A surgical swab retained in the body after surgery is known as ′Gossypiboma′. The purpose of this report is to highlight an intramural vesical gossypiboma mimicking an invasive adnexal malignancy. A 28-year-old multiparous, with open-tubal ligation three years ago, presented with painless hematuria and a nontender mass on vaginal examination. USG suggested ′pelvic endometriosis′ infiltrating into the bladder and cystoscopy showed no intraluminal extension of the mass. Contrast-enhanced computed tomography (CECT) and magnetic resonance imaging (MRI) misdiagnosed it as invasive malignancy of the fallopian tube. Exploratory laparotomy found it to be an intramural vesical gossypiboma. A pelvic gossypiboma infiltrating into the wall of the urinary bladder may easily be misinterpreted as an invasive pelvic malignancy on imaging and may make one consider unwarranted radical surgery.