Postoperative management of infants with ureteropelvic junction obstruction: a retrospective cohort study of PICU transfer, complications, and length of stay

Introduction

Ureteropelvic junction obstruction (UPJO) is a common congenital anomaly that impairs urinary drainage, leading to hydronephrosis and progressive renal damage if uncorrected. The prevailing trend favors early surgical intervention for severe cases to optimize renal recovery (1,2). Laparoscopic dismembered pyeloplasty (LP) has become a well-established treatment for infant UPJO (3); yet the safety of performing this procedure in very young infants continues to be debated. Long-term data indicate that children operated on before 1 year of age have higher rates of reoperation and readmission, reinforcing the notion that younger age at pyeloplasty correlates with increased perioperative risk (4). Clinicians thus face a dilemma: operating early to preserve kidney function while accepting a higher risk profile. A robust perioperative safety protocol is clearly needed.

Infants are uniquely challenging because they cannot verbally express symptoms, and their physiological status can deteriorate rapidly and silently (5). Standard urology wards may lack the continuous intensive monitoring and the multidisciplinary expertise required to detect and manage the cascade of non-surgical complications—respiratory, hematological, gastrointestinal—that can occur postoperatively. Often, subtle changes are first noticed by family members, delaying intervention. The pediatric intensive care unit (PICU) offers 24/7 multi-parameter monitoring, strict environmental control to reduce infection risk, and a team adept in managing multi-organ dysfunction in vulnerable infants (6).

However, there is currently no consensus on which infants with UPJO should be transferred to the PICU after surgery. Practices vary widely across institutions: some routinely transfer all infants <6 months, others use weight‑based criteria, and still others rely on intraoperative factors and anesthetic risk assessment. This inconsistency represents a genuine unmet clinical problem, and descriptive data on structured combined protocols are lacking.

To address this gap, we designed a combined-team protocol: the pediatric urology team performs the surgery, then the infant is immediately transferred to the PICU, where the critical care team assumes primary management. The urology team conducts daily rounds jointly, and discharge is decided collaboratively. This study reports a 5-year institutional experience, describing the feasibility, complication spectrum, length of stay (LOS), and costs of this protocol, and exploratorily examines associations between postoperative destination and outcomes. Given that PICU transfer decisions are subjective, influenced by age, weight, physiological reserve, and family preference, the two groups are inherently non-comparable; this work is therefore positioned as a descriptive, hypothesis-generating report, not a causal analysis. We present this article in accordance with the STROBE reporting checklist (available at https://tau.amegroups.com/article/view/10.21037/tau-2026-0465/rc).

Methods

Study design and patient enrollment

This was a single-center retrospective cohort study that consecutively enrolled all infants (≤12 months) who underwent LP for UPJO at The Second Hospital of Hebei Medical University between December 2020 and December 2025. All surgeries were performed by the same experienced surgeon using a standardized transperitoneal laparoscopic technique. Patients were divided into two groups based on postoperative destination: Group A (transferred to the PICU, n=62) and Group B (managed on the general urology ward, n=22). The decision for PICU admission was made jointly by the surgeon and the family, considering the infant’s age, body weight, physiological reserve, and family preference. We explicitly acknowledge that this decision process introduced selection bias, as younger and more fragile infants were more likely to be directed to the PICU. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Research Ethics Committee of The Second Hospital of Hebei Medical University (No. 2026-R077) and individual consent for this analysis was waived due to the retrospective nature.

Inclusion and exclusion criteria

Inclusion criteria: (I) age ≤12 months at surgery; (II) confirmed diagnosis of UPJO; (III) complete medical records and informed consent for surgery and (for Group A) PICU transfer; (IV) no prior treatment for UPJO; (V) standardized LP technique by the same surgeon.

Exclusion criteria: (I) coexisting major urological anomalies requiring simultaneous repair; (II) intraoperative conversion to open surgery or alternative technique; (III) failure to place a double-J stent requiring primary nephrostomy; (IV) simultaneous bilateral pyeloplasty; (V) incomplete clinical data (missing key operative or outcome variables); (VI) refusal of follow-up.

