“It is silly that we have codes for ‘hit by a spacecraft’ but not for ‘human trafficking,’ especially when we already have codes for domestic violence, sexual assault, and child abuse,” says Hanni Stoklosa, MD, MPH, executive director of HEAL Trafficking and emergency physician at Brigham and Women’s Hospital.

Data on the often invisible crime, which is estimated to victimize up to 45 million people globally, is hard to come by, and is key to preventing it and providing care to survivors, experts say. And since a number of studies have shown that the majority of trafficking victims access healthcare at some point while they’re being exploited, doctors are now calling on the healthcare industry to step up.

Stoklosa and her colleagues are advocating for the WHO to add codes for forced labor and sexual exploitation to the new International Classification of Diseases version 11 coding system (ICD-11) at the World Health Assembly later this month. It’s a rare opportunity—the last time new codes were voted on was decades ago.

“It’s a really crucial time window because we don’t know if the next opportunity will be 10 years or whether it will be 20 years,” Stoklosa, who also just co-authored an article on human trafficking and healthcare in PLOS Medicine, tells Fortune. “Traditionally, healthcare has not been at the table in the anti-trafficking effort and part of that was we just didn’t have any data to show that there was an interaction with healthcare.”

Because human trafficking victims often go unseen in everyday life, and many never encounter law enforcement at all, doctors are often on the front lines, whether they realize it or not.

“There are obvious health consequences of trafficking, and sometimes it’s those things that bring somebody to healthcare,” says Stoklosa. “Trafficking victims experience multiple levels of trauma, whether they be physical or mental.”

So, when a patient comes in for medical care and a doctor suspects that person has been victimized, it might be noted in that person’s medical chart, along with the specific health issue that brought them there.

This anonymized data is then analyzed by a third party, who pulls diagnostic codes out based on what the doctor has written. If a doctor suspects domestic violence (QE51.1 History of spouse or partner violence) that data is later counted and analyzed. But if a doctor writes that human trafficking is suspected, the data is not collected.

“Healthcare has a huge opportunity and responsibility to be a critical partner in further understanding vulnerability to trafficking, how to intervene, and understanding the scope of the problem internationally,” says Stoklosa. “Being able to collect data across countries on the interaction with healthcare is going to allow us to have a further sense of the global problem and its scope and breadth.”

But adding human trafficking diagnostic codes is only a first step in combatting the problem. Stoklosa co-founded HEAL—which stands for health, education, advocacy, and linkage—to focus on trafficking from a healthcare perspective, after realizing that there were likely missed opportunities earlier in her career as an emergency medicine physician to intervene in cases of human trafficking.

“When I learned what trafficking was, it was like this ‘aha moment’ and also a moment of frustration and pain,” she says. “I think one of the biggest obstacles for us is not just awareness about trafficking, which is definitely a hurdle, but actually creating the right conditions in healthcare for victims to feel emotionally and physically safe to disclose trafficking whenever it is happening.”

But doing so requires healthcare professionals to change their fundamental behaviors and be educated on how to better approach and interact with patients, she says, adding that many trafficking survivors don’t tell their doctor because they fear being judged.

“We ask, ‘Do you feel safe in your relationship?’ but the way that we ask that…if you’re staring at a computer screen and the patient knows that you’re just checking a box, it doesn’t matter,” she says, but having a true conversation can be transformative. “I can test for a heart attack, I can test for a blood clot, it’s a black and white thing, but when it comes to having these kinds of really sensitive conversations with patients, it’s not about just asking the questions.”

But even if doctors do have these conversations and mark this information down on patient charts, without a diagnostic code, this information will continue to go nowhere.

Delegates from WHO member states, including the United States, will vote on whether to add the new diagnostic codes at the World Health Assembly, taking place in Geneva from May 20 to 28.