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Introduction: While most children with classic bladder exstrophy (CBE) are born with normal kidneys, some experience renal deterioration in adulthood. Little is known about the incidence of end-stage and chronic kidney disease (ESKD and CKD, respectively) in this population. Our group has recently published on surgical outcomes in a multi-institutional cohort of 216 people with CBE. Our aim was to describe the incidence of ESKD and prevalence of CKD in this cohort of people with CBE., Methods: We retrospectively reviewed records of patients with CBE followed at five tertiary care centers described previously. The primary outcome was incidence of ESKD, defined as permanent peritoneal/hemodialysis or renal transplantation. The secondary outcome was prevalence of CKD stage 3 or higher (CKD3+, estimated glomerular filtration rate [eGFR]<60 ml/min/1.73 m 2 ) at the last appointment. Creatinine-based eGFRs were calculated using the CKD-EPI Creatinine Equation (adults) and the Schwartz formula (children). Survival analysis and Fisher's exact test were used., Results: A total of 201 patients (93 % of the original cohort) had renal function data available (63 % male). Four patients who had a primary urinary diversion remained diverted at a median follow-up of 20.1 years. None developed ESKD and one developed CKD3+. The remaining 197 patients had a primary bladder closure. At a median follow-up of 18.8 years old, 12 were diverted, 108 were augmented and 77 were neither. Three patients developed ESKD (1.5 %) at a median age of 23.4 years (1 hemodialysis, 2 transplantation). On survival analysis, the risk of ESKD was 0 % at 10 years, 1 % at 20 years and 5 % at 30 years (Figure 1). This was higher than the risk of 0.003 % at 21 years of age in the general population (p < 0.001). The median age of 141 individuals with eGFR data was 21.6 years old (65 % male). No children, 4 % of adolescents and 8 % of adults had CKD3+ (p = 0.45). On exploratory analyses, prevalence of CKD3+ did not differ by center or birth year (p ≥ 0.99)., Conclusions: The risk of ESKD and CKD among patients with CBE is not insignificant and appears to be more common than the general population. The potential role of modifiable contributing factors, such as increased bladder outlet resistance, warrants further investigation. Reliable long-term follow up is needed in this population to monitor for ESKD and CKD., Competing Interests: Conflicts of interest None., (Copyright © 2024 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Background: Girls with cloacal malformation are at risk of bladder dysfunction, with nearly 90% exhibiting some degree of dysfunction. Surgical dissection, particularly with total urogenital mobilization (TUM), has been hypothesized as a cause of worsening bladder function despite this population commonly having associated vertebral and spinal cord abnormalities that may also explain bladder dysfunction. More recently there has been great effort to select the appropriate surgical technique for cloacal repair in each patient in order to minimize dissection and potential damage to the bladder. We aimed to evaluate the effect of surgical cloacal repair on bladder function based on pre and post-surgery urodynamics (UDS) testing., Methods: A prospectively collected database of patients with anorectal malformation at a single center was queried for girls with cloacal malformations who had undergone surgical repair from 2015 to 2022. It is our current protocol to perform UDS before and after cloacal repair. Only patients who completed both pre and post-surgery UDS were included. UDS were evaluated and classified using the UMPIRE protocol., Results: A total of 48 patients were included in the cohort. The majority of patients (79.2%) had stable or improved UDS post-op leaving 10 patients (20.8%) who had worsening UDS. Long common channel (≥3 cm) was the only factor significantly associated with worsening UDS. (p = 0.03) Nearly 30% (n = 8) of those undergoing UGS had worse post-op UDS compared to 9.5% (n = 2) with TUM. All patients who worsened UDS initially had safe UDS that changed to intermediate, except for one who worsened to hostile in the setting of significant social challenges and non-compliance. Only common channel length was predictive of worsening UDS, while the type of surgical approach and spine status were not. While the overall risk of worsening UDS after TUM is only 9.5%, patients with normal spines undergoing TUM had the lowest risk, seen in only one in 15 patients (6.6%)., Conclusions: Common channel length was the most significant predictor of worsening UDS, while spine status and surgical technique (TUM vs UGS) did not significantly impact this finding. By following this established surgical protocol based on common channel and urethral lengths, is rare for the surgical cloacal repair to result in worsening post-op UDS, particularly in those undergoing TUM for short common channel and normal spine., Competing Interests: Conflicts of interest None., (Copyright © 2024 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Background: In children with cloacal malformations, renal dysfunction is a constant concern, with reported incidence as high as 50%. Multiple factors exist that may impair renal function. Our institution follows a strict renal protection protocol in this population. Incidence of renal dysfunction in these patients is unknown., Objective: We aimed to evaluate incidence of renal dysfunction while implementing this protocol in a cohort of children with cloacal malformation., Study Design: We reviewed a prospectively collected database of children with cloacal malformations managed at a single institution since implementation of a renal protection protocol. This involves regular laboratory evaluation, appropriate selection of total urogenital mobilization or urogenital separation, proactive imaging in patients with signs of impending renal dysfunction or urinary retention, and early catheterization teaching and implementation if necessary. Glomerular filtration rate (GFR) was calculated with the Schwartz formula and CKD grades assigned per standard definitions. Renal dysfunction was defined as CKD grade 3b or higher, need for renal replacement therapy (RRT) or transplantation. Descriptive statistics were computed., Results: A total of 105 children were managed under this protocol with a median follow-up of 4.2 years [IQR: 2.0-5.9]. Six children (5.7%) had renal dysfunction at most recent follow-up; of these children, only three (2.9%) progressed from normal renal function at initial evaluation to renal dysfunction (Table). No child with normal presenting renal function thus far has progressed to require dialysis or transplantation., Discussion: Previous literature estimated rates of renal dysfunction in cloaca patients as high as 50%; in contrast, we demonstrate a rate of progression to renal dysfunction of 2.9% in girls following a strict renal protection protocol. Most children who developed renal dysfunction had dysfunctional kidneys on presentation. This suggests that preservation of renal function may be possible in early childhood with a strict, multi-disciplinary renal protection protocol., Conclusion: In our cohort of patients with cloacal malformations following a strict renal protection protocol, incidence of progressive renal dysfunction is low at 2.9%. Most who go on to renal dysfunction present with impaired renal function., Competing Interests: Conflict of interest The authors have no conflicts of interest to disclose., (Copyright © 2024 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Background: Multiple factors impact ability to achieve urinary continence in cloacal malformation including common channel (CC) and urethral length and presence of spinal cord abnormalities. Few publications describe continence rates and bladder management in this population. We evaluated our cohort of patients with cloacal malformation to describe the bladder management and continence outcomes., Methods: We reviewed a prospectively collected database of patients with cloacal malformation managed at our institution. We included girls ≥3 years (y) of age and evaluated their bladder management methods and continence. Dryness was defined as <1 daytime accident per week. Incontinent diversions with both vesicostomy and enterovesicostomy were considered wet., Results: A total of 152 patients were included. Overall, 93 (61.2%) are dry. Nearly half (47%) voided via urethra, 65% of whom were dry. Twenty patients (13.1%) had incontinent diversions. Over 40% of the cohort performed clean intermittent catheterization (CIC), approximately half via urethra and half via abdominal channel. Over 80% of those performing CIC were dry. In total, 12.5% (n = 19) required bladder augmentation (BA). CC length was not associated with dryness (p = 0.076), need for CIC (p = 0.253), or need for abdominal channel (p = 0.497). The presence of a spinal cord abnormality was associated with need for CIC (p = 0.0117) and normal spine associated with ability to void and be dry (p = 0.004) CONCLUSIONS: In girls ≥ 3 y of age with cloacal malformation, 61.2% are dry, 65% by voiding via urethra and 82% with CIC. 12.5% require BA. Further investigation is needed to determine anatomic findings associated with urinary outcomes., Level of Evidence: IV., Competing Interests: Conflict of interest None., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Purpose: Urodynamic testing (UDS) is an important tool in the management of pediatric lower urinary tract conditions. There have been notable efforts to standardize pediatric UDS nomenclature and technique, but no formal guidelines exist on essential elements to include in a clinical report. We sought to identify ideal structure and elements of a pediatric UDS assessment based on expert consensus., Materials and Methods: Pediatric urologists regularly performing UDS were queried using a Delphi process. Participants were invited representing varied geographic, experience, and societal involvement. Participants underwent 3 rounds of questionnaires between November 2022 and August 2023 focusing on report organization, elements, definitions, and automated electronic health record clinical decision support. Professional billing requirements were also considered. Consensus was defined as 80% agreeing either in favor of or against a topic. Elements without consensus were discussed in subsequent rounds., Results: A diverse sample of 30 providers, representing 27 institutions across 21 US states; Washington, District of Columbia; and Canada completed the study. Participants reported interpreting an average number of 5 UDS reports per week (range 1-22). The finalized consensus report identifies 93 elements that should be included in a pediatric UDS report based on applicable study conditions and findings., Conclusions: This consensus report details the key elements and structure agreed upon by an expert panel of pediatric urologists. Further standardization of documentation should aid collaboration and research for patients undergoing UDS. Based on this information, development of a standardized UDS report template using electronic health record implementation principles is underway, which will be openly available for pediatric urologists.

