Secondary calyceal neck atresia induced by postoperative hemorrhage and hyperinflammation after FURL in a solitary functional kidney with contralateral renal atrophy: a case report

Abstract

Flexible ureteroscopic holmium laser lithotripsy (FURL) is a mainstream minimally invasive treatment for nephrolithiasis with rare late complications. We report a case of secondary calyceal neck atresia after FURL in a 71-year-old male with left renal atrophy, hypertension, and preoperative Escherichia coli urinary tract infection. Standardized anti-infective preparation was given preoperatively, with no intraoperative calyceal neck injury observed. However, severe hemorrhage and hyperinflammation occurred postoperatively, which was controlled with treatment. Three-month follow-up confirmed complete atresia of the right lower calyceal neck. This case emphasizes rigorous perioperative management and long-term surveillance in high-risk populations.

1. Introduction

Flexible ureteroscopic holmium laser lithotripsy (FURL) has been widely used in the management of upper urinary tract calculi, with the advantages of minimal trauma and rapid recovery.¹ Common postoperative complications include gross hematuria, stent-related discomfort and simple urinary tract infection.^2,3 However, severe late structural complications of the renal collecting system are rarely reported.^2,3 Calyceal neck atresia refers to complete occlusion of the infundibulum, which can lead to isolated caliectasis, recurrent infection and local renal function loss.4, 5, 6 Most reported cases are secondary to direct intraoperative laser thermal injury or mechanical mucosal tear.^7,8

Unilateral renal atrophy results in solitary functional kidney status, which is a well-recognized risk factor for perioperative adverse events.^9,10 The functional kidney undergoes compensatory hyperfiltration, with decreased mucosal tolerance to ischemia, hemorrhage and inflammation.⁹ To date, few studies have focused on calyceal neck atresia triggered by postoperative hemorrhage and hyperinflammation without intraoperative injury. This report presents a rare case of secondary calyceal neck atresia. In this report, we describe a rare case of secondary calyceal neck atresia in a patient with left renal atrophy, summarize its pathogenesis and clinical implications, and provide evidence for perioperative prevention. The study was conducted in accordance with the CARE guidelines for clinical case reporting.¹⁰

2. Case presentation

2.1. Baseline characteristics

A 71-year-old male patient, body mass index 22.4 kg/m², was admitted for nephrolithiasis. He had hypertension for 3 years, with a peak blood pressure of 160/90 mmHg. Blood pressure was irregularly controlled by oral amlodipine 5 mg once daily. He also had a 20-year history of right inguinal hernia without surgical treatment. No history of chronic kidney disease, diabetes mellitus, or previous upper urinary tract surgery or extracorporeal shock wave lithotripsy was documented.

2.2. Preoperative evaluation

Preoperative noncontrast computed tomography (NCCT) revealed left renal atrophy and multiple calculi in the right mid-lower calyces, with the largest stone measuring 1.5 × 1.3 cm. Multiple calculi were also found in the left ureter, and the left kidney was small with increased parenchymal echogenicity (Fig. 1). Urinalysis showed pyuria (576 white blood cells/μL), 3+ leukocyte esterase and positive nitrite test. Urine culture was positive for Escherichia coli at a concentration of 10⁵ CFU/mL. The patient received intravenous piperacillin-tazobactam 4.5 g every 8 hours for 4 days for preoperative infection control.

Fig. 1.

Preoperative NCCT manifestations of renal calculi.

(a, b) Coronal reformatted images demonstrate the distribution of renal calculi at different anatomical layers before treatment.

(c) Axial images display the cross-sectional distribution of renal calculi.

2.3. Surgical procedure

The operation was performed under general anesthesia in the lithotomy position. A disposable electronic flexible ureteroscope (670 mm in length, 3.6 Fr working channel) was adopted. Holmium laser lithotripsy was performed at an energy of 1.0 J and a frequency of 20 Hz in a pulverization mode. Intraoperative perfusion pressure was maintained at 150 mmHg and irrigation rate at 500 mL/min. No mucosal injury, tear or thermal damage was observed at the calyceal neck. The estimated intraoperative blood loss was approximately 5 mL. Due to the heavy load of the calculi and operative duration of 2 hours and 35 minutes, it was decided to continue with lithotripsy in the second stage. The patient was discharged on the day after the operation upon family request despite no obvious discomfort.

2.4. Postoperative complications and clinical management

On the third postoperative day, the patient was readmitted due to gross hematuria. Laboratory tests showed leukocytosis (13.56 × 10⁹/L, neutrophil percentage 94.50%), severe hematuria and pyuria. Urine culture was sterile, but procalcitonin reached 85.12 ng/mL and interleukin-6 exceeded 5000.00 pg/mL, indicating severe systemic inflammatory response syndrome. Meropenem 1.0 g every 8 hours was administered for anti-infection, combined with continuous bladder irrigation and hemostatic therapy with carbazochrome sodium sulfonate 40 mg twice daily.

Serial laboratory monitoring showed fluctuating inflammatory markers. On the ninth postoperative day, procalcitonin decreased to 57.27 ng/mL, while interleukin-6 decreased to 31.66 pg/mL. On the eleventh postoperative day, procalcitonin dropped to 8.27 ng/mL, but interleukin-6 rebounded to 504.15 pg/mL. Ultrasonography and postoperative NCCT suggested right renal calyceal hematoma, bladder blood clot, bilateral ureteral wall thickening and left renal limited effusion (Fig. 2). After adjustment of the anti-infective regimen to piperacillin-tazobactam on the fourteenth day of admission, inflammatory markers gradually returned to normal. The urinary catheter was removed on the sixteenth postoperative day. The patient experienced no dysuria following catheter removal. The patient was discharged with stable vital signs on the seventeenth postoperative day.

