title: Diagnostic accuracy of Cancer Antigen 125 (CA125) for endometriosis in symptomatic women: A multi-center study.
abstract: OBJECTIVE
  To assess the diagnostic accuracy of serum Cancer Antigen 125 (CA 125)≥30units/milliliter (u/ml) for diagnosing endometriosis in symptomatic women.
  
  
  METHODS
  Prospective observational cohort study including patients with symptoms of pelvic pain or subfertility undergoing elective diagnostic laparoscopy at two tertiary referral hospitals. We excluded patients suspected to have other gynecological pathology. We evaluated the accuracy of serum CA 125 (index test) with histologically confirmed endometriosis (reference standard).
  
  
  RESULTS
  Fifty-eight consecutive women recruited between October 2013 to March 2015. Women with endometriosis had a higher CA 125 level than those without endometriosis (mean 54.7+/-71.6 vs 16.2+/- 8.0). The specificity of CA 125≥30u/ml was 96% (95% CI 81.7-99.9%) and sensitivity was 57% (95% CI 37.4-74.5%). The positive likelihood ratio for the histological presence of endometriosis with a CA 125≥30u/ml was 15.8 (95% CI 2.3-112) providing a post-test probability of 94% (95% CI 71%-99%) in women with pelvic pain or subfertility. The area under the curve, 0.85 (95% CI 0.74-0.96) indicates high test accuracy.
  
  
  CONCLUSIONS
  CA 125≥30u/ml is highly predictive of endometriosis in women with symptoms of pain and/or subfertility. CA 125 should be considered as a rule-in test for expediting the diagnosis and management of endometriosis, CA 125 <30u/ml is, however, unable to rule out endometriosis.
authors.affiliation: Women's Health Research Unit, The Blizard Institute, Barts and the London School of Medicine and Dentistry, Yvonne Carter Building, 58 Turner Street, Whitechapel, London, E1 2AB, United Kingdom; Royal Free London NHS Trust, London, NW3 2QG, United Kingdom. Electronic address: m.hirsch@qmul.ac.uk.
authors.forename: Martin
authors.initials: M
authors.lastname: Hirsch
authors.affiliation: Nuffield Department of Primary Care Health Sciences, Radcliffe Primary Care Building, University of Oxford, Oxford, OX1 2JD, United Kingdom.
authors.forename: James M N
authors.initials: JMN
authors.lastname: Duffy
authors.affiliation: Centre for Reproductive Medicine, St Bartholomew's Hospital, Barts Health NHS Trust, West Smithfield, EC1A 7BE, United Kingdom.
authors.forename: Christine S
authors.initials: CS
authors.lastname: Deguara
authors.affiliation: Women's Health Research Unit, The Blizard Institute, Barts and the London School of Medicine and Dentistry, Yvonne Carter Building, 58 Turner Street, Whitechapel, London, E1 2AB, United Kingdom.
authors.forename: Colin J
authors.initials: CJ
authors.lastname: Davis
authors.affiliation: Women's Health Research Unit, The Blizard Institute, Barts and the London School of Medicine and Dentistry, Yvonne Carter Building, 58 Turner Street, Whitechapel, London, E1 2AB, United Kingdom.
authors.forename: Khalid S
authors.initials: KS
authors.lastname: Khan
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D018394:CA-125 Antigen / Q000097:blood*; D004715:Endometriosis / Q000097:blood* / Q000150:complications; D005260:Female; D006801:Humans; D007247:Infertility, Female / Q000209:etiology; D008565:Membrane Proteins / Q000097:blood*; D017699:Pelvic Pain / Q000209:etiology; D011446:Prospective Studies
chemical_list: D015415:Biomarkers; D018394:CA-125 Antigen; C451759:MUC16 protein, human; D008565:Membrane Proteins
keywords: Cancer Antigen 125; Diagnosis; Endometriosis