Introduction: Robotic-assisted surgery (RAS) is an increasingly utilized tool in children. However, utilization of RAS among infants and small children has not been well established. The purpose of this study was to review and characterize RAS procedures for children ≤15 kg. Methods: We performed a single institution retrospective descriptive analysis including all patients ≤15 kg undergoing RAS between January 2013 and July 2021. Data collection included procedure type, age, weight, gender, and surgical complications. Cases were further categorized according to surgical specialty: pediatric urology (PU), pediatric surgery (PS), and multiple specialties (MS). t -Tests were used for statistical analyses. Results: Since 2013, a total of 976 RAS were identified: 492 (50.4%) were performed by PU, 466 (47.8%) by PS, and 18 (1.8%) by MS. One hundred eighteen (12.1%) were performed on children ≤15 kg, consisting of 110 (93.2%) PU cases, 6 (5.1%) PS cases, and 2 (1.7%) MS cases. Procedures were significantly more common in the PU subgroup, mean of 12 cases/year, compared to PS subgroup, mean of 0.63 cases/year, ( P  < .01). The mean weight of PU patients (10.5 kg) was significantly less than PS patients (13.9 kg) ( P  < .01). Mean age was also significantly lower among PU patients (18.6 months) compared to PS (34.2 months) ( P  < .01). Conclusion: RAS among patients ≤15 kg is safe and feasible across pediatric surgical subspecialties. RAS was performed significantly more frequently by pediatric urologists in younger and smaller patients compared to pediatric surgeons. Further refinement of robotic technology and instrumentation should enhance the applicability of these procedures in this young group.

Robotic assisted (RA) retroperitoneal lymph node dissection (RPLND) has grown in popularity as it offers decreased morbidity and faster recovery compared to the open technique. Proponents of open surgery raised concerns about the oncological fidelity of the RA approach for testicular tumors where complete resection is needed. In boys > 10 years with paratesticular rhabdomyosarcoma (RMS), RPLND is indicated for staging purposes only. In this population, the RA technique should provide its benefits without concerns for oncological compromise. We present an analysis of RA-RPLND for boys with paratesticular RMS. We queried our institution's prospectively collected database of pediatric robotic cases for patients undergoing RA-RPLND post-radical orchiectomy for paratesticular mass, confirmed by pathology as RMS. Demographic, surgical, follow-up, and oncological outcomes were evaluated between 2017 and 2023. Five patients underwent RA-RPLND for paratesticular RMS. The median age was 16.1 years (15-17), with median OR time of 456 min (357-508). No conversions to open occurred. Inpatient median total opioid use was 1.8 (0.4-2.7) morphine equivalent/kg. The median lymph node yield was 27 (8-44) and post-op length of stay was 3 days (2-5). The median time to initiating adjuvant chemotherapy was 10.5 days (7-13). One patient had complications: pneumothorax attributed to central line placement and chyle leak that resolved in 1 week with dietary restriction. Our series demonstrates the feasibility, safety, and efficacy of the RA approach for RPLND in pediatric patients with paratesticular RMS. This is the most extensive case series currently in the literature and the only one exclusively done for paratesticular RMS., (© 2023. The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.)

