Doctor Roque Aras said Tuesday that the remaining needles are small and don't pose a significant threat. Aras isn't ruling out future operations, however.
The 2-year-old boy had his third surgery in 10 days on Monday to extract four needles from his neck. Doctors removed 14 more from his intestines, liver and bladder last week, and four from near his heart and lungs earlier.
Police accuse the boy's stepfather, Roberto Carlos Magalhaes, and his lover of attempted murder, though prosecutors have not yet filed charges.
Magalhaes told Globo TV he wanted to kill the child to spite his wife.