LAST week, a US woman was gravely hurt in a freak subway accident.

After her leg slipped through the 12.7cm gap between the platform and train, the woman was so severely injured her thigh bone was reportedly visible through her skin.

Boston Globe reporter Maria Cramer, who happened to witness the scene at the Boston railway station, described the horrific wound as “twisted and bloody”.

However, as bystanders rushed to call an ambulance, the 45-year-old woman pleaded with them not to — for one heartbreaking reason which sums up the tragic reality of everyday life in the US for many of its people.

According to Ms Cramer, the woman sobbed as she begged witnesses not to fetch emergency services.

“Do you know how much an ambulance costs?” she wept.

“It’s $3000 ($A4060). I can’t afford that.”

Ms Cramer said despite the woman clearly being in “agony”, she seemed to be more concerned by the financial impact of treatment.

“When I saw her sitting on the platform, she was shaking, crying, in terrible pain and very scared about what this injury would do to her financially,” she posted on Twitter.

Ms Cramer tweeted about the incident before rushing from the station to pick up her daughter from daycare.

Within an hour, it had been retweeted and liked hundreds of times and today, the original post has received 8300 retweets, 15,193 likes and hundreds of comments.

As Ms Cramer said in a later tweet: “To say this woman’s plight touched a nerve would be a gross understatement.”

Ms Cramer later reported on the incident in a newspaper article, where she described the way passengers had rallied to help the woman.

In scenes reminiscent of Australia’s 2014 viral Perth train station rescue video, CCTV footage from the Massachusetts Bay Transport Authority Transit Police Department showed groups of people pushing on the train to free the woman, while others assisted with first aid once she had been pulled from the gap.

Despite the woman’s pleas, an ambulance was called and first responders bandaged the serious wound before taking her to hospital.

Police confirmed that while no bones had been broken, the deep laceration was so severe the unidentified woman would need surgery.

In an opinion piece inspired by Ms Cramer’s tweet, The New York Times described the woman’s reaction to an ambulance being called as “one you might expect to see in an impoverished country”.

The editorial said that for many citizens of the US — the world’s 12th wealthiest nation, according to the latest International Monetary Fund data — “the clear and urgent need for medical attention is weighed against the uncertain and potentially monumental expense of even basic services, like a bandage or a ride to the hospital”.

The piece explained that the US spent “vastly more on health care than other industrialised countries” — nearly 17 per cent of America’s gross domestic product in 2014 — and that the cost was often passed on to patients who struggled to afford it.

In a subsequent tweet, Ms Cramer said that while residents of Massachusetts were required to have health insurance, deductibles can add up to $6000 ($A8120) for individuals and $12,000 ($A16240) for families, according to Brian Rosman, policy director of Health Care for All, an organisation which advocates for quality, affordable healthcare.

Ms Cramer wrote that many readers had suggested the woman should have called an Uber instead of an ambulance to transport her to hospital in a bid to slash her expenses — a practice that’s growing in popularity in the US, where average ambulance fees can range from $300 to nearly $3000.

But the journalist argued that given the severity of the woman’s injuries, it would have been too risky to have carried her to an Uber without professional medical assistance on hand.

Ms Cramer is still attempting to track down the woman, and she said on Twitter that she had been inundated by offers from strangers to help cover her medical bills.

But despite the public’s generosity, the incident reveals the sad reality of America’s “ridiculous” health care system — a feeling captured by countless Twitter users who responded to Ms Cramer’s tweets and called for urgent change.