Introduction: Sigmoid volvulus is a major cause of large bowel obstruction in older adults and can progress to bowel ischemia, necrosis, and perforation. Although prolonged complete obstruction raises concern for bowel compromise, symptom duration alone does not necessarily indicate bowel nonviability. This case highlights the importance of intraoperative assessment of bowel viability in determining surgical management. Case: A 76-year-old male with chronic constipation and recently reduced mobility presented with progressive abdominal distension, abdominal pain, and complete absence of defecation and flatus for one week. He had no fever, nausea, or vomiting. Laboratory investigations showed hyponatremia, hypokalemia, and impaired renal function. Contrast-enhanced computed tomography demonstrated marked bowel dilatation, a redundant sigmoid colon, and twisting consistent with complete mechanical obstruction due to sigmoid volvulus. After fluid resuscitation, electrolyte correction, and gastrointestinal decompression, exploratory laparotomy was performed. A 360° rectosigmoid volvulus was identified without ischemia or perforation. Detorsion and manual decompression were followed by three-point sigmoidopexy. The patient recovered uneventfully and was discharged on postoperative day 5. Discussion: This case is clinically significant because it demonstrates preserved bowel viability despite prolonged complete obstruction. Intraoperative assessment, rather than symptom duration alone, guided surgical management and allowed a non-resectional approach. Conclusion: Prolonged complete mechanical intestinal obstruction due to sigmoid volvulus may occur without bowel necrosis. Timely stabilization, diagnosis, surgical exploration, and assessment of bowel viability are essential for individualized management.