Spontaneously resolving acute appendicitis: clinical and sonographic documentation.

PURPOSE: To document findings in a subgroup of patients with acute appendicitis that spontaneously resolved. MATERIALS AND METHODS: From February 1989 through December 1995, nine patients were seen with a diagnosis of acute appendicitis that did not necessitate immediate surgery. Clinical, ultrasound (US), and pathologic findings were retrospectively reviewed. RESULTS: Four of the nine patients underwent elective appendectomy 15-84 days (mean, 52 days) after initial presentation, and five did not undergo surgery. Seven patients experienced spontaneous pain relief before admission to the hospital, and two improved within a few hours of being admitted. No patient had an indication of peritoneal irritation at physical examination. Four patients had a normal white blood cell count, and five had leukocytosis. Maximum appendiceal diameter was 9-12 mm. Five patients had inflamed periappendiceal fat. No patient had abscess or appendicolithiasis shown at US. A normal appendix was identified at follow-up (mean, 40 months; range, 1-60 months) in four of five patients who did not undergo elective appendectomy. Two patients experienced recurrent bouts of pain, and one of these patients underwent appendectomy before the planned elective procedure. CONCLUSION: On the basis of clinical, US, and pathologic findings, mild acute appendicitis spontaneously resolved in a subgroup of patients.