(This story was originally published on March 2, 2017.)

It’s an extraordinary moment in sports that often brings admiring UFC fans to their feet and produces epic live theater: Two blood-caked fighters dueling over a blood-splattered canvas.

But the bloodier a bloodfest gets, the more casual spectators begin to wonder, “Shouldn’t they stop the fight?”

Through expertly trained eyes, what constitutes egregious blood loss is a dramatically different story.

Welcome to Dr. David Watson’s universe – a largely unknown ringside physician world where you rush into the cage, awaken woozy fighters and promptly quiz them. A world where most fans vastly underestimate eye pokes to cagefighters but they stir anxiety in you. A world where the size and symmetry of a fallen fighter’s pupils could indicate a matter of life and death and the horror of a blood-covered face tends to grossly deceive.

“I’ve been ringside physician for some of the bloodiest UFC fights, where people were going, ‘Oh my God, is this doctor going to stop this fight or is he insane?'” Watson said. “There was one particular fight – I’ll leave the names out – where there was a very small laceration right up (above the left eyebrow), which is where your supratrochlear artery and vein sit. There was blood everywhere and it looked, without a doubt, nasty. The fighter weighed in at 170 pounds, so he probably fought that night at 185, 186 pounds … But if you have a 10 percent total body volume blood loss, that percentage in and of itself is not a really big deal. But the cut on this fighter looked horrendous so people were saying, ‘Stop the fight, stop the fight!’

“The reality is, the amount of blood loss was probably less than what is in (an eight-ounce) cup. I could take this cup right here, fill it with blood, and smear it on you, me and four or five people in the audience and we would all look like we were in a knife fight bleeding to death. Really, that’s how bad it would look.”

On the night in question, neither Dr. Watson nor his peers on the Nevada State Athletic Commission stopped the fight due to bleeding. Immediately after the fight, the fighter who had been “bleeding everywhere” received a grand total of two stitches.

“There was no harm to the fighter,” Watson said.

Few know better. The 51-year-old Watson has been moonlighting in the “Hurt Biz,” rushing to the aid of MMA fighters and pro boxers for the past 18 years. In addition to working for what is arguably the world’s preeminent and most influential fight commission, Watson also is a part-time associate professor at Nellis Air Force Base in Nevada and has handled thousands of chaotic, critical situations as an emergency room doc in Miami and Vegas.

“Emergency medicine is the one field where I can take care of homeless people, dirt-poor people and people I thought were underserved,” Watson said. “I also wanted to deal with sudden, horrendous life threats: roll-over car accidents with multiple fractures, people coming in who have been shot or someone attempted to murder them, people who are bleeding to death from an assault or have overdosed on drugs … I love being on the front lines and trying to help them.

“If I’m in the hospital, someone yells frantically, ‘Quick, doctor, Room 23!,’ then I have no idea what’s in Room 23, but I go in and deal with it. I’m an adrenaline junkie, and to me, being on the front lines of instantaneous action, stuff you can’t plan for, is fascinating.”

To rabid UFC and boxing fans, the sharply-dressed, barrel-chested Watson represents a familiar face, but unfamiliar story. Hundreds of times, the father of six has walked into rooms and told strangers their loved ones didn’t make it, and he gets emotional when discussing the kids he tried to save.

Despite a scholarly and stoic demeanor, Watson is a bit of a daredevil. Hundreds of times – risking damage to the hands and fingers that anchor his financial well-being – the California native has grappled against other Brazilian jiu-jitsu students. And his path to USC medical school graduate, with a later residency at Harbor-UCLA Medical Center, was far from conventional.

“When I was very young, I was homeless for quite awhile,” Watson said. “I don’t mention that to a lot of people, but it was very hard. Because of that, I would study for 17 hours a day with six books open in front of me.”

The eyes never lie

There are a couple certainties in the fight game. Most fans crave nonstop, throw-caution-to-the-wind slugfests, and you never have to wait long for the next bad judging controversy featuring outraged die-hards wondering, “What fight were you watching?!” Accordingly, UFC President Dana White is known for constantly imploring fighters, “Don’t leave it in the hands of the judges.”

As it happens, fighters tend to heed the advice of the man enabling their checks – 52 percent of UFC bouts in 2015 ended via knockout or submission, according to an article published last year in the Washington Post by Fightnomics analyst Reed Kuhn. The finish rate keeps ringside physicians on their toes and means that someone like Watson, himself an aficionado, is the rare person in a frenzied arena who can’t deeply enjoy a barn-burning fight or hair-raising moment.

“The hardest part is probably holding your emotions in when you have 18,000, 22,000 people screaming and you’re two inches from the action … but you have to,” Watson said.

As a tussle unfolds, Watson’s mind constantly scans for signs of hidden dangers.

Is that eye poke serious? Is there a laceration through the edge of the eyelid that is so tiny no one else has a clue?

“I want to take a very close look at (a poked eye) and make sure it’s not a corneal laceration, make sure it’s not a laceration right through the edge of the (eye)lid margin – which is a super big deal,” Watson said. “Because even if that injury heals perfectly, if it scars at all, then when you blink you can have a chronic corneal abrasion that could literally even lead to chronic blindness. So you have to worry about that.”

What about blood streaming into a fighter’s eyes? Let’s say a fighter has a cut on his forehead and blood gets into his eyes. Is that dangerous?

“Getting blood in your eye doesn’t damage your eye. It’s no risk to your eye – you irrigate it out and call it a day,” Watson said. “But if a fighter’s not intelligently defending himself because of the blood (temporarily compromising vision), well that’s a different story and the referee can stop the fight.”