Data collection and variable definitions

Data were extracted from electronic medical records, including: demographics (age, sex, operative side), operative time, estimated intraoperative blood loss, postoperative length of stay (LOS) (days), total hospitalization cost (Chinese Yuan, CNY), postoperative complications graded by the Clavien-Dindo classification with all complication types recorded, and 30-day readmission or unplanned interventions. Respiratory complications included upper respiratory tract infection (URTI), bronchitis, pneumonia, and laryngeal edema. Hematologic complications included anemia and hypoproteinemia. Other recorded events included fever, urinary tract infection (UTI), anastomotic urinary leakage, double-J stent-related events, gastrointestinal dysfunction, electrolyte imbalance, myocardial injury, sepsis, and skin injury. The number of complication types was defined as the count of different complication categories per patient.

Surgical procedure

A standard transperitoneal laparoscopic approach was used. After anesthesia induction, the patient was positioned in a 45° contralateral decubitus position. A pneumoperitoneum of 7–8 mmHg was established via an umbilical port. Three ports were placed. The stenotic UPJ segment was excised, the renal pelvis was trimmed, and a dismembered pyeloplasty was performed over a double-J stent using 5-0 absorbable sutures. A perirenal drain was placed in all cases.

Postoperative management

Group A (PICU)

Intensive care with 24-hour continuous monitoring. Analgesia: fentanyl. Sedation: midazolam or phenobarbital as per PICU protocol. Antibiotic prophylaxis: cefamandole. Enteral feeding was resumed on postoperative day 1. Wound and drain care was performed by the urology team. Discharge required meeting the same clinical criteria as Group B plus joint assessment by both teams.

Group B (urology ward)

Level I nursing with continuous ECG and SpO₂ monitoring; monitoring was discontinued the following day if stable. Analgesia: tramadol. Antibiotic prophylaxis: cefazolin. Enteral feeding was resumed on postoperative day 1. Drains were removed when output fell below 20 mL.

Follow-up

All patients were followed up at 1, 3, 6, and 12 months postoperatively with renal ultrasound and, when indicated, diuretic renography. This study reports short-term perioperative outcomes (within 30 days of surgery). No patient was lost to follow-up (defined as missing the 12-month visit) during the study period.

Statistical analysis

Analyses were performed using SPSS 27.0. Continuous variables are presented as mean ± standard deviation or median (interquartile range); comparisons were made using the independent t-test or Mann-Whitney U test based on normality (Shapiro-Wilk test). Categorical variables were compared using the Chi-squared test or Fisher’s exact test based on expected cell counts. For exploratory control of baseline differences, 1:1 propensity score matching (PSM) was performed using logistic regression based on age, sex, and operative side with a caliper of 0.2. Due to the small matched sample (12 pairs), PSM results are presented only as supportive exploratory findings and are not the basis for primary conclusions. Univariable and multivariable logistic regression analyses were performed to identify factors associated with PICU transfer and adverse outcomes, with adverse outcomes defined as Clavien-Dindo grade ≥ III. Age, sex, operative side, operative time, and intraoperative blood loss were evaluated in the regression analyses. Operative time and intraoperative blood loss were entered as continuous variables and expressed per 30-minute and 10-mL increase, respectively. Odds ratios (ORs) with 95% confidence intervals (CIs) were reported. All tests were two-sided, and P<0.05 was considered significant. Given the descriptive and exploratory nature of this study, no formal sample size calculation was performed; all eligible patients were included. Given the small sample size and low event count, Firth’s penalized likelihood estimation was used to reduce small-sample bias and obtain stable odds ratio estimates. Linear regression was performed using the ordinary least squares method in Microsoft Excel.

Results

Full cohort baseline and outcome comparisons

All 84 procedures were completed laparoscopically without conversion. Baseline characteristics are shown in Table 1. Group A was significantly younger than Group B (4.77±3.10 vs. 9.23±2.51 months, P<0.001) and had higher median hospitalization costs (37,080.5 vs. 31,072.26 CNY, P<0.001); however, operative time, blood loss, and LOS did not differ significantly. Complication profiles are detailed in Table 2. Ten infants (16.1%) in Group A experienced no complications, compared to none in Group B (P=0.045). The proportion of patients with Clavien-Dindo grade ≥ II complications was lower in Group A (74.2% vs. 100%, P=0.008). Respiratory complications were common: the total incidence was lower in Group A (67.7% vs. 95.5%, P=0.01), with a striking difference in bronchitis rates (17.7% vs. 50.0%, P=0.003). Most patients (80.95%) had two or fewer complication types (Table 3, Figure 1A).

