Michelle J. Semins

The Safety of Ureteroscopy During Pregnancy: A Systematic Review and Meta-Analysis

PURPOSE We performed a literature review and analysis to compare the safety of ureteroscopic stone removal during pregnancy with findings from a set of contemporary studies of that procedure in nonpregnant patients. MATERIALS AND METHODS A systematic review of MEDLINE(R) and EMBASE(R) was done to identify all reports of ureteroscopic stone removal in pregnant women. Complications were stratified according to modified Clavien criteria. We then reviewed a contemporary, multi-national meta-analysis of ureteroscopic stone removal (American Urological Association/European Association of Urology 2007 Guideline for the Management of Ureteral Calculi) to define the complication rate in a series of nonpregnant patients. Complication rates in the 2 reviews were compared using Fishers exact test. RESULTS A total of 14 reports of ureteroscopic stone removal in pregnant women were identified, representing 108 patients. Nine complications were noted. By Clavien criteria 2 complications were level 1, 6 were level 2 and 1 was level 3. When compared to the multinational meta-analysis of ureteroscopy in nonpregnant women, there was no significant difference in the ureteral injury and urinary tract infection complication rates (p = 0.191 and 0.597, respectively). CONCLUSIONS Our analysis shows that the safety of ureteroscopic stone removal in pregnant patients is not significantly different from the safety of that procedure in nonpregnant patients and in each cohort the complication rate is low. Therefore, ureteroscopic stone removal may reasonably be considered appropriate first line therapy in pregnant patients with stone disease.

The association of increasing body mass index and kidney stone disease.

PURPOSE Previous epidemiological works have reported that obesity is a risk factor for kidney stone disease. However, the effect of increasing degrees of obesity on stone formation has yet to be defined. To address this question we examined how an increasing body mass index affects the risk of kidney stone disease. MATERIALS AND METHODS We evaluated claims from a 5-year period (2002 to 2006) in a national private insurance database to identify subjects diagnosed with or treated for kidney stones. From a data set of 95,598 patients, subjects were identified by ICD-9 or CPT codes specific to kidney stone disease. Descriptive analyses were performed and odds ratios were calculated. RESULTS Gender distribution of the 3,257 stone formers was 42.9% male and 57.1% female. Obesity (body mass index greater than 30 kg/m(2)) was associated with a significantly greater likelihood of being diagnosed with a kidney stone. However, when obese patients were stratified by body mass index there were no significant differences in the likelihood of a kidney stone diagnosis, suggesting a stabilization of risk once body mass index increased above 30 kg/m(2). The association of body mass index and a stone removal procedure was significant only for men and women with a body mass index between 30 and 45 kg/m(2) relative to a body mass index less than 25 kg/m(2) (p <0.001). CONCLUSIONS An obese body mass index is associated with an increased risk of kidney stone disease. However, the magnitude of this risk appears to be stable in the morbidly obese population. Once body mass index is greater than 30 kg/m(2), further increases do not appear to significantly increase the risk of stone disease.

The Impact of Obesity on Urinary Tract Infection Risk

OBJECTIVE To perform a study to describe the way in which an increasingly obese body mass index (BMI) is associated with urinary tract infection (UTI). The association between UTI and obesity is not well characterized. In fact, previous investigations of this subject have yielded conflicting findings. UTI is increasingly being recognized as a preventable complication, and UTI rates are used to measure quality of surgical care. MATERIALS AND METHODS We evaluated claims over a 5-year period (2002-2006) in a national private claims database to identify patients diagnosed with UTI or pyelonephritis by ICD-9 coding. Descriptive analyses were performed and odds ratios were calculated. RESULTS A total of 95,598 subjects were identified for evaluation. Gender distribution was 42.9% male and 57.1% female. In the overall study cohort, the diagnosis of a UTI or pyelonephritis occurred in 13% and 0.84%, respectively. Women were 4.2 times more likely to be diagnosed with a UTI (19.3% vs 4.6%), and 3.6 times more likely to be diagnosed with pyelonephritis (1.22% vs 0.34%), than were men. At all stratifications of obesity, the obese were significantly more likely to be diagnosed with a UTI or pyelonephritis than nonobese patients. CONCLUSION Elevated BMI appears to be associated with an increased risk for UTI and pyelonephritis. Further study is needed to determine whether this association may be attributed to a cause-and-effect relationship. However, these results may serve to guide clinicians who treat obese patients, because it may be an additional benefit of weight loss.

The Effect of Restrictive Bariatric Surgery on Urinary Stone Risk Factors

OBJECTIVES Malabsorptive bariatric procedures such as Roux-en-Y gastric bypass (RYGB) place patients at risk for developing kidney stones. Stone risk factors after purely restrictive procedures such as gastric banding and sleeve gastrectomy are not well characterized. Therefore, we performed a study to examine urinary risk factors of patients who underwent restrictive gastric surgery for bariatric indications. METHODS A total of 18 patients were enrolled in the study; 14 underwent gastric banding and 4 underwent sleeve gastrectomy. All subjects collected 24-hour urine specimens; at least 6 months had elapsed between surgery and urine collection. Standard stone risk parameters were assessed, and comparisons were made with a group of normal adult nonstone-formers, routine stone-formers, and RYGB bariatric surgery subjects. RESULTS Urinary oxalate excretion of the restrictive cohort was significantly less than the RYGB cohort (35.4 vs. 60.7 mg/d; P <.001) and not significantly different from that of the normal subjects (32.9 mg/d; P = .798) and routine stone-formers (37.2 mg/d; P = .997). There were no other significant differences in urinary parameters. CONCLUSIONS Restrictive bariatric surgery does not appear to be associated with an increased risk for kidney stone disease. In particular, urinary oxalate levels were significantly less than those of RYGB subjects and not significantly different from routine stone-formers and nonstone-forming controls.

