Male sling adjustability: does it truly matter?

PURPOSE: Patients with post prostatectomy incontinence (PPI) seem to have different needs. Therefore, device post-operative readjustability may be a beneficial feature in PPI management, even though it lacks study support. The purpose of this study is to describe our surgical technique for male sling (MS) implantation, assess outcomes, and the impact of readjustability. METHODS: We performed a retrospective analysis of 89 consecutive patients who underwent PPI correction with MS Argus-T™ (Promedon, Córdoba, Argentina) from 2009 to 2021. The median follow-up was 48 months (12-120). Data were collected in a dedicated database. Perioperative variables were assessed. A descriptive statistical analysis was performed. Clinical and urodynamic variables were correlated with the need for readjustments and success. RESULTS: In this cohort, objective success was achieved in 80.5% of the patients (65.9% cured and 14.6% improved). A total of 85.4% of the patients met the criteria for subjective success (74.4% cured and 11% improved). For the subgroup of patients who received previous treatment for urethral stricture (US), 79% achieved objective success (63.2% cured, 15.8% improved), and 84.2% achieved subjective success (78.9% cured, 5.3% improved). For the subgroup of patients who received previous radiotherapy (RT) before sling surgery, 68.7% achieved objective success (37.5% cured, 31.2% improved), and 75% achieved subjective success (37.5% cured, 37.5% improved). Procedures for device readjustment were necessary for 27.7% of patients in the total study population. RT and previous US treatment were predictive factors for the need of readjustment, with rates of 66.7% and 61.1% (OR: 8.46; CI: 2.46-29.00; p = 0.001/OR: 6.41; CI: 2.05-20.03; p = 0.001, respectively). CONCLUSIONS: MS adjustability improved success rates, especially among irradiated patients and those with previous US. RT was an adverse predictor of total continence status even after readjustments.

Functional urology: Practice patterns and training aspirations among urologists in Brazil.

PURPOSE: Urology has rapidly evolved during the last decades, incorporating new technologies faster than most specialties. The challenge to maintain a competent workforce that is prepared to deliver proper contemporary treatment has become increasingly difficult and newly graduated urologists throughout the world typically lack the skills to practice many urological subspecialties. We performed a survey to evaluate the practice patterns and educational aspirations in functional urology (FU) among Brazilian urologists. METHODS: A web-based survey was sent to board-certified Brazilian urologists to collect data on clinical practice and training aspirations in four subareas of FU: female urology, urodynamics, postprostatectomy incontinence (PPI), and neurourology. We evaluated urologists' clinical and surgical workload in each subarea and investigated educational training aspirations to identify areas and training formats of interest. RESULTS: A total of 366 urologists (mean age 47.7 + 10.7 years) completed the survey. Mean time since completion of residency was 17.9 + 11.9 years. Of the respondents, 176 (53%) perform urodynamics, 285 (83.1%) SUI surgeries, 159 (47.6%) PPI surgeries, 194 (58.1%) third line OAB procedures, 168 (48.9%) pelvic organ prolapse (POP), and 88 (26.3%) bladder augmentation. Mid-urethral sling is the most performed SUI surgery and transobturator is the preferred route (64.0%). For those performing POP surgery, 40.5% use mesh in at least 50% of their cases, and the vaginal route is used in most cases (75.4%) for apical prolapse. For PPI, 64.6% use artificial sphincter in most surgeries and only 8.1% perform at least 5 surgeries/year. Being fellowship-trained and working in an academic hospital are associated with a higher chance of being active in FU. Most urologists are interested in receiving training in PPI, female SUI, and POP and a hands-on course is the preferred educational method (81%). CONCLUSIONS: Most urologists in Brazil are involved in the evaluation and treatment of FU patients, but few have a large volume of patient visits and surgical procedures. Completing a fellowship program and working in an academic practice are associated with a higher chance of being a FU practitioner. There is a high interest in training for PPI, female SUI, and POP.

Early puberty in short-haired Guinea pigs kept in laboratory animal facilities.

