Pittaway 1989.

Study characteristics
Patient sampling	Primary objective: to determine whether serum CA‐125 would be useful in differentiating between pelvic pain caused by endometriosis and that from other causes Participants: reproductive‐aged women scheduled for laparoscopy or laparotomy for investigation of chronic pelvic pain with or without infertility Selection criteria: inclusion criteria: reproductive age, pain lasting at least 3 months Study design: cross‐sectional single‐gate design, prospective recruitment
Patient characteristics and setting	Clinical presentation: pelvic pain ± infertility Age: mean age 28.9 years, range 16‐39 (endometriosis) and 26.7 years, range 14‐44 years (controls) Number of participants enrolled: 180 women Number of participants available for analysis: 163 women (all in in late follicular phase of menstrual cycle, day 7‐10) Setting: Section on Reproductive Endocrinilogy, Wake Forest School of Medicine, tertiary referral centre Place of study: Winston Salem, North Carolina, USA Period of study: over 30 months period, dates not provided Language: English
Index tests	Index test: CA‐125 Details of the index test procedure as stated: serum CA‐125 was measured in duplicate in using an immunoradiometric assay (Centocor, Malvern, PA); sample handling described, reference to a source describing laboratory technique Threshold for positive result: CA‐125 ≥16 U/ml; pre‐specified Examiners: no information provided; operators of index test were blinded to surgical data Interobserver variability: not reported
Target condition and reference standard(s)	Target condition: endometriosis Prevalence of target condition in the sample: n = 82/163 (50%): stage I‐II 54, stage III‐IV 28; controls n = 81: normal pelvis ‐ 15, adhesions ‐ 27, chronic PID ‐ 28, other ‐ 11 Reference standard: laparoscopy n = 163 (100%) Description of positive case definition by reference standard test as reported: surgical diagnosis; staging according to the rASRM classification Examiners: no information provided; CA‐125 levels were not known at the time of surgery
Flow and timing	Time interval between index test and reference standard: preoperative 7‐10 days before onset of last menses Withdrawals: 17 women were excluded from the study (were still menstruating on a day of sample collection)
Comparative
Key conclusions by the authors	Determination of CA‐125 may assist in the evaluation and treatment of women with chronic pelvic pain
Conflict of interest	Not reported
Notes	The reported data enabled calculation of the diagnostic estimates per severity of endometriosis ‐ not presented in this review
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Unclear
Did the study avoid inappropriate exclusions?	Yes
Was a 'two‐gate' design avoided?	Yes
		Unclear	Low
DOMAIN 2: Index Test All tests
Were the index test results interpreted without knowledge of the results of the reference standard?	Yes
If a threshold was used, was it pre‐specified?	Yes
Was a cycle phase considered in interpretation of the result of index test?	Yes
		Low	Low
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results interpreted without knowledge of the results of the index tests?	Yes
		Low	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