Pediatric sacral nerve stimulator explanation due to complications or cure: a survival analysis

INTRODUCTION

Historically, there have been few treatment options for children with severe refractory bladder and bowel dysfunction (BBD). Sacral neuromodulation (SNM) continues to show promising results in this challenging pediatric population with recalcitrant lower urinary tract symptoms. At the authors institution, they have begun offering explantation to those with persistent improvement after >6 months of having device turned off. The authors hypothesized that (1) SNM explantation for cure increases with extended follow-up and (2) those explanted for cure would have improved symptoms and quality of life when compared to those explanted for complication.

MATERIALS & METHODS

The authors retrospectively reviewed all consecutive patients aged <18 years who underwent SNM placements at their institution (2012-2017). They excluded those without the second stage procedure. Reasons for device explantation were categorized as cure (resolution of symptoms with the device turned off for at least 6 months) or a complication (e.g. infection, need for magnetic resonance imaging, or pain). Non-parametric tests and survival analysis were used for analysis to account for differential follow-up time. Of those explanted, surveys were electronically sent to assess BBD severity and overall quality of life.

RESULTS

Of 67 children who underwent a first stage procedure, 62 (92.5%) underwent a second stage procedure. 61 met inclusion criteria (68.9% female, 29.5% with previous filum section, median age at implantation 10.3 years). During follow-up (median 2.3 years), 12 patients (19.7%) had the SNM exchanged/revised because of lead fracture/breakage and return of urinary symptoms. To date, 50 patients remain with their SNM implanted, and 11 have been explanted. Adjusting for follow-up time, the risk of explantation was 6.5% at 2 years (2.2% for cure, 4.3% for complications) (Figure 1). Explantation increased to 24.5% at 3 years (16.5% for cure, 8.0% for complications) and 40.4% at 4 years (32.4% for cure, 8.0% for complications). Questionnaires were collected on patients after explant (median 2.2 years), with improvement in those explanted for cure compared to complication (Figure 2).

DISCUSSION

Sacral neuromodulation explantation for cure is a novel concept previously not described in the literature. Limitations of this study include the relatively small numbers and lack of objective data in the cohort that remains with SNM device implanted.

CONCLUSION

Sacral neuromodulation is a safe, viable option for the pediatric patient with refractory bladder dysfunction. Furthermore, SNM explantation for cure is an option with increasing likelihood after 2 years.

Early readmission and reoperation characteristics of ambulatory hypospadias repair

INTRODUCTION AND BACKGROUND

Hypospadias is a common birth defect. It is present in about 34.2 in 10,000 live births in North America. However, few studies have evaluated the immediate reoperation and readmission rates following elective repair.

OBJECTIVE

This study aimed to define the rates of readmission and reoperation following elective hypospadias repair, to improve pre-operative counseling on risks of the procedure.

STUDY DESIGN

The Pediatric Health Information System (PHIS) was interrogated from 2004 to 2015 for all elective hypospadias repairs (ICD-9-CM code 58.45) performed in the ambulatory surgical setting. The following were then determined: age at initial operation, insurance status, race, presence or absence of readmission or reoperation within 30 days, presence of repeat hypospadias repair (same ICD-9 code), and presence or absence of another urethral operation (ICD-9 CM code 58.XX, excluding 58.45). Mixed effects logistic regression were then performed with dependent variables of 30-day repeat encounter, 30-day emergency department (ED) visit, 30-day readmission, or 30-day reoperation; and independent variables of age, race, ethnicity, and insurance status.

RESULTS

The study identified 45,264 hypospadias repairs during 2004-2015 performed in 43 hospitals. Within 30 days of the procedures, 2826 (6.2%) had additional encounters in the ED at the same facilities, and 546 (1.2%) had readmissions. A total of 105 (0.2%) underwent second anesthetic within the first 30 days. With regards to a 30-day repeat encounter, odds of repeat encounter were significantly increased in patients aged <5 years, Black and Asian patients, and those with Medicaid. Of the 4882 repeat encounters, 954 (19.5%) had discharge ICD-9 codes related to the penis, or to postoperative complications in general.

