Retrograde ureteropyelography (RUP) is usually performed during cystoscopy and/or flexible ureteroscopy under general anesthesia and is therefore not a diagnostic modality in its own right. This procedure consists of retrograde opacification by prior catheterization of the upper urinary tract with a ureteral catheter.

Using this approach, the delineation of the upper urinary tract following opacification demonstrates performance comparable to CT urography in terms of diagnostic sensitivity and specificity (96 % and 97 %, respectively) [15]. However, there is a bias since many patients already have a suspected lesion prior to going to the operating room for a RUP. This examination is recommended by several guidelines including that of the EAU (grade C) [2] and AUA.

Technological advances have made ureteroscopy a valuable diagnostic tool for the evaluation of suspicious lesions in the upper urinary tract. Indeed, the use of flexible devices enables the complete examination of the upper tract, including the lower pole renal calices.

Ureteroscopy is particularly useful in cases of uncertain diagnoses, in cases of patients with a solitary kidney, or when conservative treatment is considered. Ureteroscopic examination is now recommended by the guidelines for the first-line screening of UTUC (recommendation of grade C) [2].

Flexible ureteroscopy allows a visual diagnosis in 95 % of cases [2]. Advances in image resolution with digital ureteroscopes reinforce the quality of this examination. The detection sensitivity could be improved by photodiagnosis using 5-aminolevulinic acid (5-ALA), especially for small lesions and carcinoma in situ, or Narrow Band Imaging (NBI) [16, 17]. The NBI system uses only a part of the visible spectra (between 415 and 540 nm), which enhances the contrast of the tumor neovascularization and thus the detection of the small lesion. The preliminary results are promising, with 22.7 % more lesions detected using this technique than with white light [17]. Further studies are warranted to evaluate whether tangential viewing within the ureter poses a limitation towards the use of these new technologies within the upper tract.

Morel et al. showed the limited applicability of rigid ureteroscopy in this context due to inability to explore the pyelocaliceal cavities [18].

However, the macroscopic visual diagnosis does not allow the infiltrating nature of the tumor to be determined. According to El-Hakim et al., the endoscopic appearance of tumors leads to errors of staging in at least 30 % of cases [19].

During the procedure, the surgeon can perform selective cytology and biopsy of a visualized suspicious lesion in addition to the visual macroscopic diagnosis. This pathologic biopsy can confirm the diagnosis with a sensitivity of 89–95 % and obtain a prognostic tumor grade and stage [20]. The reliability of biopsies for tumor staging is poor, with 45 % of tumors classified as Ta, but these are actually more invasive tumors. However, the biopsy grade is adequately correlated with the final histopathological grade in 69–91 % of cases and the final tumor stage. Often the grade of the tumor gives information about the likely stage. In fact, the detection of a grade 1 tumor on biopsy corresponds to a noninvasive tumor (≤pT1) in 68–100 % and the detection of a grade 3 tumor on biopsy corresponds to an invasive tumor (≥pT2) in 62–100 % cases [21–24]. Upper tract ureteroscopy may not identify any tumor up to 50 % of the time even in patients with positive urine cytology.

However, obtaining biopsies is not always possible. Indeed, the introduction of biopsy forceps through the working channel of the ureteroscope may limit deflection and therefore the accessibility of the lower calyx.

The assessment of UTUC depth invasion remains a challenging task in ureteroscopy. The use of endoscopic ultrasonography has been described for this task but has not been routinely used in daily practice [25]. New imaging techniques such as optical coherence tomography (OCT) or endoscopic confocal microscopy are now in development and could eventually be used for this specific evaluation and as a complement to lesion biopsies [26, 27].

The hypothesis of the possible “seeding” of cancer cells during the procedure (by hyperpressure of the cavities or trauma to the wall) is not currently discussed [28]. The delay attributable to the performance of a diagnostic ureteroscopy with biopsy does not significantly affect the long-term prognosis of the disease [29].

Although rare, complications associated with diagnostic ureteroscopy are possible (0.5–5 % of cases). These consist of perforations, stripping of the ureter, stenosis, or parenchymal infections.

This simple test is recommended (grade A) as a first-line screening to rule out any synchronous bladder tumors.