Spontaneously resolving appendicitis: frequency and natural history in 60 patients.

PURPOSE: To establish the frequency and natural history of ultrasonographically (US) documented spontaneously resolving appendicitis following conservative treatment.

MATERIALS AND

METHODS

From July 1987 to July 1997, the authors encountered 106 patients with US-diagnosed spontaneously resolving appendicitis. We retrospectively studied clinical data and US findings obtained at admission and follow-up relating to 60 patients who were treated conservatively. Over the same 10 years, 1,280 appendectomies for acute appendicitis were performed in the authors' hospital.

RESULTS

Of 60 patients, 23 (38%) had recurrent appendicitis after a median of 14 weeks (range, 2-254 weeks), with 16 (70%) having recurrence within 1 year of the first attack. US findings indicated that patients with an appendiceal diameter of at least 8 mm were more prone to recurrence than patients with an appendiceal diameter of less than 8 mm; the recurrence rates were 47% (21 of 45 patients) and 13% (two of 15 patients). The other parameters did not show a statistically significant difference.

CONCLUSION

Spontaneously resolving appendicitis occurs in at least one in 13 cases of appendicitis and has an overall recurrence rate of 38%, with the majority of cases reccurring within 1 year.