DISCUSSION

This study described the epidemiology of clinical events occurring at the same tertiary children's hospital within the first 30 days following more than 45,000 hypospadias repairs. Limitations included a cohort generated from a single set of ICD-9 codes.

CONCLUSIONS

Elective hypospadias repair had a low rate of readmission (1.2%) and reoperation (0.2%) within the first 30 days. Patients aged <5 years, of non-white race, Hispanic ethnicity, and on Medicaid had significantly higher odds of 30-day repeat encounters.

Incidence of pathologic postobstructive diuresis after resolution of ureteropelvic junction obstruction with a normal contralateral kidney

INTRODUCTION

Postobstructive diuresis (POD) after unilateral pyeloplasty or percutaneous nephrostomy (PCN) tube insertion for ureteropelvic junction obstruction (UPJO) in patients with a normal contralateral kidney is not well described.

OBJECTIVE

The objective of this study was to determine the incidence and characteristics of POD after relief of unilateral UPJO in patients with a normal contralateral kidney.

STUDY DESIGN

Children who underwent a unilateral pyeloplasty or PCN for UPJO from 2010 to 2017 with a normal contralateral kidney were retrospectively reviewed. Postobstructive diuresis was defined as urine output (UO) of >300% of expected UO. Patients with a solitary kidney or those who underwent bilateral pyeloplasty or bilateral PCN tube placement were excluded.

RESULTS

Out of 396 children meeting inclusion criteria, seven (1.8%) developed POD (4 after pyeloplasty and 3 after PCN tube placement). Median age at intervention was 1.7 years (range 11 days-18 years); median weight was 11.4 kg (range 3.7-54.2 kg). Postobstructive diuresis was more likely to occur in patients with grade 4 hydronephrosis (3.0%) and larger kidneys and if a PCN tube was placed before pyeloplasty. There was no significant difference in age, gender, kidney laterality, or function between those who developed POD and those who did not. Postobstructive diuresis was managed with additional intravenous fluids and electrolyte monitoring. Median initial postprocedure UO was 5.9 mg/kg/hr (range 3.2-10.0 mg/kg/hr). In five children who underwent PCN in whom UO could be differentiated between kidneys, median initial postprocedure UO was 6.1 mg/kg/hr (range 2.5-9.1 mg/kg/hr) from the affected side and 0.8 mg/kg/hr (range 0.4-0.9 mg/kg/hr) from the unaffected side. The median length of time to resolution of POD was 3 days (range 2-4 days). One patient developed significant acidosis and lethargy that improved with intravenous fluid management. Mild hyponatremia developed in two, hypokalemia in one, hypophosphatemia in one, acidosis in one, and hypoglycemia in 1 patient.

DISCUSSION

A low but clinically significant risk of POD occurring after relief of unilateral UPJO in children with a normal contralateral kidney is described. Limitations include retrospective analysis and small sample size due to the rarity of the condition.

CONCLUSION

Postobstructive diuresis after decompression of UPJO in patients with a normal contralateral kidney is a rare event (1.8%). However, POD does occur, and patients should be carefully monitored after these procedures given the potential for significant dehydration and electrolyte disturbances.

The ability of a limited metabolic assessment to identify pediatric stone formers with metabolic abnormalities

INTRODUCTION

American Urological Association guidelines recommend a urinary metabolic evaluation after the first stone event in all pediatric stone patients. Prior studies identified hypercalciuria and urine hypovolemia as the most common abnormalities in children with urolithiasis. Recent data suggest that hypocitraturia is most prevalent. It was hypothesized that a limited evaluation would detect the majority of clinically significant metabolic abnormalities in pediatric stone formers.

MATERIAL AND METHODS

A retrospective analysis of all children (<18 years of age) with renal/ureteral calculi evaluated at the study institution from 2005 to 2015 was performed. Children with ≥ one 24-h urinary metabolic profile after a clinical visit for renal/ureteral calculi were included. Those with bladder stones and those with undercollection or overcollection or missing urinary creatinine were excluded. Demographics and data from the first urinary metabolic profile and stone analyses were collected. The sensitivity, specificity, and positive and negative predictive value (NPV) of a limited urinary metabolic evaluation consisting of four parameters (24-h calcium, citrate, and oxalate and low urinary volume) were compared to a complete urinary metabolic profile. The number and type of metabolic abnormalities that would have been missed with this limited evaluation weredetermined.

