Mannitol-induced diuretic renal ultrasonography: a new technique

MANNITOL-INDUCED DIURETIC RENAL ULTRASONOGRAPHY: A NEW TECHNIQUE HISHAM AHMED MOSLI, M.B., F.R.C.S. (C) MOHAMED MAHMOUD RAWAS, M.B., ER.C.P. (C) HASAN MOHAMED FARSI, M.B., F.R.C.S. (C) From the Departments of Urology and Radiology, King Abdulaziz University Hospital, Jeddah, Saudi Arabia

ABSTRACT--We herein describe a new technique to improve the ultrasonic imaging of nonobstructed stone-bearing kidneys. Mannitol-induced diuresis opens up the collapsed renal collecting system and yields better ultrasonographic imaging by increasing the amount o] fluid surrounding the calculi. The potential usages of this technique include ultrasound localization ]or percutaneous stone extraction and during ultrasonographic monitoring of stones treated by extracorporeal shock-wave lithotripsy (ESWL).

'~:~mannitol-induced diuretic ultrasound, !hieh can be termed intravenous sonogram .~VS)Iis a technique used to improve renal im~fig. In addition to routine renal screening for aleuli, this technique will solve some of the dif~ities experienced during sonographic stone i~Nization for percutaneous stone extraction i~d extracorporeal shock-wave lithotripsy I~'SWL) treatment. ESWL devices utilize i~therx-ray or ultrasonography for stone loeali!~ti0n The obvious disadvantages of the for~ r are the inability to visualize radiolucent 16nes, the exposure to radiation and the high ! ~ o f these devices. ~-3In contrast, devices uti~i~g ultrasound for stone localization are able ~i'ioealize radiolueent stones without hazards Eii!~xposure to radiation and are relatively ~~l~er. ~ However, the major disadvantage of ~his latter technique is the difficulty experienced by the treating urologist in reading the imagos of a ge od and di n e~ated stones, especially when small or during ~0~tinuous monitoring. ~!:induetion of vigorous diuresis using rapiflly mannitol has allowed us to demonstrate ~h~t enough distention of renal collecting sys~e~:ean be produced, and the increase in the

amount of fluid surrounding the stones yielded improved ultrasonographie imaging. Material and Methods Eleven patients with pelvic or calieeal stones were studied. All patients were initially evaluated by intravenous pyelography (IVP). Preliminary ultrasonographic scanning was made of both renal units of all patients with a trial to localize the renal stones. The patients were then rapidly infused with 200 mL of normal saline. Renal ultrasonography was made at zero, five, ten, and fifteen minutes post-saline infusion. No measurable dilatation of the renal collecting systems was observed in any of the patients following this amount of saline. The sonographie pictures of calculi remained unchanged. Subsequently, 200 mL of 10 % mannitol were rapidly infused intravenously to each patient. Patients were re-scanned at zero, five, ten, and fifteen minutes post-mannitol infusion. There was demonstrable distention of the renal collecting system with improved sonographic visualization of stones. The excreted fluid was seen as a sonolucent halo around the stone. We obtained best sonographic pictures at the fifteen-minute

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FICORE 1. (A) Plain film: radiopaque stone is seen in region of right renal pelvis. (B) 1VP, ten-minute stone lying in nonobstructed right renal pelvis. (C) Pre-mannitol sonogram: renal collecting system i lapsed around stone. (D) Post-mannitol sonogram: collecting system is distended; echoes reflected by and acoustic shadowing are distinct. film since enough time was allowed for the mannitol to be excreted by the kidneys. Mannitol was chosen because it is a potent osmotic diuretic that is rapidly excreted by the kidneys and was expected and proved to induce distention of the nonobstructed collecting system. Abdominal compression augmented this effect. Provided that the patient is not in heart or renal failure, mannitol is safe when given in this amount. We have not observed any adverse effect in any of the patients studied. The ultrasound examinations were performed using ATL machine with 3.5 mHz transducer. Case Abstracts Case 1 The x-ray film (KUB) of this patient shows a 1-cm radiopaque stone situated in the region of

