Patient sent home with cannula -didn't know they had one

[Beliboo]

Hi

I've been in my current job since September and I'm not IV trained. A patient I cared for and discharged returned today as her cannula was still in situ. I didn't even know the patient had a cannula as there was no documentation to state she did. I'm stressed I've messed up by not being thorough. Patient was a young girl with history of self harm so I wasn't sure about her being okay me physically checking but when I asked she said she didn't have a cannula