摘要
　　在醫學上，我們為了要解決尿路結石造成輸尿管阻塞的問題，常使用雙J導管支架來釋放腎臟壓力(導管單側面上有許多滲流孔)。但置入支架也使得輸尿管進入膀胱處的單向瓣膜無法完全閉合，尿液因而易由膀胱經由輸尿管回流至腎臟，並造成腎臟細菌感染。
　　在本文中我們假設輸尿管為彈性管，支架導管為具有滲流孔的剛性硬管，並利用流體力學與彈性力學理論建立了一套適用於直輸尿管-導管支架系統之數學模型。透過理論分析及數值計算，我們具體探討導管上滲流孔之位置與流阻，以及輸尿管剛性對於尿液回流的影響。計算結果顯示尿液主要由輸尿管滲流進入支架導管內，且在系統達穩態時總回流量與滲流孔之流阻無關。但當輸尿管剛性強度變大時則因輸尿管管壁不易擴張而抑制尿液的滲流，使得輸尿管內各分段之滲流量與總回流量皆變小。

Abstract

　Clinically, when the ureter is blocked by ureteric stone, we can insert a double-J stent (having side holes) to release the pressure in kidney. When a stent is inserted, however, the valva (bladder-ureter junction) cannot be tightly closed, and urine can then reflow from the bladder to the kidney, which may result in renal infection.

　In this thesis, the ureter is assumed to be an elastic tube, while the stent is treated as a rigid tube with side holes. A model for the straight ureter-stent system is then set up using fluid mechanics and elasticity theories. In particular, the resulting mathematical equations are solved numerically, in order to evaluate the effects of the location and flow resistance of the side holes, and the rigidity of the ureter, on the total urine reflux. The numerical results indicate that, when the system is in steady state, the total reflux is not affected by the flow resistance of the side holes on the stent. However, increasing the rigidity of the ureter would decrease the total reflux of urine. These results are expected to be useful for improving stent design.

參考文獻：
[1] Having a ureteric stent: what to expect and how to manage,”http://www.bui.ac.uk/patientinformation/uretericstent/ureteric.htm, Bristol Urological Institute, England.

[2] Bitschay, J.,Brodny, M.L.,”A history of urology in Egypt Riverside Press, ”New York, 76,(1956).

[3] Sterioff, S,”Etymology of the word :stent, ”Mayo Clin Proc, 72,377-379,(1997).

[4] Taylor, W.N., McDougall, I.T., ” Minimally invasive ureteral stent retrieval., ”J Urol,168,2020-3,(2002).

[5] Zimskind, P.D.,Kelter, T.R.,Wilkerson, S.L.,”Clinical use of long-term indwelling silicone rubber ureteral splints inserted cystoscopically.,”J Urol 97,840-844,(1967).

[6] Finney, R.P.,”Experience with new double-j ureteral catheter stent.,”J Urol,120,678-681,(1978)

[7] Pilcher, J.M., Patel ,U., ”Choosing the correct length of ureteric stent: a formula based on the patient's height compared with direct ureteric measurement., ” Clin Radiol ,57,59-62,(2002).

[8] Breau, R.H., Norman, R.W.,”Optimal prevention and management of proximal ureteral stent migration and remigration. , ” J Urol , 166, 890-893,(2001).

[9] Singh, I., ”Indwelling JJ ureteral stents-A current perspective and review of literature. , ”Indian J Surg, 65, 405-412,(2003).

[10] Candela ,J.V., Bellman ,G.C., ” Ureteral stents: impact of diameter and composition on patient symptoms., ” J Endourol , 11, 45-7,(1997).

[11] Ramsay, J.W.A., ” Complications of stents related to staent material or length., ” In: Smith AD, editor. Controversies in Endourology. Philadelphia,WB Saunders,290-4,(1995).

[12] Denstedt,J.D., Reid G, Sofer M. ” Advances in ureteral stent technology., ”World J Urol,18,237-42,(2000).

[13] Robert M, Boularan AM, El Sandid, et al., ” Double J ureteric stent encrustations:clinical study on crystal formation on polyurethane stents., ” Urol Int,58,100-3,(1997).

[14] L.J.Cummings,S.L.,Waters.,J.A.D.,Wattis,S.J.,Graham, ”The effect of
urtteric stents on urine flow:Reflux,J.Math., ” Biol. , 49,56-82,(2004).

[15] Munson, B. R., Young, D. F. & Okiishi, T. H., ” Fundamentals of Fluid
Mechanics, 3rd ed., ” Wiley, New York ,(1998).