Direct visualization–assisted enteral stent placement in malignant colorectal obstruction: a case report

Abstract

Background

Malignant bowel obstruction caused by colorectal cancer is a common and serious clinical condition. Enteral stent placement is widely used as a palliative treatment or as a bridge to surgery. Accurate guidewire placement across stenotic segments remains technically challenging.

Case summary

A 39-year-old woman with sigmoid colon adenocarcinoma presented with abdominal pain and cessation of flatus and defecation for more than 20 days. Abdominal computed tomography demonstrated sigmoid colon cancer with intestinal obstruction. Colonoscopy revealed circumferential stenosis approximately 25 cm from the anus. A direct visualization system (EyeMax, Micro-Tech, Nanjing, China) was used through the biopsy channel and advanced across the stenotic segment under direct visualization. A Jagwire was successfully passed through the stricture via the EyeMax working channel. After withdrawal of the EyeMax, a self-expandable metallic stent was deployed over the guidewire under endoscopic visualization without fluoroscopy. The procedure was successful with immediate symptom relief. A delayed fecalith obstruction occurred and was effectively treated with endoscopic fragmentation. Following the procedure, the patient resumed passage of flatus and stool, and abdominal pain was significantly relieved. One month after stent placement, the patient underwent radical resection for sigmoid colon cancer without perioperative complications. During 1-year postoperative follow-up, the patient remained asymptomatic, with no evidence of recurrent intestinal obstruction, or tumor recurrence.

Conclusion

The EyeMax system enables real-time intraluminal visualization, facilitating safe and accurate guidewire placement in complex colorectal strictures. This technique may reduce reliance on blind manipulation and improve procedural safety.

Introduction

Malignant bowel obstruction is a frequent complication of advanced colorectal cancer and often leads to significant morbidity. Endoscopic placement of self-expandable metallic stents (SEMS) has become an established method for relieving obstruction and improving quality of life. This technique is also widely used as a bridge to elective surgery in selected patients (1, 2).

In conventional practice, guidewire passage is often performed under fluoroscopic or indirect endoscopic guidance, which may involve blind manipulation in near-complete obstruction. Ultra-slim endoscopy represents an alternative, but its maneuverability and visualization may be limited. Severe luminal stenosis may hinder the advancement of the guidewire, increasing the risk of complications such as perforation and bleeding (3, 4). The EyeMax system (9F, 3 mm, Micro-Tech, Nanjing, China) is a miniature direct visualization platform that can be introduced through the working channel of a standard endoscope, allowing real-time intraluminal observation and instrument guidance. However, its application in colorectal stent placement has rarely been reported. In this report, we describe the successful application of the EyeMax system in enteral stent placement for malignant bowel obstruction.

Case presentation

Chief complaints

A 39-year-old woman presented with abdominal pain and cessation of flatus and defecation for more than 20 days.

History of present illness

In the 20 days before admission, she developed progressive abdominal distension and pain accompanied by cessation of flatus and defecation.

History of past illness

The patient had been diagnosed with sigmoid colon adenocarcinoma with pelvic lymph node metastasis 3 months prior to admission. She received four cycles of chemotherapy consisting of cetuximab combined with the FOLFOX regimen.

Personal and family history

The patient had no history of substance abuse, consanguineous marriage with parental relatives, or familial genetic disorders.

Physical examination

On physical examination, the vital signs were as follows: body temperature, 36.7 °C; blood pressure, 117/84 mmHg; heart rate, 76 bpm; respiratory rate, 18 breaths/min.

Laboratory examinations

On the day of admission, laboratory tests revealed several abnormalities: routine blood tests showed a hemoglobin level of 95 g/L (normal: 115–150 g/L), blood biochemistry indicated decreased levels of albumin (39 g/L; normal: 40–55 g/L). Other parameters, including liver and kidney function, blood glucose, electrolytes, and thyroid function, were within normal ranges.

Imaging examinations

Abdominal computed tomography demonstrated sigmoid colon cancer complicated with intestinal obstruction (Figures 1A, B). Colonoscopy (CF-HQ290, Olympus, Japan with a 3.2 mm working channel) performed revealed circumferential stenosis approximately 25 cm from the anus with mucosal erosion (Figure 2A). The distal lumen diameter at the stenotic segment was approximately 3 mm. The EyeMax direct visualization system (outer diameter 3.0 mm, 1.2 mm working channel, Micro-Tech, Nanjing, China) was introduced through the biopsy channel of the colonoscope and advanced beyond the stenotic segment. The length of stenosis was measured to be approximately 3.5 cm.

