Fat Buttocks: Problem for Injections?
Fat May Block Medicines Injected Into Patients' Behinds
WebMD News Archive
Nov. 29, 2005 -- Obesity may require using longer needles to administer
shots to patients' behinds.
The reason: Fat may prevent standard needles from reaching muscles in the
buttocks, especially in obese women. That could mean that patients aren't
getting the intended dose of medicine.
Victoria Chan, MBBCh, and colleagues reported their finding in Chicago at
the Radiological Society of North America's annual meeting.
Chan works in Dublin, Ireland, at The Adelaide and Meath Hospital's clinical
Chan's study included 50 adults who were scheduled to get abdominal and
pelvic CT scans. The patients were also getting injections to their behinds.
Equal numbers of men and women took part.
Here's how those shots are supposed to work: The medicine gets injected into
the buttock muscles, then filters into nearby blood vessels.
Such shots are used for a variety of medicines, including vaccines,
painkillers, contraceptives, and antinausea drugs.
The patients in Chan's study agreed to get an extra bit of air shot into
their behinds just before their CT scan. The shot contained an air bubble in
addition to their injectable medicine. The CT scan showed whether the air
bubble made it to the buttock muscles.
The air bubble reached the buttock muscles in less than a third of the
patients (32%), Chan reports.
Men had more success with the shots than women. Shots succeeded in more than
half of the men (56%) compared with 8% of women, who usually have more fat in
their buttocks than men.
"Our study has demonstrated that a majority of people, especially women,
are not getting the proper dosage from injections to the buttocks," says
Chan in a news release.
"There is no question that obesity is the underlying cause," Chan
continues. "We have identified a new problem related, in part, to the
increasing amount of fat in patients' buttocks."
Fat vs. Muscle
Fat sits atop muscle in the buttocks. It's not as rich in blood vessels as
muscle. So injecting medicine into fat doesn't do much good.
In fact, drugs from a botched buttock injection could linger in fatty tissue
and cause infection and inflammation in the area, states the news release.
Chan suggests a simple fix: Longer needles for obese patients. "The more
fat tissue there is in the buttock, the less likely the needle will reach the
muscles underneath the fat," Chan says.