Sam Colangelo scored for the third straight game, Frank Vatrano and Alex Killorn also scored, and Lukas Dostal made 18 saves for the Ducks (27-28-7), who have lost three of four.
“We were just a little sloppy to start the game and I don’t think we got our legs moving until the end of the game," Anaheim defenseman Jackson LaCombe said. "We’ve got to figure out a way to come out with that same energy.”
The Blues took a 1-0 lead at 2:37 of the first period after Toropchenko took a wrist shot from above the left circle that slipped between Dostal's glove and left pad before sliding across the goal line.
The Blues sent the puck over the glass twice in the first period and the Ducks capitalized on the second delay of game penalty when a long wrist shot by LaCombe grazed Colangelo before hitting the net, tying the score 1-1 at 14:48.
“I'm a pretty big guy, just try to get to the front of the net and find ways to score," said Colangelo, who was playing in his fifth game since he was recalled from San Diego of the American Hockey League on Feb. 27 and 20th NHL game overall. "I think I have a pretty good shot, but if I can find any way to score, I'll take it in this league.”
St. Louis took a 2-1 lead at 10:49 of the second after Anaheim defenseman Radko Gudas fumbled a pass in his own zone. Jordan Kyrou retrieved the puck along the wall, passed to Dylan Holloway in the left circle and he fed Schenn cutting through the opposite circle for a one-timer.
"We had it, we had full possession, and we lost it," Anaheim coach Greg Cronin said. "We were all heading out for a breakout thinking it was a clean exit and, all of a sudden, three seconds later, it's in the back of our net."
