Background: Urachal cysts, though rare, can become infected or undergo malignant transformation. A rare case of small bowel obstruction caused by an infected urachal cyst is presented, which can be misdiagnosed as invasive urachal cancer.

Methods: A 31-year-old Vietnamese female presented with a 1-week history of abdominal pain and 3 days of obstipation, with no significant medical or surgical history. Her clinical examination indicated sepsis and small bowel obstruction. Imaging revealed a cystic urachal mass invading the abdominal wall and small intestine, causing obstruction. Emergency surgery confirmed bowel obstruction and perforation due to the mass. Postoperative histopathology revealed an abscessed urachal cyst with no malignancy.

Conclusions: Complicated urachal cyst infections are challenging to diagnose and can be mistaken for malignancy. This is a rare cause of bowel obstruction in a patient without prior surgery or other preexisting conditions.