Impact of Renal Anatomy on Shock Wave Lithotripsy Outcomes for Lower Pole Kidney Stones

University of Sao Paulo

Status: Completed

Conditions: Urinary Lithiasis; Urolithiasis; Kidney Calculi

Treatments: Device: SWL - Compact Delta Dornier Med Tech

Study type: Interventional

Funder types: Other

Identifiers

NCT01589484

00795812.8.0000.0068

Details and patient eligibility

About

Kidney stone disease affects almost 10% of overall population, often requiring a surgical intervention. Currently, shock wave lithotripsy is considered a first-line treatment option for patients suffering from symptomatic kidney stones smaller than 2.0 cm, providing reasonable stone-free rate. Actually, the outcomes from SWL vary largely due to several factors including stone burden, stone density, stone-skin distance (SSD), and patient's body habitus. Furthermore, the imaging exam modality (i.e. ultrasound versus computed tomography scan) performed to assess the presence of residual fragments also impacts on SWL outcome analysis.

We aim to perform a well-controlled prospective evaluation of all variables that may impact on fragmentation and clearance of lower pole calculi after SWL. These variables are assessed exclusively by a noncontrast computed tomography scan (NCCT), eliminating the necessity of an intravenous urography to study renal collecting system anatomy; an imaging exam that is not routinely performed anymore for kidney stone patients.

Full description

Variables in study:

• Age, gender, body mass index (BMI), and waist abdominal circumference
• Noncontrast computed tomography scan (NCCT): stone density (average of 3 measurements), stone size, stone area, skin to stone distance (average of 3 measurements: zero, 45o and 90o), and collecting system anatomy: infundibular length, width, and height, and infundibulopelvic angle

Study design:

All patients will be submitted to a noncontrast computed tomography scan before to SWL. A radiologist with expertise in urolithiasis will evaluate all exams.

Patients will be submitted to SWL under the following conditions: outpatient, general anesthesia, 3000 impulses, rate of 90/min, discharged from hospital in the same day with alpha-blocker (doxazosin) during 30 days.

Patients will be followed up as follow:

• One week after SWL: medical visit To evaluate complications such as pain, dysuria, hematuria, steinstrasse, visit to the emergency department.
• 12 weeks after SWL: new NCCT scan To evaluate kidney stones fragmentation and clearance.

Univariate (Student's T test) and multivariate analysis (multiple logistic regression) will be done to assess the impact of patient's corporal habitus (BMI and abdominal waist circumference), stone characteristics (size, area, density and SSD), and renal collecting system anatomy (infundibular length, width and height, and infundibulopelvic angle) on SWL outcomes (fragmentation and stone-free rates).

Enrollment: 104 patients

Sex: All

Ages: 18+ years old

Volunteers: No Healthy Volunteers

Inclusion criteria

> 17 year-old. Symptomatic single stone of 5 to 20mm located in the lower pole of the kidney. Informed consent signed.

Exclusion criteria

Patients with congenital kidney abnormalities (i.e. horseshoes kidney, pelvic kidney, ectopic kidney), patients with ureteral stent (i.e. Double J stent) in the ipsilateral kidney of the stone in study, patients with chronic kidney disease (glomerular filtration rate <60 mL/minute/1.73m2 measured by the equation "Modification of Diet in Renal Disease"), and patients with absolute contraindication to SWL (i.e. coagulopathy, pregnancy, urinary tract infection, or abdominal aneurysm >4.0cm).

Trial design

Primary purpose: Treatment

Allocation: N/A

Interventional model: Single Group Assignment

Masking: None (Open label)

---

104 participants in 1 patient group

Shockwave lithotripsy (SWL)

Experimental group

Description:

All patients will be submitted to a noncontrast computed tomography before to shockwave lithotripsy (SWL). Patients will be submitted to SWL under the following conditions: outpatient, general anesthesia, 3000 impulses, rate of 90/min, discharged from hospital in the same day with alpha-blocker (doxazosin) during 30 days.

Treatment:

Device: SWL - Compact Delta Dornier Med Tech