Bruises can be hard to see on dark skin tones. How technology is illuminating injuries.

Bruises, like people, come in all shapes and shades.

Depending on a person’s skin tone, bruises also can be difficult to see.

For victims of domestic violence and sexual assault, this means it can be harder for forensic nurses to document the full extent of their injuries. That information is important not only for medical treatment but for criminal investigations, too.

New research, recently featured in national media, is demonstrating how purple light can better illuminate bruises on black and brown skin. It’s a technique already used at Aurora Health Care, which performs about 700 forensic exams each year in Milwaukee.

Here is what the research shows, how it’s being used in Milwaukee and how it can help victims of domestic violence and sexual assault.

Purple light is better for viewing bruises

Purple light is up to five times better for viewing bruises on any skin tone than the white light usually used during exams, according to new research published by Katherine Scafide, an associate professor at George Mason University.

Blue light also worked well, but purple light with yellow goggles was most effective in detecting bruises on people with darker skin tones, said Scafide, who also worked as a forensic nurse. 

Forensic nurses have specialized training to treat traumatic injuries resulting from domestic violence, sexual assault, child abuse and trafficking.

How long has Aurora Health Center used purple light in forensic exams?

Aurora has used this technique since 2016, said Sharain Horn, vice president of Well Community at Aurora Health Care.

The health care system has a camera with a filter so injuries can be photographed under that light source. She compared it to wearing sunglasses on a bright day.

“It's a different type of filter system that allows us to see things that are already there,” Horn said. “It's not creating anything. It's not changing what's actually there. It just allows us to see those things better.”

Is this technology the only evidence of what happened to a patient?

No. 

“We don't use alternate light sources in isolation,” Scafide said. “We use it as part of our assessment toolkit.”

The exam starts with a patient describing what happened to him or her.

“This information that we're obtaining really supports what the victim has already shared with us, " Horn said. “So we would never rely solely on this photograph to detect what happened to them.” 

How can this technology address healthcare disparities

People with fair skin — who had been the subject of most of the earlier research on bruise detection — tend to have more visible injuries. This technology can make things more equitable.

“When we talk about healthcare disparities, we know that particularly individuals of color feel that they're not often heard and believe the same as other individuals,” Horn said.

Patients have reported positive experiences with the technology, Scafide said.

“Having better tools to detect the injuries can help these patients feel like their injuries are believed,” she said. “They feel like (it is) some confirmation of their experience of the trauma that they've had.”

Can these photos help determine how long ago a bruise occurred?

No. 

Healthcare providers use bruise color, swelling and pain to help gauge how recently an injury might have occurred but there is no definitive way to determine the age of a bruise.

Scafide has another federal grant to examine that issue using a dataset of about 26,000 images of bruises photographed repeatedly over four weeks. She and other researchers are going to investigate whether a type of machine learning could predict a bruise’s age within a certain error rate.

Policies on how to use the technology are important

Scafide said she will publish a guide this summer with best practices on using the technology. 

For example, some evidence shows make-up or lotions can look like a bruise under purple light. That means a person’s skin should be cleansed before being examined for bruising — but a clinician should only do that after DNA evidence has been collected.

How this technology can be used to document signs of strangulation

Strangulation is a felony in many states, including Wisconsin. It is a sign of potentially lethal domestic violence and can result in brain injury. But it does not always leave bruising or other external marks. 

Purple light can help detect trauma on the neck, Horn said. In addition, Aurora swabs the necks of patients who report being strangled to be tested for touch DNA at the crime lab.

“Most people, even someone you’ve been in close proximity to, would not have had a reason to have their DNA on your neck, short of strangulation,” Horn said. “Again, we’re using that level of technology to help support what the victim already told us.”

Where to find help

Aurora Healing and Advocacy Services for sexual assault survivors includes a 24-hour hotline at 414-219-5555 and a confidential text line 414-219-1551.

The City of Milwaukee Health Department has resources for sexual assault survivors. We Are Here Milwaukee provides information on culturally specific organizations at weareheremke.org.

The Sojourner Family Peace Center in Milwaukee operates a 24-hour confidential hotline at 414-933-2722. The National Domestic Violence Hotline is 800-799-7233.