Lab animals, such as Guinea pigs (Cavia porcellus), are crucial for scientific development, as they play an important role in the development and quality control chain of vaccines and drugs distributed by the Brazilian public health system. Investigating their biological and physiological parameters is fundamental to raise and keep these animals, so the handling of the facilities that hold them can be updated whenever new information comes up, with the well-being of the animals and alignment with the 3 Rs in mind. In the search for understanding reproductive aspects of Guinea pigs, the present study had the main goal of studying puberty by means of estrous cycle analysis in short-haired Guinea pigs. Guinea pigs have a vaginal occlusive membrane that covers the vaginal orifice. Its rupture takes place gradually and naturally, moments before labor and during estrus. The present study followed 42 females as for the presentation of the vaginal occlusive membrane. Once the membranes ruptured spontaneously, a swab was collected to study vaginal cytology. Membrane rupture was observed in 39 females; six females showed membrane rupture with less than 21 days of age (17 to 21 days). Twenty-three females were characterized as being in estrus due to cytology showing a prevalence of anucleated superficial cells. One of these females was younger than 21 days old. The opening of the vaginal occlusive membrane took place most frequently in intervals between 17 and 18 days, and the membrane remained open between one and three consecutive days. It was possible to follow three cycles of membrane opening on six females. The present study showed the need to adapt handling guidelines for C. porcellus kept in research animal facilities. The early age of puberty imposes the need of separate the female daughters from their fathers at 16 days old.

Early puberty in short-haired Guinea pigs kept in laboratory animal facilities

Lab animals, such as Guinea pigs (Cavia porcellus), are crucial for scientific development, as they play an important role in the development and quality control chain of vaccines and drugs distributed by the Brazilian public health system. Investigating their biological and physiological parameters is fundamental to raise and keep these animals, so the handling of the facilities that hold them can be updated whenever new information comes up, with the well-being of the animals and alignment with the 3 Rs in mind. In the search for understanding reproductive aspects of Guinea pigs, the present study had the main goal of studying puberty by means of estrous cycle analysis in short-haired Guinea pigs. Guinea pigs have a vaginal occlusive membrane that covers the vaginal orifice. Its rupture takes place gradually and naturally, moments before labor and during estrus. The present study followed 42 females as for the presentation of the vaginal occlusive membrane. Once the membranes ruptured spontaneously, a swab was collected to study vaginal cytology. Membrane rupture was observed in 39 females; six females showed membrane rupture with less than 21 days of age (17 to 21 days). Twenty-three females were characterized as being in estrus due to cytology showing a prevalence of anucleated superficial cells. One of these females was younger than 21 days old. The opening of the vaginal occlusive membrane took place most frequently in intervals between 17 and 18 days, and the membrane remained open between one and three consecutive days. It was possible to follow three cycles of membrane opening on six females. The present study showed the need to adapt handling guidelines for C. porcellus kept in research animal facilities. The early age of puberty imposes the need of separate the female daughters from their fathers at 16 days old.(AU)

Arteriocaliceal Fistula: A Life-Threatening Condition After Retrograde Intrarenal Surgery.

Background: Retrograde intrarenal surgery (RIRS) has emerged as a viable and safe option for renal stones <2 cm. Because of its high efficiency and relative safety, experienced endourologists have applied it to even larger stones. We present a case of arteriocaliceal fistula, which is a rare postoperative complication of RIRS. Case Presentation: A 52-year-old man with a rich history of endourologic procedures and extracorporeal shockwave lithotripsy caused by inferior caliceal calculi was subjected to RIRS. This was complicated by transient intraoperative hemorrhage, followed by recurrent hematuria and clot retention several days postoperatively. Renal arteriography revealed the presence of an arteriocaliceal fistula. This was completely resolved with selective arterial embolization. Conclusion: This case highlights that early detection and timely intervention are crucial to avoid serious consequences of post-RIRS hemorrhage resulting from arteriocaliceal fistula.

A Rare Case of an Adrenal Ganglioneuroma Treated Laparoscopically in a Patient with Left-Sided Inferior Vena Cava.

Background: Ganglioneuroma is a rare tumor derived from the neural crest that can occur in any sympathetic tissue. It corresponds to 0.3% to 2% of incidental adrenal tumors and <250 have been reported in the literature so far. Case Presentation: We present a case of a 30-year-old Caucasian woman presented with a large bilobed adrenal tumor found on a CT scan during the investigation of acute abdominal pain. The image also showed a rare anatomic variation of a left-sided inferior vena cava. Biochemical work-up for adrenal incidentaloma showed normal markers. Since we could not rule out malignancy, the patient was subjected to laparoscopic adrenalectomy and the pathology report showed an adrenal ganglioneuroma, a rare nonfunctioning tumor of the adrenal. Conclusion: Ganglioneuroma can present as a large bilobed adrenal tumor. The laparoscopic approach is feasible and safe. Preoperative planning is needed and vascular variations can be challenging during the procedure.

