Astanga Hrudaya
ऋतावतीते योनिः, सा शुक्रं नातः प्रतीच्छति। मासेनोपचितं रक्तं धमनीभ्यामृतौ पुनः॥२२॥
thereafter she will not be receptive to sukra (semen) The blood accumulated (inside the uterus) during the month, which is slightly black and of unusual smell, brought into the dhamanis (arteries)
english translation