WASHINGTON (AP) — If things are a bit tense in your doctor's office come Oct. 1, some behind-the-scenes red tape could be to blame.

That's the day when the nation's physicians and hospitals must start using a massive new coding system to describe your visit on insurance claims so they get paid.

Today, U.S. health providers use a system of roughly 14,000 codes to designate a diagnosis, for reimbursement purposes and in medical databases. To get more precise, the updated system has about 68,000 codes, essentially an expanded dictionary to capture more of the details from a patient's chart.

How precise? Get nipped feeding a bird, and the codes can distinguish if it was a goose or a parrot. Have a bike accident with one of those horse-drawn tourist carriages? Yep, there's a code for that, too.

Unusual accidents aside, the government says the long-awaited change should help health officials better track quality of care, spot early warning signs of a brewing outbreak or look for illness or injury trends.

Under ICD-10 — the 10th edition of the International Classification of Diseases — there are codes that flag novel strains of flu, for example, and even Ebola and its cousins. With increasing focus on sports concussions, the codes can reflect how long patients lost consciousness and if they needed repeat care.

"ICD-10 has the potential to create many improvements in our public health system," Andy Slavitt, acting administrator of the Centers for Medicare and Medicaid Services, told health providers in a recent conference call.

But with the deadline approaching fast, he urged providers to make sure their offices are ready, and that they take advantage of Medicare-offered testing that lets whoever handles their billing file practice claims.

Might patients see an uptick in insurance denials for coding errors that require the doctor's office to refile the claims? Dr. Robert Wergin, president of the American Academy of Family Physicians, is optimistic that providers are ready enough that patients shouldn't feel an impact.

"Sitting in the room with a patient, I don't think you'll notice anything," Wergin said.

His 10-doctor practice in rural Milford, Nebraska, has updated the electronic medical records of patients with chronic diseases, so the next time the diabetic with early kidney disease comes in, that new code is one less thing to check.

Most doctors' offices only use several dozen codes anyway, to match each specialty's typical diagnoses, Wergin noted. "Really, I probably live in a world of 140 codes."

Why are codes so important? It goes beyond documenting that the bill is accurate — no reimbursement for a wrist X-ray if the diagnosis was knee pain.

With medical care gone digital, more precise diagnosis codes could allow researchers, even doctors themselves, to get a closer look at trends in one office or the entire country, Wergin said. A search of an office's data could show how, say, all pregnant women with a urinary tract infection in the third trimester fared.

The new codes, already used in many other countries, indicate if it's a first visit or a repeat. A spike in repeat visits for strep throat might indicate a more worrisome strain is spreading. This kind of data also is used by insurers and other organizations to help determine quality of care.

CMS can't estimate how many health providers are ready for the switch but officials think most large practices and hospitals are, so the agency is intensifying its focus on smaller doctors' offices, said Dr. Mandy Cohen, CMS' chief of staff.

Private insurers told Congress months ago that they were ready. They, too, are focusing on small providers.

"Health plans are working aggressively to help them get over the hump," said Justine Handelman of the Blue Cross Blue Shield Association, who noted that the industry has had years to prepare. The U.S. postponed the deadline twice.

Still, responding to concerns from doctors, CMS has promised some flexibility in the first year of assessing claims, if the coding is close.

"There will be bumps and challenges," CMS' Slavitt said, as he appointed an ombudsman to be the contact for health providers who experience them.