A case of base rate bias, or are adolescents at a higher risk of developing complications after catheterizable urinary channel surgery?

OBJECTIVE: Adolescents are considered to be at high risk of developing complications after lower genitourinary tract reconstruction. This perception may be due to base rate bias, where clinicians favor specific information (adolescents with complications), while ignoring more general information (number of total adolescents being followed). The goal of this study was to assess whether age was a true risk factor for subfascial and stomal revisions after continent catheterizable urinary (CCU) channel procedures. MATERIALS AND METHODS: Consecutive patients aged <21 years and who underwent appendicovesicostomy and Monti surgery at the present institution were retrospectively reviewed; demographic and surgical data were collected. Time to subfascial or stomal revision was stratified by age at initial surgery (child: <8, preteen: 8-12, adolescent: 13-17, adult: ≥18 years old) and analyzed with Cox proportional-hazards regression. Secondary analyses included: different age categories at initial surgery (<8, 8-11, 12-15, 16-19, ≥20 years), analyzing age as a continuous and a time-varying covariate. RESULTS: Of the 510 patients with CCU channels (median age at surgery: 7.9 years), 63 (12.4%) had subfascial and 53 (10.4%) had stomal revision (median follow-up: 6.8 years). Median age at subfascial and stomal revision was 11.3 and 10.3 years, respectively. Preteens contributed 33.0% and adolescents contributed 29.3% of the total follow-up time (3263.9 person-years). Over 80% of revisions occurred within 5 years of surgery, regardless of age at initial surgery (P ≥ 0.57) (Summary table). On multivariate analysis, age at initial surgery was not associated with undergoing subfascial (P ≥ 0.62) or stomal revisions (P ≥ 0.69). Montis were 2.1 times more likely than appendicovesicostomies to undergo a subfascial revision (P = 0.03). No other variables were associated with the risk of subfascial or stomal revision (P ≥ 0.11). Secondary analyses provided similar results. DISCUSSION: Since the median age at surgery was 8 years old and most complications occurred within the first 5 years of follow-up, it is not surprising that most revisions occurred in 8-13 year olds. Pediatric urologists appear to base their impression of adolescents being "high risk" on specific information (adolescents having complications), while subconsciously ignoring more general information (adolescents represent a large proportion of patients in follow-up). This study had several limitations: channel complications treated non-surgically (e.g. prolonged catheterization) were not included. The findings may not be generalizable to other genitourinary reconstructive procedures or clinical settings. CONCLUSIONS: While complications were twice as high in Monti channels than appendicovesicostomies, no single age group was at increased risk. The impression that adolescents are a high-risk group appears to represent a base rate bias.

A comparison of the Monti and spiral Monti procedures: A long-term analysis.

INTRODUCTION/BACKGROUND: The Monti ileovesicostomy provides an excellent substitution for an appendicovesicostomy when the appendix is unavailable or suitable for use. The spiral Monti is a useful modification to the traditional Monti as it allows creation of a longer channel when needed. In 2007, the short-term outcomes were reported; they compared traditional and spiral Monti in 188 patients with an average follow-up of 43 months. In the present population, a total of 25 subfasical revisions were performed in 21 patients: nine (8.3%) subfascial revisions in the traditional Monti (TM) patients and 12 (15.2%) subfascial revisions in the spiral Monti (SM) patients. The study found an increased risk of subfascial revisions of either TM or SM when the stoma was located at the umbilicus versus right lower quadrant (16.8% vs 6.3%, P < 0.05). On subgroup analysis, this increased subfascial revision rate appeared to be driven by SM channels to the umbilicus rather than other stomal locations, but this trend was not statistically significant. OBJECTIVE: It was hypothesized that with longer follow-up, the spiral Monti would require more subfascial revisions due to progressive lengthening of the channel. STUDY DESIGN: A retrospective chart review was performed for all patients undergoing a traditional Monti (TM) or spiral Monti (SM) procedure at the present institution (1997-2013). Patient demographics, bowel segment used, stomal location, channel or stomal revisions, number of anesthetic endoscopic procedures performed, and indications for revision were reviewed. Kaplan-Meier analysis and Cox proportional hazards modeling was used for analysis. RESULTS: Of the 296 patients identified, 146 had Monti procedures and 150 had spiral Monti procedures (median follow-up 7.7 years). Median age at surgery was 10.6 years. Myelomeningocele was the most common underlying cause of neuropathic bladder, totaling 169 (57.1%) patients. Stomas were located at the umbilicus (106, 35.8%), right lower quadrant (183, 61.8%) and left lower quadrant (seven, 2.4%). Median follow-up for the entire cohort was 7.7 years (range: 1 month-15.7 years). Stomal stenosis rate was 7.4%, and 96.6% of the channels were continent. A total of 87 revisions were performed in 74 patients (25.0%). Of these, 55 were subfascial revisions in 49 patients (16.6%). The umbilical spiral Monti on univariate and multivariate analysis was found to be over twice as likely to undergo subfascial revision. DISCUSSION: The majority of patients with a Monti channel had durable results and did not require further channel surgery with long-term follow-up. Spiral Monti channels to the umbilicus were more than twice as likely to undergo subfascial revision compared to all other Monti channels. Overall, one in three umbilical SM channels required a subfascial revision at 10 years after the initial surgery, compared to one in six of all other Monti channels. The study was limited by being a retrospective, single-center series; however, it does represent the largest series of pure SM and TM patients. It focused only on surgical interventions, thus was likely to underestimate the overall risk of complications, as some complications were managed conservatively. As in all studies, some patients were lost to follow-up and inevitably some of these may have had complications. Correction for this was attempted through survival analysis. CONCLUSION: The present study reported durable and reliable long-term results with Monti and spiral Monti procedures based on a large patient cohort. Spiral Monti to the umbilicus was more than twice as likely to require a subfascial revision.

