The pillar was being raised as base for a building from a six-feet deep pit and the woman lost her balance and landed on the rod which pierced her stomach and came out at the rib side, police said.
Police said the woman, Arulprakasam, leaned to pick a steel plate which slipped out of her hand, and fell down in the process.
Fire service personnel rushed to the spot to cut the rod and rescued the woman who was admittedto the government Rajaji Hospital.