Full text of DOI:10.1016/S0022-5347(05)67964-5

0022-5347/00/1631-0024/0
®
THE JOURNAL OF UROLOGY
Vol. 163, 24–27, January 2000
Copyright © 2000 by AMERICAN UROLOGICAL ASSOCIATION, INC.®
Printed in U.S.A.
INFUNDIBULOPELVIC ANATOMY AND CLEARANCE OF INFERIOR
CALICEAL CALCULI WITH SHOCK WAVE LITHOTRIPSY
N. P. GUPTA, D. V. SINGH, A. K. HEMAL AND SUBHASIS MANDAL
From the Department of Urology, All India Institute of Medical Sciences, New Delhi and the Urology Centre, Command Hospital,
Lucknow, India
ABSTRACT
Purpose: We evaluate the significance of inferior caliceal radiographic anatomy and determine
its influence on successful fragmentation and clearance of inferior caliceal calculi with extracor-
poreal shock wave lithotripsy (ESWL*).
Materials and Methods: Between November 1996 and February 1998, 88 patients and 90 renal
units with single or multiple inferior caliceal calculi of all sizes and composition were treated
with ESWL. The size, number and area of calculi, length and width of the stone bearing inferior
calix and infundibulopelvic angle were determined on pretreatment excretory urography. The
infundibulopelvic angle was measured by 2 methods using the angle between the inferior caliceal
infundibular and ureteral axes (angle 1), and between the infundibular and ureteropelvic axes
(angle 2). Cases with residual fragments not clearing within 6 months of satisfactory fragmen-
tation after lithotripsy were considered failures.
Results: Overall stone clearance at 6 months was achieved in about 72% of the renal units.
Infundibular length was 30 mm. or less in 77% of successful cases and in 64% of failures.
Similarly, the smallest infundibular width of 5 mm. or more was found in 75% of successful
cases compared to 41% of failures. Angle 1 of 35 degrees or more was observed in 73% of cases with
compared to 18% without clearance. Angle 2 of 45 degrees or more was seen in 71% of successful
cases compared to 9% of failures. The chances of a patient becoming stone-free with all favorable
criteria of infundibular length 30 mm. or less, infundibular width 5 mm. or greater and infun-
dibular ureteropelvic angle 45 degrees or greater was 100% (23 patients).
Conclusions: Radiographic features of a stone bearing inferior calix and its relation to the renal
pelvis can be easily measured on standard excretory urography. An infundibular width of 5 mm.
or more and infundibulopelvic angle 1 of 35 degrees or more or angle 2 of 45 degrees or more were
statistically significant factors of radiographic anatomy in stone clearance following ESWL.
Inferior caliceal length was not statistically significant, although length of 30 mm. or less
appeared to be more favorable for stone clearance. The ideal treatment of inferior caliceal calculi
in patients with all 3 favorable criteria is ESWL.
KEY WORDS: lithotripsy, calculi
Extracorporeal shock wave lithotripsy (ESWL) is the dom- verify and define how these factors influence successful frag-
inant treatment modality for almost all urinary calculi. The mentation and clearance of calculi from inferior calices.
key factor is the satisfactory fragmentation of calculi that can
then pass spontaneously. However, the clearance rate of
lower pole caliceal calculi has been uniformly low compared
to that of calculi elsewhere.1–9 The dependent position of the
inferior calix, and its spatial anatomy and relationship to the
renal pelvis appear to be significant factors in retention of
residual fragments and, therefore, poor results of ESWL.10–14
Retention of residual fragments in the lower pole calices was
noted to be a major problem with ESWL not only for stones
originally in the lower calices, but also when fragments of
stones elsewhere migrated there.4 Caliceal anatomy of the
lower pole and its possible impact on stone clearance with
ESWL were first described by Sampaio and Aragao,13, 14 and
subsequently others demonstrated its significance.10, 15
Elbahnasy et al measured radiographic anatomical features
in a well defined manner to establish the significance of its
influence on the clearance of inferior caliceal calculi following
ESWL or ureteroscopy.10 Stone clearance has been shown to
be poorer for an acutely angled than an obtusely angled
inferior calix, and better for a shorter calix with a wider than
a longer calix with a narrower infundibulum. We determine,
MATERIALS AND METHODS
Between November 1996 and February 1998, 88 patients
with inferior caliceal calculi in 90 renal units (2 with bilateral
stones) were treated with ESWL using sedation. Stone pa-
rameters were determined on plain abdominal x-ray, and
radiographic anatomy of the inferior calix, pelvis and ureter
was evaluated on pretreatment excretory urography. Pa-
tients with inferior caliceal calculi only were included, and
those with history of recurrent or residual calculi following
surgery were excluded from analysis.