Is urodynamics necessary to identify occult stress urinary incontinence?

PURPOSE: To investigate Occult Stress Urinary Incontinence (OSUI) using physical exam (PE) and urodynamics (UDS) in women with advanced pelvic organ prolapse (POP), and compare the two methods. METHODS: This study comprised 105 women with POP stage-III and -IV, according to POP quantification (POP-Q) system, evaluated prospectively between January and December 2015. A standard history, an incontinence questionnaire and PE were completed before the investigation of the OSUI that was performed in the supine and standing positions, reducing the prolapse using gauze and Cheron dressing forceps. The stress test was performed with and without the prolapse reduction. RESULTS: The mean patient age was 65.7 years, mean parity 5.1 and mean body mass index 27.4. From a total of 105 patients, 70 (66.7%) presented with POP-Q stage III and 35 (33.3%) stage IV. Sixty-three (60%) women were identified as having OSUI, 27 (25.7%) as continent, and 15 (14.3%) having stress urinary incontinence. From the 63 OSUI subjects, 48 (76.2%) were identified in both evaluations, eight were identified only during PE, and seven only during UDS. The sensitivity to detect OSUI during PE and UDS was 88.9 and 87.3%, respectively (P = .783). The kappa value to measure the agreement between both tests was .648 (95% CI .441-.854). CONCLUSION: UDS and PE are equivalent and concordant to demonstrate OSUI, thus it is not necessary to perform UDS to exclusively identify OSUI. UDS utility in OSUI patients, to evaluate urethral and detrusor function, deserves further investigation.

Image-guided percutaneous intralesional administration of mesenchymal stromal cells in subjects with chronic complete spinal cord injury: a pilot study.

BACKGROUND AIMS: The potential of cell therapies to improve neurological function in subjects with spinal cord injury (SCI) is currently under investigation. In this context, the choice of cell type, dose, route and administration regimen are key factors. Mesenchymal stromal cells (MSCs) can be easily obtained, expanded and are suitable for autologous transplantation. Here we conducted a pilot study that evaluated safety, feasibility and potential efficacy of intralesional MSCs transplantation performed through image-guided percutaneous injection, in subjects with chronic complete SCI. METHODS: Five subjects with chronic traumatic SCI (>6 months), at thoracic level, classified as American Spinal Cord Injury Association impairment scale (AIS) grade A, complete injury, were included. Somatosensory evoked potentials (SSEP), spinal magnetic resonance imaging (MRI) and urodynamics were assessed before and after treatment. Autologous MSCs were injected directly into the lesion site through percutaneous injection guided by computerized tomography (CT). RESULTS: Tomography-guided percutaneous cell transplantation was a safe procedure without adverse effects. All subjects displayed improvements in spinal cord independence measure (SCIM) scores and functional independence measure (FIM), mainly due to improvements in bowel movements and regularity. Three subjects showed improved sensitivity to tactile stimulation. Two subjects improved AIS grade to B, incomplete injury, although this was sustained in only one of them during the study follow-up. CONCLUSION: Autologous bone marrow MSC transplantation, performed through CT-guided percutaneous injection, was shown to be safe and feasible. Further studies are required to demonstrate efficacy of this therapeutic scheme.

Management in Neonatal Priapism: Case and Review.

Neonatal priapism is uncommon and its cause is usually unknown, but it can generate anxiety for the parents and the pediatric team. The treatment in most cases is conservative and no sequelae are described.

Anterior six arms prolene mesh for high stage vaginal prolapse: five years follow-up

ABSTRACT Introduction In high stage vaginal prolapse, recurrence risk patients, anterior and apical defects need to be addressed in the same procedure. The pre-molded commercial mesh kits are expensive and not always available. Alternative effective and safe treatment ways, with lower costs are desirable. Objective To present long term follow-up of patients treated with a homemade mesh shape to correct high stage prolapses. Materials and Methods We describe prospectively 18 patients with anterior and apical vaginal prolapses, stages III and IV, repaired using this specific design of mesh. All patients were submitted to pre-operative clinical evaluation and urodynamics. Prolapse was classified using the pelvic organ prolapse quantification (POP-Q). Intervention Prolapse surgery, using a six arms prolene mesh, through a single anterior vaginal incision. Outcome Measurements: POP-Q, patients satisfaction, descriptive statistical analysis. Results Between February 2009 and Oct 2010, 18 consecutive women underwent the above-mentioned surgery. Mean age was 68 years. At a mean follow-up of .,4 years (5 to 5.8 years), 16 (89%) patients were continent, mean Ba point came from +4.7cm to - 2.5cm, mean C point from +2.8cm to -6.6cm and mean Bp point from +1.3 to -1.7cm. There were two (11%) objective failures, but all the patients were considered success subjectively. There were two cases of mesh vaginal extrusion. Conclusions The homemade six arms prolene mesh allows concomitant correction of anterior and apical prolapses, through a single anterior vaginal incision, being an effective, safe and affordable treatment option when mesh is needed.