Aim: To evaluate the sexual and reproductive health education received by patients with myelomeningocele, the most severe form of spina bifida., Method: A survey designed to assess the sexual and reproductive health education given by a healthcare provider to patients with myelomeningocele was offered to all English-speaking patients aged 12 years or older with a myelomeningocele clinic visit., Results: In total, 67 surveys were completed. Menstruation and menstrual management were discussed at a rate of 85% in females. Few patients had discussions with a provider about fertility (42%), sexuality (37%), risk of sexually transmitted infections (45%), or had a relationship with a reproductive healthcare provider (54%). Differences by sex were observed for contraceptive education. The rate of discussions increased with age. A total of 67% of female patients and 33% of male patients requested a referral to a reproductive healthcare provider., Interpretation: Sexual and reproductive health education is part of comprehensive care for all patients and those with disabilities should not be excluded. The lack of consistent education received by patients supports the need for increased attention to this topic. We encourage multidisciplinary myelomeningocele clinics to establish a process for delivering complete and patient-specific sexual and reproductive health education., (© 2023 Mac Keith Press.)

Background: We sought to evaluate long-term surgical urinary and bowel management in cloacal exstrophy (CE) in a multi-institutional study., Methods: We performed a cross-sectional study of people with CE and covered variants managed at five participating institutions. Those with <1 year follow-up or born with variants without hindgut involvement were excluded. Primary outcomes were methods of urinary and bowel management. Urinary management included: voiding via urethra, clean intermittent catheterizations (CIC), incontinent diversion and incontinent in diaper. Bowel management included: intestinal diversion (colostomy/ileostomy) and pull-through (with/without MACE). We evaluated three age groups: children (<10 years), older children (10 to <18) and adults (≥18). We assessed if management varied by age, institution or time (born≤2000 vs. >2000)., Results: A total of 160 patients were included (40% male). Median follow-up was 15.2 years (36% children, 22% older children, 43% adults). While 42% of children were incontinent in diapers, 73% of older children and adults managed their bladder with CIC, followed by incontinent urinary diversion (21%) (p < 0.001, Table). CIC typically occurred after augmentation (88%) via a catheterizable channel (89%). Among older children and adults, 86% did not evacuate urine per urethra and 28% of adults had an incontinent urinary diversion. No child or adult voided per urethra. Age-adjusted odds of undergoing incontinent diversion was no different between institutions (p = 0.31) or based on birthyear (p = 0.08). Most patients (79%) had an intestinal diversion, irrespective of age (p = 0.99). Remaining patients had a pull-through, half with a MACE. The probability of undergoing bowel diversion varied significantly between institutions (range: 55-91%, p = 0.001), but not birth year (p = 0.85)., Summary: We believe this large long-term data presents a sobering but realistic view of outcomes in CE. A limitation is our data does not assess comorbidities or patient-reported outcomes. Rarity of volitional urethral voiding in CE forces the question of whether is a potentially unachievable goal. We advocate thoughtful surgical decision making and thorough counseling about appropriate expectations, distinguishing between volitional voiding and urinary and fecal dryness., Conclusions: In this long-term, multi-institutional study of patients with CE, 94% of older children and adults manage their bladder with incontinent diversion or CIC. Nearly 80% of patients, regardless of age, have an intestinal diversion. Given that no patients were dry and voided via urethra and 86% of older patients do not evacuate urine per urethra, these data bring into question what functional goals are achievable when performing reconstructive surgery for these patients., Competing Interests: Conflicts of Interest None of the contributing authors have any conflict of interest that could bias this work., (Copyright © 2022 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Purpose: We sought to determine if children with functional constipation (FC) would have an improvement in bladder function with treatment of constipation with a bowel management program (BMP)., Methods: A single-institution review was performed in children aged 3-18 with FC who underwent a BMP from 2014 to 2020. Clinical characteristics, bowel management details, and the Vancouver Symptom Score for Dysfunctional Elimination Syndrome (VSS), Baylor Continence Scale (BCS), and Cleveland Clinic Constipation Score (CCCS) were collected. Data were analyzed using linear mixed effect modeling with random intercept., Results: 241 patients were included with a median age of 9 years. Most were White 81 and 47% were female. Univariate tests showed improvement in VSS (- 3.6, P < 0.0001), BCS (- 11.96, P < 0.0001), and CCCS (- 1.9, P < 0.0001) among patients having undergone one BMP. Improvement was noted in VSS and CCCS among those with more than one BMP (VSS: - 1.66, P = 0.023; CCCS: - 2.69, P < 0.0001). Multivariate tests indicated undergoing a BMP does result in significant improvement in VSS, BCS, and CCCS (P < 0.0001)., Conclusions: There is significant improvement in bladder function in children with FC who undergo a BMP. For patients with bowel and bladder dysfunction and FC, a BMP is a reasonable treatment strategy for lower urinary tract symptoms., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective: To describe and evaluate efficacy of a more practical, at-home regimen of parasacral transcutaneous electrical nerve stimulation (TENS) for pediatric overactive bladder (OAB)., Methods: We prospectively enrolled patients with OAB., Inclusion Criteria: age 5-13 years and willingness to try TENS., Exclusion Criteria: urinary tract anatomic abnormalities, current use of OAB medications, neurologic condition, and elevated post-void residual. Patients were instructed to complete 20-minute sessions 2x/day for 1 month. Patients completed the Vancouver Symptom Score (VSS) and 48-hour frequency-volume chart before/after treatment. Compliance was assessed with a daily log. We recorded patient-reported improvement. Primary outcome was difference in VSS before/after treatment; secondary outcomes included: differences in frequency of voids/24 hours, max voided volume in 48 hours (%EBC), mean voided volume (%EBC), and mean number incontinence episodes/24 hours., Results: We enrolled 21 patients (3 male, 18 female; median age 9.9 years). We had complete VSS data on 17 patients and frequency-volume chart data on 12 patients. Median % of TENS sessions completed was 98%. 8/17 patients reported subjective improvement. There was a significant difference between pre- and post-TENS VSS (median score: 23 pre-TENS and 21 post-TENS, P = .009). There were no differences in secondary outcomes before/after treatment., Conclusion: In our cohort of medically-refractory OAB pediatric patients, nearly half reported subjective improvement with our regimen, despite modest objective improvement. Our compliance rates suggest this regimen is practical but may be best used as an adjunct to other therapies., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Robot-assisted laparoscopic surgery (RALS) has recently been described in children < 1 year old. However, little data exist on robotic utilization in infants ≤ 6 months old, likely due to concerns for limited intraabdominal space and decreased distance between ports in this cohort. We hypothesized that the robotic approach can be successfully used for infants ≤ 6 months old. A prospectively collected database of patients undergoing urologic robotic surgery at our institution was reviewed. Patients ≤ 6 months and ≥ 4 kg were included. Patient demographics, intraoperative details, hospital length of stay, and complications were reviewed. Descriptive statistics were performed. Twelve patients ≤ 6 months old underwent urologic robotic surgery by three surgeons at our institution (2013-2019): pyeloplasty (6), ureteroureterostomy (4), heminephrectomy (1), and nephrectomy (1). Median age at surgery was 4.75 months (IQR 4, 6). Median weight was 7.09 kg (IQR 6.33, 7.78). Median console time was 105 min (IQR 86, 123). For all procedures, 8-mm robotic arm ports were used. No procedures were converted to open. Median post-operative hospital stay was 24 h (IQR). Febrile UTI was the only complication occurring within 30 days of surgery (n = 4, 33%; 7-20 days, Clavien grade 2). For those undergoing pyeloplasty or ureteroureterostomy (n = 10), postoperative ultrasound showed improved (n = 9) or stable hydronephrosis (n = 1). At a median follow-up of 19.73 months (IQR 4.27, 38.32), no patient required an unplanned secondary intervention. Robotic upper urinary tract surgery is feasible and safe in patients ≤ 6 months of age and can be performed successfully with the same technique as for older children., (© 2021. The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.)

