Surgical¹ items, such as sponges（海绵） and small instruments, left in the bodies of children who undergo surgery are quite uncommon² and rarely fatal but decidedly dangerous and expensive mistakes, according to a Johns Hopkins Children's Center study to be published in the November issue of JAMA-Archives of Surgery. Such errors added eight days, on average, to a young patient's hospital stay and nearly $36,000 in extra hospital charges, both stemming from（起源于） complications and the need for follow-up surgery to retrieve³（检索，恢复） the forgotten objects.

Analyzing⁴ more than 1.9 million records over 17 years detailing surgeries performed on children nationwide, the researchers identified 413 cases of items left behind, or 0.02 percent -- an uncommon but costly⁵ and preventable error that can cause complications and require expensive repeat surgeries, the investigators⁶ say.

The retrospective（回顾的，怀旧的） study examined patient records after the fact and did not directly analyze⁸ factors such as operating room conditions and surgical routines that increased the chance of leaving items inside a patient. Yet the researchers noted⁹ that teenage patients undergoing surgeries for gynecological（妇科的） problems had the greatest risk -- four times higher than other patients -- based on how frequently they ended up being wheeled out of the OR with a surgical item left inside them. The finding suggests that some operations may be inherently riskier¹⁰ than others.

"It's important to find out what mistakes we make as surgeons, but it is infinitely¹¹ more important to know why we're making them and how we can prevent them," says principal investigator⁷ Fizan Abdullah, M.D., Ph.D., a pediatric（小儿科的） surgeon at Johns Hopkins.

The study did find a difference in death rates between patients with and without surgical items left in them after surgery, 1.7 percent compared with 0.7 percent, but the discrepancy¹²（不符，矛盾） was so small it could have been the result of pure chance, the investigators say.

Most instances of forgotten items involved gastrointestinal（胃肠的） surgeries -- 22 percent of the 413 episodes occurred during such procedures -- followed by cardio-thoracic（胸的） surgeries (16 percent) and orthopedic（整形外科的） surgeries (13 percent).