Foreign body-induced Colovesical fistula: A case report

Abstract

Background

Colovesical fistula (CVF) is a rare condition characterized by an abnormal connection between the colon and the urinary bladder. While diverticular disease is the most common cause, this report describes a unique case of CVF resulting from an ingested foreign body.

Case presentation

A 78-year-old woman with a history of COPD and chronic lymphocytic leukemia presented with prolonged urinary symptoms, including dysuria, frequency, hematuria, and a history of pneumaturia and fecaluria. A CT scan with rectal contrast revealed thickening of the sigmoid colon, contrast material extending into the bladder, and an associated air-fluid level. Cystography and colonoscopy confirmed the presence of a CVF with inflammation and narrowing of the sigmoid colon. Remarkably, the patient spontaneously passed a “bone-like” object through the urethra, later identified as a chicken bone. She underwent a single-stage resection of the affected sigmoid colon with primary anastomosis and bladder repair. Histopathology confirmed chronic inflammatory changes consistent with fistula formation. The patient recovered uneventfully.

Discussion

CVF most commonly arises from diverticulitis, but migration of ingested foreign bodies leading to erosion into the urinary system is rare. This case highlights the importance of considering foreign body ingestion in CVFs without an identifiable cause.

Conclusion

Although rare, ingested foreign bodies—such as a chicken bone—can erode the bowel wall and cause a CVF. The spontaneous urethral passage of such objects is an even rarer event. This case underscores the importance of thorough history-taking and imaging studies to identify unusual causes of CVF.

Highlights

• •Colovesical fistula (CVF) caused by an ingested chicken bone is an extremely rare occurrence.
• •The patient spontaneously passed a bone fragment through the urethra, highlighting a highly atypical manifestation of foreign body-induced fistula.
• •The case occurred without underlying diverticulitis, malignancy, or prior abdominal surgery, making it diagnostically challenging.
• •CT imaging with rectal contrast was critical in identifying the fistulous connection between the colon and bladder.
• •Surgical management with single-stage sigmoid resection and bladder repair led to successful recovery.

1. Introduction

A colovesical fistula (CVF) is a rare yet clinically significant condition characterized by an abnormal tract between the colon and bladder. Common etiologies include diverticular disease, malignant tumors, Crohn's disease, and iatrogenic injuries following surgeries such as hysterectomy or radiation therapy [1]. The incidence of CVF has been reported to increase with advancing age, partly due to the higher prevalence of diverticular disease and other chronic inflammatory conditions in the elderly population. Diverticulitis is recognized as the leading cause of CVFs in Western countries, accounting for up to 45–65 % of cases [2,3].

The hallmark clinical manifestations of CVF are pneumaturia and fecaluria. However, the initial presentation may vary, ranging from subtle symptoms such as recurrent urinary tract infections (UTIs) and lower urinary tract irritation to more severe manifestations like gross hematuria and the excretion of feculent material through the urethra. Due to this variability, the diagnosis can be delayed, especially in patients without classical risk factors [3,4]. Diagnostic modalities such as computed tomography (CT) scans, cystography, and endoscopic evaluations (colonoscopy and cystoscopy) are essential for localizing the fistula and ruling out malignancies or other pathological causes [5]. Although pneumaturia and fecaluria are highly suggestive of CVF, determining the underlying etiology can be challenging, particularly in patients without prior abdominal surgery or known gastrointestinal disease. In this report, we present a rare case of CVF in an elderly patient with an atypical presentation, including the spontaneous passage of a “bone-like” fragment through the urethra, and notably lacking any common identifiable underlying cause such as diverticulitis, gastrointestinal malignancy, or prior abdominal surgery.

This study has been prepared following the SCARE guidelines [6].

2. Case presentation

A 78-year-old woman presented with prolonged urinary symptoms, including frequency, dysuria, occasional hematuria, and a sensation of incomplete voiding, lasting approximately two months. Prior to the onset of these urinary complaints, she reported lower abdominal pain. Notably, she experienced pneumaturia and fecaluria—raising concerns for a fistulous connection between the gastrointestinal tract and urinary system.

The patient had no history of prior abdominal surgery or gastrointestinal problems but had a medical history of chronic obstructive pulmonary disease (COPD) and chronic lymphocytic leukemia (CLL), treated with chemotherapy eight years earlier. Physical examination revealed suprapubic tenderness but was otherwise unremarkable. Her vital signs were within normal limits. Laboratory investigations showed leukocytosis (white blood cell count: 20,000/μL) with neutrophilia. Urinalysis was notable for pyuria and hematuria, and urine culture grew more than 100,000 colony-forming units/mL of Escherichia coli.

Given the clinical presentation and laboratory findings, an abdominopelvic computed tomography (CT) scan with rectal contrast was performed. The CT scan revealed segmental thickening of the sigmoid colon wall, associated with mild surrounding fat stranding. The sigmoid segment was noted to be in close contact with the dome of the urinary bladder. Rectal contrast extended into the descending colon and was also visualized within the bladder, along with the presence of an air-fluid level. These findings were highly suggestive of a CVF. Cystography confirmed the presence of a CVF (Fig. 1), and colonoscopy demonstrated inflammation and narrowing in the sigmoid colon.

