Table 2.

Included studies focused solely on anal fistulas after the PICO search

Title	Authors, year	Study design	Years	Patients	Flap type	Assessment	Follow-up	Follow-up time	Success rate	Failure rate	Other results
“Stem cell therapy in refractory perineal Crohn’s disease: long-term follow-up”	Wainstein et al. [12]	Prospective	2013–2016	8 pts with CD, 9 anal fistulas	RAF or MAF combined with adipose mesenchymal stem cells	CDAI, PDAI, MC, EUA, MRI, IBDQ	Clinical healing (complete or partial), CDAI, PDAIConfirmed	Median 31 months (21–37 months)	89% (8/9) fistulas with clinical healing; 1 fistula with partial healing	Not specified	Median PDAI significantly decreased
“Endorectal advancement flaps for perianal fistulae in Crohn’s disease: careful patient selection leads to optimal outcomes”	Roper et al. [15]	Retrospective, multicenter	2007–2017	39 pts with CD, 41 AFs	Wide-based, thick MAF	Colonoscopy, MR enterography, anoscopy or sigmoidoscopy	Clinical healing (complete closure of EO, no symptoms)	Average 27 months (1–256 months)	Primary healing 80% (33/41)	20% (8/41)	No recurrence in diverted pts; pts with longer IT before surgery more likely to achieve closure
“Ligation of the intersphincteric fistula tract and endorectal advancement flap or high perianal fistulas in Crohn’s disease: a retrospective cohort study”	Van Praag et al. [16]	Retrospective	2007–2018	37 pts with CD, 40 procedures; AF on 21 pts with CD	MAF with or without IAS fibers	MRI	Clinical healing (EO closure without discharge, pus, or feces), MRI, Vaizey IS	Median 15 months (5–44 months)	57% (12/21), 1 pt inconclusive, radiological healing 48% (10/21)	19% (4/21)	Significantly higher radiological healing rate when biological treatment and/or immunomodulatory used preoperatively, 43% pts with improved Vaizey IS
“Closing the internal opening with a rectal advancement flap increases the efficacy of mesenchymal stem cell injection for complex Crohn’s disease anal fistulas”	Fathallah et al. [17]	Prospective	2020–2023	68 pts with CD; AF on 20 pts with CD	Mesenchymal stem cells with or without AF	Anoperineal MRI, Magnifi-CD, MC, PDAI, JWS, CAF-QoL	Clinical remission (complete EO closure, no discharge or pain on pressure), MRI, Magnifi- CD, MC, PDAI, JWS, CAF-QoL	Median 16  months (9–25 months)	Complete clinical response 90% (18/20)	Not specified	Complete clinical response after suture 55% (p < 0.001), postop Magnifi-CD = 0 in 73% of AF pts (42% of suture pts, p = 0.093)

CD, Crohn’s disease; AF, advancement flap; RAF, rectal advancement flap; MAF, mucosal advancement flap; PAF, partial-thickness advancement flap; DAF, dermal advancement flap; IAS, internal anal sphincter; CDAI, Crohn’s Disease Activity Index; PDAI, Perianal Disease Activity Index; MC, Montreal classification; EUA, examination under anesthesia; MRI, magnetic resonance imaging; IBDQ, Inflammatory Bowel Disease Questionnaire; IS, incontinence score; IT, immunotherapy; JWS, Jorge–Wexner Score; CAF-QoL, Crohn’s Anal Fistula Quality of Life scale; EO, external orifice; pts, patients; Magnifi-CD, magnetic resonance novel index for fistula imaging in Crohn's disease; pts, patients