#6056 NEPHROLOGIC INVOLVEMENT IN A SURGICAL COMPLICATION: WHEN TO SUSPECT A PYELO-DUODENAL FISTULA
Authors: Salomone Luca , Tinti Francesca , Lai Silvia , Pedata Laura , Rotondi Silverio , Tartaglione Lida , Luka Klaudia , Salvati Bruno , Pasquali Marzia , Rocca Rachele , Mazzaferro Sandro 
Published: June 2023

Abstract

Background and Aims
Spontaneous pyeloduodenal fistula is a rare condition occurring primarily after urologic events, in most cases infected kidney stones, pyonephrosis, xanthogranulomatous pyelonephritis, renal tumors, and infected renal cysts, with nowadays 80 cases described. The close relationship between the kidney and the duodenum is a facilitating condition.

Method
We describe the case of a 78 yo woman admitted in April 2022 for Acute Kidney Injury associated with fever, vomiting, oliguria and metabolic alkalosis. Over the last two years the patient reported recurrent febrile episodes associated with abdominal tenderness and weight loss. Urine cultures showed recurrent bacterial growth and she received antibiotics for recurrent episodes of pyelonephritis and lower urinary tract infections (K. Pneumonie ESBL +, E. Faecalis, P. Mirabilis). She was under nephrologic follow-up with a renal function demonstrating eGFR CKD-EPI of 35-30 ml/min/1.73 m2. In past medical history she reported atrial fibrillation in DOAC, heart failure with preserved ejection fraction, hypertension, previous left occipito-parietal ischemic stroke and right parotid adenoma. On physical examination of the abdomen there was no tenderness, mild pain in the right hypochondrium, Giordano's maneuver mild positive on the right side. Because of the evidence of lithiasis in the right kidney on ultrasound with grade III hydroureteronephrosis, we performed a CT scan with contrast, finding imaging compatible with right pyelonephritis with associated grade IV hydronephrosis, in particular lithiasic formation localized at the level of the right pyelo-ureteral junction (2 × 1cm), with partial involvement of the proximal portion of the ureter, severe calico-pyelic dilatation with overall reduction of the cortico-medullary thickness; diffuse inhomogeneity of the middle and lower thirds of the renal parenchyma, with evidence of some bubbles in contextual areas and inhomogeneity of the perirenal adipose tissue. Reduced nephrographic effect in the post-contrastographic phases and lack of elimination of the contrast in the urographic phase (12 min) were reported. She was started on antibiotics piperacillin-tazobactam and underwent right percutaneous nephrostomy placement. During the procedure we evidenced a communication between the calyx of the right upper calyceal group and an intestinal loop, probably the duodenum (Fig. 1).

Results
The patient underwent elective laparotomic surgery for right nephrectomy (Fig. 2) and closure of the intestinal fistula with duodenoraffia and omental patch. She was admitted to a post-operative intensive care unit, given comorbidities and the complexity of the operation. She was discharged in 9 days without post-operative complications, with stable renal function. One month after discharge the patient died of pneumonia.

Conclusion
Pyeloduodenal fistula is an infrequent condition causing occasional or continuous passing of materials between the alimentary canal and urinary tract. The presence of gastrointestinal symptoms and urinary tract alterations may be misinterpreted when occurring. Management of this case required collaboration between several specialists, with particular skills on AKI and CKD, infective complications, interventional radiology and surgical procedures. The outcome was strongly affected by the patient's general condition and comorbidities, with a good short-term outcome but complications on the long-term follow-up. The occurrence of air in the urinary tract is strongly suggestive of communications across the renal pelvis and the gastrointestinal tract. In particular if occurring in the setting of recurrent infections and nephrolithiasis, the diagnosis of pyelo-intestinal fistula should be considered.