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STONE
DISEASE
Computerized
tomography guided access for percutaneous nephrostolithotomy
Matlaga BR, Shah OD, Zagoria RJ, Dyer RB, Streem SB, Assimos DG
Department of Urology, Wake Forest University School of Medicine, Medical
Center Boulevard, Winston-Salem, NC 27157, USA
J. Urol. 2003; 170: 45-7
- Purpose:
Access for percutaneous nephrostolithotomy (PNL) using conventional
fluoroscopic guidance may carry an increased risk of damage to surrounding
organs in patients with renal calculi and aberrant anatomy. In these
situations cross-sectional anatomical imaging may facilitate safe percutaneous
access. We describe our experience with computerized tomography (CT)
guided percutaneous access for such patients undergoing PNL.
- Materials
and Methods: Between June 2000 and December 2001, 154 patients
underwent PNL at our institution. Five of these patients (3%) required
a total of 6 percutaneous access tracks under CT guidance. All patients
in this group had anatomical abnormalities precluding standard access
to the collecting system without risk to adjacent organs. These abnormalities
included a retrorenal colon in 2 and a severely distorted body habitus
due to spinal dysraphism in 3.
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Results:
Percutaneous access was achieved without complication in all cases.
At subsequent PNL 5 of the 6 renal units (83%) were rendered completely
stone-free.
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Conclusion: CT
guided percutaneous access is infrequently required for PNL. However,
there is a select group of patients with anatomical anomalies that may
predictably require this procedure to facilitate safe and efficacious
PNL.
- Editorial
Comment
Aside from bleeding, the most common cause of morbidity associated with
percutaneous nephrostolithotomy (PCNL) is injury to surrounding organs.
With widespread use of CT imaging for the diagnosis of renal and ureteral
calculi, anatomic features associated with risky percutaneous renal
access are often identified. As the same time, patients with stones
who are known to be at risk for anatomic anomalies often undergo CT
imaging to evaluate the anatomic relations of the kidney to facilitate
fluoroscopically-guided percutaneous access. For example, if CT shows
that the spleen is located quite posteriorly and underlies the upper
pole of the kidney in its lateral aspect, then the percutaneous puncture
can be directed more medially under fluoroscopic guidance.
Matagla and colleagues, however, used CT guidance directly to obtain
percutaneous renal access in patients at risk of injury with fluoroscopically-guided
access. In doing so they reduced the chance of adjacent organ injury
and increased the likelihood of satisfactory percutaneous renal access
for PCNL. Although the risk of encountering a retrorenal colon, the
most common cause (albeit rare) of colonic injury during PCNL, may not
be sufficiently high to justify pre-operative CT imaging in all patient
candidates for PCNL, those patients with known anatomic anomalies should
undergo cross-sectional imaging as part of the routine preoperative
planning process. For those few patients in whom percutaneous renal
access cannot be safely obtained under fluoroscopic guidance, CT-guided
access offers an effective means of achieving safe, optimal renal access.
Dr.
Margaret S. Pearle
Associate Professor of Urology
University of Texas Southwestern Med Ctr
Dallas, Texas, USA
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