Cholecystitis (patho) and Cholangitis (incidence)

Cholecystitis
Cholecystitis is defined as inflammation of the gallbladder that occurs most commonly because of an obstruction of the cystic duct from cholelithiasis. 90% of cases involve stones in the cystic duct (ie, calculous cholecystitis).
Risk factors for cholecystitis mirror those for cholelithiasis and include increasing age, female sex, certain ethnic groups, obesity or rapid weight loss, drugs, and pregnancy.
http://emedicine.medscape.com/article/171886-overview

Pathophysiology
• Fixed obstruction or passage of gallstones into the gallbladder neck or cystic duct causes acute inflammation of the gallbladder wall.
• The impacted gallstone causes bile to become trapped in the gallbladder, which causes irritation and increases pressure in the gallbladder.
• Trauma caused by the gallstone stimulates prostaglandin synthesis (PGI2, PGE2), which mediates the inflammatory response. This can result in secondary bacterial infection leading to necrosis and gallbladder perforation. [3]

The pathophysiology of acalculus cholecystitis is poorly understood, but it is probably multi-factorial. Functional cystic duct obstruction is often present and related to biliary sludge or bile inspissation caused by dehydration or bile stasis (due to trauma or systemic illness). Occasionally, extrinsic compression may play a role in the development of bile stasis. Some patients with sepsis may have direct gallbladder wall inflammation and localised or generalised tissue ischaemia without obstruction.

Jaundice occurs in up to 10% of patients and is caused by inflammation of contiguous biliary ducts (Mirizzi's syndrome).

(Mirizzi's syndrome is an unusual presentation of gallstones that, when lodged in either the cystic duct or the Hartmann pouch of the gallbladder, externally compressed the common hepatic duct (CHD), causing symptoms of obstructive jaundice.)

Acute cholecystitis may resolve spontaneously 5 to 7 days after symptom onset. The impacted stone becomes dislodged with re-establishment of cystic duct patency. If cystic duct patency is not re-established inflammation and pressure necrosis may develop leading to mural and mucosal haemorrhagic necrosis. Untreated acute cholecystitis can lead to suppurative, gangrenous, and emphysematous cholecystitis.
http://bestpractice.bmj.com/best-practice/monograph/78/basics/pathophysiology.html

Cholangitis
Acute cholangitis is a bacterial infection superimposed on an obstruction of the biliary tree most commonly from a gallstone, but it may be associated with neoplasm or stricture.

Frequency
United States
Cholangitis is relatively uncommon. It occurs in association with other diseases that cause biliary obstruction and bactibilia (eg, after endoscopic retrograde cholangiopancreatography [ERCP], 1-3% of patients develop cholangitis). Risk is increased if dye is injected retrograde.
The condition mostly occurs in adults, with a reported median age at onset of 50-60 years.
http://emedicine.medscape.com/article/774245-overview
http://emedicine.medscape.com/article/184043-overview

Recurrent pyogenic cholangitis (Oriental cholangiohepatitis, hepatolithiasis) is characterized by intrahepatic brown pigment stone formation. This disorder occurs in Southeast Asia. It consists of sludge and bacterial debris in the bile ducts. Undernutrition and parasitic infestation (eg, Clonorchis sinensis, Opisthorchis viverrini) increase susceptibility. Parasitic infestation can cause obstructive jaundice with intrahepatic ductal inflammation, proximal stasis, stone formation, and cholangitis. Repeating cycles of obstruction, infection, and inflammation lead to bile duct strictures and biliary cirrhosis. The extrahepatic ducts tend to be dilated, but the intrahepatic ducts appear straight because of periductal fibrosis.
http://www.merck.com/mmpe/sec03/ch030/ch030e.html

Incidence: rare under age 40 years
http://www.fpnotebook.com/Surgery/GI/ActGlstnChlngts.htm