Figure 1.

(A, B) Abdominal computed tomography showing sigmoid colon cancer with intestinal obstruction.

Figure 2.

Colonoscopic findings and procedure of stent placement under EyeMax guidance. (A) Circumferential luminal stenosis located approximately 25 cm from the anus with mucosal erosion. (B) The EyeMax system advanced beyond the stenotic segment and placement of Jagwire into distal lumen. (C) Deployment of enteral metallic stent along the guidewire. (D) Confirmation of satisfactory stent position.

Final diagnosis

Malignant bowel obstruction secondary to sigmoid colon adenocarcinoma.

Treatment

Under direct endoscopic visualization, the EyeMax system was carefully advanced through the stenotic segment, allowing clear identification of the distal lumen. A 0.035-inch Jagwire (Boston Scientific, USA) was then inserted through the working channel of the EyeMax system and successfully passed across the stricture under continuous visualization (Figure 2B). After successful guidewire placement, the EyeMax system was withdrawn while maintaining the guidewire position. A 20-mm diameter, 8-cm long self-expandable metallic enteral stent (Micro-Tech) was successfully deployed across the stenotic segment over the guidewire into the colon (Figure 2C), the stent was placed as a bridge to surgery. The stent was deployed across the stenotic segment under direct endoscopic visualization without fluoroscopic guidance. Correct positioning and full expansion of the stent were confirmed endoscopically (Figure 2D). Symptoms initially improved. Later, recurrent abdominal pain occurred. CT showed fecal impaction in the rectum and stent lumen (Figures 3A–C). Enema treatment was unsuccessful (Supplementary Video 1).

Figure 3.

Computed tomography (CT) and colonoscopic findings of fecalith obstruction. (A, B) CT images show fecalith formation within the enteral stent. (C) Fecalith impaction within the rectum. (D) Colonoscopy demonstrates fecalith obstruction within the rectum. (E) Endoscopic snare fragmentation of the fecalith was performed. (F) Restoration of stent patency with visible passage of stool.

The procedure was successful with immediate symptom relief. However, 2 days after stent placement, the patient had recurrent abdominal pain and distension with no flatus or defecation. Colonoscopy confirmed fecalith obstruction (Figure 3D). A single fecalith measuring approximately 15 × 10 mm was located at the distal end of the stent. Fragmentation was performed using a 25 mm oval snare (Micro-Tech). The snare was gradually tightened around the fecalith under direct visualization, and mechanical fragmentation was achieved by repeated opening-closing. The procedure was technically straightforward without evidence of stent migration, perforation, or bleeding. No immediate or delayed procedure-related complications occurred. Complete clearance of fragmented debris was confirmed by post-fragmentation colonoscopy (Figures 3E, F).

Outcome and follow-up

After the procedure, the patient resumed passage of flatus and stool. The enteral stent successfully served as a bridge to surgery. One month after stent placement, the patient underwent radical resection for sigmoid colon cancer without perioperative complications. During 1-year postoperative follow-up, the patient remained asymptomatic, with no evidence of recurrent intestinal obstruction, or tumor recurrence.

Discussion

Self-expandable metallic stents have become an effective treatment for malignant bowel obstruction and are widely used as either palliative therapy or a bridge to surgery (3, 5). Compared with emergency surgery, SEMS placement can reduce morbidity, shorten hospital stay, and improve quality of life (6, 7).

However, successful stent placement depends on accurate guidewire passage through stenotic lesions. In conventional practice, SEMS placement is performed under endoscopic and fluoroscopic guidance. However, blind or semi-blind guidewire manipulation in tight strictures increases the risk of complications such as perforation and bleeding (4). Previous studies have identified guidewire-related perforation as a major procedural risk, particularly in complex or near-complete obstructions. Blind manipulation may increase the risk of perforation or bleeding (8, 9).

Although pediatric nasogastroscopes or ultra-slim endoscopes have been reported as alternatives for difficult colorectal stent placement (10, 11), but they have limitations in maneuverability, working channel size, and stability in severely angulated or tight malignant obstructions (12, 13). Instead, a dedicated direct-visualization system was selected for its smaller diameter, enhanced visualization, and guidewire compatibility. However, the lack of comparison with an ultra-slim endoscope is a limitation.

