血者水谷之精气，若伤脾胃何以生，不调液竭血枯病，合之非道损伤成。
【注】血者，水谷之精气也。在男子则化为精；在妇人则化为血，上为乳汁，下为月
水。若内伤脾胃，健运失职，饮食减少，血无以生，则经必不调。亦有女子天癸既至、逾
期不得与男子合，未期思与男子合，与夫经正行时而合，此皆合之非道，亦致不调。或
过淫、合多则液竭，产多、乳众则血枯，亦皆能损伤阴血致成经病也。
血从阳化色正红，色变紫黑热之征，黄泔淡红湿虚化，更审瘀块黯与明。
【注】血属阴，从阳化，故其色以正红为正，虽有经病，亦易为治也。若色变深红、紫
黑，乃热之征也。或黄如米泔，乃湿化也。浅淡红白，乃虚象也。更当审其有瘀、有块、色
黯、色明以治之。若黯而紫黑，兼见冷证，多属寒凝；若明而紫黑，见热证，多属热结也。
热化稠粘臭必秽，寒化清彻臭则腥，内溃五色有脏气，时下而多命必倾。
【注】凡血为热所化，则必稠粘臭秽；为寒所化，则必清彻臭腥。若是内溃，则所下
之物杂见五色，似乎脓血。若更有脏腐败气，且时下不止而多者，是危证也，其命必倾矣！
经来前后为愆期，前热后滞有虚实，淡少为虚不胀痛，紫多胀痛属有余。
【注】经来或前或后，谓之愆期，皆属经病。经来往前赶，日不足三旬者，属血热。若
下血多，色深红而浊，则为有余之热；若下血少，色浅淡而清，则为不足之热也。经来
往后退，日过三旬后者，属血滞。若色浅淡、血少，不胀痛者，则属气虚，血少涩滞，不
足之病；若色紫、血多，腹胀痛者，则属气实，血多瘀滞，有余之病也。
Blood is the essence derived from food and fluids. If the Spleen and Stomach are damaged, how can blood be generated? Disorders of menstruation, exhaustion of body fluids, and depletion of blood often result from improper sexual conduct causing injury.
[Note] Blood is transformed from the essence of food and fluids. In men, it transforms into Essence (Jing); in women, it transforms into Blood, ascending to become milk and descending to become menstrual water. If internal damage occurs to the Spleen and Stomach, impairing their transportation and transformation functions, leading to reduced dietary intake, blood cannot be generated, resulting inevitably in irregular menstruation. There are also cases where a woman has reached menarche (Tian Gui) but has not cohabited with a man past her marriageable age, or desires cohabitation before the appropriate time, or engages in intercourse during normal menstruation. These constitute improper sexual conduct, which also leads to menstrual irregularities. Excessive lust or frequent intercourse depletes Yin fluids; excessive childbirth or prolonged lactation depletes Blood. All these can damage Yin and Blood, thereby forming menstrual diseases.
Menstrual blood is transformed by Yang Qi; a bright red color is normal. A change to purple-black indicates Heat. A color resembling rice washings or pale red indicates Dampness or deficiency transformation. One must further examine for the presence of stasis, clots, and whether the color is dull or bright.
[Note] Blood belongs to Yin but requires Yang Qi for transformation; thus, a bright red color is considered normal. Even if menstrual disorders exist, they are easy to treat. If the color becomes deep red or purple-black, this is a sign of Heat. If yellow like rice washing water, it indicates transformation due to Dampness. If pale red or white, it indicates a Deficiency pattern. One must further examine for the presence of stasis, clots, and whether the color is dull or bright to guide treatment. If the color is dull and purple-black, accompanied by Cold signs, it mostly belongs to Cold Coagulation; if the color is bright and purple-black, accompanied by Heat signs, it mostly belongs to Heat Binding.
Heat-transformed blood is thick, sticky, and foul-smelling; Cold-transformed blood is clear and thin with a fishy odor. Internal organ ulceration discharges substances mixed with five colors, resembling pus and blood. If there is a rotten organ odor and profuse, continuous discharge, it is a critical condition, and life will surely be endangered.
[Note] When blood is transformed by Heat, it is necessarily thick, sticky, and foul-smelling; when transformed by Cold, it is necessarily clear, thin, and fishy-smelling. If it is due to internal organ ulceration, the discharged material appears mixed with five colors, resembling pus and blood. If accompanied by a rotten organ odor and profuse, continuous discharge, this is a critical syndrome, and life is at risk.
Menstruation occurring early or late is termed "Irregular Period" (Qian Qi). Early onset is associated with Heat; late onset is associated with Stagnation. Both have Deficiency and Excess patterns. Pale color and scant flow indicate Deficiency without distending pain; purple color and abundant flow with distending pain indicate Excess.
[Note] Menstruation arriving either early or late is called Irregular Period, belonging to menstrual disorders. Menstruation arriving early, less than thirty days apart, belongs to Blood Heat. If bleeding is heavy with deep red, turbid blood, it is Excess Heat; if bleeding is light with pale, clear blood, it is Deficient Heat. Menstruation arriving late, more than thirty days apart, belongs to Blood Stagnation. If the color is pale, blood volume is low, and there is no distending pain, it belongs to Qi Deficiency, where scant blood causes sluggish flow, constituting a Deficiency disease. If the color is purple, blood volume is high, and abdominal distending pain exists, it belongs to Qi Excess, where abundant blood causes stasis, constituting an Excess disease.