CYCLING NEWS - The 32-year-old was launched head first off his bike and landed hard on his back but avoided any major injury.
Team Dimension Data said he had bruising and abrasions, as well as a possible ankle ligament injury.
Cavendish was making his return after in a crash on the opening stage of the Tirreno-Adriatico on 7 March.
He was taken for a scan after the crash in Milan but a statement said he had avoided any major injury.
"He did sustain a new rib fracture [5th] on the same side as the one that he damaged earlier [7th]," a statement read.
He will return home on Saturday.
Cavendish has been selected by the Isle of Man to lead their road cycling team at April's Commonwealth Games in Australia.
He injured his knees, hips and hands in the fall at the Tirreno-Adriatico but opted to race in the Milan-San Remo, despite his rib not being fully healed.
He told Cycling Weekly before the event that he wanted to race to support his team-mates, describing the event as "close to my heart".