Predicting outcomes in partial nephrectomy: is the renal score useful?

ABSTRACT Introduction and Objective The R.E.N.A.L. nephrometry system (RNS) has been validated in multiple open, laparoscopic and robotic partial nephrectomy series. The aim of this study was to test the accuracy of R.E.N.A.L. nephrometry system in predicting perioperative outcomes in surgical treatment of kidney tumors <7.0cm in a prospective model. Materials and Methods Seventy-one patients were selected and included in this prospective study. We evaluate the accuracy of RNS in predicting perioperative outcomes (WIT, OT, EBL, LOS, conversion, complications and surgical margins) in partial nephrectomy using ROC curves, univariate and multivariate analyses. R.E.N.A.L. was divided in 3 groups: low complexity (LC), medium complexity (MC) and high complexity (HC). Results No patients in LC group had WIT >20 min, versus 41.4% and 64.3% MC and HC groups respectively (p=0.03); AUC=0.643 (p=0.07). RNS was associated with convertion rate (LC:28.6% ; MC:47.6%; HC:77.3%, p=0.02). Patients with RNS <8 were most often subjected to partial nephrectomy (93% x 72%, p=0.03) and laparoscopic partial nephrectomy (56.8% x 28%, p=0.02), AUC=0.715 (p=0.002). The RNS was also associated with operative time. Patients with a score >8 had 6.06 times greater chance of having a surgery duration >180 min. (p=0.017), AUC=0.63 (p=0.059). R.E.N.A.L. score did not correlate with EBL, complications (Clavien >3), LOS or positive surgical margin. Conclusion R.E.N.A.L. score was a good method in predicting surgical access route and type of nephrectomy. Also was associated with OT and WIT, but with weak accuracy. Although, RNS was not associated with Clavien >3, EBL, LOS or positive surgical margin.

Predicting outcomes in partial nephrectomy: is the renal score useful?

INTRODUCTION AND OBJECTIVE: The R.E.N.A.L. nephrometry system (RNS) has been validated in multiple open, laparoscopic and robotic partial nephrectomy series. The aim of this study was to test the accuracy of R.E.N.A.L. nephrometry system in predicting perioperative outcomes in surgical treatment of kidney tumors <7.0cm in a prospective model. MATERIALS AND METHODS: Seventy-one patients were selected and included in this prospective study. We evaluate the accuracy of RNS in predicting perioperative outcomes (WIT, OT, EBL, LOS, conversion, complications and surgical margins) in partial nephrectomy using ROC curves, univariate and multivariate analyses. R.E.N.A.L. was divided in 3 groups: low complexity (LC), medium complexity (MC) and high complexity (HC). RESULTS: No patients in LC group had WIT >20 min, versus 41.4% and 64.3% MC and HC groups respectively (p=0.03); AUC=0.643 (p=0.07). RNS was associated with convertion rate (LC:28.6% ; MC:47.6%; HC:77.3%, p=0.02). Patients with RNS <8 were most often subjected to partial nephrectomy (93% x 72%, p=0.03) and laparoscopic partial nephrectomy (56.8% x 28%, p=0.02), AUC=0.715 (p=0.002). The RNS was also associated with operative time. Patients with a score >8 had 6.06 times greater chance of having a surgery duration >180 min. (p=0.017), AUC=0.63 (p=0.059). R.E.N.A.L. score did not correlate with EBL, complications (Clavien >3), LOS or positive surgical margin. CONCLUSION: R.E.N.A.L. score was a good method in predicting surgical access route and type of nephrectomy. Also was associated with OT and WIT, but with weak accuracy. Although, RNS was not associated with Clavien >3, EBL, LOS or positive surgical margin.

Anterior six arms prolene mesh for high stage vaginal prolapse: five years follow-up.