Background: Cloacal malformations are recognized as a particularly challenging congenital condition to manage and they present with a wide spectrum of anatomical configurations making surgical repair very complicated. Urethral necrosis or urethral loss is a known and devastating complication of cloacal repair. The surgical repair of these malformations has evolved over time and historically only common channel (CC) length was measured. More recently, it has been advocated that the urethral length and the CC are both important in determining surgical repair. The purpose of our study is to evaluate if this surgical approach allows for preservation of a patent urethra., Methods: A prospective database of all cloaca patients maintained with IRB approval (IRB# STUDY00000721) was retrospectively reviewed. We included any girl with cloacal malformation who underwent primary repair at our institution between May 2014 and December 2019. Standardized preop evaluation with endoscopy and 3-dimentional imaging to assess urethral length and CC length. These measurements were used to determine operative approach. Girls with CC < 1 cm undergo posterior sagittal anorectoplasty and introitoplasty (PSARP + I), those with CC measuring 1-3 cm and urethra > 1.5 cm undergo total urogenital mobilization (TUM) and those with CC > 3 cm or urethra < 1.5 cm undergo urogenital separation (UGS). Postoperative urethral patency was determined at the time of cystoscopy and exam under anesthesia (EUA) 4-6 weeks postoperatively by visualizing a viable and healthy urethra that is catheterizable., Results: A total of 59 patients met inclusion criteria with a median age of 11.6 months. Four girls underwent PSARP + I, 19 girls had a TUM and 36 girls underwent a UGS. All of the girls who had PSARP +I (n = 4) or TUM (n = 19) had a viable and patent urethra that was catheterizable at the cystoscopy and EUA 4-6 weeks postoperatively. Of the 36 girls who had UGS, all but 2 (5.6%) had a viable and patent urethra that catheterized without problems. Overall, 97% of girls in this cohort had a patent urethra after cloacal repair using this surgical protocol., Conclusions: The use of a standard protocol that considers urethral and common channel length for cloacal repairs results in a viable and patent urethra in 97% of patients., Level of Evidence: Level II., (Copyright © 2021. Published by Elsevier Inc.)

Background: Patients with anorectal malformations (ARM) commonly have associated urologic anomalies. Few large studies exist to accurately characterize the incidence or associations between severity of malformation and urologic diagnosis. The purpose of our study was to determine the incidence of urologic diagnoses in a large cohort of children with ARM and evaluate for any correlation between severity of ARM and the incidence and number of associated urologic diagnoses., Methods: A retrospective review was performed of patients with ARM treated at our pediatric colorectal center. All patients underwent protocolized urologic screening. ARM subtypes were ordered with increasing severity as follows in males: perineal, bulbar, prostatic and bladder neck fistulae. Females were similarly categorized as perineal, vestibular and vaginal fistulae followed by cloaca with <3 cm common channel and cloaca with >3 cm common channel. The following urologic diagnoses were assessed to determine whether a correlation existed with the severity of the ARM subtype: hydronephrosis, vesicoureteral reflux (VUR), solitary kidney, renal ascent anomalies (ectopic or pelvic), renal fusion anomalies (horseshoe or cross fused kidney), duplex kidney, hypospadias and undescended testicle. ARM subtypes were defined by distal rectal anatomy., Results: A total of 712 patients were included in our study with a mean age of 4 years and of whom 45% were male. The overall rate of urologic anomalies was greater in males than females (65% vs 56% p < 0.026). In both sexes, the rate of urologic anomalies increased with increasing severity of ARM subtype (p<0.00010) finding that males with bladder neck fistula and females with cloacal malformations, particularly with long common channels, being the highest incidence. In males and females, the rate of hydronephrosis increased as the complexity of ARM increased and this correlated significantly (p < 0.0001 vs p < 0.0003 respectively). Similarly, the incidence of VUR also increased as complexity of ARM increased in both males and females (p = 0.01 and p<0.0001 respectively). The remaining urologic diagnoses were not significantly correlated with severity of ARM., Conclusions: Urologic anomalies occur at a high rate in children with ARM and appear to increase in frequency with increasing complexity of ARM subtype. These findings stress the importance of proper ARM screening and proactive collaboration with a clinician with expertise in pediatric urology early in the management of such children to improve early recognition of urologic diagnoses., Level of Evidence: Level III., (Copyright © 2021. Published by Elsevier Inc.)

