antibiotic is adequate.  Bacteria commonly associated with acute cholecystitis include E. Coli, B. Fragilis, Klebsiella, Enterococcus, and Pseudomonas species.

Laparoscopic cholecystectomy is the standard of care for the surgical treatment of cholecystitis.  Surgery is typically performed after symptoms have subsided, but during the hospitalization for acute illness. 

Contraindications for laparoscopic surgery include high risk for general anesthesia, morbid obesity, signs of gallbladder perforation (abscess, peritonitis, or fistula), giant gallstones or suspected malignancy, or end-stage liver disease with portal hypertension and severe coagulopathy.

Open cholecystectomy is still, also, a valid approach to gallbladder removal, when laparoscopic surgery cannot be performed or the procedure must be converted from laparoscopic to open.