Which condition presents with abdominal pain relieved by defecation and is associated with altered bowel habits?

Irritable bowel syndrome (IBS) is characterized by abdominal pain that is distinctively relieved by defecation, along with changes in bowel habits. Patients with IBS often experience a combination of diarrhea, constipation, or alternating patterns of both. The abdominal discomfort typically arises due to a combination of gastrointestinal motility disturbances and heightened visceral sensitivity.

In IBS, relief of pain post-defecation is a key feature, underscoring the functional nature of the disorder where the bowel's reaction to stimuli plays a significant role in symptomatology. The association of altered bowel habits is a hallmark of IBS, differentiating it from other conditions that may also cause abdominal pain but do not share this pattern of symptom relief.

The other conditions listed do not fit this clinical presentation. For example, gastroesophageal reflux disease predominantly presents with esophageal symptoms and does not feature bowel habit alterations. Diverticulitis presents with localized pain, often with associated fever and leukocytosis, but lacks the characteristic relief with bowel movements seen in IBS. Peptic ulcer disease primarily causes epigastric pain that is often relieved by eating, but it does not reflect the changes in bowel habits typical of IBS.