虫垂炎 I: 概要

Appendicitis develops from obstruction of the appendiceal lumen, commonly caused by fecaliths, lymphoid hyperplasia, or foreign bodies like tumors. In children, lymphoid hyperplasia is more prevalent due to active immune response, while fecaliths predominate in adults. This obstruction triggers content stagnation, increased intraluminal pressure, bacterial overgrowth, and eventual infection leading to inflammation.

Appendicitis typically begins with dull, aching periumbilical pain caused by visceral pain, then shifts to sharp, well-localized pain in the right lower quadrant at McBurney's point, halfway between the umbilicus and right iliac crest. This progression occurs as parietal peritoneum irritation develops. The characteristic pain migration is a significant diagnostic indicator, though atypical presentations occur in young children, elderly, and pregnant patients.

Key physical findings include Rovsing's sign, where increased right lower quadrant pain occurs during left lower quadrant palpation, indicating peritoneal irritation. Rebound tenderness, abdominal rigidity, and muscle guarding reflect peritoneum inflammation. The psoas sign and obturator sign indicate irritation of specific muscles. Localized tenderness at McBurney's point further supports diagnosis, though not all signs appear in every patient.

Appendicitis presents with low-grade fever, anorexia, nausea, and vomiting alongside abdominal pain. These symptoms result from the body's inflammatory and immune response to infection. External factors like coughing or sneezing aggravate pain, reflecting inflammation of the appendix and surrounding structures. Patients often seek comfort by lying still and flexing the right leg to reduce abdominal tension.

Appendicitis progresses from initial obstruction causing content stagnation and distention to increased intraluminal pressure, venous congestion, and lymphatic obstruction. This leads to ischemia and bacterial overgrowth, triggering immune response and acute inflammation. Without intervention, the condition may progress to perforation. Understanding this sequence helps clinicians recognize the urgency of clinical manifestations and management.

Classic appendicitis symptom progression is absent in very young children, elderly patients, and pregnant women, complicating early diagnosis. Overlapping symptoms like nausea, vomiting, and anorexia also occur in other abdominal conditions. Additionally, atypical pain presentations and variable physical examination findings in these populations require heightened clinical suspicion and careful assessment to avoid diagnostic delays.

The appendix is a small, narrow, blind tube extending from the inferior part of the cecum, widely regarded as a vestigial organ that has lost much of its original function through evolution. Despite its diminished physiological role, the appendix can become inflamed, causing appendicitis. Understanding its anatomical position and vestigial nature helps explain why obstruction and inflammation occur in this structure.