This document discusses prone versus supine positioning for percutaneous nephrolithotomy (PCNL). It provides a history of prone positioning being the traditional approach, with supine positioning being described later. The advantages of supine positioning include the surgeon working more comfortably, less risk of anesthesia issues, and ability to perform other procedures simultaneously like ureteroscopy. Prone positioning allows for easier upper pole access and kidney positioning. Overall, the evidence suggests no overwhelming differences in outcomes between positions, so surgeon preference can help determine which to use based on patient factors.

1. Prone versus supine PCNL
Goutam ku. Mishra

2. INTRODUCTION
Percutaneous nephrolithotomy (PCNL) is the treatment of choice for
renal stones ≥2 centimetres .
The traditional prone position for PCNL is favoured by a majority of
urologists
familiarity with the procedure,
larger surface area for choice of puncture site
potentially more direct approach to the kidney

3. History
 The classic prone position When PCNL was initially described in
1976 .
 In the late 1980s, Valdivia-Uria et al described PCNL with the patient
in the supine position,
 In 1987–88, Valdivia-Uria et al, reported a safe percutaneous access
to the kidney with the patient supine and 10 years later they reported
the in vivo experience.

4. Supine positioning
 May be purely supine with legs separated and flexed.
 A 3-L water or air bag is situated under the lumbar fossa of the
target kidney.
 The edge of the bag and the patient’s flank are alongside the
surgical table edge, in order to facilitate the free movement of the
nephroscope.
 The patient’s legs may be extended (with their feet oriented
upwards or slightly obliquely) or
flexed on leg supports.

5. Lumbar fossa is draped over the 3-L sac right
at the edge of the table Patient’s legs are completely extended.

6. Mixed position. Patient’s legs are flexed on supports, but with the contralateral leg lower to
facilitate ureteral access using a rigid ureterorenoscope.

7. Puncture
 It is easy to explore the kidney with an ultrasound 3.5-mhz
probe and calculate the direction in which the needle must
be Inserted.
 The skin entry point must be situated one or two
Fingers above the 3-L bag & is always behind the post
axillary line.
 Puncture is done in an ascending direction
Selected calyx is well distended with contrast, and then renal
capsule is palpated with the tip of the needle.

8. Advantages of supine
 Surgeon works comfortably
 Surgeons hand are not in X ray field
 No need to change the position of the patient
 Less anasthesia risk
 Intervention is better tolerated in high risk patients
 Good in obese patients , as skin to stone distance is
less

9.  In certain cases loo-regional anesthesia with IV
sedation is tried ,if required conversion is easier .
 Risk of puncturing the colon is less ,as the 3-L bag
elevates the lumbar fossa, the kidney and the colon
are elevated too.
 Ability to perform simultaneously PCNL and URS.
With the two endoscopes inside the kidney it is easier to find,
fragment, remove,and deliver the stone fragments to be extracted
through the Amplatz sheath .

10.  Ascending nature of the tract , maintains low intra
renal pressure , no need of auxiliary instruments
to extract the stone fragments

11. Disadvantages of supine
 There is usually a delay in the filling of the inferior calyces with the
contrast, because the inferior renal pole is more elevated than the
superior one can be overcome by keeping the patient in anti
tendelenburg position for some minutes.
 Distention of the collecting system will be greater in the prone than in the
supine position
 In some thin patients with renal ptosis, the kidney can be hypermobile in
the supine position
(overcome by fixing the kidney during tract establishment by means of contralateral
abdominal compression)

12.  Patients with wide hips and thin calyces, it can be more
difficult in the supine position to reach the upper calyx with a
rigid nephroscope. (can be solved by performing
simultaneously a URS, or by using a flexible nephroscope)
 In the supine position upper pole is more medial and
posterior, making access more difficult when required.

14. Prone
 At present, the majority of PCNLs are performed with the patient
prone and access is obtained through a posterior or posterolateral
calyx.
 Though the prone position confers numerous advantages, with the
main disadvantages being the time required for patient repositioning
& anesthetic concerns in the morbidly obese.
 Prone–flexed position, a simple modification to conventional prone
positioning, has several additional advantages.

16. Configuration of OR table
with padding and C-arm.

17. Prone

18. Proneflexed patient position

19.  Prone PCNL has a wide choice of access sites.
 Upper pole access is easier when the pt is prone.
 An upper pole puncture has many advantages, including the ability to
work down the renal axis, with minimal torque, as the more mobile
lower pole rotates to align with the nephroscope.
 Selection of an upper pole calyx is indicated in obese patients,
 Upper pole access indicated in patients with staghorn calculi, or
stones in a horseshoe kidney, and facilitates access to multiple lower
pole calyces, with a single tract.
 Dilation into the upper pole is easier, due to more adherent
attachments to Gerota’s fascia limiting renal mobility .

