Congenital gastrojejunal fistula in an asymptomatic adult: A case report

Abstract

BACKGROUND

Gastrojejunal fistula is a rare clinical entity. Most reported cases are secondary, resulting from conditions such as peptic ulcer disease, malignancy, or prior surgery. We present a rare case of congenital gastrojejunal fistula, definitively diagnosed in an asymptomatic adult, to add to the limited data on this rare malformation.

CASE SUMMARY

A 56-year-old man underwent gastroscopy during a routine physical examination, which revealed a mucosal depression in the upper greater curvature of the stomach with smooth surrounding mucosa. He had no abdominal symptoms, and physical examination was unremarkable. Abdominal contrast-enhanced computed tomography and upper gastrointestinal contrast study suggested a gastrojejunal fistula. Diagnostic laparoscopy confirmed a congenital gastrojejunal fistula with a small orifice in the gastric fundus, allowing only minimal passage of food directly into the jejunum. Because the patient was asymptomatic and the fistula had no impact on his growth, development, or quality of life, no therapeutic intervention was performed, and regular follow-up was recommended.

CONCLUSION

This case highlights that incidentally identified gastrojejunal fistulas in adults may be congenital and underscores the value of multimodality imaging with laparoscopy for diagnosis.

Key Words: Congenital; Gastrojejunal fistula; Imaging examination; Diagnosis; Case report

Core Tip: We report a rare case of congenital gastrojejunal fistula in an asymptomatic 56-year-old man, diagnosed incidentally on routine gastroscopy. Contrast-enhanced computed tomography, upper gastrointestinal contrast study, and diagnostic laparoscopy confirmed the diagnosis. To our knowledge, no adult cases of this condition have been previously reported. This case highlights the essential role of multimodality imaging for accurate anatomical assessment and guiding appropriate management.

INTRODUCTION

Internal fistulas are usually caused by other abdominal diseases. These include tuberculosis, necrotizing enterocolitis, Crohn’s disease, abdominal trauma, peptic ulcer disease, previous surgery and cancer. In rare cases, if no clear cause can be found, the fistula is called a primary fistula. We report a rare case of congenital gastrojejunal fistula, which was diagnosed after comprehensive exclusion of all secondary causes.

CASE PRESENTATION

Chief complaints

A 56-year-old male patient underwent gastroscopy during routine physical examination, which revealed a mucosal depression in the upper greater curvature of the stomach with smooth surrounding mucosa. He was admitted to the Department of Gastrointestinal Surgery for inpatient management and further evaluation.

History of present illness

The patient had no symptoms such as abdominal pain, abdominal distension, diarrhea, nausea, vomiting, acid reflux, melena, hematochezia, fever, fatigue, or weight loss.

History of past illness

The patient had no history of necrotizing enteritis, Crohn’s disease, tuberculosis, peptic ulcer, foreign body ingestion, abdominal trauma, previous surgery, or malignancy.

Personal and family history

No significant family history was reported.

Physical examination

The patient was well-developed. Height was 160.0 cm, weight was 70.0 kg, and body mass index was 27.3 kg/m². The vital signs were within normal limits, and physical examination was otherwise unremarkable.

Laboratory examinations

Laboratory tests revealed no significant abnormalities in the complete blood count, routine stool examination, or fecal occult blood test. Tumor markers, including carbohydrate antigen (CA) 19-9, CA125, and carcinoembryonic antigen, were all within normal limits.

Imaging examinations

Gastroscopy revealed an isolated, well-demarcated mucosal depression on the posterior fundic wall near the greater curvature. The surrounding mucosa was smooth, with no inflammation or ulceration (Figure 1). Contrast-enhanced computed tomography (CT) demonstrated a focal discontinuity in the posterior wall of the gastric fundus, which communicated with an adjacent jejunal loop located posteroinferiorly. The intervening fat planes were well preserved, with no evidence of inflammatory stranding, fluid collection, or abscess formation. The gastric wall showed no thickening, mass lesion, or abnormal enhancement (Figure 2). Upper gastrointestinal contrast study confirmed that contrast material passed directly from the stomach into the jejunum, bypassing the duodenum. The fistula appeared as a narrow, smooth, and straight tract, with no dilatation, tortuosity, or irregularity. The maximum diameter of the fistula was 3.8 cm. Gastric emptying was normal, and there was no evidence of pyloric or duodenal obstruction (Figure 3A). Diagnostic laparoscopy revealed an isolated, smooth, cord-like tubular structure arising from the jejunum approximately 5 cm distal to the ligament of Treitz. It traversed the transverse mesocolon and coursed posterior to the pancreas, ultimately reaching the posterior wall of the gastric fundus near the greater curvature. The total length of the fistula was approximately 4 cm. No surrounding adhesions or inflammatory changes were observed (Figure 3B).

