Takahashi 1990.

Study characteristics
Patient sampling	Primary objective: to discover clinical usefulness of levels of CA‐125 in menstrual blood in patients with endometriosis Participants: women undergoing laparoscopy or laparotomy for infertility or pelvic pain Selection criteria: not stated Study design: observational single‐gate, prospective recruitment and sample collection; consecutive patients
Patient characteristics and setting	Clinical presentation: infertility/pelvic pain Age: reproductive‐aged women Number enrolled: 104 women Number available for analysis: 104 women (all in menstrual phase of the cycle) Setting: university hospital ‐ Department of O&G, Shimane Medical University Place of study: Izumo, Japan Period of study: not stated Language: English
Index tests	Index test: CA‐125 in menstrual fluid Description of positive case definition by index test as reported: CA‐125 level by RIA (commercial kit Centocor Inc, Malvern, PA); sample handling described; threshold > 100,000 U/ml ‐ not pre‐specified Examiners: not stated; unclear if blinded to reference standard Interobserver variability: not provided
Target condition and reference standard(s)	Target condition: endometriosis Prevalence of target condition in sample: n/N = 38/104 (36%): stage I‐II 20, stage III‐IV 14; controls 66: normal pelvis 30, other pelvic pathology 36 Reference standard: laparoscopy/laparotomy Description of positive case definition by reference test as reported: visual typical appearance of disease, staged according to rAFS classification Examiners: not stated
Flow and timing	Time interval between reference test and index test: sample was collected pre‐operatively with interval of 1‐4 weeks Withdrawals: none reported
Comparative
Notes	Conclusion: Obtaining CA‐125 concentration in menstrual discharge was found to be more sensitive than serum CA‐125 levels drawn during menses in endometriosis.
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Yes
Did the study avoid inappropriate exclusions?	Yes
Was a 'two‐gate' design avoided?	Yes
		Low	Low
DOMAIN 2: Index Test All tests
Were the index test results interpreted without knowledge of the results of the reference standard?	Unclear
If a threshold was used, was it pre‐specified?	No
Was a menstrual cycle phase considered in interpreting the index test	Yes
		High	Low
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Unclear
Were the reference standard results interpreted without knowledge of the results of the index tests?	Unclear
		Unclear	Low
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Yes
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Yes
		Low