Objective: To better understand why children born with cloacal anomalies are at a high risk of renal insufficiency, this study aims to determine baseline renal volume in children with cloacal anomalies compared to controls. We hypothesized children with cloacal anomalies would be born with less renal volume., Methods: An IRB approved database of children with cloacal anomalies was reviewed. Controls were female patients with 2-vessel umbilical cord or preauricular tags who underwent screening renal ultrasound. Children were included if they had a renal ultrasound in the first 3 months of life. Cloacal exstrophy, horseshoe and cross-fused ectopic kidneys were excluded. Total and individual kidney volumes were compared between the 2 groups., Results: The study cohort consisted of 109 patients, 46 (42.2%) cloaca patients and 63 (57.8%) controls. In unadjusted analyses, average total renal volume for cloaca and control patients was 22.4 cm 3 vs 25.5 cm 3 respectively (P = .1006), and there was no significant difference when adjusting for age (P = .3915). The estimated difference in renal unit volume between cloaca patients without solitary kidneys and controls was -1.6 cm 3 (95%C.I.: -3.6, 0.4; P = .1201), and there was no significant difference when adjusting for age (P = .4725). The age-adjusted difference in renal unit volume between cloaca patients with solitary kidney and controls was 1.8 cm 3 (95%CI: -1.1, 4.8; P = .2148)., Conclusions: Children with cloacal anomalies have similar baseline renal volumes as children without cloacal anomalies. Therefore, the increased risk of renal insufficiency in this patient population appears to be due to renal injury postnatally., (Copyright © 2020. Published by Elsevier Inc.)

Introduction: Minimally invasive (robotic and pure laparoscopic) pyeloplasty has been increasingly used for treatment of ureteropelvic junction obstruction (UPJO). However, few large-scale studies have compared these two modalities directly., Methods: We performed a retrospective single-center review of all patients who underwent pure laparoscopic (LP) or robotic pyeloplasty (RALP) between 2007 and 2018. Patients were excluded if the initial surgery at our institution was a redo pyeloplasty or if they lacked follow-up information. Outcomes of interest included operative time, length of stay, and complication rates, including rates of secondary procedures. We compared these outcomes between groups using Student's t test for continuous variables and a Chi-square for categorical variables., Results: A total of 282 patients were identified. Forty-eight were excluded based on study criteria; therefore, our total study cohort was 234 patients: 119 RALP and 115 LP cases. Overall mean postoperative follow-up time was 20.8 months, with no significant differences between groups. Mean operative time was shorter in the LP group when compared the RALP group (3 h 7 min vs. 3 h 41 min, p < 0.001). There were no significant differences between groups in length of stay (1.22 days vs 1.50 days, p = 0.095). Complications occurred in 52 patients (22.2% of overall cohort) with no difference in incidence between groups. Twenty-five patients (14 in the RALP group and 11 in the LP group) underwent unplanned secondary procedures; 19 of these patients (9 in the RALP group and 10 in the LP group) needed a procedure to address secondary obstruction., Conclusion: We demonstrated no significant differences between RALP and LP in regards to complication rates. Surgeons performing RALP and LP have the potential to offer the same level of care for the surgical management of UPJO, especially in countries where robotic technology may not be readily available., Competing Interests: Conflict of interest The authors of this study have no conflicts of interest to disclose., (Copyright © 2020 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Anorectal malformations (ARM) are well recognized to be associated with anomalies in other organ systems. The introduction of screening protocols has increased the diagnosis of these anomalies and greater collaboration with other specialties has influenced the treatment and follow-up of patients with ARMs. Much of the medical literature regarding the treatment of anorectal malformations has focused on technical details of operations and early post-surgical outcomes. Recently, an increase in published data regarding the long-term sequelae of an ARM diagnosis has resulted in an emphasis extended follow up in this population. Patient support groups have highlighted complex issues in ARM patients persist into adulthood have advocated for improved transitional care. This article describes the benefits of long-term follow-up and identifies key issues in ARM patients with respect to urologic and gynecologic health. A collaborative model of care is outlined and suggested timings of screening for potential problems is described., (Copyright © 2020. Published by Elsevier Inc.)

It has been described that patients with more complex anorectal malformations (ARM), lower sacral ratios and spinal anomalies have poorer rates of fecal and urinary continence. While the ARM subtype has been shown to be an independent predictor of fecal continence, it is not well understood how each of these anatomic factors impact urinary continence. The purpose of this study was to identify anatomic factors associated with urinary continence in children born with ARM. We performed a retrospective review of a large prospectively collected database of children with ARM. Inclusion criteria included diagnosis of ARM, age >4 years, available lateral sacral ratio measurement and presence of spinal MRI. Any child with incomplete or absent continence data was excluded. Continence was defined as voiding per urethra volitionally, dry between voids and ≤1 urinary accident per week. Bivariable tests of association and log-binomial regression models were used to examine association between anatomic factors and urinary continence. A total of 434 patients were included in the study. 57.8% (n = 251) were male. Median age was 8.4 years (IQR 6.0-12.3). With regards to severity of ARM, 20.3% (n = 88) were complex, 23.3% (n = 101) were moderate and 56.5% (n = 245) were simple. Lateral sacral ratio included 11.1% (n = 48) that were <0.4, 36.2% (n = 157) 0.4-0.7 and 52.8% (n = 229) > 0.7. Spine status was found to be myelomeningocele in 4.4% (n = 19), low conus or tethered cord in 34.8% (n = 151) and normal or fatty filum in 60.8% (n = 264). Overall 62.2% were continent. ARM severity, lateral sacral ratio and spine status were each independent predictors of urinary continence on univariate and multivariable analysis. We conclude that in children born with ARM, the severity of ARM, lateral sacral ratio and spine status each independently predict urinary continence. These results allow us to better understand these complex patients and their ability to develop urinary continence. This is crucial in enabling proper patient and family counseling and thus, setting appropriate expectations., (Copyright © 2020 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Robotic surgery has been slow to be fully accepted in the world of pediatric urology largely because of its initial application directed towards adult use and because of the inherent high cost associated with it. However, as previously shown, it has now become the gold standard for adolescent pyeloplasty in The United States. As the adoption of robotic surgery in children has become more widespread, its use has been applied to a broader spectrum of procedures with similar success rates to standard laparoscopy. These procedures include nephrectomy, heminephrectomy, ureteral reimplantation, and ureteroureterostomy. However, it has also shown feasibility and comparable success when compared to open surgery in procedures that were previously deemed too complex to be done by standard laparoscopy. For example, bladder neck reconstruction with Mitrofanoff and Malone procedure as well as bladder augmentation. This review objective is to provide an overview of robotic surgery in pediatric urology, with a focus on the more common cases such as pyeloplasty and reimplantation as well as more complex bladder reconstruction procedures., Competing Interests: None declared., (Copyright® by the International Brazilian Journal of Urology.)