20. Prone flexed modification
 The working space is further increased
 In this position, the kidneys are displaced inferiorly in the retroperitoneum ,
 Due to this modification, a supra-11th rib access may be converted to a
supra-12th rib, or a supra-12th to an infracostal access.
 The flank is significantly flattened, eliminating interference from the buttock
during rigidnephroscopy through a lower pole tract

21. Lateral and lateral–flexed
positions
 Most helpful in morbidly obese patients(only viable option in BMI >50)
 Is familiar to any urologist who performs open and laparoscopic renal surgery
 Increased distance between the 12th rib and iliac crest gives wider surface
for puncture
 Disadvantage to flank positioning is that percutaneous access usually
requires either ultrasound guidance or use of “triangulation” using the C-arm
image intensifier, as opposed to the “bullseye” technique because of the
restricted arc of rotation of most C-arms,

23. Lateral flex position

25.  The first report on supine PCNL, by Valdivia Uria et al in 1998, included 557
patients
 In their original report, Valdivia Uria et al. expressed a preference for puncture of
anterior calyces, with low complication rates; however, transfusion rates were not
reported.
 1720 supine procedures reported in the literature to date, only one case of bowel
injury has been reported
(0.00058%).
 A review of all studies published to date demonstrated an overall transfusion rate
of 4.6% (range 0–20%) with PCNL performed in the supine position.

26.  According Falahatkar et al , De S M et al, the transfusion rate for PCNL
performed in the supine position was 8.8% versus 4.3% when performed
prone (182 and 207)patients, respectively; P = .07).
 In a review, de la Rosette et al. examined the effect of patient positioning,
concluding that for obese patients or those with staghorn calculi, the
prone position was associated with similar bleeding rates, but decreased
operative times, and slightly improved stone-free rates compared to the
supine position

27.  Compared with prone position, and percutaneous tract length is longer than in
the prone position (Azhar et al, 2011; Duty et al, 2012).
 With optimal placement of pads and bolsters, the prone position may provide
better ventilation than the supine position (Edgcombe et al, 2008, Atkinson et
al, 2011).
 In a large, multi-institutional and retrospective study of percutaneous
nephrolithotomy, including 4637 patients and 1138 patients with prone and
supine positioning, respectively, operative time and stone-free rates favored the
prone position, but some patient safety parameters favored the supine position
(Valdivia et al, 2011).

28.  Two meta-analyses of supine versus prone positioning for percutaneous nephrolithotomy, 1
incorporating two randomized controlled trials and 2 case-control studies (Liu et al, 2010) and 1
including the same 4 studies plus 27 case series (Wu et al, 2011), both documented conclusions that operative
time is shorter in the supine position but that there are no differences in other parameters.
 The flank (lateral decubitus) position, which first was described by Kerbl and colleagues (1994), is
less commonly used for percutaneous renal surgery. This position allows simultaneous access to the anterior
and posterior aspects of the kidney and appears to be particularly useful for morbidly obese
patients or those with spinal deformities in whom both supine and prone positioning are difficult (Gofrit et al,
2002; Basiri et al, 2008b; El-Husseiny et al, 2009).
o Randomized trials comparing flank to prone position (Karami et al, 2010) and flank to supine to prone positions
(Karami et al, 2013) showed no difference in outcomes.

29.  Mario Sofer,* Guido Giusti, Silvia Proietti, Ishai Mintz, Maharan Kabha, Haim
Matzkin and Galit Aviram published in The journal of urology about the
upper calyx approachability through lower calyx in supine vs prone positions.
 The upper calyx was successfully approached in 20% of prone and 80% of
supine percutaneous nephrolithotomies (p <0.0001)
possibly due to a thinner body wall, a thinner muscular layer, a lower muscleto-
fat thickness ratio and a wider angle between the lower and upper calyx axes.

30. Conclusion
 Appreciation of the calyceal anatomy and the ability to choose the appropriate posterior
calyx for percutaneous access in the prone position will allow the operator to perform the
procedure with minimal morbidity.
 Prone–flexed positioning is a simple modification that
is well tolerated by the patient and offers significant surgical advantages.
o The lateral position is well-suited to the morbidly obese patient, while the lateral-flexed
position adds further advantages and is familiar to all urologists.
o Although both the supine and flank positions offer some potential benefits over prone
positioning in certain settings, particularly morbid obesity and spinal deformities, the
evidence suggests no overwhelming differences, so surgeon preference can determine the
choice of position for percutaneous renal surgery.

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