MMA is the only sport in which the referee can rightfully and forcefully tackle an athlete – and be thanked for it later. But the third person in the cage often walks a tightrope. Stop a fight too soon when a fighter has more to give, and fans will rain down with boos and believe you deprived them of a more spectacular ending or prevented the possibility of a riveting come-from-behind victory. Conversely, you can be the referee who stops the fight too late and is widely and viciously toasted – not to mention one who shoulders the guilt and shame of letting a fighter absorb too many blows and unnecessary damage. Refereeing is a typically thankless job with your every mistake publicly paraded and replayed for all the world to see.

Watson, by comparison to refs, rushes in and out of the ring and cage in relative anonymity. He’s someone whose face you might recognize, but aren’t exactly sure why you know it. Within a cage or ring, he’s seen it all – or most of it: a fighter whose big toe is dangling because it got stuck in the canvas; fighters who get knocked unconscious before they even hit the ground and then spontaneously urinate or defecate on themselves; fighters knocked unconscious, and who stay unconscious for two or three minutes.

“Sometimes you will see a (knocked out) fighter twitch a little bit – it’s not actually a seizure; it looks like a seizure but technically it’s not. It’s called post-concusssive myoclonus,” Watson explained.

There has never, in the UFC’s 24-year history, been a fighter death following or linked to an event. The mere mention of this causes the interviewer, and then Watson himself, to repeatedly knock knuckles on a wooden table – part in jest, part hoping for continued good fortune.

“We’ve had three (boxing) deaths in Nevada in the last 15 years or so; one of them died shortly after being in the ring,” said Watson, noting that pro fighters in Nevada must undergo brain and physical exams and testing for diseases such as HIV/Hepatitis B before being approved by the NSAC. “Throughout the world, there are nine to 11 deaths per year for all fights (mostly boxing), so it’s a real enemy and it does happen. And it’s, ironically, not always from trauma suffered inside the ring. You wonder was that trauma suffered before going into the ring? Was there something there first that a brain image didn’t pick up?

Cage crashers

When he darts into the cage following a knockout, TKO or submission, Watson operates on the assumption that every second is vital. One of the first things Watson studies – even if the fighter is still out cold – are the all-important pupils of the eyes. Is one pupil dilated and much bigger than the other? Both pupils being dilated is not necessarily cause for alarm, but assymtrical pupils would be a huge warning sign indicating a possible brain herniation or a brain bleed, meaning the brain might be flowing out of the foramen magnum, which is where the brain and spinal cord meet. Fortunately, such a scenario is extremely rare in the fight game and more commonly seen in traumatic car accidents. But it is incumbent upon ringside physicians to consider such worst-case scenarios.

“You don’t have a blown pupil and you’re wide awake. It just doesn’t work that way,” Watson said. “So that’s a critical thing when you respond to an accident scene – a roll-over car accident at 85 miles per hour. You’re looking for pupils that are assymetrical because it indicates a possible brain bleed.

“So someone gets knocked out and we jump in the ring and take a look at them – and their pupils are usually larger than normal, but not assymetrical. As they come to, their pupils will get smaller and go back to baseline.”

Also paramount following a knockout or TKO is immediately gauging the fighter’s short- and long-term memory. A smattering of the standard questions Watson poses to knocked-out fighters includes:

What year is this? What round is this? Who are your two kids? What are their names? What happened to you? Who is the president? Who are you fighting?

Watson agrees with what many fighters and top coaches will tell you: The jaw line is the jackpot for turning out someone’s lights, the most vulnerable location. A hard kick anywhere near the neck or head, if it lands, can produce incredible amounts of force and knock someone out. But generally speaking, a much weaker force striking the jaw, at just the right angle, can create a massive amount of torque and whip on the head that irritates “the verticular activing system of the brain stem, which is your wake-up center,” Watson said. “If there’s enough torque, you’re out cold.”

Pundits have long theorized why some fighters possess granite chins, others glass jaws. Nearly two decades embedded with the world’s toughest athletes causes Watson to pinpoint a mix of physiology and psychology to explain why some fighters refuse to go down.

“It’s the warrior mindset that enables the person to go farther,” he said. “Some fighters have the mindset, ‘I will not go down.’ That warrior spirit matters a lot, as well as neck strength, torque, the power of the blow and your physiology.”

Returning once more to the wonderous sight of bloody fighters, Watson said the growing popularity of the UFC creates an ever-growing number of educated fans who won’t freak out when the red stuff flows.

“Now again, granted, you could lose enough blood that we would stop the fight,” he said. “But people used to see a few drops of blood and think, ‘Oh my God, stop the fight!’ We are more concerned with the well-being of the fighter. We don’t want someone to have brain trauma. We don’t want a severe concussion or any concussion. We don’t want any long-term injury to the fighter. But a little tiny cut with a lot of blood, in and of itself, is not a risk.”

Like the once-beleaguered sport he has grown with, Watson has survived and defied daunting odds to take the long, grueling road from homeless kid to distinguished doctor. Years ago very few people aspired to be a ringside physician at a UFC event. In the early 2000s, working a UFC event was far from a glorious gig. But now the same colleagues who once turned their noses up at the UFC think Watson’s got a really cool gig and hit him up for tickets.

“I was one of the few doctors on the commission in the early days who were absolutely excited to work the UFC and cagefighting events,” Watson said. “It’s absolutely fascinating. I love the sport. I’ve always loved it.”

Frank Curreri is a Las Vegas-based writer, Brazilian jiu-jitsu black belt and TEDx speaker who specializes in mindset training. He can be reached at frank@frankcurreri.com.