Figure 1 Endoscopic view of the fundic orifice of a gastrojejunal fistula (arrows). A small, smooth orifice on the posterior fundus with no surrounding ulceration. A-C: The same lesion viewed from different distances and angles under endoscopy.

Figure 2 Contrast-enhanced computed tomography showing the fistula (arrows). A: Axial view; B: Coronal view; C: Sagittal view. A focal defect in the posterior fundic wall communicates with an adjacent jejunal loop; fat planes are preserved, without inflammatory stranding.

Figure 3 Appearance of the fistulous tract on upper gastrointestinal contrast study and diagnostic laparoscopy (arrows). A: Upper gastrointestinal contrast study. Jejunum opacifies from the stomach, confirming the communication; B: Diagnostic laparoscopy. A smooth, isolated, cord-like tract arises approximately 5 cm distal to the ligament of Treitz, courses through the transverse mesocolon and behind the pancreas to the fundus, with no adhesions.

FINAL DIAGNOSIS

The patient had no clinical symptoms and no significant abnormalities on laboratory tests. There was no history of necrotizing enterocolitis, Crohn’s disease, tuberculosis, peptic ulcer disease, foreign body ingestion, abdominal trauma, prior surgery, or malignancy. No relevant family history was reported. Gastroscopy revealed a smooth, isolated mucosal depression, with no evidence of the significant mucosal disruption, ulceration, or infiltration typically associated with acquired fistulas. Contrast-enhanced CT demonstrated that the fat planes were well preserved, with no evidence of the surrounding inflammation, abscess, or mass typically associated with acquired fistulas. Upper gastrointestinal contrast study showed that the fistula appeared as a narrow, smooth, and straight tract, with no evidence of the irregularity, ulceration, or stricture around the orifice typically associated with acquired fistulas. Although the imaging findings suggested a fistula, they could not completely rule out an underlying neoplastic or inflammatory cause. Given that the patient had no significant symptoms, we conducted a multidisciplinary discussion and a thorough risk-benefit assessment. After communicating with the patient and obtaining informed consent, we decided to perform diagnostic laparoscopy to obtain a definitive histological diagnosis and guide further management. Intraoperatively, the fistula appeared as an isolated, smooth, cord-like tubular structure with no surrounding adhesions or inflammatory changes. This was considered consistent with a congenital developmental anomaly, leading to a diagnosis of congenital gastrojejunal fistula. For clarity, we present a diagnostic workflow (Figure 4).

Figure 4 Diagnostic workflow. A 56-year-old asymptomatic male underwent screening gastroscopy during a routine physical examination, which revealed a mucosal depression in the upper greater curvature of the stomach. Subsequent imaging and laparoscopy confirmed a congenital gastrojejunal fistula. CT: Computed tomography.

TREATMENT

In this patient, the fistulous tract did not impair growth or quality of life, likely because the small gastric orifice in the fundus permitted only limited direct passage of ingested contents into the jejunum. For this patient, surgical resection offered no therapeutic benefit, so periodic surveillance was elected. The patient was scheduled for annual clinical assessments, including symptom review, nutritional status evaluation, and a complete blood count to monitor for anemia. Further endoscopic or imaging evaluation was to be performed only if symptoms developed. The patient was counseled regarding the theoretical long-term risks, such as bile reflux gastritis or marginal ulceration, and potential symptoms including abdominal pain, nausea, bilious vomiting, gastrointestinal bleeding, and perforation were discussed. The patient agreed to this conservative management approach.

OUTCOME AND FOLLOW-UP

The patient was closely followed up after discharge and remained asymptomatic at the time of manuscript preparation.

DISCUSSION

Gastrojejunal fistula is a rare clinical entity. Most cases reported previously are secondary, resulting from etiologies that include caustic ingestion[1], gastric ulcer[2-4], gastric cancer[5], post-gastrostomy[6], and partial gastrectomy[7]. Management options for fistulas include conservative treatment, endoscopic therapy, and surgical intervention. The choice of treatment depends on several factors, including defect size, fistula location and accessibility, the patient’s hemodynamic stability, timing of diagnosis, and resource availability. Currently, most secondary fistulas are managed surgically[7]. Congenital gastrojejunal fistula arises from congenital developmental anomalies and is even rarer than secondary gastrojejunal fistula. To date, no reports of congenital gastrojejunal fistula in adults have been identified. In a report on congenital fistulas in children, Ravindranath et al[8] described an 8-year-old child who had experienced recurrent painless abdominal distension, belching, flatulence, and growth retardation since infancy. Upper gastrointestinal endoscopy and contrast study both revealed a jejunocolic fistula. Intraoperatively, an isolated, fibrotic tubular structure with no surrounding adhesions was identified, suggesting a congenital developmental anomaly. The fistula was resected en bloc, followed by jejunojejunal and colocolic anastomosis. Postoperative pathological examination showed no evidence of inflammation or infectious pathology, confirming the diagnosis of a congenital jejunocolic fistula.

