In vertebrates, the gallbladder is a small hollow organ where bile is stored and concentrated before it is released into the small intestine. In humans, the pear-shaped gallbladder lies beneath the liver, although the structure and position of the gallbladder can vary significantly among animal species. It receives and stores bile, produced by the liver, via the common hepatic duct and releases it via the common bile duct into the duodenum, where the bile helps in the digestion of fats. The gallbladder can be affected by gallstones, formed by material that cannot be dissolved – usually cholesterol or bilirubin, a product of haemoglobin breakdown. These may cause significant pain, particularly in the upper-right corner of the abdomen, and are often treated with removal of the gallbladder called a cholecystectomy. Cholecystitis, inflammation of the gallbladder, has a wide range of causes, including result from the impaction of gallstones, infection, and autoimmune disease.

Common bile duct stone, also known as choledocholithiasis, is the presence of gallstones in the common bile duct (CBD) (thus choledocho- + lithiasis). This condition can cause jaundice and liver cell damage. Treatment is by cholecystectomy and endoscopic retrograde cholangiopancreatography (ERCP).

Pancreatitis is a condition characterized by inflammation of the pancreas. The pancreas is a large organ behind the stomach that produces digestive enzymes and a number of hormones. There are two main types, acute pancreatitis and chronic pancreatitis. Signs and symptoms of pancreatitis include pain in the upper abdomen, nausea and vomiting. The pain often goes into the back and is usually severe. In acute pancreatitis a fever may occur and symptoms typically resolve in a few days. In chronic pancreatitis weight loss, fatty stool, and diarrhea may occur.Complications may include infection, bleeding, diabetes mellitus, or problems with other organs.

Hernia repair refers to a surgical operation for the correction of a hernia—a bulging of internal organs or tissues through the wall that contains it. It can be of two different types: herniorrhaphy; or hernioplasty. This operation may be performed to correct hernias of the abdomen, groin, diaphragm,  or at the site of a previous operation. Hernia repair is often performed as an ambulatory procedure.

Gastroesophageal reflux disease (GERD), also known as acid reflux, is a long-term condition in which stomach contents rise up into the esophagus, resulting in either symptoms or complications. Symptoms include the taste of acid in the back of the mouth, heartburn, bad breath, chest pain, vomiting, breathing problems, and wearing away of the teeth. Complications include esophagitis, esophageal stricture, and Barrett’s esophagus.

Hemorrhoids, also called piles, are vascular structures in the anal canal. In their normal state, they are cushions that help with stool control. They become a disease when swollen or inflamed the unqualified term “hemorrhoid” is often used to refer to the disease. The signs and symptoms of hemorrhoids depend on the type present. Internal hemorrhoids often result in painless, bright red rectal bleeding when defecating. External hemorrhoids often result in pain and swelling in the area of the anus. If bleeding occurs it is usually darker. Symptoms frequently get better after a few days. A skin tag may remain after the healing of an external hemorrhoid.

Colonoscopy  or coloscopy  is the endoscopic examination of the large bowel and the distal part of the small bowel with a CCD camera or a fiber optic camera on a flexible tube passed through the anus. It can provide a visual diagnosis (e.g., ulceration, polyps) and grants the opportunity for biopsy or removal of suspected colorectal cancer lesions. Colonoscopy can remove polyps as small as one millimeter or less. Once polyps are removed, they can be studied with the aid of a microscope to determine if they are precancerous or not. It can take up to 15 years for a polyp to turn cancerous.

Upper GI endoscopy is a procedure in which a doctor uses an endoscope—a flexible tube with a camera—to see the lining of your upper GI tract. A gastroenterologist, surgeon, or other trained health care professional performs the procedure, most often while you receive light sedation to help you relax. An upper GI endoscopy can be used to identify disorders or problems such as GERD (gastroesophageal reflux disease) Narrowing (strictures) or blockages. Larger than normal veins in your esophagus (esophageal varices)

Colorectal surgery is a field in medicine dealing with disorders of the rectum, anus, and colon. The field is also known as proctology, but this term is now used infrequently within medicine and is most often employed to identify practices relating to the anus and rectum in particular. The word proctology is derived from the Greek words proktos, meaning “anus” or “hindparts”, and -logia, meaning “science” or “study”.

Surgical forms of treatment for these conditions include: colectomy, colostomy, polypectomy, strictureplasty, hemorrhoidectomy (in severe cases of hemorrhoids), anoplasty, and more depending on the condition the patient has. Diagnostic procedures, such as a colonoscopy, are very important in colorectal surgery, as they can tell the physician what type of diagnosis should be given and what procedure should be done to correct the condition. Other diagnostic procedures used by colorectal surgeons include: proctoscopy, defecating proctography, sigmoidoscopy. In recent times, the laparoscopic method of surgery has seen a surge of popularity, due to its lower risks, decreased recovery time, and smaller, more precise incisions achieved by using laparoscopic instruments.