Left Behind after Surgery
Researchers work to produce a surgical sponge that the body can absorb
By Charli Kerns

No patient enjoys waking from a surgery only to realize something was left behind. Likewise, no doctor takes pleasure in reopening the patient to retrieve that missing something. These fears are not unfounded. Surgical sponges—cotton sponges that absorb liquids from a surgical site—have a lengthy history of ending up on the wrong side of the stitches, with an average 5,000 cases a year. Doctors have even developed a special term for it called gossypiboma.

Doctors use several techniques to avoid gossypiboma, which include having one individual solely for counting the equipment before and after surgery. Some manufacturers embed a strip of radio-opaque material into the sponge, which can pinpoint the sponge’s location. However, even though these techniques often work, the potential problem remains. The sponge is still inside the body.

Researchers Devon Anderson, Jonathan Guerrette, and Nathan Niparko from Dartmouth University are working on a solution to the forgotten sponge problem. Since the fall of 2009, the team has been trying to produce a bioabsorbable sponge, one that the body can absorb over a short period of time.

The sponge is a product formed by mixing cellulose and alginate, both of which are oxidized, a process that transforms the chemical fabrics into bioabsorbable material. Cellulose helps form the walls of most plant an aimal cells, while alginate is a biomaterial derived from seaweed.

Both cellulose and alginate are already used commercially in the hospital, the former as a hemostat for blood and the latter as a dressing for wounds. Together, they have the features necessary to create the biodegradable sponge.

“We’re trying to find the right percentages, ratios, and viscosity to produce the desired results,” said Anderson, biomedical researcher at Thayer College of Engineering at Dartmouth. The sponge is essentially a medical soufflé. Every measurement must be just right or the end product becomes nothing more than thin white paste, which Jonathan, Dartmouth graduate student in chemical engineering, said was all they got at the beginning.

“We’ve come a long way since our first trial runs,” said Guerrette, who works on the chemistry compositions for the research. After finding the right recipe, the team mixes the ingredients by electrospinning. Put simply, the components are spit out of a needle at a very fast rate onto aluminum foil hanging 17 centimeters away, leaving the solvent behind.

“It was incredibly exciting for us when we saw the first results of the electrospinning, and there were actually fibers on the aluminum that would peel off,” said Nathan, the logistics member of the team.

The team will soon move on to work with animal model testing and see how the sponge will react to flesh. Though a commercial application may be far off, the group is starting to see the light at the end. Devon said, “To walk through the process and find a product we’re really happy with is exciting.”