Purpose: A complication of the surgical management of anorectal malformations (ARMs) is a retained remnant of the original fistula (ROOF) formerly called a posterior urethral diverticulum (PUD). A ROOF may have multiple presentations or may be incidentally discovered during the work-up of ARM after previous surgery. We sought to define the entity and the surgical indications for excision of a ROOF when found., Methods: We performed a retrospective cohort study of all male patients who presented to our center following previous repair for ARM at another institution, who came for evaluation of problems with urinary and/or fecal continence, from 2014 to 2017. Charts were reviewed for symptoms, original type of malformation, preoperative imaging, treatment, and postoperative follow-up., Results: Of 180 referred male patients, 16 had a ROOF. 14 underwent surgical repair to address this and for other redo indications, and 2 did not require intervention. 13 patients had an additional reason for a redo such as anal mislocation or rectal prolapse. Indications for ROOF excision were urinary symptoms (e.g. UTI, dribbling, passage of mucous via urethra, stone formation), to make a smoother posterior urethra for intermittent catheterization, or for prophylactic reasons. Patients were repaired at an average age of 4.2 years, using a PSARP only approach with excision of the ROOF for all except one patient who needed a laparotomy due to abdominal extension of the ROOF. No patient needed a colostomy. The original ARM repairs of the patients were PSARP (9), laparoscopic assisted (4) and abdominoperineal pullthrough (3). Preoperative evaluation included pelvic MRI, VCUG, and cystoscopy. The ROOF was visualized on 14 of 16 MRIs, 10 of 14 VCUGs, and 14 of 15 cystoscopies. Urinary symptoms associated with a ROOF and ease of catheterization were improved in all repaired cases., Conclusion: Patients not doing well from a urinary or bowel standpoint post ARM pull-through need a complete evaluation which should include a check for a ROOF. Both modalities MRI and cystoscopy are needed as a ROOF can be missed on either alone. A VCUG was not reliable in identifying a ROOF. Excision is needed in patients to improve urinary symptoms associated with these lesions and to minimize the small but theoretical oncologic risk present in a ROOF., Level of Evidence: Level III., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Introduction: Increasing concerns regarding potential negative effects of early use of inhalational and intravenous anesthetics on neurocognitive development have led to a growing interest in alternative forms of anesthesia in infants. The study institution's outcomes with spinal anesthesia (SA) for urologic surgery in infants aged less than 90 days are reported and their outcomes with a matched cohort of patients who underwent general anesthesia (GA) are compared., Methods: This is a retrospective single-center analysis. Patients aged less than 90 days who underwent SA for four urologic surgeries (inguinal hernia repair, scrotal exploration, posterior urethral valve ablation, and ureterocele puncture) were identified from the study institution's SA database. An age- and procedure-matched control cohort was identified from a list of patients who underwent the aforementioned four procedures under GA since 2013. Outcomes of interest included success rate of SA, complications from spinal placement, narcotic use, need for supplemental medications and oxygen, and length of hospital stay., Results: Forty patients were identified; 20 in the SA and 20 in the GA group. Mean patient age was 54 (standard deviation, 35) days. There were no significant differences between the groups in age, gender, weight, history of prematurity, or presence of comorbidities. Eighty percent of SA patients had successful SA; reasons for conversion to GA included failure of spinal needle placement (75%) and agitation during operative procedure (25%). Ninety-six percent of patients who received GA (primarily or converted) had an endotracheal tube (ETT) placed. No patient in the SA group had a complication from spinal needle placement. Patients in the SA group were less likely to receive narcotics during the operative procedure (P = 0.001) and also had a lower mean morphine equivalent dose/kilogram (P = 0.002). Patients in the SA group were also less likely to receive any supplemental medications during the operative procedure (P = 0.001), particularly intravenous corticosteroids (P < 0.001). There were no significant differences in the length of hospital stay., Conclusions: The use of SA has clear advantages for this medically vulnerable population. For the majority of patients, it obviates the need for ETT placement and airway management and avoids the potential negative effects of GA on neurocognitive development. It also decreases the use of narcotics and other supplemental medications. In scenarios in which the benefit of surgery must be weighed against the risk of GA, such as neonatal torsion, SA may allow a paradigm shift in the timing of surgery., (Copyright © 2018 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Cicatrix formation, which can form after neonatal circumcision to entrap the glans penis, presents a therapeutic challenge. Previous studies in the literature have described either using a topical steroid cream or stretching of the scar tissue with an instrument but not a combination of both modalities. In our experience, monotherapy has resulted in significant recurrence and/or need for further treatment. We present our successful experience that combines cicatrix stretching with a hemostat using local anesthesia in the office followed by several weeks of topical steroids with a minority of patients needing any additional therapy., (Copyright © 2018 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Objective: To determine if intradetrusor injection of onabotulinumtoxin-A (BTX-A) would reduce postoperative narcotic and anticholinergic requirements in children undergoing open continent bladder reconstruction., Materials and Methods: After institutional review board approval, we retrospectively reviewed all bladder reconstructions performed. Bladder reconstruction was defined as the following procedures in any combination: bladder neck reconstruction and sling, bladder neck closure, Mitrofanoff, Monti, or bladder augmentation. We identified 15 children who underwent reconstruction with BTX-A injection and compared these with 15 children who did not receive BTX-A. Postoperative narcotic and anticholinergic requirements were recorded as well as length of stay, time to diet, time to return of bowel function, and complications. All medications were converted to morphine mEq/kg per day or mg/kg per day to standardize for patient size and length of stay., Results: Thirty patients who underwent open bladder reconstruction were included. Fifteen received BTX-A injection and 15 did not. The BTX-A group required significantly less narcotic medication postoperatively compared with the no-BTX-A group (0.32 vs 0.85 morphine mEq/kg per day; P = .0002). The BTX-A group also required significantly less anticholinergic medication compared with the no-BTX-A group (0.22 vs 0.88 mg/kg per day; P = .024). There was no significant difference between the groups with respect to length of stay (98.27 vs 9.287 days; P = .34) or return of bowel function (5.53 vs 4.93 days; P = .994). Complication rate between the groups was similar (P >.99)., Conclusion: Intraoperative injection of BTX-A significantly reduced postoperative narcotic and anticholinergic requirements in patients who underwent open continent bladder reconstruction. This is an encouraging alternative treatment to manage postoperative pain with no associated risk of significant complications., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objective: To characterize the utilization of delayed phase computed tomography (CT) imaging in blunt renal trauma and determine if the omission of delayed phase CT imaging affected clinical outcomes in children., Materials and Methods: A prospectively collected trauma database was reviewed between 2006 and 2016 to identify patients aged ≤21 years with a diagnosis of renal injury from blunt trauma. Demographic characteristics, injury grade, Injury Severity Score, non-kidney organ injuries, radiologic studies, and clinical course were reviewed. Patients were categorized into 2 groups: those who received CT with delayed images in the emergency room and those who did not., Results: In total, 121 patients met the inclusion criteria. Delayed scans were obtained in 50 patients (41%) but omitted in 71 (59%). Age, weight, non-kidney organ injuries, and imaging location did not differ between groups. Injury Severity Score was higher in the no-delay group than in the delay group (median 16 vs 10, respectively, P = .40). Median length of stay was 3 days without significant differences by cohort (P = .24). The proportion of patients who received abdominal CT scans after admission, underwent a urologic procedure, or were readmitted did not differ significantly between groups., Conclusion: This study was unable to demonstrate a difference in outcomes between patients who had a CT with delayed imaging and patients who did not. This questions the universal necessity for delayed images after blunt renal trauma. Future prospective studies are necessary to develop pediatric trauma guidelines that balance imaging needs and radiation exposure., (Copyright © 2017 Elsevier Inc. All rights reserved.)