The EyeMax system (9F, Micro-Tech, Nanjing, China) is a miniature, direct visualization platform with an outer diameter of 3.0 mm and a 1.2 mm working channel, designed to be introduced through the biopsy channel of a standard colonoscope. The EyeMax direct visualization system, similar to Spyglass, has been utilized for the diagnosis of pancreatic and biliary tract diseases (14). The system used shares conceptual features with cholangioscopy, but its small caliber and direct visualization facilitate guidewire advancement when fluoroscopy alone is insufficient. Recent studies have reported the application of the EyeMax system in pancreaticobiliary diseases, as well as in the management of colonic diverticular bleeding and appendicitis (15–17). Recent reports have shown the value of choledochoscopy in challenging settings, such as diagnosing biliary metastasis from gastric cancer (18). Inspired by these, our case extends direct visualization to malignant colorectal obstruction during enteral stent placement. The EyeMax system allows real-time visualization of the stenotic lumen, enabling precise identification of the true lumen and controlled guidewire advancement. This may reduce procedural risk and improve technical success, particularly in near-complete obstructions. The EyeMax system offers a unique advantage by being passed through the biopsy channel of a standard colonoscope, eliminating the need for a second endoscopic insertion. The most important finding of this case is the feasibility of direct visualization–assisted guidewire placement using the EyeMax system (Figure 4).

Figure 4.

Schematic workflow and endoscopic images of EyeMax-assisted enteral stent placement.

However, this technique also has limitations. First, this is a single case report, and the safety and efficacy of this approach require validation in larger studies. Second, the additional device may increase procedural complexity and cost. Third, the applicability of the EyeMax system may be limited in extremely tortuous anatomy.

Another important aspect highlighted by this case is delayed stent obstruction caused by fecalith formation. Although less common than tumor-related stent dysfunction, fecalith obstruction represents a distinct and increasingly recognized cause of stent failure. In a personal series of 100 patients with stage IV obstructing colorectal cancer, fecal impaction necessitated repeat colonoscopic intervention in 19% of cases during follow-up (19). Similarly, a large multinational registry of 167 patients reported fecal impaction-related stent occlusion in 1.2% of cases (20). In comparison, tumor growth accounted for 8% of recurrent obstructions in the same series, highlighting that fecalith obstruction is a comparably frequent phenomenon requiring vigilant post-stenting management. The pathophysiology of fecalith formation is likely multifactorial. Contributing factors include reduced colonic motility, altered stool consistency, partial stent expansion, and tumor-related luminal irregularities. These factors may promote stool stasis within the stent, ultimately leading to impaction and recurrent obstruction (8, 21). Furthermore, the patient's prior chemotherapy with cetuximab and FOLFOX may have contributed to altered stool consistency and reduced colonic motility, a known side effect of certain chemotherapeutic agents (22). Furthermore, treatment strategies for stent obstruction depend on the underlying cause. While tumor-related obstruction may require repeat stenting or surgical intervention, fecalith obstruction can often be managed using minimally invasive endoscopic techniques (9, 23). In the present case, snare-assisted fragmentation effectively restored luminal patency without the need for re-intervention or surgery. This case also underscores the importance of post-stenting management. Preventive strategies, including bowel regimen optimization, stool softeners, and patient education, may help reduce the risk of fecal impaction.

Conclusion

This case demonstrates that the EyeMax system is a feasible tool for direct visualization–assisted guidewire placement in malignant colorectal obstruction. This technique may be useful both in palliative settings and as a bridge to surgery in selected patients with malignant colorectal obstruction.

Funding Statement

The author(s) declared that financial support was not received for this work and/or its publication.

Data availability statement

The original contributions presented in the study are included in the article/Supplementary material, further inquiries can be directed to the corresponding author.

Ethics statement

The studies involving humans were approved by Shandong Provincial Third Hospital. The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study. Written informed consent was obtained from the individual(s) for the publication of any potentially identifiable images or data included in this article.

Author contributions

TH: Writing – original draft. JL: Writing – review & editing.

Conflict of interest

The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Correction note

This article has been corrected with minor changes. These changes do not impact the scientific content of the article.

Generative AI statement

The author(s) declared that Generative AI was not used in the creation of this manuscript.

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Supplementary material

The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fmed.2026.1848674/full#supplementary-material