It's been described as a "last warning shot" before death.

Women who survive strangulation are up to seven times more likely to go on to die at the hands of their partner, according to recent studies in the US.

And there are side effects that aren't always obvious to treating doctors, paramedics or police officers — everything from voice changes to blood clots, strokes and paralysis.

Survivors and medical professionals are now pushing for increased training and awareness around non-lethal strangulation — something they say could help save lives.

Sue* was strangled by her partner about a year ago in Queensland, and knows too well that the side-effects can be delayed, and severe.

"I have PTSD. I have vocal cord dysfunction," she says.

"I'll get halfway through a sentence and have to stop because I can't swallow properly and I can't breathe properly because the neck just spasms because of the damage done to the vocal cords.

"I have a dent in the back of my arm, which will be there forever, from trying to protect myself.

"I have ongoing back issues. I tore my major stomach muscle, which has never repaired, so that means I have a weak leg now.

"It's not just about the instant that it happened, it's all the after-effects and the aftermath that it leaves you with."

Law professor Heather Douglas has also heard of cases involving memory loss, loss of consciousness, anxiety, paralysis and miscarriage.

"Gael Strack, who is an educator in the US around strangulation and prevention, describes it as the 'last warning shot'," she says.

Spotting the hidden signs

When somebody has been choked, it's not always obvious to first responders.

Dr Vanita Parekh, the head of Clinical Forensic Medical Services at Canberra Hospital, says 50 per cent of people who report an attack will have no marks on their neck.

"About 35 per cent will have very minor marks, and 15 per cent will have enough injury to be photographed," she says.

Without appropriate training, she says, it can be "very difficult" to spot other signs of non-lethal strangulation — like memory loss and increased anxiety.

Strangulation may lead to side effects that aren't always obvious to first responders. ( ABC News: Margaret Burin )

So she engaged members of Canberra's professional community — including doctors, nurses, paramedics, police, counsellors, crisis centres, judges and magistrates — to work together on a training model.

"We needed everybody to be on board and [to] understand how important and how serious strangulation was and how we need to deal with it," she says.

"And we had some fantastic outcomes in terms of CT angiography."

A CT angiogram can be used to see if there is injury within the vessels in the neck.

Dr Parekh convinced radiologists in Canberra to provide the test free of charge, specifically for patients affected by domestic or sexual violence, as well as those who have a refugee status.

As a result of the training, she says, an ambulance officer attending a domestic violence incident referred a patient who said she had been choked.

The test found the woman had a clot and she was given drugs to dissolve it.

Dr Parekh says it potentially saved the woman's life.

"Not just her life ... but also [avoiding] having that devastating consequence of having a major stroke at a very young age," she says.

Sue didn't have a CT angiogram until eight months after the strangulation event.

"I have no blood clots, for which I am eternally grateful for," she says,

"I have been left with [symptoms that are] life-altering, [but] I'm here. I'm still upright and vertical."

Training goes national

The ACT is a small, urbanised and well-resourced place but similar programs are being introduced in other states.

The Red Rose Foundation is a Queensland-based organisation which works to end domestic violence-related death and to support survivors.

The Red Rose Foundation is focusing on training Queensland Ambulance officers. ( ABC News: Giulio Saggin )

Chief executive Betty Taylor is hopeful the state can follow the ACT's lead in providing free angiograms to anyone identified as having been strangled.

"We want to pilot two strangulation trauma centres, where we hope to employ forensic nurses [who can] monitor and support women for up to six months post the strangulation episode," she says.

She also hopes to have a statewide phoneline to give women ongoing support, and help them look out for dangerous symptoms.

Ms Taylor says her organisation across Australia has trained approximately 600 police officers, magistrates and prosecutors, and is now focusing its efforts on frontline health services.

"Where we are just embarking on it is with Queensland Ambulance because often they are the first on the scene and they need to know how to read the signs," she says.

What is the law doing?

As understanding of the dangers of strangulation has increased, various jurisdictions have been updating their laws.

In NSW, a quarter of all murder victims have, at some point, been subject to strangulation.

Until recent changes to the law, prosecutors had to prove a victim had been rendered unconscious or unable to resist, or that the strangulation occurred in the course of an indictable offence.

But a new offence now only requires proof of intentional choking, strangulation or suffocating without consent.

In 2016, Queensland also introduced a new strangulation offence: Choking, Suffocation or Strangulation in a Domestic Setting.

Professor Douglas says it "doesn't require that the person has any specific intent to cause injury or cause death".

"It's simply the case that if a person chokes or suffocates or strangles a person unlawfully, they could be found guilty of that offence," she says.

Ms Taylor says there have been around 1,900 charges brought since the act came in and roughly 450 people have been imprisoned.

But she says "legislation as written and legislation as implemented are two different things", and many offences get "plea-bargained down", partly because of a lack of solid definition around strangulation.

She says it is, "a huge issue that is missing within the Act".

"Sometimes, I think it comes down to ... police and prosecutors, defence barristers [who] would all have their own interpretation of strangulation rather than be guided by a solid definition in law."

However, Professor Douglas says the new laws have been successful in that they are leading to prosecutions for non-fatal strangulations, which might have otherwise not been prosecuted at all.

Sue's attacker was convicted of assault, fined and subject to a five-year order preventing him from approaching her. But he avoided jail time.

Sue believes the way in which she described what happened to her to police had an impact on the legal outcome of the case.

"I kept saying, 'He tried to strangle me'," Sue says.

"What I learnt since that is because I put the word 'tried' in there it meant that he attempted to do it but didn't actually make good enough contact to do it.

"If I had my time over I'd never say the word 'tried'."

*Name has been changed for privacy reasons.