Figure 1 Postoperative complication burden, severity, and costs in the overall cohort. (A) Distribution of concurrent complication types per patient (n=84). Most infants (80.95%) experienced two or fewer complication types. (B) Positive correlation between Clavien-Dindo grade and number of concurrent complication types. (C) Distribution of postoperative hospital stay stratified by Clavien grade. Patients with severe complications (≥ Grade 3) had a significantly longer postoperative hospital stay compared to those without complications or with lower-grade complications. (D) Relationship between age at surgery and hospitalization cost with fitted trend lines, showing that younger age was associated with higher costs. ns, not significant; ***, P<0.001; ****, P<0.0001. Group A: PICU transfer; Group B: general ward care.

Notably, 4 patients (18.2%) in Group B required unplanned transfer to the PICU due to postoperative deterioration: respiratory failure (n=2), sepsis (n=1), and anastomotic leak with hemodynamic instability (n=1). No patient in Group A required escalation beyond the already-provided PICU care.

Univariable and multivariable logistic regression analyses of factors associated with PICU transfer are shown in Table 4. In univariable analysis, younger age, operative side, and longer operative time were associated with PICU transfer. In multivariable analysis, younger age (OR, 0.61; 95% CI: 0.46–0.75; P<0.001) and operative side (OR, 0.15; 95% CI: 0.03–0.60; P=0.01) remained independently associated with PICU transfer, whereas sex, operative time, and intraoperative blood loss were not significantly associated. Univariable and multivariable logistic regression analyses of factors associated with adverse outcomes are shown in Table 5. For adverse outcomes defined as Clavien-Dindo grade ≥ III, no evaluated factor was significantly associated in either univariable or multivariable analysis (all P>0.05).

Propensity score-matched exploratory analysis

PSM yielded 12 well-balanced pairs (Table 6). In this matched cohort, the cost difference remained significant (median 36,011.18 vs. 31,199.99 CNY, P<0.001). Group A had a lower proportion of Clavien-Dindo grade ≥ II complications (58.3% vs. 100%, P=0.01) and a significantly lower incidence of bronchitis (0% vs. 41.7%, P=0.01) (Table 7). The increase in URTIs in Group A (41.7% vs. 25.0%) should be interpreted cautiously given the small matched sample and potential residual confounding. The PSM findings are exploratory and are not intended to establish a causal effect of PICU care.

Relationships between complications, stay, and cost

There was a clear positive correlation between Clavien grade and the number of concurrent complication types (Table 3, Figure 1B). Violin plots showed that while LOS was similar for Clavien ≤ II, it was significantly and variably prolonged when complications reached ≥ Grade III (Figure 1C). Figure 1D displays hospitalization costs by age and group. This study did not perform a multivariable regression analysis of hospitalization cost, and therefore no independent cost predictor is claimed.

Discussion

LP is increasingly used for treating UPJO in children (7). This study describes a 5-year single-center experience with a combined urology-PICU protocol for postoperative management of infants with UPJO. Our protocol features routine transfer of selected infants to the PICU, where the critical care team assumes primary management and the urology team provides daily joint rounds until discharge criteria are met. The critical finding is that, despite being significantly younger—a factor previously associated with higher surgical risk (8,9)—patients in the PICU group did not have longer operative times, greater blood loss, or longer LOS in our study. Although the PICU group had lower rates of Clavien-Dindo grade ≥ II and respiratory complications, particularly bronchitis, these observational differences should be interpreted cautiously because of substantial confounding by indication and baseline non-comparability.

