President Trump’s campaign released an update on the former president’s health Saturday, one week after he survived an attempted assassination at a rally at Butler, Pennsylvania.

The memo, from Congressman Ronny Jackson, who is a staunch supporter that served as Trump’s White House physician, offers new details on the nature of the GOP nominee’s injuries and the treatment he received in the immediate aftermath of the attack.

It is the most thorough accounting to date of the former president’s condition since the night of the shooting, which also left one rally-goer dead and injured two others.

According to Dr. Jackson, Trump sustained a gunshot wound to the right ear that came “less than a quarter of an inch from entering his head, and struck the top of his right ear.”

The bullet track, he said, “produced a 2 cm wide wound that extended down to the cartilaginous surface of the ear. There was initially significant bleeding, followed by marked swelling of the entire upper ear.”

While the swelling has resolved and the wound “is beginning to granulate and heal properly,” he said Trump is still experiencing intermittent bleeding, requiring the dressing that was on display at last week’s Republican National Convention.

“Given the broad and blunt nature of the wound itself, no sutures were required,” Dr. Jackson wrote.

Trump was initially treated by medical staff at Butler Memorial Hospital. According to Dr. Jackson, doctors “provided a thorough evaluation for additional injuries that included a CT of his head.”

Trump, he said, “will have further evaluations, including a comprehensive hearing exam, as needed. He will follow up with his primary care physician, as directed by the doctors that initially evaluated him,” he wrote.

“In summary, former President Trump is doing well, and he is recovering as expected from the gunshot wound sustained last Saturday afternoon,” he added.

Dr. Jackson said in the letter that, as Trump’s former doctor, he was worried and traveled to Bedminster, New Jersey, where Trump had flown late Saturday after he returned from Pennsylvania, “to personally check on him, and offer my assistance in any way possible.”

He said he has been with Trump since that time, evaluating and treating his wound daily, and would remain with Trump through the weekend, including traveling to Michigan, where Trump held his first rally since the shooting, joined by his new running mate, Senator Vance. At Saturday’s rally, the white gauze on Trump’s ear was replaced by a skin-colored bandage.

Trump’s campaign and federal law enforcement had released little information on his condition or treatment in the days after the attack, declining to disclose medical records or hold briefings with the doctors who treated him at the hospital.

Trauma surgeon Babak Sarani, who said he has been treating more patients with wounds from AR-15 style rifles, said the description in the letter was “exactly in line with what you would expect from a bullet wound.”

While the indirect damage is still usually minor, he said the risk of extensive damage is greater than if another gun were used.

“If a bullet whizzes by your ear from a low-caliber handgun, it’s not a big deal. … You get a headache or feel dizzy like a bad concussion,” the chief of trauma at George Washington Hospital at Washington, D.C., Dr. Sarani, said. “But if the bullet is from an assault rifle, the energy is bigger, broader, and you’re more likely to develop bruises.”

He added, “in Trump’s case, he got very lucky. The majority of the energy was released in the air. If it had hit him in the head, we would be having a completely different conversation.”

A former Secret Service agent, Rich Staropoli, said the AR-15-style rifle used by the gunman fires a 5.56 millimeter bullet at such high speeds — more than 2,000 miles an hour — that just the air pressure as it passes can cause extensive damage.

“The shock wave alone could have ripped his ear off,” Mr. Staropoli said of Trump. “It’s amazing the bullet nipped him” and didn’t do any other damage.

“It’s a one in a billion type of thing,” he added. A fraction of a millimeter closer, “and this would be a different story. It really is incredible the thin line here between just a nick and devastating bodily damage.”