A case of nephrocolic fistula presenting primarily with changes in bowel habits

Abstract

We report a rare case of nephrocolic fistula in a 56-year-old female presenting with a three-month history of altered bowel habits. Initial colonoscopy revealed a sinus tract in the descending colon. Her hemoglobin was 79 g/L, and she had a history of nephrolithiasis and trauma. Further imaging, including CT and contrast studies, confirmed a nephrocolic fistula. Surgical intervention involved left hemicolectomy, excision of the fistula tract, and renal repair. This case highlights the importance of considering nephrocolic fistula in patients with gastrointestinal symptoms and a history of urinary tract pathology.

1 Introduction

Nephrocolic fistula is a rare and complex clinical condition characterized by the formation of an abnormal communication between the urinary and gastrointestinal systems. Its etiology is diverse, typically involving chronic inflammation, infection, trauma, iatrogenic injury, or malignancy. This report presents a case of nephrocolic fistula manifesting primarily as altered bowel habits and anemia. By contributing to the existing literature, this study aims to provide a detailed analysis of the clinical features, diagnostic challenges, and therapeutic strategies associated with nephrocolic fistula, offering valuable insights for clinicians managing this rare and complex condition.

1.1 Case description

A 56-year-old female patient presented with altered stool characteristics. She reported changes in stool consistency, including loose stools, occasional hematochezia, and an increased frequency of 5–10 bowel movements per day, with symptoms progressively worsening over the past 6 months. The patient had self-administered probiotics and gastrointestinal medications with minimal effect. Her medical history was significant for a 10-year history of nephrolithiasis. One month prior, she underwent a left ureteral stent placement at another hospital due to kidney stones, without lithotripsy. Post-treatment, her bowel symptoms improved, but anemia prevented further intervention. Additionally, she had undergone pelvic internal fixation surgery for trauma 4 months prior.

Upon admission, laboratory tests revealed a hemoglobin level of 79 g/L. Given the gastrointestinal symptoms, a colonoscopy was performed, which showed two tumor-like lesions resembling fistulous openings located 38–40 cm from the anal verge in the descending colon ( Fig. 1 ). Biopsy of the lesions indicated inflammatory granulation tissue, with no evidence of malignancy. Abdominal CT imaging further revealed a soft tissue mass at the anterior margin of the left kidney, in continuity with the adjacent descending colon, accompanied by minimal gas accumulation, suggesting the possibility of an intestinal fistula. Additionally, there was evidence of colonic wall edema and thickening in the descending colon ( Fig. 2 ).

Urinalysis showed 3+ leukocytes/HPF, 0–1 erythrocytes/HPF, and 3+ leukocyte esterase, indicating a urinary tract infection. Gastrointestinal contrast studies, performed via rectal administration, confirmed multiple fistulous tracts in the medial wall of the descending colon ( Fig. 3 ). Based on these findings, the diagnosis of a nephrocolic fistula was confirmed.