The Clavien-Dindo classification is widely used to assess complications following pyeloplasty (10,11). Our analysis revealed a high burden of non-surgical complications (respiratory, hematological, gastrointestinal) that are often underreported in the literature. The lower proportion of Clavien-Dindo grade ≥ II and respiratory complications in the PICU group, with a compensatory rise in upper respiratory infections, is a hypothesis-generating observation that requires prospective validation. We cannot determine from this retrospective study whether PICU care itself prevented progression of respiratory illness because the groups were non-randomized and differed substantially at baseline. One illustrative case was a 3-month-old in Group A who developed acute respiratory failure from severe laryngeal edema; the PICU team performed prompt reintubation and mechanical ventilation, achieving a full recovery. Beyond respiratory issues, PICU bedside ultrasound enabled rapid diagnosis of intra-abdominal collections and stent obstructions. Minor declines in urine output, often subtle, were routine triggers for closer assessment in the PICU but may be overlooked in a busy ward.

The four unplanned transfers from Group B to the PICU (18.2%) further emphasize that not all infants initially managed on the general ward may subsequently require escalation of care. These unplanned transfers underscore the need for more objective triage criteria, but the present retrospective study cannot determine whether any precautionary PICU transfers were unnecessary.

Common urological complications include UTI and anastomotic leak, related to indwelling double-J stents and drains (12,13). In our study, there were no significant differences in urology-specific complications between groups, suggesting stable surgical quality.

The difference in analgesia and sedation protocols deserves attention. The PICU employed a more proactive “analgesia-first” strategy with fentanyl and midazolam/phenobarbital, likely reducing physiological stress. Internationally, pain and sedation are often assessed separately using scales like FLACC, COMFORT, or the State Behavioral Scale (14-16). Opioids are the mainstay for analgesia, with fentanyl often preferred in renal impairment (17); NSAIDs or acetaminophen may be used adjunctively (18). Non-pharmacologic interventions like music therapy (19,20) and oral sucrose (21,22) are recommended. Sedatives include benzodiazepines, α2-agonists, propofol, and ketamine (23). In Chinese PICUs, the CRIES scale is used for pain assessment in infants, while COMFORT-B and the Bispectral Index guide sedation (24). Morphine is the most widely used opioid, though fentanyl is used off-label in infants <1 year; sedation often combines opioids with benzodiazepines or α2-agonists (25), and non-pharmacologic methods such as massage and music therapy are also employed (26), along with family-centered care, noise reduction, and avoidance of physical restraints (27-29). Optimized sedation may have indirectly contributed to lower complication rates, and future studies should attempt to disentangle the effect of sedation from that of monitoring intensity.

Our observed median stay of 8 days is longer than what is reported from some high-volume centers with fast-track discharge protocols. This reflects our institutional context, including a conservative drain management policy and a higher baseline complication rate. We regard this as an area for quality improvement. Hospitalization costs were higher in the PICU group in both the full and matched cohorts. Because no formal cost-effectiveness analysis or multivariable cost regression was performed, these cost differences should be interpreted descriptively rather than as evidence of economic benefit or harm.

Limitations

PICU transfer was not randomized but was based on clinical judgment (age, weight, physiological reserve) and family preference. The two groups were inherently non-comparable, and observed differences in outcomes may reflect baseline patient heterogeneity rather than a causal effect of PICU care. Although we used PSM and multivariable regression to address measured factors, residual confounding from unmeasured clinician judgment and family preferences remains unavoidable. Due to the retrospective design, complete data on weight, hydronephrosis severity, and American Society of Anesthesiologists (ASA) grade were not available for all patients; these variables may be potential confounders and represent additional limitations. The study design also does not allow us to reliably identify “unnecessary” precautionary PICU transfers because the decision was subjective and based on clinical judgment and family preference. The present study therefore provides descriptive evidence rather than validated criteria for determining which infants require PICU care. Future prospective multicenter studies are required to develop, Validate objective triage criteria for PICU triage and perform formal cost-effectiveness assessment. The relatively small number of Clavien-Dindo grade ≥ III adverse outcomes may also have limited the statistical power and stability of the multivariable analysis for this endpoint.

