GWS STAR Lachie Whitfield has revealed the full extent of a health scare that forced him to spend three months on the sidelines, admitting it could take a year and a half for his bruised liver to fully heal.

Whitfield, one of the Giants' most important players, made a belated start to the season in a round-seven win over Adelaide.

The club's reigning best and fairest felt short of match fitness and that he fumbled too much while tallying 30 "scrappy" possessions in the comeback game.

Far more importantly, Whitfield will back up and tackle Essendon at Giants Stadium on Saturday after pulling up well and not feeling any fresh pain near his right ribs.

It required an awful lot of hard work and patience from the running machine to get to this point after a nasty collision with teammate Zach Sproule during an intra-squad match in February.

Doctors diagnosed a bruised liver as Whitfield's source of pain, but they were also concerned about another vital organ.

MEDICAL ROOM The full AFL injury list

"A couple of different things affected my lungs," Whitfield told AAP.

"Some of the leaking blood got in there.

"The early part of my recovery was about getting the fluid out of there.

"Then because the liver got inflamed, it pushed up and my right lung was raised. So that made it harder to get air in.

"I didn't realise that until I started running ... I'd jog a couple of laps and be completely out of breath, so I had more scans and needed another week or two off."

Whitfield recalled his nine-day hospital stint and internal bleeding in remarkably candid, calm and clinical fashion.

"I had my appendix out in 2019," the former No.1 draft pick said.

"So I felt a little bit of deja vu, but I wasn't too stressed. The doctors and nurses did a superb job, it felt like a pretty calm environment.

"The only thing that worried me was the uncertain timeline, I didn't know how long it would take to get better.

"Some of my issues are a little bit ongoing. The liver is going to take 12-18 months to fully recover, but it's good enough for me to play and it's not hindering me."

Club medicos were predictably cautious with Whitfield, who undertook what he termed "a mini pre-season" over the past two months while trying to gain weight and boost his energy levels.

The club estimates the 26-year-old lost at least five kilograms from an already slender frame.

"I sort of refused to get on the scales," Whitfield said.

"But looking in the mirror, I would guess I lost a fair bit.

"It was pretty frustrating, watching on, so it was just good to get out there and test my body."