Currently, there are no universally accepted diagnostic criteria for congenital gastrojejunal fistula, because the condition is extremely rare and large-scale studies are lacking. In clinical practice, the diagnosis depends on a combination of two factors: Strict exclusion of acquired causes and the presence of characteristic supportive findings. In this case, secondary etiologies were systematically excluded based on the patient’s asymptomatic history, normal laboratory results, and imaging studies showing no inflammation, mass, or involvement of adjacent organs. Critically, the diagnosis was further confirmed by intraoperative findings: Surgery revealed an isolated, smooth, fibrotic cord-like tract running from the jejunum to the gastric fundus, with no surrounding adhesions, inflammation, or mass effect. This anatomical picture is inconsistent with an acquired fistula, and these features were considered sufficient to establish a clinical diagnosis of a congenital anomaly. Performing surgical resection in an asymptomatic patient solely for the purpose of pathological confirmation would have exposed the patient to unnecessary operative risks without any therapeutic benefit; therefore, no therapeutic intervention was performed. Although the diagnosis remains one of exclusion, it is an exclusion based on a comprehensive, multimodality evaluation. The combination of clinical, imaging, and surgical findings provides a high level of diagnostic certainty for a congenital origin.

The patient’s fistula did not cause symptoms such as abdominal pain, distension, diarrhea, or weight loss, and had almost no impact on his growth, development, or quality of life. Nevertheless, from a pathophysiological perspective, the presence of a congenital gastrojejunal fistula still carries several theoretical long-term risks that require attention during follow-up. First, the gastrojejunal fistula bypasses the duodenum, which may disrupt normal intestinal peristalsis and lead to stasis of jejunal contents. At the same time, gastric acid entering directly into the jejunum may alter the microbial balance of the distal gut, allowing colonic-type bacteria to colonize and overgrow in the jejunum, thereby increasing the risk of small intestinal bacterial overgrowth. This condition may present clinically as abdominal distension, diarrhea, and nutrient malabsorption. Second, the altered anatomy may also affect the normal flow of bile. Although chyme bypasses the duodenum, bile and pancreatic juice are still secreted normally and accumulate in the duodenum. These digestive fluids may reflux retrogradely into the stomach via the fistula or the pylorus, causing chemical injury to the gastric mucosa, known as bile reflux gastritis. If present long-term, this may increase the risk of gastric intestinal metaplasia and even malignancy. In addition, because the jejunal mucosa lacks the protective mechanisms present in the duodenal mucosa, when gastric acid enters the jejunum directly through the fistula, the jejunal mucosa is continuously exposed to a high concentration of gastric acid. This predisposes to marginal ulceration near the jejunal fistula site. In severe cases, this may be complicated by bleeding, perforation, or stricture. From a nutritional and metabolic perspective, bypassing the duodenum can lead to inadequate mixing of bile and pancreatic juice with chyme, thereby impairing the absorption of fats and fat-soluble vitamins. If the fistula output increases or persists long-term, loss of intestinal fluid may also lead to protein-energy depletion, ultimately resulting in malnutrition and impaired growth and development. Furthermore, although the congenital fistula itself is structurally stable, if drainage is impaired or the fistula becomes obstructed for any reason, intestinal contents may accumulate in the peritoneal cavity, forming a localized abscess and potentially leading to intra-abdominal infection. In summary, although this patient has remained asymptomatic long-term due to a small fistula orifice and minimal shunting, the presence of these theoretical risks suggests that regular clinical evaluation is necessary to detect and manage possible complications in a timely manner.

CONCLUSION

This rare case suggests that a congenital gastrojejunal fistula should be suspected when a fistula is incidentally discovered in an asymptomatic adult with no history of abdominal surgery, trauma, peptic ulcer disease, inflammatory bowel disease, or malignancy, and when imaging shows no evidence of inflammation, mass, or adjacent organ involvement. Second, the combination of endoscopy, cross-sectional imaging, and diagnostic laparoscopy is essential for accurate anatomical delineation and appropriate management decision-making. Finally, when the patient is completely asymptomatic, the fistula orifice is small and located in the gastric fundus, resulting in minimal shunting, and intraoperative findings confirm an isolated, non-inflammatory, cord-like tract without mass effect or adhesions, then conservative surveillance with regular clinical follow-up is a safe and reasonable option. In such cases, surgical intervention offers no therapeutic benefit and would expose the patient to unnecessary operative risks. These key points may assist clinicians in recognizing and managing similar rare cases in the future.