Evaluation of a Diuresis Enhanced Non-Contrast Computed Tomography for Kidney Stones Protocol to Maximize Collecting System Distention.

Purpose: In urolithiasis patients, preoperative non-contrast computed tomography (NCCT) commonly fails to provide sufficient distention of the renal collecting system to allow reliable preoperative planning for how best to approach a stone. Our objective was to evaluate the effect of a novel protocol, including oral hydration and an oral diuretic, on the distention of the renal collecting system. Patients and Methods: Twenty patients with a prior NCCT, who were scheduled to undergo a subsequent NCCT for urolithiasis assessment, were enrolled. Each patient was instructed to ingest 1 L of water and 20 mg of oral furosemide 30 to 60 minutes before their scan (DRINK [DiuResIs Enhanced Non-contrast Computed Tomography for Kidney Stones] protocol). Patients' prior NCCT scan (non-DRINK) was used for comparison. Three-dimensional (3D) reconstruction of DRINK and non-DRINK NCCT studies was performed to determine the volume and surface area of the collecting system. In addition, three faculty endourologists measured the width of the upper and lower pole infundibula and renal pelvis in the axial, coronal, and sagittal views. Results: Among the 20 patients, 13 completed the DRINK protocol as specified. For these 13 patients, 3D reconstruction of the DRINK study collecting systems showed a 63% and a 36% increase in collecting system volume and surface area, respectively (p = 0.02 and p < 0.01, respectively). Also, measurements of the CT images demonstrated a significant (p < 0.05) increase in the collecting system widths in 67% of measurements. Conclusion: The DRINK protocol significantly increased the visible collecting system volume and surface area; in the majority of cases, the upper and lower pole infundibular widths and the width of the renal pelvis were also expanded.

Renal Collecting System Injury During Percutaneous Nephrolithotomy, More Likely When Using Continuous Flow Sheaths?

Background: Renal collecting system injuries are a rare occurrence during percutaneous nephrolithotomy (PCNL). However, when they do happen, the potential for complications rises exponentially the longer the injury goes undetected. This case highlights a possible higher rate of injury when using continuous flow sheaths. Case Presentation: A 65-year-old woman with history of large volume obstructing left-sided renal pelvis stone had an emergent ureteral stent placed for infection and was referred for interval management. Patient was taken for PCNL in the prone split-leg position where a continuous flow ureteral access sheath and a continuous flow nephrostomy sheath was used. Puncture and dilatation were performed under endoscopic guidance to avoid collecting system injury during access. The anesthesiologist discovered abnormalities in the patient's pulmonary ventilation settings. This allowed the surgical team to quickly halt the procedure and place the patient supine where a distended abdomen was discovered consistent with irrigation fluid extravasation into the abdominal cavity. Given concern for abdominal compartment syndrome, interventional radiology was then called to assist in placing a drain in the right lower quadrant of the patient to evacuate the irrigation fluid. This is the second such occurrence in a span of 6 months when using continuous flow ureteral access and nephrostomy sheaths. Conclusion: Renal collecting systems injuries are infrequent when access is obtained under endoscopic guidance. Prompt recognition of physiologic breathing abnormalities allowed the surgical team to quickly treat the injury, preventing further complications from arising in the setting of a diagnosis where time to detection plays an important role in prognosis. However, given that this is the second such injury, the usage of continuous flow sheaths and their rate of associated complications and injuries must be thoroughly examined.

A Technique to Flush Out Stone Fragments Through a Ureteral Access Sheath During Retrograde Intrarenal Surgery.

Background: Retrograde intrarenal surgery (RIRS) has become the preferred treatment option for selected renal stones <20 mm. However, laser fragmentation of stones often results in residual small fragments that may prompt subsequent stone events. We describe a simple technique to facilitate removal of these fragments. Case Presentation: A 68-year-old woman underwent elective RIRS for a 13 mm right renal pelvic stone. After laser fragmentation of the stone there were numerous <2 mm fragments too small to allow removal by a standard retrieval basket (i.e., NCircle® and NCompass® Nitinol Stone Extractors, Cook Medical, Bloomington, IN). A smaller ureteral access sheath (UAS) was advanced into the kidney within the preexisting larger UAS and, using a connecting piece from a Foley catheter, stone fragments were suctioned out through the smaller sheath. Stone-free status was corroborated endoscopically and with postoperative CT. Conclusion: Stone fragments were flushed from the kidney using a simple irrigation technique through a coaxial UAS.

Non-invasive characterization of real-time bladder sensation using accelerated hydration and a novel sensation meter: An initial experience.

AIMS: The purpose of this investigation was to develop a non-invasive, objective, and unprompted method to characterize real-time bladder sensation. METHODS: Volunteers with and without overactive bladder (OAB) were prospectively enrolled in a preliminary accelerated hydration study. Participants drank 2L Gatorade-G2® and recorded real-time sensation (0-100% scale) and standardized verbal sensory thresholds using a novel, touch-screen "sensation meter." 3D bladder ultrasound images were recorded throughout fillings for a subset of participants. Sensation data were recorded for two consecutive complete fill-void cycles. RESULTS: Data from 14 normal and 12 OAB participants were obtained (ICIq-OAB-5a = 0 vs. ≥3). Filling duration decreased in fill2 compared to fill1, but volume did not significantly change. In normals, adjacent verbal sensory thresholds (within fill) showed no overlap, and identical thresholds (between fill) were similar, demonstrating effective differentiation between degrees of %bladder capacity. In OAB, within-fill overlaps and between-fill differences were identified. Real-time %capacity-sensation curves left shifted from fill1 to fill2 in normals, consistent with expected viscoelastic behavior, but unexpectedly right shifted in OAB. 3D ultrasound volume data showed that fill rates started slowly and ramped up with variable end points. CONCLUSIONS: This study establishes a non-invasive means to evaluate real-time bladder sensation using a two-fill accelerated hydration protocol and a sensation meter. Verbal thresholds were inconsistent in OAB, and the right shift in OAB %capacity-sensation curve suggests potential biomechanical and/or sensitization changes. This methodology could be used to gain valuable information on different forms of OAB in a completely non-invasive way.