A medical expert has provided an update on Zac Miller after the boxer suffered a vile injury that left former world champion Carl Frampton astonished.

On Saturday night, Miller squared off against Gully Powar for the British featherweight title on the undercard for the main event light heavyweight title fight between Joshua Buatsi and Willy Hutchinson.

But the competitive slugfest at the AO in Manchester Arena had to be stopped by the referee in the tenth round following a horrific swelling on his head.

The injury, a hematoma, was caused by an accidental clash of heads which took place five rounds earlier.

Miller fought on but the swelling above his left eye continued to increase, while another hematoma appeared on the right side of his head and also grew in size. There was also a large cut.

In the ninth round, ringside doctors intervened but allowed Miller to continue. However, the contest did not last much longer as in the tenth round, the ringside doctor got involved again and the referee announced the stoppage on his advice.

Boxer's fight stopped after injury branded 'worst ever seen'.

Powar won via unanimous technical decision from the judges' scorecards and collected the vacant title. On commentary, Carl Frampton said, "It’s the worst thing I’ve ever seen,"

The 29-year-old was then taken to hospital and a health update was issued by his team following his second career defeat.

"We're really pleased to say that Zak Miller is doing well following last night's injury," a statement from his manager Kevin Maree read on social media.

"An accidental clash of heads caused significant swelling to the top of his head. Zak was assessed thoroughly by the medical team at the venue before being taken straight to hospital for further checks," Maree stated on Instagram.

"He was kept in hospital for observation and underwent a full assessment. Thankfully, the medical team are happy with how he is doing, and we expect him to be back to his handsome self very soon."

Medical experts give opinion on hematoma recovery process

Hematomas are common in combat sports, with the heavy blows causing small blood vessels to rupture and often large lumps on the face - an area which does not have much soft tissue to act as protection.

No official timeline has been given for Miller's recovery and potential return to action. However, SPORTbible has spoken to a medical expert who has weighed in on how long it will take for Miller to heal up.

Facial plastic surgeon Henry D. Sandel IV, MD, FACS, explained: "The swelling looks dramatic, but an isolated hematoma in this location can be relatively straightforward to treat.

"A hematoma is a collection of blood under the skin. In this case, the blow most likely ruptured a small blood vessel just beneath the skin of the forehead or scalp. Even a small vessel can produce this much swelling.

"This hematoma needs to be drained. The encouraging thing is its location. A surgeon can usually reach it through a small incision, sometimes under local anesthetic. Once the blood is removed and any active bleeding is controlled, a small drain can be left in place for a day or two to help keep blood from collecting again.

"I’d expect the swelling to improve considerably within about a week after drainage if healing goes smoothly.

"Another blow to the same area could cause it to bleed again. When he can return to boxing depends on how the area heals, whether he has a concussion or another injury, and when he’s medically cleared."

Dr. Stephanie Power, another trained plastic surgeon of Power Plastic Surgery, could not yet offer an exact comment on Miller's instance but did provide insight into the rough timeline he has and the recovery process he will go through.

She stated: "A large forehead or scalp hematoma that isn’t treated surgically can take several weeks or longer to fully resolve. The swelling usually peaks in the first two to three days. The bruising then spreads and fades over two to three weeks, and it often drifts down around the eyes. In general, a boxer should avoid repeat trauma to the area for four to six weeks.

"Factors that affect recovery: The biggest factor is whether the hematoma is still expanding, because that can mean active bleeding. Others are the size of the collection, any underlying fracture or concussion, and whether the blood becomes infected or hardens into firm scar tissue. Repeat trauma and blood-thinning medications or supplements can also slow healing."

Dr. Power added that a small stable hematoma is normally managed with ice, elevation, compression and rest, while an extremely large one that's still expanding "may need surgery to clear out the old blood and stop any active bleeding".

Early draining is advised to help prevent infection as well as any permanent lumps.