"Fortunately it's nothing serious," Ancelotti said to Italian broadcasters after the game.
"He had a CT scan and it has come back clear. He needs to remain under supervision, but he is fine. He was conscious."
Napoli gave a further update on their official Twitter account, saying Ospina would stay in a clinic overnight for observation."
Ancelotti's side were pegged back after taking a two-goal lead in the first half, but pulled away after the break to reduce Juventus's lead at the top of Serie A to 15 points.
Amin Younes's curled finish on his first start of the season gave Napoli an early lead before Jose Callejon doubled their advantage with a bundled finish.
Udinese responded in impressive fashion as Kevin Lasagna’s strike got them back in the game on the half-hour before Seko Fofana drove a finish past Ospina to draw the visitors level.
Arkadiusz Milik headed Napoli back in front from a corner in the second half and Dries Mertens made sure of the points when he darted inside and found the net with 20 minutes remaining.
Earlier, Lazio thrashed Parma 4-1 in Rome and relegation-threatened Empoli recorded a vital 2-1 win over second-bottom rivals Frosinone, while bottom side Chievo produced a shock by holding European hopefuls Atalanta to a 1-1 draw in Bergamo.
(Reporting by Alasdair Mackenzie; Editing by Ken Ferris and Clare Lovell)
