Gallstones also known as cholelithiasis are stony hard deposits of bile. Gall bladder is a small pear shaped organ which is located in close proximity with the liver (beneath the liver). Bile is a type of digestive juice which is produced in the liver and then stored and concentrated in the gall bladder. Gall bladder again releases the stored bile in the gut (duodenum of the small intestine) where it helps in digestion of food (especially fatty food).
The size of gallstone can be diverse; sometimes it is as small as a grain of sand and sometimes it is as large as a golf ball. Gallstones formed in gall bladder may sometimes get dislodged and block other parts of the biliary tract like pancreatic duct or common bile duct leading to pancreatitis or ascending cholangitis respectively.In people suffering from symptomatic gall are treated with surgical removal of gall bladder however treatment is not required if there is no symptom.

Symptoms
There may not be any symptom of gallstone; in these cases the presence of the stones is detected as an incidental finding upon ultrasound done for investigation of other diseases. Usually symptoms arise when the stones get lodged in a duct and block the passage. Common presenting symptoms include
I. Sudden onset excruciating pain in the right upper abdomen. The pain usually spread to the right shoulder or the area in between the two shoulder blades. Gallstone pain characteristically last for 30 minutes to several hours and in most of the cases is accompanied with nausea and vomiting. Usually this type of gallstone attack occurs after consuming fatty food or during the night, after a drink, etc.

There are several complications associated with gallstone; these are
1) Inflammatory damage to the gall bladder itself or otherwise known as cholecystitis. In this condition the gallstone(s) gets lodged in the narrow neck portion of the saccular gall bladder there by obstructing the passage and bile flow, accumulation of excess amount of bile and inflammatory damage to the gall bladder following secondary infection by several infecting bacteria namely Escherichia, Enterobactor, Klebsiella, Bacteroides etc. This condition is known as cholecystitis and it is characterized by severe degree of abdominal pain along with fever.

2) Obstruction of the common bile duct: sometimes the gallstones may escape from the gall bladder and get lodged in the common bile duct or other biliary ducts which help in passage of bile from the gall bladder in the small gut. This condition is known as choledocolithiasis.

3) Obstruction of the biliary tract by the gallstones (choledocolithiasis) may lead to acute cholangitis characterized by inflammatory damage of the biliary ducts along with infection by several bacteria.

4) Obstruction of the pancreatic duct (pancreatitis): Sometimes a dislodged gallstone from the gall bladder can get impacted in the pancreatic duct blocking it. Hence back flow of the pancreatic juices can lead to inflammatory damage to the pancreatic tissue (pancreatitis). Here there is self digestion of the pancreatic tissue. Pancreatitis is a serious condition which is characterized by severe abdominal pain and requires urgent hospitalization.

5) Gall bladder cancer which is itself very rare is known to have a relationship with gallstones.