What is the chance of not being able to access the ureter up to the target stone at ureteroscopy (URS) in an unstented ureter? What figure do you quote your patients during consultation? On a recent operating list, 2 consecutive patients attended for treatment of their intrarenal stones. The cystoscopic image of the ureteric orifice of both patients are shown (Figures 1 and 2). Now with this knowledge, what do you think are the chances of successful access?

Figure 1. Cystoscopic image of left ureteric orifice in patient 1.

Figure 2. Cystoscopic image of left ureteric orifice in patient 2.

URS is the most common treatment modality used to treat upper urinary tract stones. It is estimated that over 8000 ureteroscopic procedures were performed in those 18 to 64 years of age with private insurance in 2021 in the US.¹ One of the fundamental parts of the procedure is the ability to safely pass the ureteroscope up the ureter to the location of the stone. Whilst the presence of a stent in situ facilitates this due to passive dilatation of the ureter, the routine placement of a ureteral stent prior to URS is not recommended by international guidelines.^2-4 Specifically the European Association of Urology (EAU) guidelines state, “Routine stenting is not necessary before URS” and the AUA Guideline Statement 15 states, “Placement of a ureteral stent prior to URS should not be performed routinely.”^2-4

Despite this, failure to access up the ureter is a commonly encountered clinical scenario; factors that might influence this include gender, history of prior stone disease/URS, stone location, and the size of instrumentation in use.^5-8 In our cases, patient 1 was a 64-year-old female with no prior urological surgery. Patient 2 was a 61-year-old male with previous history of ipsilateral URS. Both patients were unstented. Now with this knowledge, what do you think are the chances of successful access?

According to surgeon preference, an attempt to pass a flexible ureteroscope (Karl Storz Flex X2) was made for both patients. For Patient 2, the flexible ureteroscope was easily passed to the kidney over a single guidewire and laser lithotripsy successfully performed. In patient 1, passage of the flexible ureteroscope was not possible. There was an attempt to dilate the ureter using a semi-rigid ureteroscope (Karl Storz 8F Semi-rigid Ureteroscope) between 2 wires, but the distal ureter remained unpassable, and the decision was made to stop and insert a ureteral stent.

Preoperatively both patients were quoted the same risk of 5% to 10% for failed access, which aligns with contemporary estimates from the literature.^5-8 For example, Cetti et al reported a need for prestenting in 8.4%.⁵ Viers et al reported a failure rate of 16%, with a history of previous surgery or stenting reducing that risk.⁶ In a larger multi-institutional review of 535 patients, Fuller et al reported a rate of 7.7%, with younger female age being a risk factor for failure.⁷ Most recently, Morgan et al reported a failure rate of 15.4% at their institution, with proximal stone location being associated with failure.⁸

Whilst intrinsic tightness can occur at any point in the ureter, the proximal ureter is the most common site of stone location for failed access.⁶ The options when this scenario is encountered include both active methods such as the use of semi-rigid ureteroscope dilatation, access sheath dilatation, coaxial serial dilatation, and balloon dilatation, or passive dilation with only ureteral stent placement. In fact, of the 3 institutions in the study by Fuller et al, 1 center used a 12F balloon dilator, 1 center used serial dilators, and the third center did neither and placed a stent. Each of these modalities is associated with different rates and severity of adverse events that need to be balanced with the treatment objectives.^5-8

For such a commonly encountered clinical scenario, there is a lack of professional consensus and guidance on how to proceed. The EAU guidelines simply state, “Prior rigid URS can be helpful for optical dilatation followed by flexible URS, if necessary” and “If ureteral access is not possible, insertion of a JJ stent followed by URS after seven to fourteen days offers an alternative.”³ The International Association of Urolithiasis guideline on retrograde intrarenal surgery suggests “placement of a stent is advisable to allow passive ureteric dilatation.”⁴ They also offer that limited evidence suggests 3 to 7 days of preoperative α-blockers may facilitate access sheath insertion in patients without prestenting. This concurs with the EAU guidance which says that “medical expulsion therapy before URS might reduce the risk for intra-operative ureteral dilatation.” The lack of standardization on how to manage this scenario results in practice variability usually dictated by experience and teaching in residency/fellowship.

Do join us at the plenary session on Saturday, May 4, 2024, at the AUA Annual Meeting in San Antonio, where we will dive deeper into the evidence supporting management options for dealing with this tricky situation.