The Iron, who were already without influential midfielder Matthew Sparrow and wideman Ian Morris through injury and both Cliff Byrne and Cleveland Taylor through suspension, lost left-back Marcus Williams and midfielder Ian Baraclough during this game.
Both players were carried off on stretchers and manager Nigel Adkins, who was ironically enough the club physiotherapist in a former employment, will need to undertake a head count prior to the next match at Doncaster Rovers on Saturday.
Cheltenham looked in control and had the best player on the pitch in Steven Gillespie until the former Liverpool trainee foolishly got himself sent off for a high, late challenge on defender Lee Ridley.
The home side enjoyed the best of the first half by making their extra man in midfield count against a Scunthorpe side operating with three up front.
Cheltenham's energy and attacking ideas paid off with a beautifully taken goal on 17 minutes.
Left-back Craig Armstrong began the move with a ball up the line that was flicked on by new signing Paul Connor.
Gillespie took a touch and spun past his marker with a clever turn of skill before beating goalkeeper Joe Murphy with an angled drive from 15 yards.
Gillespie almost added a second when John Melligan sprinted through the middle and released him with a clever pass. This time Murphy was equal to his shot with a diving stop.
Scunthorpe offered very little as an attacking force until the sending off on the hour mark. Indeed, Cheltenham could have gone further in front from a Gillespie shot that drifted inches wide.
Scunthorpe midfielder Neil MacKenzie hit the base of a post with a long-range free-kick but the visitors took control of the game for the last 30 minutes.
Leading scorer Billy Sharp forced a fine save from goalkeeper Shane Higgs with 15 minutes left and four minutes later the equaliser arrived when Sharp rose to head home a Jim Goodwin free-kick from close range.
Andy Crosby of Scunthorpe and Cheltenham's Kayode Odejayi both went close with late efforts but a draw was probably the fair result.