This study investigated whether boys with balanitis xerotica obliterans (BXO) have increased rates of obesity compared with boys with no concern for BXO (NCB). Boys ≤18 years old with circumcision pathology-confirmed BXO were compared with an age-matched group who had NCB during circumcision. Boys with BXO were found to have a mean body mass index of 70.64 percentile for age compared with 52.43 percentile in age-matched controls ( P = .0005). The rate of obesity was significantly higher in boys with BXO (42%) compared with 12.4% in boys with NCB (odds ratio = 5.12; 95% CI = 2.6 to 10.06). Given the increasing rates of childhood obesity and the long-term health consequences of both BXO and obesity, special attention should be paid to this population. Further research is needed to determine if BXO in obese children may represent an early indicator of a systemic disease process where intervention may be warranted., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: Cloacal malformations represent a uniquely complex challenge for surgeons. The surgical approach to date has been based on the common channel (CC) length with two patient groups considered: less than or greater than 3cm, which we believe is an oversimplification. We reviewed 19 patients, referred after surgery done elsewhere. Eight had postoperative urinary complications, 3 had constant urinary leakage and had been left after surgery with a urethra <1cm, .5 with an original 3 to 5cm common channel, who had undergone total urogenital mobilization (TUM), experienced peri-operative urethral loss needing a vesicostomy, and later, a Mitrofanoff. These patients together with a review of the cloacal and urological literature led us to design a new algorithm where urethral length is a key determinant for care., Methods: We prospectively collected data on 31 consecutive cloaca patients referred to our team (2014 to 2016) and managed according to this new protocol. The CC length, urethral length, surgical technique employed, and initial outcomes were recorded., Results: Of 31 primary cases, CC length was 1 to 3cm in 20, 3 to 5cm in 9, and greater than 5cm in 2. In the 1 to 3cm and the 3 to 5cm groups, a urethra less than 1.5cm led us to perform an urogenital separation. We only performed a TUM if the urethra was greater than 1.5cm. Using this protocol, we performed a urogenital separation in 1 of 20 in the 1 to 3cm CC group, 6 of 9 in the 3 to 5cm CC group, and 2 of 2 in the greater than 5cm CC group. Seven patients underwent separation, who with the previous approach, would have had a TUM. Thus far, no urinary leakage or urethral loss has occurred in any patient, but follow-up is less than 3years., Conclusion: Urethral length appears to be a vitally important component in cloacal reconstruction. A short urethra left after repair can lead to urinary leakage. A TUM done under the wrong circumstances can lead to urethral loss. We describe a new technical approach to cloacal repair which considers urethral length but recognize that long term urological outcomes will need to be carefully documented., Type of Study: Clinical cohort study with no comparative group., Level of Evidence: Level 4., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Objective: To identify if any preoperative variables are associated with postoperative complications after pediatric sacral neuromodulation (SNM)., Materials and Methods: A review of all patients undergoing SNM with an implantable pulse generator at our institution was performed. Postoperative infection, lead migration, lead breakage, and need for reoperation were recorded in a prospective database. We collected demographic information and indication for the procedure. We defined indication for procedure as either primarily bowel or primarily bladder symptoms. Multivariate analysis was used to determine any associations between preoperative factors and postoperative complications., Results: Sixty-three children (34 females, 29 males) underwent SNM from 2012 to 2015. Mean age was 11.5 years, and body mass index (BMI) was 51st percentile for age. SNM was placed for primarily bowel symptoms in 49% and for primarily bladder symptoms in 51%. Follow-up was 1.9 years (0.19-4.3). Reoperation was required in 25%, with mean time to reoperation of 10.9 months (0.9-31.5). Lead migration occurred in 17.4%, and wound infection in 8%. There were no significant associations between patient age, gender, or BMI, and need for reoperation, wound infection, or lead migration. Low BMI had no increased risk of lead complications (P = .115). There was a significant increase in lead migration in the children who underwent SNM for primarily bladder symptoms (P = .0034)., Conclusion: There is no association between age, gender, or BMI and postoperative complications in this large cohort of pediatric SNM. Children with primarily bladder symptoms may have higher rate of lead complications for unclear reasons., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The absence of sperm in the ejaculate after vasectomy reversal is commonly caused by failure to recognize and subsequently bypass epididymal or proximal vasal obstruction at the time of vasectomy reversal. If intra-operative proximal obstruction is suspected, vasoepididymostomy (VE) is recommended rather than vasovasostomy (VV). We sought to calculate the associated risk of needing VE, rather than VV with time from original vasectomy (obstructive interval) using a large cohort of vasectomy reversal patients. We reviewed the electronic and paper vasectomy reversal database by a single surgeon from 1978 through 2012. We performed univariate analysis to identify variables that predicted the need for VE rather than VV, and then combined only significant univariates into our multi-variable analysis. 2697 total men underwent vasectomy reversal, and 239 were repeat procedures. Of the 5296 individual testes operated on, 1029 were VE. Significant variables that predicted the need for VE on univariate analysis included: age, obstructive time interval, vasectomy reversal after previous VV (repeat vasectomy reversal), and year the procedure was performed. On multi-variable analysis significant risk factors for VE were age above 50 (OR 1.36), repeat vasectomy reversal (OR 5.78), and greater obstructive time interval (OR 1.56). For every 3 years since original vasectomy, the risk of needing VE increases by 56%. There is a linear relationship between obstructive interval and need for VE. Men undergoing repeat vasectomy reversal have five times greater risk of requiring VE and men greater than 50 years of age are also at higher risk. Using these pre-operative predictors is helpful in identifying patients who will benefit from referral to an experienced surgeon who can perform VE., (© 2015 American Society of Andrology and European Academy of Andrology.)

