Once one of the wives of the Prophet ﷺ did Iʿtikaf along with him and she was getting bleeding in between her periods. She used to see the blood (from her private parts) and she would perhaps put a dish under her for the blood. (The sub-narrator ʿIkrima added, ʿAisha once saw the liquid of safflower and said, "It looks like what so and so used to have.")
أَنَّ النَّبِيَّ ﷺ اعْتَكَفَ مَعَهُ بَعْضُ نِسَائِهِ وَهْىَ مُسْتَحَاضَةٌ تَرَى الدَّمَ فَرُبَّمَا وَضَعَتِ الطَّسْتَ تَحْتَهَا مِنَ الدَّمِ وَزَعَمَ أَنَّ عَائِشَةَ رَأَتْ مَاءَ الْعُصْفُرِ فَقَالَتْ كَأَنَّ هَذَا شَىْءٌ كَانَتْ فُلاَنَةُ تَجِدُهُ