URETERAL PERISTALTIC FLOWS IN THE PRESENCE OF MICROLITHS: A REVIEW

A detailed review is presented on research contributions in peristaltic transport in the human ureter in the presence of microliths. The studies reviewed are differentiated based on methodologies deployed, namely analytical, numerical and CFD simulation techniques and also experimental (clinical) investigations. Various 2D and 3D models are discussed along with more advanced fluid structure interaction (FSI) studies. The propagation of the incompressible urine flow results in reflux nephropathy. As such, the peristaltic waves spread near the outlet of the tube which manifests in a depletion in the flow rate. Due to the maximum pressure gradient, urine backflow occurs. A full understanding of ureter reflux has however not yet been achieved. This review surveys approximately 101 journals addressing the obstruction inside the ureter and the associated hydrodynamics. As such it consolidates many different efforts in the field in a single source which will serve as a guide to both clinical researchers (e.g., physicians) and also mathematical and engineering research groups and is hoped that it will assist in the development of new integrated approaches for robust treatments. The extensive survey of the scientific literature in this review article confirms that stones (monoliths) detected in the proximal part of the nephron are generally larger than those identified in distal parts. These papers defined the position and shapes of microliths. Due to bolus transport inside the ureter flow, varying pressure and velocity balances are also appraised. The more advanced FSI simulations provide much-needed insight into visualizing actual ureteral transport. Some future pathways for collaborative efforts in improving healthcare for patients are also suggested.