What do the medical terms constipation and melena mean?

Constipation: Constipation is a condition characterized by bowel movements that are infrequent, difficult to pass, or incomplete. It can be caused by various factors, including changes in diet, dehydration, certain medications, and underlying medical conditions. Symptoms of constipation may include infrequent bowel movements, hard or dry stools, straining during bowel movements, and a feeling of incomplete bowel evacuation.

Melena: Melena, also known as black stools, refers to the presence of dark, tarry, or black stools. This discoloration is typically caused by the presence of partially digested blood in the stool. Melena is a sign of upper gastrointestinal bleeding, which can be caused by various conditions such as bleeding ulcers, esophageal varices, tumors, or other lesions in the upper digestive tract. The dark color of the stool is due to the reaction between stomach acid and hemoglobin, which is the oxygen-carrying protein in red blood cells. The blood undergoes chemical changes and turns into a dark, tarry substance.

It's important to seek medical attention if you experience persistent constipation or notice black, tarry stools. These conditions can indicate underlying medical issues that may require evaluation and treatment.