Validity of Administrative Coding in Identifying Patients With Upper Urinary Tract Calculi

PURPOSE Administrative databases are increasingly used for epidemiological investigations. We performed a study to assess the validity of ICD-9 codes for upper urinary tract stone disease in an administrative database. MATERIALS AND METHODS We retrieved the records of all inpatients and outpatients at Johns Hopkins Hospital between November 2007 and October 2008 with an ICD-9 code of 592, 592.0, 592.1 or 592.9 as one of the first 3 diagnosis codes. A random number generator selected 100 encounters for further review. We considered a patient to have a true diagnosis of an upper tract stone if the medical records specifically referenced a kidney stone event, or included current or past treatment for a kidney stone. Descriptive and comparative analyses were performed. RESULTS A total of 8,245 encounters coded as upper tract calculus were identified and 100 were randomly selected for review. Two patients could not be identified within the electronic medical record and were excluded from the study. The positive predictive value of using all ICD-9 codes for an upper tract calculus (592, 592.0, 592.1) to identify subjects with renal or ureteral stones was 95.9%. For 592.0 only the positive predictive value was 85%. However, although the positive predictive value for 592.1 only was 100%, 26 subjects (76%) with a ureteral stone were not appropriately billed with this code. CONCLUSIONS ICD-9 coding for urinary calculi is likely to be sufficiently valid to be useful in studies using administrative data to analyze stone disease. However, ICD-9 coding is not a reliable means to distinguish between subjects with renal and ureteral calculi.

Management of stone disease in pregnancy.

Purpose of review Nephrolithiasis is a not infrequent complication of pregnancy. The occurrence of a stone event in a pregnant woman is a complex situation. Therefore, a clear understanding of the management options available and their relative advantages and disadvantages for this unique population is important. Recent findings When initial, conservative measures have failed in the treatment of a pregnant woman suffering from an acute stone event, management options have historically been of a temporizing nature: generally, either ureteral stent placement or nephrostomy drainage. However, with recent advances in surgical technology and surgeon technique, a more definitive approach to these patients has become more widely adopted. Indeed, several recent case series have reported the complication rate for ureteroscopy during pregnancy to be low. Furthermore, a meta-analysis of case series of ureteroscopy during pregnancy suggests definitive endoscopic treatment is well tolerated in this patient population. Summary In a pregnant patient without contraindications to ureteroscopy, the definitive endoscopic treatment of an acute stone event is a reasonable management strategy, should conservative measures fail. Although further investigation with randomized control trials is ideally needed to confirm these results, at present, the published case series and meta-analysis confirm the safety of ureteroscopy in pregnant patients in the appropriate setting. A multidisciplinary approach is key to the successful management of this complex patient population.

The effect of gastric banding on kidney stone disease.

OBJECTIVES To evaluate the likelihood of being diagnosed with, or treated for, an upper urinary tract calculus after gastric banding. Bariatric surgical procedures are being increasingly utilized in the treatment of patients with morbid obesity. Certain malabsorptive bariatric procedures have been associated with an increased risk for kidney stone formation. However, the kidney stone risk of gastric banding, a restrictive bariatric procedure, is unknown. METHODS We identified 201 patients who underwent gastric banding and a control group of 201 obese patients who did not have bariatric surgery in a national private insurance claims database within a 5-year period from 2002-2006. All patients had at least 2 years of continuous claims data follow-up. Our 2 primary outcomes were the diagnosis and the surgical treatment of a urinary calculus. RESULTS After gastric banding, the diagnosis of an upper urinary tract calculus occurred in 3 subjects (1.49%), as compared with 12 subjects (5.97%) in the comparison cohort (P = .0179). One subject in each cohort (0.50%) underwent a surgical procedure for the treatment of an upper urinary tract (P = 1.0000). CONCLUSIONS Gastric banding is not associated with an increased risk for kidney stone disease or kidney stone surgery in the postoperative period. Additional long-term studies are required to confirm these findings.

Ureteroscope Cleaning and Sterilization by the Urology Operating Room Team: The Effect on Repair Costs

BACKGROUND AND PURPOSE Flexible ureteroscopes are fragile devices, and the costs associated with their repair and replacement can be considerable. Although surgical use can degrade ureteroscope function, the cleaning and sterilization process can also cause great damage. We performed a study to define the effect of having the urology nursing staff process and sterilize all ureteroscopes, rather than the central processing core; the total repair cost and cost per use were analyzed. MATERIALS AND METHODS From April 2007 to March 2008, all ureteroscopes were processed by the urology nursing staff. We analyzed the average cost per use as a measure of the effectiveness of this strategy. For all endoscopic stone removal cases, a flexible ureteroscope is opened onto the operative field; therefore, after every endoscopic procedure, the flexible ureteroscope needs processing and sterilizing. The number of times each ureteroscope was processed and the type and cost of repairs were recorded. RESULTS From April 2007 to March 2008, 11 ureteroscopes were processed 478 times; average uses before repair was 28.1. Seven ureteroscopes were returned for repair because of: loss of deflection (2); loss of fiberoptic bundles (2); failed leak test (3). No ureteroscope damage was because of processing. The total repair cost in this 12-month period was

Half Fourier Single-shot Turbo Spin-echo Magnetic Resonance Urography for the Evaluation of Suspected Renal Colic in Pregnancy

57,664.50. Amortizing repair costs over use gives a value of

A prospective, multi-institutional study of flexible ureteroscopy for proximal ureteral stones smaller than 2 cm

120.63 cost per use. CONCLUSIONS Training the urology nursing staff to clean and sterilize ureteroscopes is a reasonable means to reduce processing-related damages.