Stone parameters included number, size (maximum diam-
eter) and area of stones. Area was calculated by multiplying
the maximum diameter (length) with the next maximum
(width) dimension perpendicular to the maximum diameter
as seen on plain abdominal x-ray. Inferior caliceal anatomy
parameters included length, width and infundibular uretero-
pelvic angle. The length of the calix was measured from the
most distal point to the midpoint of the lower cortical lip at
the renal sinus. The width was measured at the narrowest
point of the infundibulum (fig. 1). The infundibular uretero-
pelvic angle was measured by 2 methods using the angles
Accepted for publication August 27, 1999.
* Dornier Medical Systems, Inc., Marietta, Georgia.
24

INFERIOR CALICEAL CALCULI AND SHOCK WAVE LITHOTRIPSY
25
A, method of measuring caliceal length (L) and width (W). B, method of measuring angles. IA, infundibular axis. UA, ureteral axis. UPA,
ureteropelvic axis. I, angle 1. II, angle 2.
subtended by the infundibular axis on the ureteral axis (an- 22 to 67 and 22 to 60 years old, respectively. Of the patients
gle 1), and between the infundibular and ureteropelvic axes 2 who had undergone open surgery previously and had re-
(angle 2). The ureteropelvic axis was drawn by joining the
midpoint of the renal pelvis at the renal sinus between
the upper and lower cortical lips, and the ureteral axis was
drawn at the level of the lower pole of the kidney (fig. 2).
Patients underwent 1 session of 3,000 to 4,000 shocks with
a maximum energy level of 3 to 4 to achieve successful
fragmentation of stone(s), and some underwent multiple ses-
sions to achieve satisfactory results. In most patients an in
situ procedure was performed, while a few required a ure-
teral stent before the procedure. Inversion therapy was used
in 3 cases.16 Patients were followed and assessed for stone
fragmentation and clearance by plain abdominal x-rays on
days 1 and 14, and 3 and 6 months after treatment. They
were advised to consume 3 to 4 l. per day and to collect
fragments by passing urine through a plastic strainer. Pa-
tients routinely received antibiotics and analgesics for 3 days
after treatment.
The significance of patient age and sex, stone side, size and
area, and length, width and angle factors of inferior caliceal
anatomy versus stone clearance were evaluated and statisti-
cally analyzed. The categorical variables of patient sex and
side of the stone versus stone clearance were analyzed using
the Pearson chi-square test. The size and area of the stone,
and length, width and angle factors of the inferior caliceal
anatomy versus stone clearance were analyzed using the
Student t or Wilcoxon rank sum test depending on the dis-
tribution of data. Logistic regression was applied to deter-
mine the predictors of stone clearance. Data were analyzed
using statistical software, with p Ͻ0.05 considered statisti-
cally significant.
sidual or recurrent calculi, and 2 with poor stone fragmenta-
tion were excluded from study. After lithotripsy 1 patient
with a solitary kidney died of acute infection and septicemia.
There were 7 patients lost to followup. Thus, 12 renal units of
90 were excluded from analysis of stone clearance. Ureteral
stenting was done as an auxiliary procedure before ESWL in
11 cases and between treatments in 1. The number of stones
in each renal unit varied from 1 to 4, and 15 units had 2 or
more. Stones ranged from 5 to 30 mm., and the area per calix
ranged from 20 to 450 mm.2. Of the 78 renal units analyzed
56 (about 72%) had stone clearance 6 months after treat-
ment. Statistical analyses of parameters of stones and infe-
rior caliceal anatomy versus clearance are shown in the
table.
The calix was 30 mm. or less in 77% of renal units with
stone clearance compared to 64% of failures, and the caliceal
width was 5 mm. or more in 75% and 41%, respectively.
