Membrey was moving back with the flight of the ball in a marking contest before falling to the ground, with the back of the 28-year-old's head slamming into the Adelaide Oval surface.
The Saints attacker remained on the turf for some time before being helped to his feet by club medical staff, with Membrey in an unsteady and dazed state as he slowly made his way from the ground in the arms of medicos.
A failed head injury assessment will automatically mean Membrey will be sidelined for the following 12 days under the AFL's concussion protocols, forcing the forward to spend more time in the club's casualty ward.
— AFL (@AFL) May 14, 2023
Membrey missed the opening five rounds of the season after requiring minor knee surgery in the pre-season, with his return a welcomed one for Ross Lyon amid an ongoing injury crisis at Moorabbin.
Membrey wasn't alone in sustaining an injury, with a knee complaint ending skipper Jack Steele's afternoon.
The Saints confirmed a precautionary measure was taken to remove Steele from the remaining moments of the game in the final quarter.
Jack Steele (knee) will sit out the remainder of the game as a precaution.
— St Kilda FC (@stkildafc) May 14, 2023
His midfielder counterpart in Rory Laird was also subbed out in the last stanza after copping a knock to the ribs in the dying stages, with Ned McHenry coming into the match with just over half a quarter to go.
The injury looks unlikely to limit Laird's chances of facing the Western Bulldogs next week in Ballarat.