The woman was found lying in a field in Khanewal, near Multan city, yesterday.
She was taken to a hospital in Jhang and a medico-legal examination at a nearby rural health centre confirmed she had been raped.
Doctors at the centre said she might need surgery.
Police registered a case against three suspects named by the woman's family, The Express Tribune reported.
Police officials said the teacher was kidnapped on her way to school on April 8. She was tortured and gang raped before being left in the field near her home.
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When her condition deteriorated, they threw her in the field and fled, she said.
Residents of the area condemned the incident and demanded that the rapists be publicly hanged.
Police officer Zulfiqar Ahmed said his men were looking for the suspects.