Obstructive rectal cancer incidentally diagnosed after a barium meal study: a case report of sequential endoscopic stenting and elective laparoscopic resection

Introduction: Barium meal study (BMS) has been widely used in Japan for gastric-cancer screening. Although complications are rare, intestinal obstruction due to retained barium can occur, especially in patients with preexisting gastrointestinal pathology. However, incidental diagnosis of obstructive rectal cancer after a BMS is extremely rare. Presentation of case: A 72-year-old asymptomatic man underwent a BMS following a positive fecal occult blood (FOB) test. Four weeks later, he developed constipation and abdominal distension. Imaging revealed retained barium and rectal wall thickening. Emergency colonoscopy identified an obstructive rectal tumor, and a self-expandable metallic stent was placed. After successful clearance of retained barium, elective laparoscopic anterior resection with primary anastomosis was performed. Postoperative recovery was uneventful. Pathological diagnosis was pT4aN1aM0 rectal cancer. The patient completed adjuvant chemotherapy and remains disease-free 12 months postoperatively. Discussion: This case illustrates a rare diagnostic pathway in which obstructive rectal cancer was incidentally diagnosed after BMS. It is important to consider underlying malignancy when prolonged constipation develops following BMS. Limitations of this report include the inability to perform magnetic resonance imaging owing to stent placement, which compromised local staging and may have influenced the decision to omit neoadjuvant therapy. Furthermore, the delay in acting upon the positive FOB test may have contributed to disease progression, underscoring the need for improved coordination between screening and diagnostic services. Conclusion: To our knowledge, this is the first reported case of obstructive rectal cancer incidentally diagnosed after a BMS and successfully managed with sequential endoscopic stenting and single-stage laparoscopic resection.