Date: 5562
From: Rabbi Moshe Sofer
To: Unknown recipient
A comprehensive analytical essay written in Mattersdorf in 1801/1802 on when blood seen by a woman with a wound near the makor may be attributed to that wound rather than to niddah impurity. The Chasam Sofer argues a middle position: the woman need not have observed blood exiting the wound, but must know it is a blood-containing wound; outside the time of the veses this leniency is reliable, while at the time of the veses Tosfos's stringency applies. He concludes the analysis is lehalachah velo lema'aseh, pending further study.
Source: Shu"t Chasam Sofer YD §142