Successful separation of ischiopagus tripus conjoined twins with comparative analysis of methods for abdominal wall closure and use of the tripus limb.

The authors report the successful delivery, preoperative management, and postoperative courses of ischiopagus tripus twin girls successfully separated at 5 months of age. Surgical objectives were predicated on survival and optimum postseparation reconstructive potential for both girls. Each twin has subsequently undergone additional procedures, and both are doing well 2 years after separation. The authors reviewed 17 known cases of ischiopagus tripus separation, comparing anatomic findings, use of the tripus limb, operative strategies, and attainment of abdominal closure. This 18th case includes the first report of splitting the tripus limb and giving each girl a femur. The authors found that detailed systemic investigation, advanced coordinated teamwork with appropriate technical support, applications of new technologies or reapplication of existing technologies, meticulous planning, and favorable anatomy were vital in yielding favorable outcomes.

Experimental pyelonephritis in piglets: diagnosis with MR imaging.

PURPOSE: To compare findings at magnetic resonance (MR) imaging with those at histopathologic examination in the detection of experimentally induced pyelonephritis in piglets. MATERIALS AND METHODS: MR imaging was performed in 23 piglets with and nine piglets without experimentally induced pyelonephritis. Escherichia coli were injected into the bladder of the 23 piglets with surgically created vesicoureteral reflux. Imaging was performed with unenhanced and contrast material-enhanced T1-weighted and fast multiplanar inversion-recovery (IR) and fast spinecho T2-weighted sequences. MR images and pathologic findings were reviewed independently by two pediatric radiologists and a pathologist, respectively, in a blinded fashion. RESULTS: Sixty-four kidneys and 192 renal zones were evaluated. Coronal gadolinium-enhanced fast multiplanar IR imaging was the only sequence that was sensitive and specific for the diagnosis of pyelonephritis. For the two reviewers, respectively, sensitivity was 85% (n = 75) and 92% (n = 81) of 88 histopathologically positive zones and specificity was 95% (n = 99) and 94% (n = 98) of 104 pathologically negative zones. Findings at gadolinium-enhanced fast multiplanar IR imaging were not statistically different from findings at histopathologic examination in the detection of pyelonephritis. Interobserver reproducibility for the contrast-enhanced fast multiplanar IR sequence was excellent (kappa statistic = 0.82 and 0.90, respectively, for interpretation of a renal zone and of a kidney). CONCLUSION: Contrast-enhanced fast multiplanar IR imaging is a sensitive and specific test for detection of experimental pyelonephritis in this piglet model.

Rectus fascial wrap: early results of a modification of the rectus fascial sling.

We describe an operation that increases bladder neck resistance in patients with urinary incontinence. It is a modification of the rectus fascial sling that was designed as an adjunct to augmentation cystoplasty and is used in association with clean intermittent catheterization. The operation is performed by circumferentially wrapping a rectus fascial defatted free graft around the bladder neck and suturing it to appose the bladder neck. The procedure was done in 17 patients, including 10 with myelodysplasia, 3 with sacral lipoma, 3 with bladder exstrophy and 1 with nonneurogenic neurogenic bladder. Leak point pressure improved in patients in whom it was measured preoperatively and postoperatively. Complications developed in 5 patients, including difficulty with catheterization in 2, ventral hernia at the graft harvest site in 1, bladder calculus in 1 and detrusor hyperreflexia in 1. Early results with the bladder fascial wrap indicate that it has the ability to improve continence in patients with a dysfunctional bladder neck who have undergone augmentation.

