The information provided here is not a replacement for a doctor. You shouldn't use it for the purpose of self-diagnosing or self-medicating but rather so you can have a more informed discussion with a professional TCM practitioner.
Because it is a herb specifically indicated to treat lochiorrhea as can be seen on Lotus Receptacle's page.
Lotus Receptacles is a Warm herb that tastes Bitter. It targets the Liver.
Its main actions are: Invigorates the Blood and breaks Stasis.