Patients who come to the emergency room with abdominal pain present a diagnostic challenge to doctors the symptom could be attributed to a number of conditions. A computer tomography (CT) scan gives doctors a view of the troublesome area, but also subjects the patient to a dose of potentially hazardous radiation.

So doctors face a dilemma they can turn to CT, to save time and improve their diagnosis, or they can err on the side of caution, and spare their patient the radiation.

A new study highlights the benefits of CT scans , adding to the growing debate surrounding this type of medical imaging.

In the study, doctors recorded their diagnoses of patients with abdominal pain before and after a CT scan.

The researchers found the scan results prompted doctors to change their diagnoses in nearly half the 584 cases. There was a 126 percent increase in a diagnosis of "no acute condition," meaning there was nothing critically wrong with the patient.

"There are many reasons why a patient would come into the emergency room, from simple things like constipation to things like appendicitis ," said study researcher Hani Abujudeh, a radiologist at Massachusetts General Hospital in Boston. Patients with constipation are discharged; those with appendicitis are taken right to the operating room, Abujudeh said.

With a CT scan, "doctors are very informed, they know the right information, and they can triage and manage the patient appropriately," Abujudeh said.

But other experts say, because of the cancer risks associated with CT scans , and their increasingly widespread use, doctors should avoid using them when they're not necessary.

"There is no doubt that CT is a powerful diagnostic tool, and this study provides more evidence of its diagnostic usefulness. But we must weigh this benefit against the risks," said Diana Miglioretti, a biostatistician at Group Health Research Institute in Seattle, who researches the advantages and disadvantages of CT scans but who was not involved in the study.

Radiation exposure is of special concern for patients who receive multiple CT scans. In addition, there is a risk that improperly performed scans may expose patients to radiation overdoses. And patients with recurring conditions, such as renal stones, could end up with high doses from routine scans, Miglioretti said.

Future studies should identify the patients who will benefit most from CT scans, and cases in which scans are unlikely to change diagnoses. Scan information should be documented in patients' records so it is easy to identify patients who've had high levels of exposure, she said.

Improving diagnosis

The researchers collected information on patients in the emergency room of Massachusetts General Hospital between November 2006 and February 2008. All were adults who complained of abdominal pain that was not due to trauma.

Forty-nine percent of patients had their diagnosis changed after a CT scan. And the scans increased how certain doctors said they were about their diagnosis, from 70.5 percent to 92.2 percent, on average.

The CT scans reduced the number of people that doctors said would need further observation by 44 percent, and increased the number of people sent home from the hospital by 55 percent. Overall, the scans reduced the number of planned admissions to the hospital by nearly 20 percent. And about a quarter of patients who had been thought to need surgery before the scan were sent home afterward without an operation.

The study did not look at costs, but suggests scans might save money by reducing unnecessary procedures, Abujudeh said.

However, Miglioretti noted that the scans can reveal other findings that turn out to be benign. Such findings may lead to follow-up tests and treatments patients don't need.

Patients were not followed up over time to assess the potential harms of CT, such as overdiagnoses or increased radiation exposure, Miglioretti said.

Reducing radiation

One problem with CT scans is that radiation doses can vary one patient might receive a much higher radiation dose from an abdominal CT than another, Miglioretti said.

Studies should try to identify why this is, and manufacturers of imagining machines should work to prevent it. For instance, machines could come with displays that present easy-to-understand dosing information.

Doctors should develop reference radiation levels for particular CT exams so that it's easy to tell which machines and hospitals are providing unnecessarily high radiation doses, Miglioretti said.

And manufacturers should work to reduce the amount of radiation CT machines give off, Miglioretti said.

"Manufacturers have developed dose-reduction software that produces high-resolution CTs with lower radiation exposure, but this software is so expensive that many facilities have not purchased it," she said.

The new study will be published in the February issue of the American Journal of Roentgenology.

Pass it on: The results of CT scans often lead doctors to change their diagnosis and management of patients. However, the benefits of these scans need to be considered against their risks.

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