When a sponge is retained, it often presents with specific features on an X-ray or CT scan:

: A "burlap" or "soap-bubble" appearance may occur if gas becomes trapped within the fibers of the sponge, often indicating a secondary infection or abscess formation.

Surgical sponges are not inherently visible on standard X-rays because cotton is radiolucent (transparent to X-rays). To prevent them from being left behind, modern surgical sponges are manufactured with a —usually a thin, blue strip made of barium sulfate.

: In long-term cases, the body may form a granuloma around the sponge, which can eventually calcify. Clinical Significance and Prevention

: Operating room teams perform multiple manual counts of all sponges, needles, and instruments before, during, and after surgery.

: If the count is "off," a mobile X-ray (C-arm) is brought into the operating room to scan the surgical site before the patient is closed.