Angle 1 was more than 45 degrees in 73% of treatment
successes compared to 18.2% of failures. Similarly, angle 2
was 45 degrees or more in 71% of treatment successes com-
pared to only 9% of failures. The infundibulopelvic angle was
the most significant factor (p Ͻ0.00001), followed by infun-
dibular width (p Ͻ0.0048). The length of the calix, and stone
size and area were not statistically significant for stone clear-
ance. However, 77% of patients with clearance had a caliceal
length of 30 mm. or less compared to 64% of failures. The
chances of a patient becoming stone-free with all 3 favorable
criteria of infundibular length 30 mm. or less, infundibular
width 5 mm. or greater and infundibular ureteropelvic angle
45 degrees or greater was 100% (23 patients). Only 1 of 4
cases with all unfavorable criteria had stone clearance. The
chance of becoming stone-free was 100% (33 cases) with
angle 2 of 45 degrees or greater and width 5 mm. or greater,
RESULTS
A total of 88 patients and 90 renal units, including 2
patients with bilateral renal stones, were treated for inferior and 96.8% (30 of 31) with angle 2 of 45 degrees or greater and
caliceal calculi with ESWL. The 62 men and 26 women were length 30 mm. or less. The predominant stone composition

26
INFERIOR CALICEAL CALCULI AND SHOCK WAVE LITHOTRIPSY
Statistical analysis of variables in clearance of inferior caliceal calculi following ESWL
Unadjusted Odds
Ratio (95% CI)
Variables
Clearance
Failure
p Value
0.5
No. men (%)
No. women (%)
39
(70)
(78)
17
5
(30)
(22)
1.48 (0.47–4.67)
17
No. stone side (%):
Rt.
31
25
(78)
(66)
9
(22)
(34)
0.25
0.56 (0.20–1.52)
Lt.
13
Mean mm. stone size (SD)
Mean mm.2 stone area (SD)
Mean mm. calix length (SD)
Mean mm. calix width (SD)
Mean degrees angle 1 (SD)
Mean degrees angle 2 (SD)
13.88 (5.66)
131.5 (91.0)
27.02 (6.34)
6.75 (2.71)
43.41 (14.21)
51.68 (13.15)
14.36 (3.71)
156.86 (79.22)
29.00 (4.92)
4.82 (2.58)
26.36 (12.07)
31.82 (11.17)
0.34
0.98 (0.89–1.07)
0.996 (0.99–1.00)
0.95 (0.87–1.03)
1.34 (1.08–1.66)*
1.14 (1.07–1.22)
1.19 (1.09–1.29)†
0.09
0.19
0.0048
0.00001
0.00001
* Adjusted odds ratio was 1.16 (0.86 to 1.56).
† Adjusted odds ratio was 1.19 (1.09 to 1.29).
was calcium oxalate monohydrate as determined on x-ray axes, and not the ureteropelvic axis as in our study. Others
diffraction crystallography.
have found the angle to be obtuse in a larger percentage of
cases. Means of angles 1 and 2 were approximately 39 and 46
degrees overall, respectively, 43 and 52, respectively, in pa-
tients who became stone-free, and 26 and 36, respectively,
in those with treatment failure. Infundibulopelvic angle 1
was 35 degrees or more in 73% of treatment successes com-
pared to only 18% of failures. There was a strong association
(p ϭ 0.00001) between the angle and rate of stone clearance.
Angle 2 was 45 degrees or more in 71% of cases with com-
pared to only 9% of those without clearance, which was also
statistically significant (p ϭ 0.00001). Logistic regression
analysis of factors that were significant with univariate anal-
ysis revealed angle 2 to be the most significant with a higher
adjusted odds ratio of 1.17 (table 1). While others noted
poorer stone clearance with an acutely angled compared to
an obtusely angled inferior calix, almost all of our cases had
acute angle, angle 1 of 35 degrees or less and angle 2 of 45
degrees or less associated with poor stone clearance.
The unfavorable factors of inferior caliceal anatomy inher-
ent in its position and angulation are responsible for a poorer
stone-free rate following ESWL. Different adjunctive treat-
ment modalities to achieve better clearance of stone frag-
ments have been suggested.4 Forced diuresis, inversion ther-
apy, a cobra catheter for direct irrigation of the stone
containing inferior calix and percutaneous irrigation have
been used to enhance clearance.16–18 In 1 study inversion
therapy was a safe and beneficial adjunctive treatment for
inferior caliceal fragments after ESWL, while others did not
find it useful to improve the results of ESWL for these cal-
culi.16, 19 In our 3 cases inversion therapy appeared to be
beneficial. However, its usefulness cannot be categorically
stated as we did not perform a controlled trial of this proce-
dure. Our cases with all favorable criteria of infundibular
length 30 mm. or less, infundibular width 5 mm. or greater
and an angle 2 of 45 degrees or greater had 100% stone
clearance.
