Oral symptoms can be similar to lesions occurring elsewhere in the digestive tract, with a pattern of swelling, inflammation, ulcers, and fissures.

If these signs are present, then patients are more likely to also have anal and esophageal lesions and experience other extra-intestinal disease manifestations.

[5]: 853, 863–868 Oesophageal disease may result in a sore throat, throwing up blood, difficulty swallowing or vomiting.

[6][7] As well as peptic ulcers, vomiting blood may result from abnormal arteries or veins that have ruptured, including Dieulafoy's lesion and Gastric antral vascular ectasia.

Congenital disorders of the stomach include pernicious anaemia, in which a targeted immune response against parietal cells results in an inability to absorb vitamin B12.

[9] Segmental or diffuse gastrointestinal wall thickening is most often due to ischemic, inflammatory or infectious disease.

[5]: 879–887 Diseases of the small intestine may present with symptoms such as diarrhoea, malnutrition, fatigue and weight loss.

Investigations pursued may include blood tests to monitor nutrition, such as iron levels, folate and calcium, endoscopy and biopsy of the duodenum, and barium swallow.

Functional colonic diseases refer to disorders without a known cause, including irritable bowel syndrome and intestinal pseudoobstruction.

Constipation may result from lifestyle factors, impaction of a rigid stool in the rectum, or in neonates, Hirschprung's disease.

Tests that specifically examine the function of the large intestine include barium swallows, abdominal x-rays, and colonoscopy.

Faecal incontinence can result from mechanical and neurological problems, and when associated with a lack of voluntary voiding ability is described as encopresis.

Chronic liver disease may result in a buildup of fluid in the abdomen, yellowing of the skin or eyes, easy bruising, immunosuppression, and feminization.

[11] Portal hypertension is often present, and this may lead to the development of prominent veins in many parts of the body, such as oesophageal varices, and haemorrhoids.

When symptoms occur, such as in acute pancreatitis, a person may experience acute-onset, severe mid-abdominal pain, nausea and vomiting.

In severe cases, pancreatitis may lead to rapid blood loss and systemic inflammatory response syndrome.

Pancreatic disease might be investigated using abdominal x-rays, MRCP or ERCP, CT scans, and through blood tests such as measurement of the amylase and lipase enzymes.

Disease might be investigated using ultrasound or ERCP, and might be treated with drugs such as antibiotics or UDCA, or by the surgical removal of the gallbladder.

In general, a significant factor in the etiology of gastrointestinal cancers appears to be excessive exposure of the digestive organs to bile acids.