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807
Technical
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Infusion of Air into the Collecting System to Avoid Needle Blockage During Percutaneous Nephrostomy After Extracorporeal Shock-Wave Lithotri psy James
H. Ellis,1’2 David
Percutaneous
C. Mckay,1
nephrostomy
after
and L. Paul Sonda2
extracorporeal
shock-
wave lithotripsy (ESWL) can be complicated by stone fragments in the renal collecting system [1 2]. The needle can become plugged with small stone fragments, or guidewire manipulation can be restricted by larger stone fragments. One solution to the problem of needle obstruction is to use an 18gauge needle for the initial puncture instead of a smaller bore needle [1 1. We present a patient in whom percutaneous nephrostomy after ESWL was complicated by blockage of not only the 21 -gauge Cope needle used in the first puncture attempt but also an 18-gauge needle used on subsequent attempts. Air was infused into the collecting system to displace the fragment-filled urine and provide a stone-free target for access. ,
Report
Case
A 45-year-old man was referred from another hospital after ESWL treatment of a right-sided staghom calculus. His distal ureter had become scopic
obstructed
retrograde
Percutaneous initial needle
opacification
with
stone
fragments
catheterization nephrostomy puncture
(steinstrasse),
attempts was
was
and cysto-
were unsuccessful.
performed performed
at our with
institution.
a 22-gauge
An Chiba
under fluoroscopic guidance from a direct posterior approach pelvis, guided by the residual stone fragments in the
into the renal
Received September 9, 1991 ; accepted I Department of Radiology, Liversity
after revision October
of
Michigan
Medical
30, 1991. Center, 1500
collecting
system.
posterior
midpole
21-gauge
Cope
After calix
needle
opacification,
was chosen. (Cook
2Department
of Surgery (Section of Lfrology), University April
1992 0361-803x/92/1584--0807
of Michigan C American
MediCal Roentgen
Inc., Bloomington,
approach
to a with a aspiration
performed
was
IN). After
of a small amount of urine, flow ceased and a wire could not be advanced through the needle, which had become obstructed with stone material presentwithin the urine. A second attempt with another 21 -gauge Cope needle met with the same result; even though no urine was aspirated, the needle became blocked from the fragments as urine flowed retrogradely through the needle because of internal renal pelvic pressure. We then elected to attempt puncture with 1 8-gauge HawkinsAkins blunt-tipped needles (Cook Inc.). Despite careful positioning without syringe punctures with
aspiration, and rapid insertion of a guidewire, two these needles also were blocked from retrograde
flow. Neither standard 0.035-in. (0.089-cm) nor 0.01 8-in. (0.046cm) guidewires could be advanced through these needles. We then decided to infuse air as a contrast agent. The original opacifying needle was blocked, so we placed a new 22-gauge Chiba needle from a posterolateral approach into a lower pole infundibulum. An initial attempt to pass a 0.01 8-in. wire was unsuccessful, but it urine
was
possible
to carefully
infuse
a few
milliliters
of contrast
material
followed by air. With air filling the posterior (nondependent) caiices, another puncture with an 18-gauge needle was made into an aircontaining
calix
by
using
careful
fluoroscopic
positioning
and
aspiration of the needle. Through this needle, a 0.035-in. wire easily advanced into the collecting system, and tract dilatation catheter placement were readily accomplished.
E. Medical
Center Dr., Ann Arbor, MI 48109-0330.
J. H. Ellis.
AJR 158:807-808,
a posterolateral Puncture
Center,
Ann Arbor,
Ray Society
Ml 481 09-0330.
Address
no was
reprint requests
and
to
ELLIS
808
Discussion
Gas has proved
to be a very useful
contrast
medium
in
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percutaneous nephrostomy, with several advantages over other types of contrast material. As it is lighter than urine, it will identify the nondependent portions of the collecting sys-
tem, which, position,
with
the patient
are the target
in a prone, or prone-oblique calices [3]. For percutaneous
posterior
stone extraction, gas has several other reported advantages over opaque contrast media: it is better for delineating small calculi, which might be obscured by opaque contrast material [4]; it prevents misidentification of areas of edema or bubbles as filling defects; and it can help differentiate small opaque caliceal stones from Randall’s plaques and foci of medullary calcinosis in patients with concomitant nephrolithiasis that has been treated percutaneously [5]. In our patient, we were unable to introduce a guidewire when the lumen of the 21 -gauge Cope needle used for the initial puncture became blocked by small fragments of stone that had formed a sludge in the urine in the collecting system. Two additional puncture attempts with 1 8-gauge needles were made, but the lumens of these needles also became occluded with stone, and we were unable to pass a wire into
the collecting collecting
system
a small amount
system.
Our solution
with a 22-gauge
of air before
was
Chiba
the needle
to puncture
needle
the
ET AL.
AJR:158,
April 1992
facilitate entry into the collecting system. As carbon dioxide was not readily available, after ensuring needle placement within the collecting system by infusing a small amount of contrast material, we used air to create an “air pocket” to puncture, thereby avoiding contact with the sludge of small stone fragments and preventing occlusion of the needle lumen. If readily available, carbon dioxide would be the preferred choice because of its proved safety in the event that inadvertent intravascular injection should occur, as well as the fact that it quickly diffuses away in case of extravasation and thus does not obscure visibility [3, 6]. There are no known contraindications to the use of carbon dioxide, and its use as a contrast agent has been described in a patient who had had a severe reaction to iodine [6]. In our institution, we have favored the use of percutaneous nephrostomy and endourologic techniques to debulk staghorn calculi before ESWL treatment of any remaining stone material [1]. This treatment sequence avoids the problem we
describe
here. However,
in patients
in whom
ESWL
is per-
formed as the primary therapy and percutaneous nephrostomy subsequently becomes necessary, air or carbon dioxide infused into the collecting system can be a useful technique to assist in the performance of percutaneous nephrostomy.
and to infuse
became
occluded.
The air rose into the posterior calices, displacing the fragmentfilled urine. Puncturing one of the air-filled calices enabled us to establish access to the collecting system without the lumen of the needle becoming occluded, and thus to pass a guidewire and subsequently a catheter into the collecting system. Cochran et al. [1 ] have emphasized that percutaneous nephrostomy can be more difficult after ESWL because of stone fragments in the collecting system. They suggested the use of a larger bore needle for the initial puncture to obtain entry into the collecting system despite the presence of small stone fragments. In our case, access could not be obtained with either large or small needles. Percutaneous access required the use of a lighter-than-urine contrast medium to
REFERENCES 1 . Cochran ST, Liu E, Barbaric ZL. Percutaneous nephrostomy in conjunction with ESWL in treatment of nephrolithiasis. AJR 1988;151 :103-1 06
2. Tegtmeyer
CJ, Kellum CD, Jenkins A, et al. Extracorporeal
shock wave
lithotripsy: interventional radiologic solutions to associated problems. Radiology 1986;161 :587-592 3. Hunter DW, Salomonowitz E, Casta#{241}eda-Zu#{241}iga WR, Young A, Mercado 5, Amplatz K. Carbon dioxide as a lighter-than-urine contrast medium for percutaneous nephrostomy. Radiology 1984;152:21 1-212 4. Khan AU, Leary FJ, Greene LF. Pneumopyeiography. Urology 1976;8: 92-93
5. Banner MP, Stein EJ, Pollack HM. Technical refinements in percutaneous nephroureterolithotomy. MR 1985;145: 101 -1 07 6. Salomonowitz E, Casta#{241}eda-Zu#{241}iga WR, Lange PH, et al. Percutaneous stone removal-use of carbon dioxide as contrast material. Radiology 1984;1 50:833-834