1. Art and Diseño

Rev Mex Urol 2014;74(4):211-215
ÓRGANO OFICIAL DE DIFUSIÓN DE LA SOCIEDAD MEXICANA DE UROLOGÍA,
COLEGIO DE PROFESIONISTAS, A.C.
www.elsevier.es/uromx
Original article
Kidney stone management with percutaneous nephrolithotomy:
experience at a referral hospital
A. Heinze-Rodrígueza,*, R. Suárez-Ibarrolaa, B. N. Várguez-Hernándeza, J. A. VázquezRojasb, L. Gómez-de Regilc, J. A. Aguilar-Morenod, E. Cruz-Nuricumbod and M. VillalobosGollase
a
Urology Speciality Residency, Hospital Regional de Alta Especialidad de la Península de Yucatán, Mérida, Yuc., Mexico
b
Undergraduate Internship, School of Medicine, Universidad Nacional Autónoma de México, Mexico City, Mexico
c
Medical Science Research, Hospital Regional de Alta Especialidad de la Península de Yucatán, Mérida, Yuc., Mexico
d
Urology Service, Hospital Regional de Alta Especialidad de la Península de Yucatán, Mérida, Yuc., Mexico
e
Nefrourology Division Management, Hospital Regional de Alta Especialidad de la Península de Yucatán, Mérida, Yuc., Mexico
KEYWORDS
Percutaneous
nephrolithotomy;
Kidney stones;
Treatment; Lithiasis;
Mexico.
Abstract
Background: Percutaneous nephrolithotomy (PNL) is the treatment of choice for stones > 2 cm
and for those of greater density.
Aims: The aim of this article was to report on the experience in kidney stone management
through PNL at a regional referral hospital center.
Methods: A retrospective study was conducted that included patients presenting with kidney
stones that underwent PNL at the Hospital de Alta Especialidad de la Península in Yucatán,
Mexico, within the time frame of February 2009 and May 2013.
Results: A total of 155 kidney units were operated on; 40 men (25.8%) and 115 women (74.2%).
The mean age was 44 years and 16 of the patients had only one kidney (10.3%). The stone type
was staghorn in 101 cases (65.2%) and the body mass index (BMI) was 27 or higher in 57.4% of the
patients. The stone-free rate was 37.3% after the first procedure; the complication rate was
14.3% according to the Clavien-Dindo scale and bleeding was the most frequent negative event.
Conclusions: PNL is a safe and efficacious technique in the treatment of kidney stones > 2 cm.
Upon treating a high proportion of staghorn stones, the stone-free rate was low and more
secondary procedures were required. An in-depth analysis of other factors that could have an
influence on the pathophysiology of the disease or treatment results should be carried out.
* Corresponding author at: Calle 7 N° 433, por 20 y 22, Fraccionamiento Altabrisa Mérida, C.P. 97130, Mérida, Yuc., México. Telephone:
(999) 9427600, ext. 54201. Email: heinze01gmail.com (A. Heinze-Rodríguez).
212
Palabras clave
Nefrolitotomía
percutánea; Litiasis
renal; Tratamiento;
Litiasis; México.
A. Heinze-Rodríguez et al
Manejo de litiasis renal con nefrolitotomía percutánea: experiencia de un hospital de
referencia
Resumen
Introducción: La nefrolitotomía percutánea (NLPC) es el tratamiento de elección para litos > 2
cm y aquellos con mayor densidad.
Objetivo: Reportar la experiencia en un centro hospitalario regional de referencia, en el manejo
de litiasis renal mediante NLPC.
Material y métodos: Se realizó un estudio retrospectivo, que incluyó a los pacientes con litiasis
renal sometidos a NLPC dentro del Hospital de Alta Especialidad de la Península de Yucatán,
México, desde febrero de 2009 a mayo de 2013.
