A World Cup player had to wear a swim cap after a head injury. Here's why

Netherlands soccer star Danielle van de Donk looked like she was going for gold in the 50-meter freestyle in the midst of a 1-1 draw with the U.S. Women's National Team in the World Cup on Wednesday night.

Van de Donk was sporting a black swim cap in the middle of the July 26 soccer game after banging heads in the 94th minute with U.S. star Rose Lavelle in pursuit of the ball.

So why did the 31-year-old midfielder look like Katie Ledecky out there? It had to do with the bleeding from the cut on her head.

Why did van de Donk wear a swim cap during the World Cup game against the U.S.?

Van de Donk sustained a head injury when she collided with an opposing player and put the swim cap on to reduce the bleeding.

"The scalp has a lot of vasculature in it," Dr. Marie Schaefer, who is part of the sports medicine department at the Cleveland Clinic, tells TODAY.com. "A lot of the blood flow comes to the scalp, and cuts in that area are hard to stop because they require a lot of pressure to keep everything from bleeding."

The 31-year-old midfielder was still wearing the cap after the game when she told reporters that the unorthodox gear was necessary to keep her on the field.

"Yes, it is OK," she said in Dutch about her injury, according to ESPN. "A lot of blood, so I can’t take it off. Unfortunately."

Did van de Donk wear the swim cap for a concussion?

No, van de Donk had to wear a swim cap during the Netherlands-U.S. Women's World Cup Game because she was bleeding from her head.

"The compression provided by the swim cap helps stop the bleeding and also prevents blood from getting on the player’s jersey," the medical staff of NJ/NY Gotham FC, a team in the National Women's Soccer League, said in a statement to TODAY.com. "If blood appears on a player’s jersey, the player is temporarily removed from the match and required to change into a clean jersey before returning to play."

Van de Donk said the cap was necessary because, by rule, players are not allowed to return to the field if the medical and athletic training staff cannot stop the bleeding. The swim cap stopped any blood from running down her face while also putting pressure on the wound to slow the bleeding.

"I thought, ‘It will stop soon,'" van de Donk said. "Then the medical team was there. And then I heard, ‘Swim cap, swim cap!’ I said, ‘No, I don’t really want that!’ But I had to. Otherwise I couldn’t continue."

Schaefer did not see the size of van de Donk's wound, but noted that head wounds can often require staples to close.

"The scalp is really tight and taut, so it just keeps trying to pull away," she said.

The cap can also be used to hold a bandage in place over the wound without having to wrap tape all around the player's head.

"The benefit of using a swim cap is it that it can be applied more quickly, which helps the player return to action sooner," the NJ/NY Gotham FC medical staff said.

Swim caps in soccer

It's not the first time that a swim cap has popped up at a professional soccer game. Dario Benedetto, a striker for the French team Marseille, wore one in 2020 after a bloody collision with an opposing defender.

The Gotham FC staff added that “it’s fairly common” for soccer players to use a swim cap for that purpose.

Van de Donk's skull wasn't the only thing clashing with Team USA, either. She made a physical tackle of U.S. captain Lindsey Horan, her teammate with the French team Lyon, that was not called by the officials.

The two players shoved each other and exchanged words before being separated by an official. It lit a fire under Horan, who headed in the game-tying goal shortly afterward.

Horan and van de Donk then hugged it out after the game.

"Me and (Danielle) always go up against each other. It is a physical battle,” Horan told FOX Sports. “I respect her so much because that’s how it should be. It should be competitive at all times.”

This article was originally published on TODAY.com