Fig.: to examine something very thoroughly, in every minute detail

After the B-B-Q party we went over the whole backyard with a fine-tooth comb in the hope of finding my lost contact lens, but nothing doing!

Dopo la grigliata abbiamo passato al setaccio tutto il giardino dietro casa nella speranza di trovare la lente a contatto che avevo perso, ma niente da fare!

I didn't trust the new accountant, so I went over the balance sheet with a fine-tooth comb and - wouldn't you know it! - I found big mistakes

Non mi fidavo del nuovo ragioniere, perciò ho deciso di controllare il bilancio fino all'ultima virgola e - manco a dirlo! - ho trovato errori grossolani

We went over all the documents at the office with a fine-tooth comb to find the shipping note, but the document was nowhere to be found

Abbiamo passato al setaccio tutti i documenti in ufficio, ma della bolla di spedizione nessuna traccia

A fine-tooth comb is a comb with close-set teeth, which was used to find and comb out head lice