Background: Ureteric colic is a major clinical and economic burden on the National Health Service. There has been a recent paradigm shift to consider definitive surgery as the primary intervention at the time of initial presentation. Objective: To systematically evaluate the outcomes of primary/emergency ureteroscopy versus delayed/elective ureteroscopy. Methods: We performed a critical review of MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials–CENTRAL, CINAHL, Clinicaltrials.gov, Google Scholar and individual urological journals in April 2020. A robust database search was performed using a combination of the terms ‘primary ureteroscopy’, ‘immediate ureteroscopy’, ‘delayed ureteroscopy’ and ‘emergency ureteroscopy’. Adult patients (> 16 years) with ureteric stones presenting as an emergency were included. Results: Twelve studies met the inclusion criteria, with 4 studies directly comparing primary/emergency to delayed/elective ureteroscopy for an acute presentation of ureteric colic. Across the studies, 1708 patients underwent primary/emergency ureteroscopy for ureteric calculi and 990 underwent delayed ureteroscopy. No significant differences in stone-free rates were found between both groups with primary/emergency achieving 85% and delayed/elective 91% ( p = 0.68). The majority of stones treated were located in the distal ureter in both groups. Overall, there were no differences in complications between the groups ( p = 0.42) or major complications (0.17). However, there were fewer minor complications in the primary URS group ( p = 0.02). Ureteral catheter or double-J stent insertion was used in 71% of delayed/elective ureteroscopy cases, compared to 46.8% of primary/emergency cases (p = 0.001). For patients undergoing primary/emergency ureteroscopy, 6.4% patients required auxiliary procedures. In the delayed/elective group, 7.6% required further definitive treatment (NS). Conclusion: Primary ureteroscopy is a safe and feasible procedure, when performed in suitable patients in the acute setting. It is associated with significantly lower stent usage, equivalent stone clearance, no increase in overall or major complications including sepsis, and fewer minor complications when compared to delayed/elective ureteroscopy. Prospective studies will do well to explore this area further but on current evidence, primary ureteroscopy is the safe procedure. Level of evidence: Not applicable