Elsevier

Urology

Volume 79, Issue 1, January 2012, Pages 67-71
Urology

Endourology and Stone
Anatomical Variation Between the Prone, Supine, and Supine Oblique Positions on Computed Tomography: Implications for Percutaneous Nephrolithotomy Access

https://doi.org/10.1016/j.urology.2011.06.019Get rights and content

Objective

To determine anatomical variations between the prone, supine, and supine oblique positions that are likely to affect percutaneous renal access.

Material and Methods

Twenty patients underwent computed tomography urograms in the supine and prone positions. Twenty patients underwent supine oblique and prone scans. Mean nephrostomy tract length, maximum access angle, and anterior–posterior renal position were calculated.

Results

Mean nephrostomy tract length was shorter in the prone position (82.6 mm right kidney, 85.4 mm left kidney) compared with the supine position (108.3 mm right kidney, P <.001; 103.7 mm left kidney, P <.001). Prone tract length was also shorter than supine oblique tract length (86.1 mm vs 96.5 mm; P = .048). Mean maximum access angle was significantly greater (P = .018 right kidney; P = .007 left kidney) in the prone position (right kidney 99.7°, left kidney 104.0°) compared with the supine position (right kidney 87.7°, left kidney 89.4°). The same was true for the prone compared with the supine oblique position (75.8° vs 58.7°; P = .004). No difference was noted in anterior–posterior renal position between the supine and prone positions (20.3 mm vs 26.7 mm; P = .094) or supine oblique and prone positions (22.8 mm vs 15.6 mm; P = .45).

Conclusions

The prone position is associated with a significantly shorter nephrostomy tract length and more potential access sites, which may improve ease and safety of percutaneous renal access.

Section snippets

Material and Methods

After we obtained Institutional Review Board approval, 40 patients from the Smith Institute for Urology who were deemed to need computed tomography urograms (CTU) as part of their clinical care were prospectively enrolled in the study. No specific indication for CTU was required. However, CTUs were most commonly ordered as part of a standard hematuria workup.

The initial 20 patients underwent imaging in the supine and prone positions. The last 20 patients were imaged in the supine oblique (right

Patient Demographics

Twenty patients underwent both supine and prone CTUs. There were 16 males and 4 females ranging in age from 48.6–86.4 years (mean 68.2). Mean body mass index (BMI) was 26.4. BMI did not differ between the 2 genders (P = .679). There were 10 men and 10 women who underwent both supine oblique and prone CTUs. Their ages ranged from 37.3–80.4 years (mean 53.6). The average BMI within this cohort was 29.5, which was also comparable between men and women within this cohort (P = .95). None of the

Comment

Percutaneous renal access to treat stone disease may be obtained in the supine or prone position. A variety of advantages and disadvantages have been attributed to both supine and prone PNL. In general, many of these arguments revolve around facilitating collecting system access while minimizing the risk of visceral injury. The purpose of the present study was to determine whether any anatomical differences exist between the supine, supine oblique, and prone positions, and if so, to comment on

Conclusions

Comparison of patients with supine and prone, as well as supine oblique and prone, CTUs showed the prone position to be associated with a significantly shorter nephrostomy tract length and a greater number of potential puncture sites. A shorter tract length may improve ease of percutaneous access and nephroscope mobility within the collecting system, leading to improved stone-free rates and decreased risk of bleeding. A greater range of potential access angles may result in decreased risk of

References (14)

There are more references available in the full text version of this article.

Cited by (0)

View full text