Introduction: It is generally accepted that there is a risk of hypertension after renal trauma, particularly in high-grade and devascularizing injuries. Hypertension following renal trauma is estimated to occur in five percent of adults, however, the incidence is unknown in the pediatric population., Materials and Methods: We performed a retrospective review of all pediatric trauma patients at Primary Children's Hospital in Salt Lake City, Utah between 2002 and 2012. We included all children age ≤17years old with American Association for Surgery of Trauma (AAST) grade 3-5 renal injury. Hypertension was defined as persistent hypertension that required anti-hypertensive medications. Our primary outcomes were incidence of hypertension during the acute trauma and in long-term follow., Results: A total of 62 children were identified with AAST grade 3-5 renal injuries during our study period. Follow up blood pressures were recorded in 36 (58%) of these children with a median follow of 4.1years (IQR 2.1-5.1years) after trauma. Four children (6.5%) were identified to have some degree of hypertension while hospitalized after trauma and started on anti-hypertensive medication. Two out of these four children remained on hypertensive medication at follow up, while the remaining two children's hypertension resolved. No children who were normotensive in the immediate post-trauma period, developed delayed hypertension during long-term follow up., Conclusions: There is a low risk of developing hypertension following severe renal trauma in the pediatric population. Patients who develop long-term problems with hypertension after renal trauma manifest it during the initial hospitalization, rather than subsequently during the long-term., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Plication techniques are not a panacea for deformities associated with Peyronie's disease or congenital curvature. However, they do provide certain advantages, both theoretic and real, over competing procedures such as grafting. Depending on the technique, plication procedures have minimal risk of de novo erectile dysfunction, minimal risk of injury to the dorsal neurovascular bundle, and may be used for a variety of angulation deformities, including multiplanar curvature and severe degrees of curvature. A variety of incisions may be used, including the classic circumcision with degloving but also ventral raphe, dorsal penile inversion, and penoscrotal. These may be helpful in preventing postoperative morbidity and in sparing the prepuce if desired. Plication may also be combined with procedures such as penile prosthesis for correction of residual curvature. Lastly, despite its complications, plication techniques are very well tolerated, are relatively simple to perform and result in the very high satisfaction rates.

Intracorporeal papaverine self-injection is a new therapy for erectile dysfunction. Although reports of side effects are few, complications, such as priapism and fibrosis, have been described. We report a case of papaverine-induced obliteration of the corpus cavernosum with resulting inability to place a penile prosthesis.

The presence or absence of basement membrane (BM) was examined in normal and neoplastic adult prostatic tissue as well as prostate cell lines using immunohistochemistry and electron microscopy. Immunohistochemical studies using antibodies directed against laminin and type IV collagen were done on 55 samples of human prostate representing various grades of prostate carcinoma. The percentage of glandular structures surrounded by BM was determined. Benign prostates (n = 15) had BM around 99% of the acini. Gleason Grade II adenocarcinoma (n = 9) had 65%, Grade III (n = 5) had 23%, Grade IV (n = 12) had 15%, and Grade V (n = 7) had 0% BM around glandular structures, respectively. None of the metastases (n = 7) had visible BM. By transmission electron microscopy, 32 prostates were examined for the glandular profile of BM. One hundred percent of the acini in the benign prostates (n = 17) had BM. Of the low grade carcinomas, Gleason I and II (n = 4), 44% of the acini had BM, and of the high grade carcinomas, Gleason IV and V (n = 7), 34% had BM. None of the metastases (n = 4) had BM by electron microscopy. We conclude that, in prostatic carcinoma, there is a progressive loss of BM with decreasing differentiation, and that in prostate carcinoma metastases there is a complete loss of epithelial BM.

An elderly lady with subacute onset of disabling hemiballismus experienced sustained remission on dimethylaminoethanol 150 mg/day. Two exacerbations followed interruption of therapy. Remission followed resumption of therapy. No undesirable side effects occurred with this treatment. A lady age 85 experienced a very favorable sustained reduction of hemiballismus when treated with dimethylaminoethanol (DMAE or Deanol). Her age and hypertension made the risk of thalamotomy unacceptably high. DMAE was tried because of reports of reduction of chorea, and other dyskinesias with this drug.

Eighty-one third-year and early fourth-year medical students were taught a simple schema for generating differential diagnoses. Significant gain in listing correct diagnoses was realized following training.

Long-term experiments with animals in space require a life-support system that provides optimal conditions of life at lowest energy demand. Experimental studies of different physicochemical and biological systems are compared. While such experiments are limited by energy requirements, it is possible to choose a certain system by comparing the exact energy balances of the different ecological systems.