Fig. 1.

Cystography revealed the entrance of contrast media from the bladder into the rectosigmoid colon, suggestive of a fistula.

After obtaining a more detailed history, the patient reported that approximately two weeks prior to her current admission, she had presented to a local primary hospital with complaints of genital pain and swelling at the urethral opening. At that time, she experienced a painful episode of urination accompanied by erythema, tenderness, and purulent discharge from the urethral meatus. During this episode, she spontaneously passed a hard, bone-like object through the urethra. The attending physician advised her to retain the object and referred her to a tertiary care center for further evaluation. However, the patient did not seek additional medical care at that point, believing her symptoms had resolved. In the days following this event, she continued to experience persistent dysuria, urinary frequency, and occasional hematuria. During her later admission to our hospital, she brought the expelled object with her, as shown in Fig. 2.

Fig. 2.

Bone-like object that was spontaneously passed through the urethra. (Left: external surface; right: internal surface).

Subsequently, the patient underwent laparotomy (Fig. 3). During surgical exploration, dense adhesions were noted between the sigmoid colon, the uterine fundus, and the dome of the urinary bladder. After careful dissection of these adhesions, the fistulous tract was identified between the bladder and the sigmoid colon. However, there was no evidence of diverticular disease, malignant tumors, or other gastrointestinal pathology. The bladder defect was repaired in two layers with absorbable sutures. The affected segment of the sigmoid colon containing the fistulous tract was resected, and a colorectal anastomosis was performed using a stapling device.

Fig. 3.

Adhesions caused by a severe inflammatory process (a) and defect in the bladder dome (b).

Histopathological examination of the resected bowel showed a partially epithelialized pseudocystic space with extensive granulation tissue, consistent with fistula formation. A Foley catheter was left in place for 10 days postoperatively to ensure adequate bladder healing. The patient recovered uneventfully, and the foley catheter was removed without complication. She was discharged in stable condition.

3. Discussion

CVF is a relatively rare but significant pathological condition. Diverticulitis is widely recognized as the most common underlying cause, with reported rates varying from 60 % to over 80 %. However, in regions where diverticular disease is less prevalent, malignancy, radiotherapy, or inflammatory bowel disease such as Crohn's disease may be the predominant causes [1,3]. CVFs are more common in males, with a male-to-female ratio of 3:1. The lower incidence in females is thought to result from the interposition of the uterus and adnexal structures between the bladder and the colon. Women who present with a CVF commonly have a history of hysterectomy [7]. The classic triad of pneumaturia, fecaluria, and recurrent UTIs is highly suggestive of a CVF. However, not all patients present with the complete triad, leading to diagnostic delays [3].

In this study the patient lacked any of the common underlying causes for CVF such as diverticulitis, malignancy, or prior abdominal surgery, yet she exhibited symptoms such as fecaluria and recurrent UTIs, raising suspicion of CVF. After reviewing her medical history, she reported an unusual presentation—passing a calcified or “bone-like” object through the urethra—which ultimately turned out to be a chicken bone.

In addition to mechanical injury from the ingested bone, the patient's chronic medical conditions—particularly CLL—may have predisposed her to fistula formation. While previous reports have described CVF development shortly after cytotoxic chemotherapy due to mucosal injury and immunosuppression [8], our patient had completed treatment years prior. Nonetheless, long-standing immune dysregulation, compounded by advanced age and chronic inflammation, may have impaired her ability to resolve localized inflammation, allowing the foreign body to erode through the bowel and into the bladder.

The accidental ingestion of foreign bodies is a relatively frequent occurrence, especially among children and the elderly. While most swallowed objects harmlessly traverse the gastrointestinal tract and exit the body without incident, a small percentage may deviate from the expected path, leading to potentially severe complications. These objects may become lodged in areas of anatomical narrowing and angulation, resulting in obstruction or perforation of the bowel [9]. Rarely, foreign bodies that have perforated the bowel wall can erode into adjacent structures, leading to the formation of an internal fistula. Most CVFs caused by foreign bodies originate at the bladder dome (62 %), followed by the posterior wall (28.5 %) and trigone (9.5 %) [1].

In terms of diagnosis, a multimodal imaging approach is pivotal. A CT scan with oral or rectal contrast is commonly employed to visualize the tract, while cystography can further define the communication. Additionally, a colonoscopy is necessary to assess the integrity and pathology of the intestinal mucosa as well as to identify underlying pathology and exclude malignancy. According to the literature, the average detection rates are as follows: cystoscopy, 35–46 %; cystography, 20–30 %; barium enema, 30 %; colonoscopy or sigmoid colonoscopy, 8.5–55 %; and abdominal computed tomography, 90–100 %. Among these modalities, contrast-enhanced CT has proven to be the most valuable single diagnostic test in detecting CVF [4,7].