Resultados: Se intervinieron un total de 155 unidades renales, 40 hombres (25.8%) y 115 mujeres
(74.2%). La edad promedio fue 44 años. Dieciséis fueron pacientes monorrenos (10.3%). Los litos
fueron del tipo coraliforme en 101 casos (65.2%). El 57.4% de los pacientes tenía un índice de
masa corporal (IMC) de 27 o más. Con una tasa libre de litos de 37.3% después del primer
procedimiento. La tasa de complicaciones fue de 14.3% según la escala de Clavien-Dindo, siendo
lo más frecuente el sangrado.
Conclusiones: La NLPC es una técnica segura y eficaz en el tratamiento de la litiasis renal > 2
cm. Al tratar una proporción alta de litos coraliformes se encuentra una tasa libre de litos baja
y se requieren de más procedimientos secundarios. Se deben analizar a fondo otros factores que
pudieran influir en la fisiopatología o los resultados del tratamiento.
0185-4542 © 2014. Revista Mexicana de Urología. Publicado por Elsevier México. Todos los derechos
reservados.
Introduction
Methods
Urolithiasis is one of the primary reasons for urologic
medical consultation at the health services of the State of
Yucatán. Both incidence and prevalence have increased in
the last few years.1 A directly proportional relation between
prevalence and age has been described. According to the
international literature, this entity tends to be more
common in men than in women.2-6
Biologic as well as environmental determinants have been
considered risk factors for presenting with lithiasis. 3
Included among these are obesity, genetic alterations, low
liquid intake, water hardness, chronic degenerative diseases
(e.g. diabetes mellitus), high environmental temperatures,
metabolic alterations, and neoplasias.
In the Mexican population in particular, prevalence is
reported at 5.5%, which is a high rate when compared with
that of other countries.5-7
Since its description in the 1970s, percutaneous
nephrolithotomy (PNL) has become important in the surgical
management of this entity.8 PNL is currently regarded as the
treatment of choice for stones > 2 cm and those with a high
density (> 900 HU).9
PNL complication rates are reported at around 6.7%, and
the most common are urinary tract infections (3.3%),
bleeding (1.4%), fever (1.7%), and sepsis (1.7%).10
The aim of this article was to report the experience in
managing renal lithiasis through PNL at a regional referral
center and to describe the characteristics of the patients
and the results obtained since the establishment of the
Urology Service in 2009.
A retrospective study was carried out that included all the
patients with renal lithiasis that underwent PNL at the
Hospital de Alta Especialidad de la Península de Yucatán, in
Mexico, within the time frame of February 2009 and May
2013. The cases were retrieved from the list of programmed
surgeries and a thorough review of the medical records was
carried out for the purpose of obtaining the demographic
and anthropometric information, the preoperative and
postoperative biochemical data, clinical data, stone
characteristics, surgical variables, and results. The presence
of complications was also taken into account.
The stones were classified in accordance with the
modified Guy classification, 11 adding the variable of
multiple infundibular stricture. The complications were
coded according to the Clavien-Dindo classification. 11
Stone-free status was considered when there were no
stone residuals ≥ 4 mm in the computed tomography (CT)
scan. In the case of bilateral stones, each kidney unit was
considered separately.
Statistical analysis
The chi-square test was used to analyze the categorical
variables of sex or the presence of complications. Statistical
significance was set at a p<0.05. The dimensional scaling
variables were analyzed through the Student’s t test.
The statistical tests were processed with the SPSS® version
19.0 software.
Kidney stone management with percutaneous nephrolithotomy: experience at a referral hospital Results
A total of 155 patients were included, 40 (25.8%) of
which were men and 115 (74.2%) of which were women.
The mean age was 44 years (range: 15-78); 16 patients
(10.3%) had a solitary kidney. The majority of stones
were of the staghorn type and were present in 101
patients (65.2%), followed by renal pelvic stones in 29
(18.7%), and multiple stones in 10 cases (6.5%). A total
of 57.4% of the patients had a body mass index (BMI) of
27 or higher (table 1).
Approach through the lower calyx was performed in 71%
of the patients, followed by the middle calyx in 26%, and
the upper calyx in 6%. The majority were carried out with
the patients in the prone position (95%) and 100% were
guided by fluoroscopic control.