Fig. 2.

Postoperative NCCT manifestations at postoperative day 11.

(a, b) Coronal reformatted images demonstrate residual calculi and calyceal status at different anatomical layers.

(c) Axial images display cross-sectional calculi distribution and calyceal morphology.

2.5. Follow-up and diagnosis

Follow-up NCCT showed significant reduction of right mid-lower calyceal calculi. At the 3-month follow-up after the operation, NCCT revealed severe isolated hydronephrosis of the right lower calyx. Subsequent flexible ureteroscopy failed to identify the ostium of the right lower calyx, confirming complete calyceal neck atresia (Fig. 3). The patient remained asymptomatic without lumbago. Regular surveillance with urinary ultrasound and renal function examination every 3∼6 months was recommended.

Fig. 3.

Postoperative NCCT obtained 3 months after intervention.

(a, b) Coronal reformations demonstrate residual stone distribution and hydronephrosis at different planes.

(c) Axial view shows renal calculi and hydronephrosis.

3. Discussion

For this case, we discuss the risk factors and pathogenesis of secondary calyceal neck atresia, as well as the management and preventive strategies of its clinical complications. The possible high-risk factors of the reported case include both the patient and the anatomical aspects^{8 11 12}. Unilateral renal atrophy leads to solitary functional kidney status. This condition significantly increases the risk of postoperative complications. The solitary kidney bears the whole renal load, leading to compensatory hyperfiltration and impaired urothelial repair capacity.¹¹ Such patients have a lower tolerance to hemorrhage and inflammation, which makes them more susceptible to irreversible fibrotic changes.¹² In addition, anatomical factors should not be ignored either.^4,6,9,13,14 Anatomically, the mid and lower calyces are characterized by slender infundibula, acute angles and narrow lumens. During FURL, perfusion fluid is prone to stasis, which causes mucosal congestion and edema, creating a favorable microenvironment for subsequent scar formation after hemorrhage and inflammation. These anatomical characteristics, combined with solitary kidney status, constitute the high-risk background for calyceal neck atresia in this case.

Iatrogenic calyceal neck stenosis is generally caused by intraoperative laser thermal damage or mechanical mucosal avulsio.⁵ However, no intraoperative damage was observed in this case, indicating a novel pathogenic pathway driven by postoperative hemorrhage and hyperinflammation. Postoperative submucosal hemorrhage triggers hematoma organization, fibroblast proliferation and extracellular matrix deposition. Meanwhile, severe systemic inflammation, evidenced by extremely elevated procalcitonin and interleukin-6, aggravates local mucosal damage and inflammatory cell infiltration. Persistent inflammatory stimulation promotes collagen deposition and circumferential scar contracture of the calyceal neck, leading to progressive stenosis and eventual complete atresia. This synergistic effect of hemorrhage and inflammation represents an independent risk factor for calyceal neck occlusion, which is different from the traditional mechanism of direct surgical trauma.¹⁵

For high-risk cases, whole-process management should be further strengthened.^2,5 On the one hand, urinary tract infection should be thoroughly eradicated before surgery to reduce the risk of postoperative severe inflammation and sepsis.^12,16,17 On the other hand, surgeons should minimize laser energy near the calyceal neck and strictly control perfusion pressure to reduce mucosal congestion and potential bleeding.^2,5 Furthermore, serial detection of procalcitonin and interleukin-6 is helpful for early identification of occult hyperinflammation, even when urine culture is negative.^2,17,18 Moreover, solitary kidney patients need regular thin-slice NCCT surveillance within 6 months after surgery to detect early calyceal neck stenosis and avoid irreversible atresia.

For patients with established calyceal neck atresia, conservative follow-up is suitable for asymptomatic individuals. Endoscopic infundibulotomy or percutaneous drainage can be considered for those with recurrent infection or progressive caliectasis.

4. Conclusion

Secondary calyceal neck atresia can occur after FURL in patients with solitary functional kidney due to contralateral renal atrophy. Postoperative hemorrhage combined with hyperinflammation can induce irreversible fibrosis and scar contracture of the calyceal neck, independent of intraoperative injury. For high-risk patients, standardized perioperative anti-infective and hemostatic management, dynamic monitoring of inflammatory markers and long-term imaging surveillance are essential to prevent this severe late complication.

CRediT authorship contribution statement

Mingguo Zhou: Writing – original draft, Validation, Resources, Methodology, Investigation, Data curation, Conceptualization. Quliang Zhong: Validation, Supervision. Qiang Wang: Writing – review & editing, Validation, Supervision, Resources.

Ethics declaration

Written informed consent to take part in the study and to publish the article has been obtained from all participants or their legal representatives. The privacy rights of participants have been observed.

This study was performed in compliance with relevant laws, regulatory frameworks and guidelines where the research took place. The Medical science ethics committee of the Guizhou hospital of the first affiliated hospital of Sun Yat-sen university granted an exemption. The authors provided the following explanation: This case report was based on routine clinical care, no research-related intervention was performed. Written informed consent for publication of this case and accompanying images was obtained from the patient. This study was exempted from institutional ethics review.

This research follows the CARE guidelines and the CARE checklist.

Statement of ethics

This study was reviewed and approved by medical science ethics committee of the Guizhou hospital of the first affiliated hospital of Sun Yat-sen university. We obtained informed consent from the patient.

Data availability statement

The datasets generated and/or analyzed during the current study are not publicly available due to patient privacy and ethical restrictions, but are available from the corresponding author on reasonable request.

Funding sources

This study was not supported by any sponsor or funder.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.