Flexible and navigable suction ureteric access sheath and direct‐in‐scope suction in endourology: a systematic evidence map of study characteristics and research trends

OBJECTIVE: To characterise the global research landscape of suction technologies in flexible ureteroscopy, specifically the flexible and navigable suction ureteric access sheath (FANS) and direct-in-scope suction (DISS), mapping study design, geographical and temporal trends, risk of bias, and clinical and experimental applications. METHODS: A systematic search of PubMed, the Excerpta Medica dataBASE (EMBASE), and Web of Science was performed per Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (International Prospective Register of Systematic Reviews: CRD420261371338). All study designs were eligible, including randomised controlled trials (RCTs), prospective and retrospective observational studies, experimental studies (in vivo, ex vivo, in vitro), and case series. Country was assigned by first-author affiliation as a proxy for research leadership. Risk of bias was assessed with design-appropriate tools: the Cochrane Risk of Bias 2 (RoB 2) tool for RCTs, Risk Of Bias In Non-randomised Studies of Interventions (ROBINS-I) for non-randomised studies, Quality Assessment Tool For In Vitro Studies (QUIN) for laboratory studies, and the Newcastle-Ottawa Scale for case series. RESULTS: A total of 154 studies were included (2022-2026). Annual publication rate increased from three studies in 2022 to >80 in 2025. China accounted for 48.7% of publications, followed by Singapore (11.7%) and Armenia (5.2%). Retrospective comparative studies were the largest design group (49 [31.8%]), followed by in vitro experiments (22 [14.3%]), prospective comparative studies (19 [12.3%]), and RCTs (11 [7.1%]). Most clinical studies were single-centre (55.8%); multicentre collaboration was more common in prospective and European Association of Urology-affiliated research. Adult urolithiasis accounted for 72% of clinical studies; paediatric studies, 2.6% (FANS only). Under ROBINS-I, 61% of observational studies were rated moderate risk of bias; 81% of RCTs raised some concerns under RoB 2; laboratory studies were predominantly low risk. CONCLUSIONS: This evidence map shows FANS and DISS have generated a rapidly expanding literature, heavily dominated by single-centre retrospective studies from Asia. RCT-level evidence is emerging for FANS, while DISS evidence remains earlier-stage and less mature. Standardised outcome reporting, multicentre prospective designs, and broader geographic representation are the priorities this evidence map identifies for the field.