Purulent fluid was retrieved in the initial aspiration in 355
patients, representing 22.6% of the patient total. Renal dilation
was performed with Amplatz dilators in 87 cases (56.1%), Alken
in 56 (36.1%), and with a balloon dilator in one case (0.6%). A
nephrostomy catheter was placed at the end of the procedure in
98.7% of the patients, and only 2 patients (1.3%) were tubeless.
Table 1 General characteristics of patients that underwent percutaneous nephrolithotomy
Total (percentage)
Sex
Age
Men
115 (74.2%)
Women
40 (25.8%)
Mean years
Range
43.55
BMI
Guy classification
15-78
Mean (Kg/m )
Range (Kg/m2)
28.9
18-29 - 44.06
Total (Percentage)
I
32 (20%)
II
7 (4.5%)
III
27 (17.4%)
IV
86 (55.5%)
2
Total (Percentage)
Solitary kidney
Solitary kidney
16 (10.3%)
No solitary kidney
139 (89.7%)
Total (Percentage)
Obstructive stone
Yes
28 (18.%1)
No
127 (81.9%)
Total (Percentage)
Number of tracts
1
2
132 (85%)
21 (13.5%)
Total (Percentage)
PNL kidney
Right
82 (53.2%)
Left
70 (45.5%)
Bilateral
2 (1.3%)
Total (Percentage)
Disease site
Pelvis
29 (18.8%)
Upper
1 (0.6%)
Middle
3 (1.9%)
Lower
10 (6.5%)
Multiple calyces
10 (6.5%)
Staghorn
101 (65.6%)
Total (Percentage)
Puncture
Upper
213
6 (3.9%)
214
A. Heinze-Rodríguez et al
Middle
26 (17.1%)
Lower
110 (72.4%)
Multiple
10 (6.6%)
Total (Percentage)
Tachycardia
Yes
27 (17.8%)
No
130 (84.4%)
Stone density HU
Mean HU
Range HU
1,064
410-2,000
Intraoperative radiation
Mean
10.44 minutes
Range
3-32 minutes
Residual stones
Mean mm3 11.63
Range mm3 0-120
Total (Percentage)
Stone-free
Yes
57 (37.3%)
No
96 (62.7%)
Total (Percentage)
Complications
Without complications
132 (85.2%)
I
6 (3.9%)
II
12 (7.7%)
III
0
IV-A
3 (1.9%)
IV-B
1 (0.6)
V
0
Blood loss mL
Mean (mL)
Range (mL)
242
20-2,000
Fever
Total (Percentage)
Yes
24 (15.6%)
No
130 (84.4%)
HU: Hounsfield units; PNL: Percutaneous nephrolithotomy; BMI: body mass index.
We had a stone-free rate of 37.3% after the first
procedure.
The complication evaluation according to the ClavienDindo classification resulted in a rate of 14.3%. The mean
blood loss was 242 mL (range:10-2,000 mL).
Discussion
Our study population had an inverse relation to that of the
international medical literature, a woman:man ratio of 3:1,
which could be explained by a higher incidence of stones
associated with urinary tract infections. There could also be
an endemic component that should be studied in future
projects.
It is important to mention that the stone characteristics
could have an effect on the lithiasis-free rate found in our
study; 53% of the population presented with staghorn
stones, which could have influenced the success rate being
lower than expected.12 In addition, only rigid equipment was
previously used, given that flexible equipment and lasers
were not available at our hospital until 2013. An important
relation was found with respect to the amount of blood loss
and the complication rate, which can be partially explained
by the fact that the patients that presented with bleeding
had to have blood product transfusion and so were classified
on the Clavien-Dindo scale with grade II complications.
Conclusions
PNL is a safe and efficacious technique for treating renal
lithiasis with stones > 2 cm. Hormonal, genetic, and
environmental factors should be carefully analyzed in
relation to its pathophysiology. The present study makes it
clear that etiologic studies in the region need to be carried
out, due to the demographic variations found in this
population.
Conflict of interest
The authors declare that there is no conflict of interest.
Kidney stone management with percutaneous nephrolithotomy: experience at a referral hospital Financial disclosure
No financial support was received in relation to this article.
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