title: Catamenial appendicitis.
abstract: BACKGROUND
  Reproductive-aged women undergoing appendectomy for suspected appendicitis have twice the rate of negative histology as age-matched men. The reason for this discrepancy is unknown.
  
  
  METHODS
  Three patients with peritoneal endometriosis and recurrent symptoms of acute appendicitis coincident with menses underwent resection of a noninflamed appendix with long-term symptom resolution. Standard pathological evaluation failed to demonstrate evidence of appendiceal endometriosis or appendicitis. Additional evaluation demonstrated a marked increase in number of mast cells in the appendiceal muscularis compared with normal appendices.
  
  
  CONCLUSIONS
  The term "catamenial appendicitis" has been coined to describe these cases, and a mechanism of pathogenesis of right lower quadrant pain and nausea in patients with histologically confirmed endometriosis is proposed.
authors.affiliation: Department of Obstetrics, Gynecology, University of Missouri, Columbia, Missouri 65212, USA. barrierb@health.missouri.edu
authors.forename: Breton F
authors.initials: BF
authors.lastname: Barrier
authors.forename: Shellaine R
authors.initials: SR
authors.lastname: Frazier
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Brennaman
authors.forename: Jessica C
authors.initials: JC
authors.lastname: Taylor
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Ramshaw
mesh_terms: D015746:Abdominal Pain / Q000473:pathology* / Q000601:surgery*; D000293:Adolescent; D000328:Adult; D001062:Appendectomy; D001065:Appendix / Q000473:pathology*; D004715:Endometriosis / Q000473:pathology / Q000601:surgery*; D005260:Female; D006801:Humans; D010532:Peritoneal Diseases / Q000473:pathology / Q000601:surgery*