1. A. NEFFATI, N. DALI, O. NESSEJ, A. AMANAMANI, L. BEN FARHAT, L. HENDAOUI - Radiology Department, Mongi Slim Hospital, Marsa, Tunisia PERCUTANEOUS NEPHROSTOMY PLACEMENT UNDER CT GUIDANCE: INDICATIONS, TECHNIQUE AND BENEFITS INTV 7

2. Introduction: Percutaneous nephrostomy is a well established therapy for urinary drainage in patients with supravesical urinary tract obstruction and for urinary diversion in patients with urinary fistulas, leaks, traumatic/iatrogenic ureteral dissection. Percutaneous nephrostomy can be easily performed using CT as an alternative to standard fluoroscopy-guided puncture.

3. Objectives: Our purpose is to present our experience with CT guided percutaneous nephrostomy to enumerate the indications, to describe the technique and to expose its benefits in comparison with standard fluoroscopy-guided puncture.

4. Subjects and methods : 9 nephrostomy in 8 patiens [5 women and 3 man] with an average age of 54 years. All patients had a suparvesical urinary tract obstruction for different reasons: Ureteral stenosis on a prostate tumor (n=1) Ureteral stenosis after uretero-ileal anatomosis ( n= 1) Ureter invasion in a uterine cervix cancer( n=2)

5. Subjects and methods : Ureteral invasion in recto-sigmoid cancer (n=1) Pyonephrosis caused by an ureteral stone( n=2) Ureteral localisation of a systemic saroidosis (n=1) Accidental suture of the ureter (n=1)

6. Technique: Patient is placed in the supine oblique position. A routine series of diagnostic CT scans is realized to localize the kidney and renal pelvis. After the appropriate scan is selected, a metal marker is placed on the skin at a prospective entry point. The area is rescanned to determine the suitablility of this metal marker to the renal pelvis.

7. Technique: A 18 gauge disposable needle is inserted into the abdominal wall. but is not advanced until a repeat scan is taken. [Img1-2] On the repeat scan the needle is accurately advanced through the renal parenchyma and the lawer calyx to the measured depth. A repeat scan can be taken to confirm the position of the needle tip within the pelvis and we should have a return of urine.

8. Technique: At this time metallic stylet is inserted through the needle and this latter is removed, leaving the metallic stylet within the renal pelvis. [Img3-4] After that, a 6F then an 8F dilators [Img5-6] are introduced in the metallic stylet successively followed by the introduction of the nephrostomy tube 8F or 10F that will be leaved in the renal pelvis after removing the stylet. [Img7-8]

9. Img 1 Img3Img4 Img 2

10. Img 5Img 6 Img 7 Img 8

11. Results : Percutaneous access was achieved without major difficulties in all cases. Full decompression of the obstruction was obtained in all patients. We noted one catheter dislodgement and the most common complication was pain at the puncture site. There was a perirenal hematoma in two cases and an urinoma in one cases. The ablation of the catheter was done in 5 cases after etiological treatment. Placement was permanent in 3 cases.

12. Ureteral stenosis on a prostate tumor

13. Accidental suture of the right ureter

14. Pyonephrosis caused by an ureteral stone

15. Ureter invasion in a uterine cervix cancer Perirenal hematoma (arrow)

16. Ureteral localisation of a systemic saroidosis urinoma

17. Discussion: Percutaneous nephrostomy is useful technique for the evaluation and temporary drainage of obstructed collecting systems. CT provides many advantages wicth facilitate accurate needle placement into the renal pelvis and drainage of collecting system.

18. Discussion: INDICATIONS: - preservation of renal function * obstructive renal failure * unilateral fonctional deficit - drainage of infected cavities * an obstacle pyelonephritis * a pyonephrosis - dewatering of a fistula

19. Discussion: ADVANTAGES: The ability of CT to image subtle density differences which are not dependent on contrast material. In patients whose renal function has declined, the “water” density pelvis can still be visualized and the percutaneous nephrostomy successfully performed.

20. Discussion: The crosssectional anatomic display. The kidneys and contiguous organs within the anatomic slice are clearly displayed, permitting excellent visualization of a small renal pelvis, with or without contrast material and affording the opportunity for accurate needle placement.

21. Discussion: Elimination of overlying shadows which may be confusing on a conventional radiograph or with fluoroscopy.

22. Discussion: COMPLICATIONS: * perirenal or subcapsular hematoma * urinary extravasation with urinoma * abcess * injury to abdominal viscera * damage to intraabdominal neves * pneumoithorax

23. Conclusion : Percutaneous CT-guided nephrostomy is a reliable, safe, fast, and highly effective method associated with a low complication rate that involves no radiation for the interventional radiologist.