Metabolic Acidosis After Enteroplasty for Myelomeningocele
Long-term followup of children who undergo augmentation cystoplasty has shown a high cumulative rate of complications including bladder stones, bladder perforation, infection, excessive mucous production and metabolic abnormalities related to incorporation of the bowel into the urinary tract. Adams et al (page 302) from Dallas, Texas retrospectively evaluated the records of 71 children with spina bifida who had undergone ileal or colonic enterocystoplasty. Exclusion criteria were preoperative renal insufficiency, preexistent metabolic acidosis, or gastric or ureteral augmentation. All patients routinely underwent yearly laboratory evaluation of electrolytes, blood urea nitrogen, creatinine, complete blood count and venous blood gases including ph, bicarbonate and partial pressure of carbon dioxide. The primary outcome measures were the comparative shifts in venous blood gases and electrolytes to determine new onset of metabolic acidosis for each patient and the entire cohort before and after surgery. Followup, which ranged from 1 to 138 months (mean 46.8) after enterocystoplasty, was intended to include potential changes immediately after surgery and after extended periods. No difference in pH, bicarbonate, partial pressure of carbon dioxide, electrolytes, blood urea nitrogen or creatinine was noted in any of the 71 patients before and after surgery. Specifically, hyperchloremia did not develop in any patient. The authors conclude from their longitudinal data and limited followup that development of metabolic acidosis is not a clinically significant risk in patients with a normal preoperative creatinine and electrolytes. The risk of metabolic acidosis in patients with preexistent renal insufficiency who undergo augmentation enterocystoplasty warrants future study.
Comparison of Flank, Dorsal Lumbotomy and Laparoscopic Approaches for Dismembered Pyeloplasty
The approach to pediatric pyeloplasty for ureteropelvic junction obstruction varies by individual surgeon and institutional preferences. Braga et al (page 306) from Toronto, Canada retrospectively compared the operative time, complications and success rate of 41 consecutive patients older than 3 years who underwent laparoscopic pyeloplasty by an experienced single surgeon between 2005 and 2008 with 67 age-matched controls who underwent open pyeloplasty by either a flank (42) or dorsal lumbotomy (25) approach between 2003 and 2008. After adjusting for a significantly lower frequency of retrograde pyelography in open vs laparoscopic cases, mean operative time for laparoscopy (165 minutes) was significantly longer than that for the flank (117) and dorsal lumbotomy (113) approaches (p = 0.008). Mean hospital stay was significantly shorter for the laparoscopic group (2.3 days) compared to the flank (3.6) and dorsal lumbotomy (3.3) approaches (p = 0.01). Complications occurred in 4 (10%) laparoscopic, 2 (5%) flank and 2 (7%) dorsal cases (p = 0.23). Pyeloplasty failed in 2 laparoscopy, 1 flank and 2 dorsal cases. Although failure rates were not significantly different between laparoscopy (5%) vs open surgery (4.5%) (p = 0.63), mean followup was significantly shorter for laparoscopy (28 months) vs flank (49) and dorsal (47) surgery (p = 0.02), reflecting the more recent implementation of laparoscopic pyeloplasty to treat children with ureteropelvic junction obstruction. The authors conclude that their findings do not support a particular surgical approach over the others when comparing laparoscopic with open surgical pyeloplasty in children older than 3 years.
Risk Factors and Treatment Success for Ureteral Obstruction After Renal Transplantation
Urological complications following renal transplantation in children include ureteral obstruction, extravasation, lymphoceles, urinary calculi, urinary infection and vesicoureteral reflux. From a retrospective evaluation of the institutional transplant database of 526 pediatric renal transplants performed from 1984 to 2008, Smith et al (page 317) from Minneapolis, Minnesota identified 42 patients in whom ureteral obstruction developed which required intervention. Donor and recipient demographics, treatment indications, graft characteristics, surgical techniques, treatment course, complications and graft outcomes were analyzed. Urodynamics were not routinely performed before or after transplantation, and patients were not formally assessed for functional vs anatomical obstruction. Ureteral obstruction presented within the first 100 days after transplantation in almost half of the cases. There was no significant difference in living vs cadaveric donor, graft harvest technique, human leukocyte antigen mismatch, type of ureterovesical anastomosis, mean ischemia time (cadaveric transplants) or stented vs nonstented anastomoses between patients with and without obstruction. Univariate and multivariate analyses revealed that renal failure secondary to posterior urethral valves was the only significant independent risk factor for the development of ureteral obstruction (univariate OR 4.93, p <0.0001; multivariate point estimate 7.59, p <0.0001). The authors conclude that a history of posterior urethral valves in children undergoing renal transplantation is a significant risk factor for ureteral obstruction and is likely due to local factors such as ischemia, bladder wall thickening, noncompliance secondary to prior obstruction and collagen remodeling.
Lower Urinary Tract Symptoms and Chronic Renal Failure
Lower urinary tract symptoms (LUTS) are common in children after renal transplantation, even in those without urological disorders. However, less is known about the incidence of LUTS in children before transplantation, particularly in those without urological disorders. Oborn and Herthelius (page 312) from Stockholm, Sweden report the findings from a consecutive enrollment of 27 boys and 13 girls with chronic renal failure into a study of lower urinary tract dysfunction before entering a local transplant program. The conditions causing renal failure were classified as urological disorders in 13 cases (posterior urethral valves 5, vesicoureteral reflux without or without multicystic kidney 7 and neuropathic bladder 1). Bladder function was assessed by a comprehensive voiding history, bladder diary, uroflowmetry and bladder ultrasound for post-void residual urine. The number, type and timing of previous urinary tract infections (UTIs) were recorded and classified as febrile or nonfebrile. Overall, daytime incontinence was reported in 20%, large bladder capacity in 47.5%, small bladder capacity in 12.5%, discontinuous flow of urine in 20% and increased post-void residual less than 20 ml in 15% of patients. These symptoms of bladder dysfunction were found in 100% of patients with urological disorders and 59% of those without urological disorders. A history of febrile UTIs was significantly more common in children with vs those without bladder dysfunction. The highest frequency of UTIs (78%) was found in children with emptying dysfunction. The authors conclude that LUTS are common in children with chronic renal failure due to urological and nonurological disorders, and that these children are at higher risk for febrile UTIs. They recommend that not only children with urological disorders, but also those with chronic renal failure due to nonurological disorders be screened and treated for underlying bladder dysfunction before renal transplantation.
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