In a surprise policy reversal, Humana Insurance Co. will begin offering a broad-network health plan in the Houston area, potentially covering thousands who just days ago felt shut out of the city's top hospitals, the insurer confirmed on Wednesday.

The 11th-hour move by Humana to begin offering a high-deductible Preferred Provider Plan comes as patients - some in the middle of lifesaving treatment - have scrambled in recent weeks to find coverage before their existing plans disappear.

The Humana bronze plan is scheduled to become available Dec. 18 through the carrier's subsidiary, ChoiceCare Network, and will cover inpatient and outpatient care as well as prescription drugs, the company said. The plan can be bought through an insurance broker or directly from the company but will not be offered on the Affordable Care Act's federal exchange.

When the individual health insurance market opened on Nov. 1 in Houston, both through the federal exchange and in the private market, customers and health care providers realized there were no longer any PPO plans offered by major insurers, creating a void where a year before there were 19 such plans. Those with group plans were not affected.

Additionally, the Health Maintenance Plans, or HMOs, that were offered as replacements had pushed Houston's most prestigious medical institutions out of network in many of insurers' plans, leading to continuing worry that access would be curtailed or even eliminated for those who need it most.

Rumors have flourished over the past several days on social media that a large insurer was about to re-enter the PPO market in Houston.

Humana on Wednesday did not offer an explanation for reversing its earlier decision.

In late October, the insurer said in an email to the Houston Chronicle that it would not be offering any PPO plan on the federal exchange in Texas but would offer a plan in the private market in some cities. The Houston area was noticeably absent.

PPO plans, typically more expensive to customers, offer a wider choice of doctors and hospitals and are favored by people used to having full coverage or those with complex medical needs. By contrast HMOs are cheaper but more restrictive in where patients can go.

Among the hospitals that appear to be in-network under the new plan are the University of Texas M.D. Anderson Cancer Center, Houston Methodist, Texas Children's Hospital and Memorial Hermann - the very institutions mostly cut out of Blue Cross Blue Shield's HMO plans, according to area insurance brokers and some of the hospitals.

Late Wednesday, officials at M.D. Anderson would not officially verify it was in network because officials there said they were waiting for written confirmation from the insurer.

"It's a relief," said a cautiously optimistic Renee Mathew, a 52-year-old Sugar Land woman who is about to lose coverage for herself and her 21-year-old son when her current Humana PPO plan ends in three weeks

She is at high risk for breast cancer and gets screenings every six months at M.D .Anderson. Her next appointment is Dec. 31.

"What if this is the one where they find something?" she said.

Mathew does not qualify for a subsidy on the exchange and instead pays $1,100 per month for herself and her son. When she heard Wednesday of the new possibility she felt hopeful for the first time in more than a month.

"I want to look at the network and look at the numbers, but the deciding factor will be if it covers my doctors," she said.

Jason Bohmann, a Houston insurance broker, cautioned the coverage probably will not come cheaply.

Enrollees must meet a $6,450 deductible before coverage kicks in, he said. While he does not yet know all of the details, he said a plan that appears to be identical offered by Humana in Dallas cost a healthy couple in their 50s almost $700 each per month. That would mean they could both have to pay close to $15,000 out of pocket every year in deductibles and premiums alone.

"We have no options here now, so anything is good," he said of the race to find plans with wider choice for his clients.

Blue Cross and Blue Shield executives said it had become too expensive to continue with PPO plans and to cover patients in care at the expensive medical facilities. The company has said it will help those who lost coverage find other doctors and hospitals.

Patients have countered they would be willing to pay more if just given the chance to keep continuity of care.

Humana, too, has previously said it was dropping PPOs to "retain the overall affordability and access of the individual health plans."

But an email obtained by the Chronicle sent from the company to a Houston insurance broker said, "Humana has decided to launch our Bronze ChoiceCare PPO plan that has been available in other counties across the state in the 26 counties surrounding Houston and Austin that previously had no PPO offerings available to clients."

Hospitals included in the new plan were just starting to get word on Wednesday.

"This is great news for our patients who had no options if they wanted to continue getting care from Houston Methodist," said Mick Cantu, executive vice president at the Methodist Hospital System.

Still, many like Mathew find all of the uncertainty both dizzying and infuriating. She places the blame squarely at the feet of any insurance company dictating where people can go for care.

"Let's see where the top executives go when they get cancer," she said. "I love Obamacare. I think it's done a lot of good helping people get coverage. But this is a loophole that is being exploited."