After surgically removing a large gel ball blocking the intestines of a baby girl, Texas doctors are warning parents about a new kind of water-absorbing balls often sold as playthings.

The colored balls, marketed under the brand name Water Balz by Ohio-based DuneCraft Inc, are small to begin with, but can grow to the size of a racquetball when placed in water.

For orally fixated toddlers, that can be a problem, said Dr. Oluyinka Olutoye, a pediatric surgeon at Texas Children's Hospital in Houston.

"It goes in small and grows on the inside and may not come out," he told Reuters Health.

That was the case for an eight-month-old girl, who was brought to Texas Children's with stomach problems. Her parents suspected she had eaten one of her sister's Water Balz, and their concerns grew when they read on the label that the balls expand up to 400 times if placed in water.

Olutoye and his colleagues could see on x-rays that part of the child's small intestine was distended, as if something was blocking it, but they couldn't see the culprit. Over the next 48 hours, the girl's belly grew bigger and bigger and her symptoms didn't go away.

"The blockage allows fluid and gas to accumulate, it is just like you step on a hose," said Olutoye, whose report appeared Monday in the journal Pediatrics.

Finally, the doctors took the baby to the operating room. They cut her intestine open and drew from it a bright-green Water Balz nearly an inch and a half across.

She recovered and is doing fine, according to Olutoye.

The surgeon said that as this type of product becomes more common, parents and doctors alike need to be aware of the danger it poses if swallowed. He explained that if the intestine is blocked long enough, the building pressure may eventually cause it to rupture.

"If this is not taken care of really quickly, there can actually be a perforation… and you can die from it," said Olutoye.

DuneCraft's CEO Grant Cleveland said he was sorry to learn of the incident. He noted that the Water Balz product already carries warnings on the label and is recommended for kids over 3.

"An eight-month-old has no business being near that product," he told Reuters Health. "Trying to turn it in to a public risk is absurd."

The new report is the first in humans, said Olutoye, although there have been cases of birds dying after eating a similar gel product used in gardening and agriculture. He added warned that the balls should be kept away from pets.