Hidden calyceal diverticulum – using 3D modelling for surgical planning and treatment

• Calyceal diverticular stones can be difficult to localise on conventional imaging. • Diverticulae with a narrow mouth can be difficult to identify during pyeloscopy. • Three dimensional modelling can assist in pre-operative planning to delineate calyceal diverticular anatomy in relation to the collecting system. • Suction-based ureteric access sheaths are useful adjuncts to facilitate efficient lithotripsy within a calyceal diverticulum. Calyceal diverticula are congenital cavities lined with non-secretory epithelium that communicate with the collecting system via a narrow isthmus. While often asymptomatic, urinary stasis may result in stone formation and warrant treatment. When the diverticulum mouth is narrow, identifying calyceal diverticula to treat stones may be challenging. In this study, we demonstrate the utility of 3D Modelling in pre-operative planning to facilitate effective management. We select a case of a 40-year-old female referred to an endourologist for management of symptomatic right-sided calyceal diverticular stones. Previous attempts at pyeloscopy failed to visualise the diverticulum. Non-contrast CT imaging suggested stones occupying a right lower pole calyx. 3D modelling using volume rendering was used pre-operatively, delineating stone and collecting system anatomy, revealing stones within a calyceal diverticulum in the posterior mid-pole calyx (Figure 1). Subsequent targeted pyeloscopy was performed with the aid of a suction access sheath. Suction was used to collapse the diverticulum, facilitating efficient lithotripsy. A ureteric stent is inserted at the completion of the case. Complete stone clearance was confirmed on a Day 1 post-operative CT KUB. The patient was discharged home on Day 2 and no post-operative complications were encountered. Calyceal diverticular stones may be difficult to localise on conventional imaging. In this case, we highlight the utility of pre-operative 3D Modelling to enable localisation of hidden calyceal diverticular stones. Additionally, we describe the use of a suction ureteric access sheath to facilitate complete stone clearance.