Wa `alaykum As-Salamu waRahmatullahi wa Barakatuh.

It was narrated from Mu`awiyah bin Abi Sufyan that he asked Umm Habibah, the wife of the Prophet (peace be upon him): “Did the Messenger of Allah (peace be upon him) pray in a garment in which he had had intercourse?” She said: “Yes, so long as he saw no filth on it.” This means that excrements flowing of a woman’s vagina during intercourse are pure.

As for the question, if she sees her female sperm, she must have a full bath. It was narrated that Khawlah bin Hakim said: “I asked the Messenger of Allah (peace be upon him) about a woman who has a wet dream and he said: ‘If she sees sperm, let her perform Ghusl.'” (An-Nasa’i, it has been graded as an authentic hadith.)

Sperm is pure. It has been related by Muslim in his Sahih ( hadith no. 288) from `A’ishah (may Allah be pleased with her) who said: I remember scratching sperm from the garment of the Messenger of Allah (blessings and peace of Allah be upon) thoroughly, then he prayed in it. Her not washing of sperm and just scratching is an evidence that sperm is pure. Based on this view, if a woman swallows sperm, it does require having a ritual bath. It is sufficient to clean her mouth by just washing it.

Almighty Allah knows best.