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the right kidney (Fig. 1A). IVP confi presence in the right renal pelvis with struction (Fig. 1B). Sonographic scan f fore mannitol diuresis is shown in Figt Post-diuretic fifteen-minute sonograI (Fig. 1D) demonstrates significant distel the renal collecting system with fluid sm ing the stone seen as a sonolucent halo a~ ous improvement of the sonographic pic Case 2 The plain film shows a small stone lower pole of the left kidney (Fig. 2A). 11 firms the location of this small stone in a structed lower calix (Fig. 2B). The pretol ultrasound film demonstrates the shadowing of the stone lying in the cc calix (Fig. 2C) and post-mannitol film demonstrates the enhanced picture (Fig

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Ua~.9.. (A) KUB film" stone is seen in lower pole region of left kidney. (B) IVP,, five-minute film: stone ~iji~g in left lower ealix. (C) Pre-mannitol sonogram, small stone is seen with difficulty. (D) Post-mannitol showing dilatation of collecting system and better visualization of the stone.

Comment study our primary aim is to develop a ~hnique _ to improve _ the sonog r ap hic ima g in g ~fthe nonobstructed stone-bearing kidneys tTh~final goal is to propose its use in stone local~z~tion both for percutaneous puncture and in ,-~SWL treatment with lithotriptors using ultra~6hnd localization. and Malekzadeh4 could detect renal ultrasonography in 100 percent of while the stones were only visual~rcent in the KUB film. It is obvious gh rate of detection depends highly [ty of the transducer and the expe7 e ultrasonographer. 3 In adults, fat make the examination difficult and ne detection is impossible in obese ~ e n t s . 2 The criteria for ultrasound diagnosis ~~rolithiasis- are. a focus of high echo reflec-

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tions within the renal collecting system with acoustic shadowing. 4 But these highly reflected echoes can be confused with renal sinus echoes or renal scarring. The acoustic shadowing may diminish with fragmentation and widening of the stone particles during and after ESWL treatment. 4 Goldberg et al. 5 described the usefulness of the technique of furosemide diuretic ultrasound for the assessment of obstructed renal units. However, their 5 control patients did not show any measurable dilatation of the collecting system following oral ingestion of 1 L of water and intravenous injection of 20 nag furosemide. 5 Contrary to this observation, we found that the rapid infusion of 200 mL of 10 % mannitol was followed by demonstrable distention of both renal collecting systems of the patients studied. In stone-bearing nonobstrueted kidneys stone visualization was made easier and more adequate

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using this technique since a degree of hydronephrosis was induced by the diuretic. This is supported by the fact that the hydronephrosis makes calculi more easily demonstrable sonographically. 6 We hope that the introduction of IV mannitol diuresis will help urologists operating lithotriptors using ultrasound stone localization. Department of Urology King Abdulaziz University Hosp. P.O, Box 6615 Jeddah 21452 Saudi Arabia

(DR. MOSLI)

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ACKNOWLEDGMENT. To Miss Yolanda Bacani for typing the manuseript. iiii

References 1. Marberger M, Turk C, and Steinkolger I: Painless piezoel~i tric extracorporeal lithotripsy, J Urol 139:695 (1988). 2. Vallaneien G, et ah Piezoelectric extracorporeal lithotri~i by ultrashort wave with EDAP LT 01 device, ~[ Urol 139. 68~ (1988). 3. Martin X, et ah Ultrasound stone loealization for extraeo~ poreal shockwave lithotripsy, Br J Urol 58:349 (1986). ~i'; 4. Diament MJ, and Malekzadeh M: Ultrasound and tli~; diagnosis of renal ureteral ealeuli, J Pedo 109:980 (1986). 5. Goldberg SD, WitcheU S, Drohomyereky A, and St. L0~!. E: Diuretic ultrasound: technique for assessment of obstructed :r~.~ hal unit, Urology 32:546 (1988). 6. Coleman BG: Ultrasonography of the upper genitourina~ tract, Urol clin North Am 12 633 (1985) ' :~ii~

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