An H2 Blocker is a medication class that reduces stomach acid production. It works by blocking histamine type-2 (H2) receptors on acid-producing cells in the stomach. H2 Blocker drugs are commonly used for acid-related symptoms such as heartburn and dyspepsia. They are also used in hospitals for selected ulcer-prevention and bleeding-related situations.

A Proton Pump Inhibitor is a medication that reduces how much acid the stomach makes. It is commonly used in gastroenterology to treat acid-related disorders of the esophagus and stomach. Clinicians often shorten the term to PPI after first mention. It is used in outpatient clinics, hospitals, and perioperative settings when acid suppression is needed.

Ileitis means inflammation of the ileum, the final segment of the small intestine. It is a descriptive clinical term used in gastroenterology, radiology, pathology, and surgery. It can be acute (short-lived) or chronic (ongoing), depending on the cause. Clinicians use it to frame the differential diagnosis and guide testing when the terminal ileum appears abnormal.

Jejunitis means inflammation of the jejunum, the middle segment of the small intestine. It is a descriptive clinical term rather than a single disease. Clinicians use it to localize inflammation when symptoms or tests suggest small-bowel involvement. It appears in gastroenterology, radiology, pathology, and GI surgery discussions.

Duodenitis means inflammation of the duodenum, the first part of the small intestine. It is commonly used as an endoscopic, histologic, and clinical diagnosis in gastroenterology. The term describes a pattern of mucosal injury rather than a single cause. Duodenitis can be acute (short-term) or chronic (long-standing).

Meckel Diverticulum is a small pouch in the wall of the small intestine that is present from birth. It forms when an embryologic connection between the intestine and the umbilicus does not fully disappear. It is most often discussed in gastroenterology and surgery when evaluating unexplained intestinal bleeding, abdominal pain, or bowel obstruction.

Hirschsprung Disease is a congenital disorder where part of the colon lacks normal enteric nerve cells. It causes functional bowel obstruction because the affected segment cannot relax and propel stool effectively. It is most commonly discussed in pediatric gastroenterology and pediatric surgery. It is also relevant in neonatal care when evaluating delayed passage of meconium and severe constipation.

Toxic Megacolon is an acute, severe complication of colitis where the colon becomes dangerously dilated and inflamed. It is typically accompanied by systemic toxicity, meaning whole-body signs of serious illness. Clinicians most often discuss it in the setting of inflammatory bowel disease and severe infectious colitis. It is used as an emergency diagnosis because it can progress to perforation and sepsis.

Lymphocytic Colitis is a form of microscopic colitis that causes chronic, non-bloody watery diarrhea. It is diagnosed by colon biopsies showing increased lymphocytes (a type of white blood cell) in the colon lining. The colon often looks normal during colonoscopy, so the diagnosis depends on pathology. It is commonly discussed in gastroenterology clinics, endoscopy units, and surgical pathology reports.

Collagenous Colitis is a type of microscopic inflammation of the colon that causes chronic, watery diarrhea. It is called “microscopic” because the colon can look normal on colonoscopy, but biopsies show characteristic changes. It is most commonly used as a clinicopathologic diagnosis in gastroenterology to explain persistent non-bloody diarrhea.