RESULTS

Of 410 patients, 21 were excluded for age ≥18 years, 13 for bladder stones, 248 for overcollections, 38 for undercollections, and 10 for missing creatinine. This left 80 patients for inclusion: median age 11.4 years, 60% female, and 96.3% white. Of the entire cohort, 69.6% had hypocitraturia, 52.5% had low urine volume, and 22.5% had hypercalciuria. Sensitivity was 87.5%. Specificity could not be calculated because no patients had a normal complete metabolic evaluation. The NPV was zero, and the positive predictive value was 100%, but these are artifacts resulting from the absence of patients with a normal complete metabolic evaluation. Of the 80 patients, 10 had at least one abnormality missed by a limited metabolic evaluation (Table 1). The missed abnormalities were high pH (n = 6), abnormal 24-h phosphorus (low in 1 patient and high in 1 patient), low 24-h magnesium (n = 3), low 24-h potassium (n = 3), and high 24-h sodium (n = 4).

DISCUSSION

A limited urinary metabolic evaluation would have detected the vast majority of clinically significant metabolic abnormalities in the study sample. Approximately two-thirds of the study patients submitted inadequate 24-h urine specimens.

CONCLUSIONS

A simplified approach to metabolic evaluation in first-time stone formers with a stone analysis available was proposed. This streamlined approach could simplify the metabolic evaluation and reduce health care costs.

Is renal scintigraphy necessary after heminephrectomy in children?

INTRODUCTION

Heminephrectomy remains an excellent option for a poorly functioning moiety in a duplicated collecting system. A primary concern during heminephrectomy is the potential for a significant functional loss in the remaining ipsilateral moiety. As the gold standard for the assessment of differential renal function, renal scintigraphy is often used in the postoperative evaluation of children undergoing heminephrectomy. However, this imaging modality is costly, invasive, and associated with exposure to radiation. Doppler renal ultrasound (RUS) avoids these concerns and is able to evaluate for structural and functional abnormalities.

OBJECTIVE

The present study sought to compare Doppler RUS to renal scintigraphy in determining the viability of the remaining ipsilateral moiety in children who underwent heminephrectomy for a poorly functioning moiety in a duplicated collecting system.

MATERIALS AND METHODS

The institutional database of children who underwent open heminephrectomy for a poorly functioning moiety in a duplicated collecting system between 2006 and 2013 was reviewed. Only children who underwent both a postoperative Doppler RUS and renal scan were included. A blinded pediatric radiologist independently reviewed all Doppler RUS. Vascular flow on Doppler RUS was correlated with the preservation of renal function in the remaining ipsilateral moiety on renal scintigraphy.

RESULTS

A total of 29 children were identified for inclusion. Demographic and operative data are provided in Table. The average pre-operative and postoperative differential renal function in the ipsilateral kidney was 41.6% and 38% on renal scintigraphy, respectively, for an average decrease of 3.6% (-18% to +12%). Doppler RUS demonstrated the presence of vascular flow to the remaining ipsilateral moieties of all children after heminephrectomy. Renal scintigraphy confirmed the viability of these moieties in all children.

DISCUSSION

The first study comparing Doppler RUS to renal scintigraphy was performed to determine the viability of the remaining ipsilateral moiety after heminephrectomy. While no cases of complete functional loss were observed, an average decrease of 3.6% in the ipsilateral renal function favorably compared with other series of children undergoing open heminephrectomy. The limitations of the study included its retrospective design at a single institution. The interpretation of Doppler RUS by an individual pediatric radiologist may also have lead to interobserver variability and impacted the reproducibility of the study, while the absence of any cases of complete functional loss may have impacted its generalizability.

CONCLUSIONS

Doppler RUS is an accurate imaging modality for determining the viability of the remaining ipsilateral moiety after heminephrectomy and may obviate the need for renal scintigraphy.

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.