The idiom go over with a fine-tooth comb came into use in the mid-1800s. We will examine the meaning of the expression go over with a fine-tooth comb, where it came from and some examples of its use in sentences.
To go over something with a fine-tooth comb means to review something in a painstaking manner, to closely examine something in detail, to scrutinize something thoroughly. The term may be rendered as go over something with a fine-tooth comb or go through something with a fine-tooth comb, the latter phrase being more common in British English. Sometimes the idiom is rendered as go over with a fine-toothed comb or go through with a fine-toothed comb. Any of these versions of the idiom may be considered correct. Remember that the hyphen should be added between fine and tooth or fine and toothed, never tooth and comb. The idiom go over with a fine-tooth comb comes from the action of using a literal, physical, fine-tooth comb. Such combs are often used in the treatment of a lice infestation. A special comb with narrow, closely-spaced teeth is used to comb out the lice nits.
Sponsors send money in, voters make requests, and the organizers draw up disbursement lists, which they go over with a fine-tooth comb. (The Huffington Post)
“If you go over with a fine-toothed comb and start analyzing the history of basketball, men and women, who of them have truly played against great competition from the beginning of the season to the end of the season?” (The Chicago Tribune)
“But as coaches we go through with a fine tooth comb and find what are our learnings here. and we go and fix it and review it.” (The Bristol Post)
“We had to go through with a fine-toothed comb every shot of him that could be potentially misinterpreted as stalker-y, or sketchy, because there were takes where his intensity of feeling sometimes came off as darkness.” (Newsweek Magazine)