Al‐Jefout 2009.

Study characteristics
Patient sampling	Primary objective: to detect small unmyelinated nerve fibres immunohistochemically (using the pan‐neuronal marker protein gene product 9.5 (PGP 9.5)) in the functional layer of endometrium in women undergoing diagnostic laparoscopy for pelvic pain or infertility Participants: reproductive‐aged women undergoing laparoscopy for infertility, pelvic pain or both Selection criteria: exclusion criteria: hormonal treatment for 3/12 months prior to surgery, pregnancy, unwillingness to participate Study design: observational single‐gate, prospective recruitment and sample collection
Patient characteristics and setting	Clinical presentation: pelvic pain symptoms alone (n = 52), infertility alone (n = 24), pelvic pain + infertility (n = 20), no pain and no infertility (n = 3) Age: mean age 33.9 years (range 20‐50 years) Number enrolled: 103 women Number available for analysis: 99 women (menstrual cycle phase n = 15; proliferative n = 39; mid‐cycle n = 14; secretory n = 31) Setting: Royal Prince Alfred Hospital, a tertiary referral centre Place of study: Sydney, Australia Period of study: 12 December 2007 to 10 December 2008 Language: English
Index tests	Index test: endometrial nerve fibres: PGP 9.5 Description of positive case definition by index test as reported: presence of endometrial nerve fibres in functional layer by IHC staining for PGP 9.5 (Immunostaining on a Dako Autostainer Model S3400 (Dako, Australia); image analysis by using an Olympus microscope BX51 and digital camera DP70 (Olympus, Japan)); laboratory technique described Examiners: 2 people with experience in nerve fibre counting, blinded to the patients' data and each others' results Interobserver variability: close (98%) correlations between the 2 operators
Target condition and reference standard(s)	Target condition: endometriosis Prevalence of target condition in the sample (n/N) = 64/99 (64%): stage I‐II 33, stage III‐IV 31; controls n/N = 35/99 Reference standard: laparoscopy + histology Description of positive case definition by reference test as reported: visualisation of endometriotic lesions with surgical staging of the disease according to rAFS system; biopsy confirmation of lesions was available in almost all cases. Examiners: 5 gynaecologists with extensive experience in endometriosis
Flow and timing	TIme interval between index test and reference standard: prior to laparoscopy Withdrawals: 4 participants were excluded due to poor sample quality (assessed prior to nerve fibre counting)
Comparative
Notes	Conclusion: Endometrial biopsy, with detection of nerve fibres, provided a reliable diagnosis of endometriosis that is close to the accuracy of laparoscopic assessment by experienced gynaecological laparoscopists
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?	Yes
If a threshold was used, was it pre‐specified?	Yes
Was a menstrual cycle phase considered in interpreting the 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