Vidal‐Sicart 2007.

Study characteristics
Patient sampling	Prospective study; enrolment appears to be consecutive but this is not clear. Comprised a validation study (50 women) and an applications study (20 women)
Patient characteristics and setting	50 women with vulval SCC, including 7 women who had stage III lesions clinically. We excluded the data from these 7 women, resulting in 43 assessable women (64 groins) Mean age: not reported Setting: 3 tertiary hospitals in Spain; recruitment from June 1998 to July 2005
Index tests	Tc‐99m and blue dye Histological methods: standard section with H&E staining was used for SNs; if negative, ultrastaging with IHC stains was performed
Target condition and reference standard(s)	TC: groin lymph node involvement RS: complete IFL
Flow and timing	1 day pre‐operatively, 2 to 4 x 37 MBq Tc‐99m (0.1 ml) was injected intradermally around the tumour. Dynamic and planar imaging was done (30 minutes and 2 hours later). SN locations were marked on the skin. Delayed imaging was obtained where necessary. Blue dye (1 ml) was injected 2 to 10 minutes prior to skin incision Detected intra‐operatively by gamma probe and visually (blue nodes). SNs with 10 x background activity were removed. After removal, the field was scanned to check for 'other significant activity' SND and IFL were performed during the same operation
Comparative
Notes	As the individual patient data were reported, we were able to exclude the data for 7 women with stage III at enrolment from our analyses Midline was not defined and the numbers of women with midline/lateralised lesions was not reported. Instead, the number of women considered to have bilateral or unilateral lymphatic drainage was reported We extracted groin SN assessment data from the individual patient data presented in Table 1 of the primary article Failed SN detection per groin was not reported, however, half (2/4) of the undetected nodes were node‐positive in the opposite groin
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Unclear
Was a case‐control design avoided?	Yes
Did the study avoid inappropriate exclusions?	Unclear
		Unclear	Unclear
DOMAIN 2: Index Test Test group
Had the test operator performed 10 or more procedures?	Unclear
		Unclear	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?	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
Were other imaging tests performed prior to the index test to rule out groin lymph node metastases?	Unclear
		Unclear