INTRODUCTION: In high stage vaginal prolapse, recurrence risk patients, anterior and apical defects need to be addressed in the same procedure. The pre-molded commercial mesh kits are expensive and not always available. Alternative effective and safe treatment ways, with lower costs are desirable. OBJECTIVE: To present long term follow-up of patients treated with a homemade mesh shape to correct high stage prolapses. MATERIALS AND METHODS: We describe prospectively 18 patients with anterior and apical vaginal prolapses, stages III and IV, repaired using this specific design of mesh. All patients were submitted to pre-operative clinical evaluation and urodynamics. Prolapse was classified using the pelvic organ prolapse quantification (POP-Q). INTERVENTION: Prolapse surgery, using a six arms prolene mesh, through a single anterior vaginal incision. OUTCOME MEASUREMENTS: POP-Q, patients satisfaction, descriptive statistical analysis. RESULTS: Between February 2009 and Oct 2010, 18 consecutive women underwent the above-mentioned surgery. Mean age was 68 years. At a mean follow-up of 4 years (5 to 5.8 years), 16 (89%) patients were continent, mean Ba point came from +4.7cm to -2.5cm, mean C point from +2.8cm to -6.6cm and mean Bp point from +1.3 to -1.7cm. There were two (11%) objective failures, but all the patients were considered success subjectively. There were two cases of mesh vaginal extrusion. CONCLUSIONS: The homemade six arms prolene mesh allows concomitant correction of anterior and apical prolapses, through a single anterior vaginal incision, being an effective, safe and affordable treatment option when mesh is needed.

The use of operant instrumental conditioning with positive reinforcement for collection of saliva from marmosets (Callithrix jacchus) for research purposes

In order to improve the welfare of captive wild animals used in research, it is necessary to apply methods that minimize the stress to which the animals are constantly subjected. Stress produces physiological changes that may interfere with the results of laboratory experiments, and voluntary cooperation through learning may minimize the anxiety experienced by laboratory animals. It is therefore important to develop non-invasive methods for the collection of biological samples and the performance of laboratory exams. The aim of this study was to train common marmosets (Callithrix jacchus) for the collection of saliva samples. Instrumental operant conditioning with positive reinforcement (reward) was applied to 24 adult marmosets of both genders. All animals were satisfactorily conditioned for the rapid and effective collection of saliva samples.(AU)

Para que haja uma melhora no bem-estar de animais silvestres utilizados em pesquisa é necessário o emprego de técnicas que reduzam os efeitos estressantes, aos quais os animais são constantemente submetidos. Sabemos que o estresse pode ocasionar alterações fisiológicas podendo alterar os resultados de um experimento e que a cooperação voluntária obtida através do aprendizado pode minimizar sensações de ansiedade vivida por animais mantidos em laboratório. Sendo assim, a busca de métodos não-invasivos para a coleta de material biológico e exames laboratoriais é de grande importância. O objetivo do presente estudo foi condicionar um grupo de primatas Callithrix jacchus para coletas de saliva com finalidade de pesquisa. Para tanto utilizamos a técnica do condicionamento operante com auxílio instrumental e reforço positivo (recompensa) em 24 saguis adultos, de ambos os sexos. Segundo as condições deste estudo, o condicionamento para coleta de saliva foi realizado de forma satisfatória, rápida e eficiente demonstrando que a utilização do método de condicionamento instrumental com recompensa nesta espécie pode ser efetuado com sucesso.(AU)

The use of operant instrumental conditioning with positive reinforcement for collection of saliva from marmosets (callithrix jacchus) for research purposes

In order to improve the welfare of captive wild animals used in research, it is necessary to apply methods that minimize the stress to which the animals are constantly subjected. Stress produces physiological changes that may interfere with the results of laboratory experiments, and voluntary cooperation through learning may minimize the anxiety experienced by laboratory animals. It is therefore important to develop non-invasive methods for the collection of biological samples and the performance of laboratory exams. The aim of this study was to train common marmosets (Callithrix jacchus) for the collection of saliva samples. Instrumental operant conditioning with positive reinforcement (reward) was applied to 24 adult marmosets of both genders. All animals were satisfactorily conditioned for the rapid and effective collection of saliva samples.