Onlay-tube-onlay urethroplasty technique in primary perineal hypospadias surgery.

We extended the principles of the onlay flap to the most severe hypospadias cases. Four patients with perineal hypospadias required central division of the urethral plate to correct chordee despite dorsal plication. The urethra was reconstructed in 1 stage by proximally and distally onlaying to the remaining urethral plate a flap with its central portion tubularized to fill the gap where there was no longer a urethral plate. All patients have good cosmetic and functional results at 1 year of followup. There were no strictures or diverticula but 1 fistula developed. This technique extends the principles and advantages of an onlay flap to those severe hypospadias cases that require division of the urethral plate to correct chordee.

The multicystic dysplastic kidney and contralateral vesicoureteral reflux: protection of the solitary kidney.

The diagnosis of multicystic renal dysplasia is confirmed by a combination of sonography and radionuclide scan. If the contralateral kidney is normal by these criteria, further radiological examination is often omitted. We prospectively studied 29 patients with a diagnosis of multicystic renal dysplasia by voiding cystourethrography to determine the condition of the solitary contralateral kidney. Eight patients (28%) were found to have contralateral vesicoureteral reflux, of whom 6 had normal ultrasound examinations and would not have undergone further radiographic study based on ultrasound criteria alone. Contralateral vesicoureteral reflux in association with multicystic renal dysplasia puts solitary kidneys at risk for pyelonephritic scarring. Therefore, voiding cystourethrography should be performed as part of the initial evaluation of all infants with multicystic renal dysplasia.

Vaginoplasty: combination therapy using labia minora flaps and lucite dilators--preliminary report.

The treatment of vaginal agenesis is varied. The combination of creating a vaginal cavity with local skin flaps, then progressively dilating to a functional size has been successful in the past. We describe a technique using tubularized labia minora vascularized flaps to create a deep vaginal pouch that is widened and elongated with lucite dilators. The new vagina has an epithelial lining of nonhair-bearing skin. Three teenage girls, 2 with the Mayer-Rokitansky syndrome and 1 with mixed gonadal dysgenesis, underwent this procedure without any postoperative complications. Since neither abdominal surgery nor skin grafting was required there were no extra scars, excessive neovaginal secretions or need for long-term splinting during the 1-year followup period. The patients have almost normal-appearing genitalia postoperatively and neovaginas averaging 2 cm. wide and 6.3 cm. deep before dilation. We recommend this procedure as first line treatment for teenage girls with vaginal agenesis.

Improved lymphocyte cytotoxicity against murine renal cell carcinoma.

In this paper we describe the generation of antibody dependent cellular cytotoxicity against a murine renal cell carcinoma. Using human recombinant interleukin-2 and in vitro adherence to plastic, we generated lymphokine activated killer and adherent lymphokine activated killer cells. Adherent lymphokine activated killer cells had significant (p less than 0.05) higher unrestricted cytotoxicity than LAK cells. Using a rabbit antibody against Renca developed in our laboratory, we induced significant (p less than 0.01) antibody dependent cellular cytotoxicity using fresh spleen, lymphokine activated killer and adherent lymphokine activated killer cells. The strongest antibody dependent cellular cytotoxicity killing was mediated by adherent lymphokine activated killer cells and was restricted only to the renal cell carcinoma target. Using FACS cell surface analysis and antibody and complement depletion of selected effector cell subsets, we also demonstrate that the antibody dependent cellular cytotoxicity effector cell population consists of asialoGM1+ Lyt 2.1- natural killer cells. This first description of antibody dependent cellular cytotoxicity against renal cell carcinoma by activated natural killer cells suggests a novel method for more efficient use of cytotoxic effector cells against this type of cancer.

Prevention of interference by dextran with biuret-type assay of serum proteins.

In assay of serum proteins by use of the biuret reaction, dextran can cause turbidity by formation of an insoluble complex of dextran with copper and tartrate (or EDTA) in strongly alkaline solution. Whether or not the turbidity occurs depends on the tartrate concentration: turbidity is maximal at about 10 g/L, absent at 20 g/L or more, and only slight and delayed at 4 g/L. Two biuret reagents, containing respectively 5.6 and 22.5 g of tartrate per liter, obviate the interference, but the former is suitable only when a short (5 min) incubation is used. Both reagents show linear calibration curves and yield virtually identical results.