The Philadelphia Eagles placed quarterback Jalen Hurts on injured reserve after a follow-up ultrasound showed movement in a superficial blood clot in his calf, according to the team. The designation means Hurts must miss at least four games. Philadelphia said his health and safety were its priority while it determined treatment.

The team’s account traces Hurts’ calf treatment to Oct. 8, when he sought care after practice. He told staff he had been cleated during Philadelphia’s Oct. 4 game against the Los Angeles Rams. The Eagles said he had practiced in full on Wednesday and Thursday before that first treatment session, then received treatment and practiced in full on Friday, when he was added to the practice report.

After the team traveled to London, an ultrasound on Saturday found the superficial clot. The Eagles said medical staff and doctors in London reviewed the result and considered activity and mobility important. They concluded Hurts could safely play and recommended another ultrasound within 72 hours of the game and the flight back to Philadelphia.

Hurts played against the Jacksonville Jaguars in London without limitation, the team said. He received treatment Monday and Tuesday and practiced in full Wednesday. The Eagles said they stayed in communication with the league office during the London trip and the following week.

A follow-up scan Wednesday night showed movement in the clot, prompting the team to rule Hurts out of its next game, against the Carolina Panthers. Philadelphia then placed him on injured reserve. The team’s statement did not specify a treatment plan or give a more precise timetable for his return.

Hurts is set to miss the Panthers game and matchups against the Eagles’ three NFC East rivals. Philadelphia has a bye in Week 10, and the source report says Hurts would first be eligible to return in Week 11, when the Eagles are scheduled to face the Pittsburgh Steelers. Eligibility to return does not establish that he will be ready to play then.

Tanner McKee, a third-year backup, is in line to start against Carolina. The source report says he has started two NFL games, with Philadelphia winning one and losing one. It also notes that the Eagles have already been without DeVonta Smith and Saquon Barkley.

The report explains that blood clots can pose serious health risks if they block blood flow or travel to other parts of the body. The team’s statement, however, described Hurts’ condition as a superficial clot and did not report that he had experienced any of those complications.