Long-Segment Right Colon Volvulus in a Young Adult With Severe Developmental Disability: An Unusual Presentation and a Diagnostic Challenge.

A 22-year-old woman with severe developmental disability, percutaneous endoscopic gastrostomy dependence, and chronic constipation presented with progressive abdominal distension and obstipation. Initial abdominal radiography demonstrated diffuse gaseous distension without a clear transition point, and she was discharged after symptomatic management. She returned within 24 hours with worsening distension, tachycardia, leukocytosis, and an elevated lactate level. Computed tomography of the abdomen and pelvis demonstrated marked dilation of the right colon with a maximal diameter of approximately 13 cm, along with pronounced cephalad displacement and organ shift, raising concern for toxic megacolon or acute colonic pseudo-obstruction. A water-soluble contrast enema demonstrated abrupt tapering at the distal transverse colon with a classic bird's beak configuration, consistent with mechanical torsion. Urgent exploratory laparotomy confirmed a long-segment right-colon volvulus involving the cecum, ascending colon, and proximal transverse colon with obstruction at the mid-transverse colon. The patient underwent decompression and right hemicolectomy with primary ileocolic anastomosis and recovered without complication.