DISCUSSION
Inferior caliceal calculi have a low clearance rate following
ESWL compared to calculi elsewhere in the pelvicaliceal
system. Others have reported a stone clearance rate from
41% to 79%.1–9 We noted an overall stone clearance rate of
72% in 56 of 78 units. A total of 15 units (19%) had 2 to 4
calculi. Stone size varied from 5 to 30 mm., with 24 (31%) up
to 10, 45 (58%) 11 to 20 and 9 (11%) 20 to 30 mm. The
stone-free rate was 72.1% for calculi up to 10, 51.3% for those
11 to 20 and 38.7% for those more than 20 mm.9 Others have
reported a stone clearance rate of only 54% for stones 1 cm. or
less in largest diameter.10 In our study stone clearance was
88%, 62% and 78% for stones up to 10, 11 to 20 and 20 to 30
mm., respectively. Similarly the area of the stones ranged
from 20 to 450 mm.2, with 31 (40%) up to 100, 34 (44%) 101
to 200, 9 (11%) 201 to 300 and 4 (5%) more than 300 mm.2.
The respective stone clearance rates for these categories were
approximately 84%, 62%, 66% and 75%. In our cases size and
areas of stone were not statistically significant (p ϭ 0.34 and
0.09, respectively).
The anatomy of the calices and its role in the treatment of
inferior caliceal calculi with ESWL or endoscopy have been
reported by others.11–14 The length of the calix ranged from
15 to 55 mm. in our patients with stone clearance, compared
to 20 to 40 mm. in those with treatment failure. Of the
patients 77% with caliceal lengths up to 30 mm. were stone-
free compared to 64% with a length of more than 30 mm.
However, the length of the calix was not a significant factor
for clearance (p ϭ 0.19). Mean width of the inferior calix was
6.75 mm. in patients with stone clearance compared to 4.82
mm. in those with treatment failure (see table). Statistical
analysis revealed that width was a significant factor for stone
clearance (p ϭ 0.0048). Caliceal width was 5 mm. or more in
75% of stone-free cases compared to 41% of failures. Of the
patients with a caliceal width of 5 mm. or more 82% had
clearance compared to 52% with a width of 4 mm. or less.
An angle of more than 90 degrees between the lower in-
CONCLUSIONS
Our study revealed that inferior caliceal infundibulopelvic
fundibulum and renal pelvis has been reported in 74% of anatomy has a significant role in determining the stone-free
cases with assessment of resin casts of the pelvicaliceal sys- rate following satisfactory fragmentation of stone with
tem.13 In 1 study a pelvicaliceal angle of more than 90 de- ESWL. Various factors of renal anatomy can be easily meas-
grees was found in 36% of cases.15 In another study an ured on standard excretory urography. Infundibulopelvic an-
infundibular ureteropelvic angle of 90 degrees or more was gle 1 of more than 35 or angle 2 of more than 45 degrees, and
found in only 12% of cases.10 We measured the angle in 2 an infundibular width of more than 5 mm. are statistically
ways, and infundibulopelvic angle 1 ranged from 15 to 95 and significant factors associated with stone clearance. Our in-
angle 2 ranged from 10 to 95 degrees. Only 1 of our cases had fundibulopelvic angle findings are different from those of
an angle of more than 90 degrees. Our infundibular uretero- others. Although the length of the calix was not statistically
pelvic angle findings are noticeably different from others. significant, it appeared to be associated with a more favor-
The reason for this discrepancy in some reports was due to able outcome when it was 30 mm. or less. Thus, using these
the difference in the methodology of measurement of the radiographic parameters ESWL can be selected as a treat-
angle.10, 15 In those studies the infundibulopelvic angle was ment modality for a predictably favorable outcome in indi-
the angle subtended by the infundibular and renal pelvic vidual cases.

INFERIOR CALICEAL CALCULI AND SHOCK WAVE LITHOTRIPSY
27
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