Conclusions

In our institutional experience, a combined urology-PICU protocol for postoperative management of infants with UPJO was feasible and was associated with differences in complication patterns, particularly respiratory events. However, because of substantial confounding by indication and the non-randomized design, these findings do not establish a causal effect of PICU care. Younger age and operative side were independently associated with PICU transfer in multivariable analysis, whereas no evaluated factor was independently associated with Clavien-Dindo grade ≥ III adverse outcomes.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://tau.amegroups.com/article/view/10.21037/tau-2026-0465/rc

Data Sharing Statement: Available at https://tau.amegroups.com/article/view/10.21037/tau-2026-0465/dss

Peer Review File: Available at https://tau.amegroups.com/article/view/10.21037/tau-2026-0465/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tau.amegroups.com/article/view/10.21037/tau-2026-0465/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Research Ethics Committee of The Second Hospital of Hebei Medical University (No. 2026-R077) and individual consent for this analysis was waived due to the retrospective nature.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Babu R, Vittalraj P, Sundaram S, et al. Comparison of different pathological markers in predicting pyeloplasty outcomes in children. J Pediatr Surg 2020;55:1616-20. [Crossref] [PubMed]
2. van der AA F, Roskams T, Blyweert W, et al. Identification of kit positive cells in the human urinary tract. J Urol 2004;171:2492-6. [Crossref] [PubMed]
3. Wedel T, Spiegler J, Soellner S, et al. Enteric nerves and interstitial cells of Cajal are altered in patients with slow-transit constipation and megacolon. Gastroenterology 2002;123:1459-67. [Crossref] [PubMed]
4. Echeverria P, Reed L F, Gatti JM, et al. Latitudes and attitudes: A multinational study of laparoscopic pyeloplasty in children. J Pediatr Urol 2023;19:86.e1-6. [Crossref] [PubMed]
5. Elsner B, Pauen S, Jeschonek S. Physiological and behavioral parameters of infants' categorization: changes in heart rate and duration of examining across trials. Dev Sci 2006;9:551-6. [Crossref] [PubMed]
6. Than K, Mun-Price C, Klein MJ, et al. PICU admission and complications following adenotonsillectomies in pediatric patients: A retrospective cohort study. Int J Pediatr Otorhinolaryngol 2022;158:111166. [Crossref] [PubMed]
7. Abbas T, Elifranji M, Al-Salihi M, et al. Functional recoverability post-pyeloplasty in children with ureteropelvic junction obstruction and poorly functioning kidneys: Systematic review. J Pediatr Urol 2022;18:616-28. [Crossref] [PubMed]
8. Avery DI, Herbst KW, Lendvay TS, et al. Robot-assisted laparoscopic pyeloplasty: Multi-institutional experience in infants. J Pediatr Urol 2015;11:139.e1-5. [Crossref] [PubMed]
9. Gao J, Zhang S, Wang L, et al. Safety and efficacy of robotic-assisted laparoscopic pyeloplasty for ureteropelvic junction obstruction in infants under 6 months. Sci Rep 2025;15:13737. [Crossref] [PubMed]
10. He Z, Li J, Zhang Y, et al. Implementation of robot-assisted laparoendoscopic single-port surgery in infant urology. Int Urol Nephrol 2026;58:2413-20. [Crossref] [PubMed]
11. Rassweiler JJ, Teber D, Frede T. Complications of laparoscopic pyeloplasty. World J Urol 2008;26:539-47. [Crossref] [PubMed]
12. Li L, Qiu M, Gong B, et al. Systematic review and meta-analysis of ureteral stent for risk factors of restenosis after laparoscopic pyeloplasty. Ann Palliat Med 2021;10:10527-34. [Crossref] [PubMed]
13. Murphy KR, Hong JG, Wandalsen G, et al. Nebulized Inhaled Corticosteroids in Asthma Treatment in Children 5 Years or Younger: A Systematic Review and Global Expert Analysis. J Allergy Clin Immunol Pract 2020;8:1815-27. [Crossref] [PubMed]
