The colonoscopy: it may be the most dreaded screening test out there, and it's the next procedure we're covering as part of PriceCheck.

On PriceCheck, we're crowdsourcing prices of common health tests and procedures. KQED, along with our colleagues at KPCC in LA, and ClearHealthCosts.com, a health cost transparency start up in New York, are shining a light on health care costs by asking  you --members of our community -- to share what you've paid for various health care procedures.

We turned to crowdsourcing because health care prices are wildly variable and opaque. It sometimes stuns people to find out there is no central database of prices. Gag clauses in contracts between doctors and insurers forbid both parties to disclose prices.

But you can use our form to help bring prices into the open. Just get the explanation of benefits your insurance company sent for the colonoscopy, and enter price charged, price the insurance company paid and your co-pay (which should be zero for a screening colonoscopy -- more on that below.)

Our PriceCheck database already contains entries for colonoscopy prices -- they range from $1,000-$5000 in the Bay Area. Surprised by that range? It's in line with the price variation reported both by policy experts and our community on PriceCheck for other procedures.

After we get more shared prices (usually in a few weeks), we'll report them back to you on State of Health.

Under the Affordable Care Act (ACA), certain screening tests --including the colonoscopy -- are mandated to be covered at no cost to the patient. But we should all care about the wild variation in prices because as health care costs rise, health insurance premiums go up. If you have employer-sponsored health insurance, that can mean your own part of the premium will go up. Public insurance programs like Medicare and Medicaid get more expensive, too, and those are paid for through taxes.

Colonoscopy is "a messy one" for other reasons, too, says Maribeth Shannon with some irony. She specializes in market transparency and accountability at the California HealthCare Foundation.

She's not just referring to the procedure itself. Colonoscopy is messy because of the way it's billed.  Here are some things to ask about before you go in for the procedure:

Screening or diagnostic: In a screening colonoscopy, a doctor threads a flexible tube with an attached camera into the colon to look for abnormalities, like a polyp. If a polyp is found, it can be removed during the procedure. After the ACA first took effect, patients who had polyps removed discovered that this action changed the colonoscopy from a "free" screening test to a diagnostic test, and they were on the hook for a big bill.

Federal rules about the free screening colonoscopy have since been updated. "(P)olyp removal is an integral part of a colonoscopy," says the federal government, and must be included at no cost to the patient. Still, Maribeth Shannon says that "consumers should check with their health plan and ask 'what happens if a polyp is found -- you're going to treat that as preventive, right?'"

Anesthesia: You might think that anesthesia would be included with the price of a colonoscopy. After all, it's not surprising that many patients would want to be anesthetized when they are having a colonoscopy. But for quite awhile, patients were being billed for anesthesia, which by itself can run be $1,000 or more.

That's what happened to Gareth Tyrnauer of Sebastopol. He was delighted when his insurer sent him a letter that said a colonoscopy would be covered 100 percent. "I'd be a fool not to do this," he recalls thinking. But, after the procedure, he got a $1,200 bill -- just for the anesthesia. He called his insurer's customer service to fight the bill, saying he told the representative, "I've got a piece of paper right here and it says 'it's 100 percent covered. What part of 100 percent don't I understand?'" He ultimately won.

Earlier this month, the federal government stepped in again and issued a clarification that insurers may not charge for anesthesia used in connection with a preventive colonoscopy.

In-network is key: Make sure you know in advance who is involved in the procedure, warns Dena Mendelsohn, a health policy analyst with Consumers Union in San Francisco. "Consumers should be sure to confirm that the facility where they're going is in-network and the provider they will have is in-network."

Quality: In health care, determining quality of a procedure can be as difficult as determining how much it might cost. A strong predictor of quality is volume of procedures. A doctor or facility that has high volume is likely to be doing a higher quality job. Mendelsohn says many health insurance plans have tools for their customers on their websites and sometimes that includes volume. How much is the right amount? Hard to know, she says, but consumers could compare "hundreds or thousands versus dozens."

Mendelsohn also recommends avoiding a large university medical center for a colonoscopy. "Large universities are tailored toward more complicated procedures," she says. "Since a screening colonoscopy is more routine, it's not necessarily the case that going to a large university will get you a better colonoscopy."

Other options: If you've been dreading have a colonoscopy, you're not alone. But there are other non-invasive options for colon cancer screening, including the fecal-occult blood test. If you've been avoiding a colonoscopy, you may want to learn more about this option.

An earlier version of this story misstated how screening and diagnostic colonoscopies were billed after some aspects of the Affordable Care Act went into effect. We regret the error.