Meibody 2011.

Study characteristics
Patient sampling	Primary objective: to test the hypothesis that small demyelinated nerve fibres in functional layer of endometrium are present in higher density in women with endometriosis, which is more significant in secretory phase. Participants: women undergoing laparoscopy/laparotomy for infertility or pelvic pain Selection criteria: inclusion criteria: reproductive age, regular menstrual cycle; exclusion criteria: unwillingness to participate and use of hormonal medications for the past 3/12 months Study design: observational single‐gate, prospective collection of samples
Patient characteristics and setting	Clinical presentation: chronic pelvic pain ‐ 23/27, dyspareunia ‐ 5/27, dysmenorrhoea ‐ 7/27, infertility ‐ 5/27 Age: mean age 39.5 ± 5.9 years, endometriosis; 41.6 ± 5.7 years, controls Number enrolled: 27 women Number available for analysis: 27 women (all in proliferative cycle phase) Setting: university hospital ‐ Minimally Invasive Surgery Research Center, Rassoul Akram Hospital, Iran University of Medical Sciences Place of study: Tehran, Iran Period of study: 2007‐2009 Language: English
Index tests	Index test: endometrial small nerve fibres in eutopic endometrium ‐ PGP 9.5 Description of positive case definition by index test as reported: Presence of nerve fibres detected by IHC staining for PGP 9.5 seen in 10 HPF (IHC by using Dako Denmark A/S Produktionsej42 DK‐2600, Denmark and Olympus microscope; assessment of 3‐4 sections per slide; density of NF was also calculated by intensity of staining); laboratory technique described Examiners: pathologist was blinded to reference standard result Interobserver variability: not reported
Target condition and reference standard(s)	Target condition: endometriosis Prevalence of target condition: n/N = 12/27 (44%): stage not reported; controls 15 Reference standard: Laparoscopy/laparotomy + histology Description of positive case definition by index test as reported: visualisation of the endometriotic lesions with surgical staging of the disease and histological confirmation Examiners: 3 experienced gynaecologists in endometriosis
Flow and timing	Time interval between index test and reference standard: endometrial biopsy was obtained prior to surgery Withdrawals: none reported
Comparative
Notes	Conclusion: Assessment of neural fibre density in endometrial biopsy by PGP 9.5 staining is as accurate as surgical assessment by experienced gynaecologists.
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	No
Did the study avoid inappropriate exclusions?	Yes
Was a 'two‐gate' design avoided?	Yes
		High	Unclear
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