Para que haja uma melhora no bem-estar de animais silvestres utilizados em pesquisa é necessário o emprego de técnicas que reduzam os efeitos estressantes, aos quais os animais são constantemente submetidos. Sabemos que o estresse pode ocasionar alterações fisiológicas podendo alterar os resultados de um experimento e que a cooperação voluntária obtida através do aprendizado pode minimizar sensações de ansiedade vivida por animais mantidos em laboratório. Sendo assim, a busca de métodos não-invasivos para a coleta de material biológico e exames laboratoriais é de grande importância. O objetivo do presente estudo foi condicionar um grupo de primatas Callithrix jacchus para coletas de saliva com finalidade de pesquisa. Para tanto utilizamos a técnica do condicionamento operante com auxílio instrumental e reforço positivo (recompensa) em 24 saguis adultos, de ambos os sexos. Segundo as condições deste estudo, o condicionamento para coleta de saliva foi realizado de forma satisfatória, rápida e eficiente demonstrando que a utilização do método de condicionamento instrumental com recompensa nesta espécie pode ser efetuado com sucesso.

Low-intensity laser therapy and led (light emitting diode) therapy in mechanical resistance of Rattus norvegicus chest inscision with implant of steel wire for sternal suture

INTRODUCTION: Low-intensity laser (LILT) and LED therapy are indicated in repairing surgical incisions, which occur in cardiac surgery. One major concern in this case is the presence of metallic wire used for sternal sutures, its temperature may rise while using a laser or LED. This study aimed to analyze the tensiometric properties of the skin tissue with longitudinal incision and metallic wire implant used for sternal suture irradiated with LILT and LED. METHODS: Twenty-five subjects (Rattus norvegicus) were submitted to thoracic incision with implantation of metallic wire, and subsequently divided into five groups: GI (control group); GII (laser group 6J/cm²); GIII (laser group 10J/cm²); GIV (LED group 6 J/cm²); and GV (LED 10J/cm²). Photobiomodulation was performed on a daily basis for eight consecutive days and the local temperature was measured before and after phototherapy. After euthanasia the tissues were subjected to tensiometric and histological analysis. RESULTS: All irradiated groups showed increase in break strength (p = 0.009), and decrease in tissue deformation strength compared with the control group (p = 0.03). CONCLUSION: Both LILT and LED can promote wound healing at the tested doses with increased tissue resistance, although its elasticity is reduced. The imprecision of the assessing instruments precluded an accurate measurement of a possible local tissue heating post irradiation and future studies are need to elucidate this effect.

Is there an association between urolithiasis and Roux-en-y gastric bypass surgery?

PURPOSE: Several studies have documented high incidence of urinary lithiasis after jejunoileal by-pass. Roux-en-y gastric bypass surgery (RYGB) is currently the most common bariatric procedure. Because of its difficult for absorption, RYGB has a potential risk to increase the incidence of lithiasis. This study was conducted in order to test the hypothesis that RYGB increases the incidence urolithiasis after 50% of excessive weight loss. MATERIALS AND METHODS: We performed a retrospective cohort study to evaluate 58 patients who underwent RYGB at the Obesity Service at Santa Casa de Misericordia de Sao Paulo, between 2000 and 2005, with minimum follow-up of 10 and maximum of 72 months, after the procedure. RESULTS: Forty-five (77.6%) patients had >or= 50% loss of weight excess. There was no difference between the frequency of urolithiasis before and after the procedure, and nephrolithiasis was observed after surgery in only one patient, however this had been detected before the procedure. CONCLUSION: In the period studied, RYGB does not seem to affect the incidence of urolithiasis after weight reduction. This may be due to its smaller malabsorptive component as compared with jejunoileal "by-pass", thereby possibly not significantly influencing the oxalate metabolism.

Is there an association between urolithiasis and roux-en-y gastric bypass surgery?

Purpose: Several studies have documented high incidence of urinary lithiasis after jejunoileal by-pass. Roux-en-y gastric bypass surgery (RYGB) is currently the most common bariatric procedure. Because of its difficult for absorption, RYGB has a potential risk to increase the incidence of lithiasis. This study was conducted in order to test the hypothesis that RYGB increases the incidence urolithiasis after 50 percent of excessive weight loss. Materials and Methods: We performed a retrospective cohort study to evaluate 58 patients who underwent RYGB at the Obesity Service at Santa Casa de Misericordia de Sao Paulo, between 2000 and 2005, with minimum follow-up of 10 and maximum of 72 months, after the procedure. Results: Forty-five (77.6 percent) patients had ¡Ý 50 percent loss of weight excess. There was no difference between the frequency of urolithiasis before and after the procedure, and nephrolithiasis was observed after surgery in only one patient, however this had been detected before the procedure. Conclusion: In the period studied, RYGB does not seem to affect the incidence of urolithiasis after weight reduction. This may be due to its smaller malabsorptive component as compared with jejunoileal ¡°by-pass¡±, thereby possibly not significantly influencing the oxalate metabolism.