The management of CVF depends on the underlying etiology, patient condition, and fistula complexity [10]. Conservative treatment, including bowel rest, total parenteral nutrition, antibiotics, and immunosuppressive therapy, is primarily reserved for select patients with Crohn's disease or those who are unfit for surgery, though it is rarely curative. Surgical intervention remains the definitive treatment, with a preference for a one-stage resection and primary anastomosis whenever feasible. In more complex cases, such as those involving extensive inflammation, abscess formation, or radiation-induced fistulae, a multi-stage approach with initial fecal diversion may be required. While surgery offers a high success rate, recurrence is possible, particularly in cases involving malignancy or radiation damage, necessitating individualized treatment strategies [4,5,10].

In this case, due to localized inflammatory changes and the patient's stable condition, a single-stage surgical repair was performed, including segmental resection of the sigmoid colon with colorectal anastomosis and a two-layer bladder closure. A Foley catheter was then left in place for 10 days to minimize stress on the repair site and reduce the risk of dehiscence.

To date, very few case reports in the literature describe the passage of calcified debris or foreign material through the urinary tract secondary to CVF. In a case report by Clement, a 66-year-old man presented with sepsis and renal complications and was found to have a fistula between the sigmoid colon and bladder. Imaging and colonoscopy revealed a “catheter-like” foreign object lodged in a colonic diverticulum, which was ultimately identified as a chicken bone. The fistula was successfully treated with surgical intervention, involving resection of the affected sigmoid colon and repair of the bladder [11]. Similarly, Khan et al. reported a case of a 56-year-old man who presented with symptoms such as hematuria, dysuria, pneumaturia, and urinary frequency. Initial investigations showed diverticulosis, but no fistula was identified at the time. The patient was treated with antibiotics, and his symptoms resolved. However, three years later, he developed recurrent pneumaturia and occasional fecaluria. Further imaging and cystoscopy confirmed a CVF. During surgery, a 4 cm chicken bone lodged in a diverticulum was identified as the underlying cause [12].

In another study, a 42-year-old woman was admitted with abdominal pain and fever. A CT scan revealed a pelvic abscess containing a thin foreign body, later identified as a fish bone. The patient was initially treated conservatively. However, one month later, she returned with symptoms of mechanical ileus, and follow-up imaging showed that the foreign body had migrated to the urinary bladder. Finally, the fish bone, measuring 3.5 cm, was removed using intraoperative cystoscopy [13]. The case reported by Verbrugge et al. (2024) described a 64-year-old male who had accidentally swallowed a chicken bone, leading to sigmoid colon perforation and subsequent abscess formation. Despite the initial endoscopic removal of the bone and conservative antibiotic treatment, the patient developed persistent abdominal pain, followed by urosepsis. A CT scan later revealed a CVF, identified by the presence of air in the bladder and an extensive inflammatory mass adjacent to the sigmoid colon [14].

These results raise the possibility that ingested foreign bodies may perforate the intestinal wall and erode into adjacent structures, leading to the formation of a CVF. The rarity of these cases underscores the importance of considering the possibility of a fistula caused by foreign bodies in patients with no underlying risk factors, to ensure timely diagnosis and treatment, thereby improving patient outcomes.

4. Conclusion

Although rare, ingested foreign bodies can erode the bowel wall, causing a CVF. The passage of a foreign body through the urethra—such as a chicken bone in this case—is an even rarer occurrence, as such objects typically lodge within the gastrointestinal tract, leading to complications such as perforation or abscess formation. Clinicians should maintain a high index of suspicion for rare etiologies such as foreign body-induced CVF to ensure timely surgical intervention and optimize outcomes.

CRediT authorship contribution statement

Yasser Asghari and Novin Nikbakhsh contributed to the study conception and design surgical intervention, patients' management, and follow up. Material preparation and data collection performed by Fatemeh Shahrahmani, Hamed Salamatfar and Sekineh Kamali Ahangar. The first draft of the manuscript was written by Fatemeh Shahrahmani and Yasser Asghari. All authors read and approved the final manuscript.

Patient consent

Written, informed consent was obtained from the participating patient for the publication of anonymized information in this article.

Ethical approval

Ethical approval was exempted for this case report by the Ethics Committee of Babol‌‌ University of Medical Sciences, as the study involved a retrospective review of a single patient's clinical course with no experimental intervention, and all identifying information has been removed to protect patient confidentiality.

Guarantor

Yasser Asghari is the guarantor of the paper. He accepts full responsibility for the integrity of the work, had access to all data, and made the final decision to submit for publication.

Sources of funding

The authors declare that there was no direct or indirect financial support by extramural sources for the study.

Declaration of generative AI

During the preparation of this work, the authors did not utilize any generative AI or AI-assisted technologies.

Declaration of competing interest

The authors declare that they have no related conflicts of interest to this work.