The mass showed up by accident. A 78-year-old woman was having a CT scan for a pancreatic cyst when radiologists spotted a lesion in her right pelvis. An MRI measured it at 4.5 centimeters and read it as a solid ovarian tumor. She had no symptoms, so her doctors chose to watch it.
Eight years later, it had grown to 6 centimeters and was filled with fluid. The differential now included an ovarian fibroma, a Brenner tumor, and a mucinous cyst. Surgeons opened her abdomen to take it out.
It was gauze left inside her during a hysterectomy 38 years earlier.
What Happened in the Operating Room
The case was published in the Journal of Surgical Case Reports by Hirofumi Kawahara and colleagues at Saiseikai Sendai Hospital and Kagoshima University Hospital in Japan. The patient's surgical history was extensive: an appendectomy at 13, an operation for an ectopic pregnancy at 23, and a total hysterectomy at 40, all through open incisions. Records from the hysterectomy no longer existed.
Once the surgeons reached the mass, they found it sitting behind the peritoneum and firmly adherent to her intestine. There was central necrosis and fibrosis. Then the bleeding started. They lost 1,510 grams of blood over an operation lasting three hours and 33 minutes, transfused two units of red cells along with fresh frozen plasma, and managed only a biopsy before closing. She went home nine days later. Pathology confirmed it: fibrous tissue containing cross-sections of gauze fibers, surrounded by multinucleated giant cell granulomas. Given where the mass was located, the authors concluded it almost certainly originated from the hysterectomy.
The medical term is gossypiboma, from the Latin for cotton. Some clinicians prefer textiles, since modern sponges are often synthetic.
Sixteen months later, she came back with abdominal pain. Imaging showed the remaining mass had opened a fistula into her small intestine and formed an abscess, with fluid also collecting between the mass and her bladder. Removing it was judged too dangerous. Surgeons instead created a diverting ileostomy laparoscopically to reroute her bowel contents and control the infection. Adhesions were so dense that even during that operation, they could not locate the sponge. She was discharged after 24 days with a stoma.
This Is Not as Rare as It Should Be
Retained surgical items are classified in the United States as a never event, meaning an error serious enough that it should never happen. It happens anyway.
The Joint Commission's annual sentinel event review logged 119 reports of unintended retention of a foreign object in 2024, 8 percent of the 1,575 sentinel events reported that year, and more than in any of the four prior years. The counts ran 105 in 2020, 97 in 2021, 99 in 2022, and 110 in 2023. Severe harm was associated with 43 percent of the 2024 cases.
Those figures understate the problem because reporting to The Joint Commission is voluntary. The Japanese authors cite a published frequency of roughly one retained sponge per 1,000 to 1,500 operations, while the Association of PeriOperative Registered Nurses estimates one in every 10,000 surgical procedures. Fear of litigation keeps the true number unknown. Roughly 53 percent of reported gossypibomas follow gynecologic surgery, and about 6 percent produce no symptoms at all.
A descriptive study of 319 retained-sponge events reported to The Joint Commission over five years found that human factors and leadership were the most frequently cited contributing categories. In nearly 70 percent of reports, the documented harm was unexpected additional care or an extended hospital stay; severe temporary harm was recorded in 14.7 percent, and one patient died.
Why X-Rays and Sponge Counts Keep Missing Them
Surgical sponges are manufactured with radiopaque markers so they show up on a plain film. That works when someone thinks to look, and the marker is intact. AORN puts the detection rate for retained items on X-ray at only 67 percent.
Time destroys the rest of the clues. As the Japanese authors note, the characteristic imaging appearance of a gossypiboma fades over years as the body walls it off with fibrous tissue, leaving something that appears on MRI like a solid tumor. In this patient's case, imaging never suggested a foreign body throughout nine years of surveillance.
The classic risk factors were mapped by Atul Gawande and colleagues in a New England Journal of Medicine study of retained instruments and sponges: emergency surgery, an unexpected change in the operation partway through, and higher patient body mass index. Uncontrolled bleeding, long operations, rushed counts, and staff changeovers all raise the odds.
The Uncomfortable Lesson
Retained sponges provoke two different biological responses. One is an aseptic reaction that walls off the object in a granuloma and may cause no symptoms for decades. The other is an exudative reaction that produces pus, abscesses, and fistulas. The authors believe this patient had the first for 38 years, and that the operation itself tipped her into the second.
That is the part worth sitting with. She was fine until doctors went looking. Their conclusion is that when a retained sponge is suspected before an operation, rather than discovered during one, the surgical plan and referral can be built around its complete and safe removal. Once a surgeon is already inside and staring at dense adhesions and heavy bleeding, the options narrow fast.
For patients, the practical takeaway is modest but concrete. Anyone with a history of open abdominal or pelvic surgery who develops an unexplained mass should make sure that history is on the record. Preoperative suspicion is what changes the outcome. Concerns about a previous operation or a new finding on imaging are worth raising directly with a physician.
Key Questions Answered
What is a gossypiboma?
A mass formed when the body walls off a surgical sponge or gauze left inside after an operation. It is also called a textiloma when synthetic materials are involved.
How often does this happen?
Published estimates range from one in 1,000 to 1,500 operations to one in 10,000 procedures. The Joint Commission received 119 reports of retained foreign objects in 2024, though reporting is voluntary and incomplete.
Why was it mistaken for an ovarian tumor?
Over decades, the imaging features that would identify a sponge disappear as fibrous tissue encases it. On MRI, the result can look like a solid ovarian mass.
Can a retained sponge be harmless?
About 6 percent of reported cases are asymptomatic. This patient had none for 38 years, and complications only followed the attempt to remove it.
Which surgeries carry the most risk?
Abdominal and pelvic procedures, with gynecologic cases accounting for a large share of reported gossypibomas. Emergency operations, unexpected changes in procedure and uncontrolled bleeding raise the risk further.
What should patients do?
Keep a record of prior surgeries and share it when a new mass is found. Preoperative suspicion of a retained item lets surgeons plan for complete removal under safer conditions.
