A TEENAGER stabbed at a South Australian high school suffered a "life-threatening" lung puncture, a court has heard.

Prosecutors told Adelaide Magistrates Court on Tuesday they were still working on their case against Amber Brea Rover, who is facing one count of aggravated assault causing serious harm over the incident.

It is alleged Ms Rover stabbed a female classmate, who can't be named due to her age, at a school in the state's Riverland region in July.

Police have previously alleged the 18-year-old concealed the knife inside her sleeve before the confrontation, which sent the school into lockdown. Both students were transferred to Adelaide for treatment, where Ms Rover underwent surgery for an undisclosed condition.

The court heard on Tuesday the victim was treated for a "life-threatening" punctured lung injury.

Prosecutors said almost 40 statements had been collected from classmates, police and medical experts, but were yet to be reviewed by the Director of Public Prosecutions.

The director will also deal with questions over Ms Rover's mental state, after a court last month heard she was an "acute patient" of James Nash House. A magistrate ordered she should remain in custody at the secure mental health facility.

Magistrate Simon Smart on Tuesday remanded her to reappear before the court next month.