"Pseudo coffee bean sign" without sigmoid volvulus: A case report and literature review

Sigmoid volvulus is a common acute abdominal condition in clinical practice. Delayed treatment can lead to serious consequences. Abdominal plain radiography is an important diagnostic modality for this condition, with the "coffee bean sign" representing its classic radiological finding. However, a "pseudo coffee bean sign" without evidence of intestinal obstruction may also be encountered clinically, necessitating further differential diagnosis.

We report a 72-year-old male admitted with "left lumbar pain lasting 8 hours." Comprehensive computed tomography (CT) revealed left ureteral calculi with associated left-sided hydronephrosis. Urinalysis showed 67 white blood cells per microliter (reference range: 0-15/μL).

Left ureteral calculi with hydronephrosis and urinary tract infection.

The patient underwent left ureteroscopic lithotripsy (URS). On postoperative day 1, a follow-up kidney-ureter-bladder (KUB) radiograph revealed the sigmoid colon dilation, consistent with the "coffee bean sign." The radiology department reported this as a critical finding.

Further comprehensive abdominal CT revealed sigmoid colon redundancy and gaseous distension, with no evidence of sigmoid volvulus or necrosis. At the 1-month follow-up after discharge, the patient remained asymptomatic.

The "coffee bean sign" is a classic radiological finding in sigmoid volvulus; however, it may also be present in a small number of patients with sigmoid colon redundancy. When plain abdominal films are inconclusive, CT or barium enema should be promptly performed to rule out intestinal obstruction.