14. Curley MA, Harris SK, Fraser KA, et al. State Behavioral Scale: a sedation assessment instrument for infants and young children supported on mechanical ventilation. Pediatr Crit Care Med 2006;7:107-14. [Crossref] [PubMed]
15. Boerlage AA, Ista E, Duivenvoorden HJ, et al. The COMFORT behaviour scale detects clinically meaningful effects of analgesic and sedative treatment. Eur J Pain 2015;19:473-9. [Crossref] [PubMed]
16. Beltramini A, Milojevic K, Pateron D. Pain Assessment in Newborns, Infants, and Children. Pediatr Ann 2017;46:e387-95. [Crossref] [PubMed]
17. Kudchadkar SR, Yaster M, Punjabi NM. Sedation, sleep promotion, and delirium screening practices in the care of mechanically ventilated children: a wake-up call for the pediatric critical care community*. Crit Care Med 2014;42:1592-600. [Crossref] [PubMed]
18. Nour C, Ratsiu J, Singh N, et al. Analgesic effectiveness of acetaminophen for primary cleft palate repair in young children: a randomized placebo controlled trial. Paediatr Anaesth 2014;24:574-81. [Crossref] [PubMed]
19. Vittinghoff M, Lönnqvist PA, Mossetti V, et al. Postoperative Pain Management in children: guidance from the Pain Committee of the European Society for Paediatric Anaesthesiology (ESPA Pain Management Ladder Initiative) Part II. Anaesth Crit Care Pain Med 2024;43:101427. [Crossref] [PubMed]
20. Vittinghoff M, Lönnqvist PA, Mossetti V, et al. Postoperative pain management in children: Guidance from the pain committee of the European Society for Paediatric Anaesthesiology (ESPA Pain Management Ladder Initiative). Paediatr Anaesth 2018;28:493-506. [Crossref] [PubMed]
21. Lago P, Garetti E, Merazzi D, et al. Guidelines for procedural pain in the newborn. Acta Paediatr 2009;98:932-9. [Crossref] [PubMed]
22. Tekgündüz KŞ, Polat S, Gürol A, et al. Oral Glucose and Listening to Lullaby to Decrease Pain in Preterm Infants Supported with NCPAP: A Randomized Controlled Trial. Pain Manag Nurs 2019;20:54-61. [Crossref] [PubMed]
23. Wolf A, McKay A, Spowart C, et al. Prospective multicentre randomised, double-blind, equivalence study comparing clonidine and midazolam as intravenous sedative agents in critically ill children: the SLEEPS (Safety profiLe, Efficacy and Equivalence in Paediatric intensive care Sedation) study. Health Technol Assess 2014;18:1-212. [Crossref] [PubMed]
24. Subspecialty Group of Emergency Medicine, the Society of Pediatrics, Chinese Medical Association. Expert consensus on analgesia and sedation for children in pediatric intensive care units of China (2024). Zhonghua Er Ke Za Zhi 2024;62:196-203. [Article in Chinese]. [Crossref] [PubMed]
25. Zhan Y, Lin S, Lin L, et al. Correlation Between Analgesic and Sedative Drug Withdrawal and Salivary Cortisol Levels in Children in PICUs: A Prospective Cohort Study. Pharmacotherapy 2025;45:801-8. [Crossref] [PubMed]
26. Huang YL, Lei YQ, Liu JF, et al. The music video therapy in postoperative analgesia in preschool children after cardiothoracic surgery. J Card Surg 2021;36:2308-13. [Crossref] [PubMed]
27. Khalesi N, Khosravi N, Ranjbar A, et al. The effectiveness of earmuffs on the physiologic and behavioral stability in preterm infants. Int J Pediatr Otorhinolaryngol 2017;98:43-7. [Crossref] [PubMed]
28. Rennick JE, Stremler R, Horwood L, et al. A Pilot Randomized Controlled Trial of an Intervention to Promote Psychological Well-Being in Critically Ill Children: Soothing Through Touch, Reading, and Music. Pediatr Crit Care Med 2018;19:e358-66. [Crossref] [PubMed]
29. Davidson JE, Aslakson RA, Long AC, et al. Guidelines for Family-Centered Care in the Neonatal, Pediatric, and Adult ICU. Crit Care Med 2017;45:103-28. [Crossref] [PubMed]