Surgical items, such as sponges（海绵） and small instruments, left in the bodies of children who undergo surgery are quite uncommon 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 retrieve（检索，恢复） the forgotten objects.

Analyzing 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 costly and preventable error that can cause complications and require expensive repeat surgeries, the investigators say.

The retrospective（回顾的，怀旧的） study examined patient records after the fact and did not directly analyze factors such as operating room conditions and surgical routines that increased the chance of leaving items inside a patient. Yet the researchers noted 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 riskier than others.

"It's important to find out what mistakes we make as surgeons, but it is infinitely more important to know why we're making them and how we can prevent them," says principal investigator 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 discrepancy（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).