疡患成脓，污秽之质，恶臭之气，好洁者望望然去之，惟恐或浼，似不必形诸楮墨，辨
其色相矣。虽然察色辨证，四诊之要，惟脓与水，皆血肉所蕴酿，可以验体质之盛衰，决病
情之夷险。阅历有得，一望可知，又安能置之弗谈，颟顸从事。故以脓之形质言之，则宜稠
不宜清。稠浓者，其人之元气必充；淡薄者，其人之本真必弱。惟脓成于内，日久不泄，攻
孔深巨，蕴酿多时，则其质多不稠浓。决而去之，如水直流，色泽不晦，气臭不恶，尚是正
宗，未为败象。其孔深脓多者，中必间以腐肉，累累如猪脂之筋膜，如腐渣之成团，则即其
肌肉间之血络筋膜，腐化不尽，随流而去也。凡大证溃决之后，二三日间，必常流清淡之脓
，甚者亦间有腐肉自出（如腐肉形巨，塞住决口，则脓水不畅，而肿不消，痛不减，必当设
法
尽
言之，攻孔虽巨，成脓虽多，决溃之余，痛除毒泄。胃旺能食者，往往不旬日而收全绩。其
经旬累日而不愈者，多是失治之坏证，未必皆其证之不易治也。）如其乍溃之时，脓本无多
，而竟清澈如水，或浊腻晦黯，如黑豆汁，如污泥浆，则必气血久衰，正气不敌，无力化脓
。参之其人形色，无不形容枯槁，色脱肉消，脉细而微。如其胃气尚佳，可投滋补，或能冀
其转败为功。抑或有邪未清，或胃纳亦惫，碍难补益，则虽有卢扁，亦难挽回元气于无何有
之乡
浊稠浓，而色泽鲜明者，气火有余，宜投清理。即或脓质不稠，色白或黄，纯净莹洁者，亦
必顺证。若脓色如青如绿，稀薄不浓者，则蕴之多日，蒸酿而质薄者也。其有脓中兼以瘀血
，色紫成块，则血络亦腐，血自络出。积而成瘀也。有脓中杂见鲜血者，即络中之血与脓俱
泄也。若脓血不分，形色不纯者，已有正虚邪盛之虑。若脓血不稠，色杂不一，或淡白如粉
浆，或污浊如秽水，则正气不充，不能托毒透泄之象。日久迁延，多有变幻。而甚者则紫黯
晦滞，如降香之磨汁，杂以污泥；如腐败之猪肝，捶为烂酱；或且气则腥秽恶臭，色则黑白
难名，如井底之淤泥，如沟中之积污，是脓是血，是水是浆，不可方物者，则正气不存，血
肉之质，已为异物，皆不治之证也。
疮疡病变化脓后，产生污秽的脓液和恶臭的气味，喜好清洁的人对此厌恶躲避，唯恐沾染，似乎不值得用笔墨详细记载并辨别其色泽形态。然而，观察色泽以辨证候，是望、闻、问、切四诊中的关键要点。脓液与浆水，都是由血肉蕴酿而成，可以通过它们来检验体质的盛衰，判断病情的轻重安危。经过阅历有所心得，一望便知，又怎能置之不谈而糊里糊涂地处理呢？因此，从脓液的形质来说，应该是稠厚而不宜清稀。脓液稠浓的，说明患者的元气必定充盛；脓液淡薄的，说明患者的本元必定虚弱。
如果脓液在体内形成，日久不排出，且溃破的孔洞深大，蕴酿时间较长，那么脓液的质地往往就不够稠浓。一旦决破流出，像水一样直流，色泽不晦暗，气味不恶臭，这仍然是正宗的顺证，不是败象。对于孔洞深、脓液多的情况，中间必然夹杂着腐肉，累累如猪脂般的筋膜，或像腐渣结成团块，这是肌肉间的血络筋膜未能完全腐化，随脓液流出的现象。
凡是重症溃破之后，两三天内，必然会经常流出清淡的脓液，严重的也偶尔有腐肉自行排出（如果腐肉体积巨大，堵塞了溃破的口子，就会导致脓水不畅，肿胀不消，疼痛不减，必须设法将其排尽）。虽然溃破的孔洞很大，成脓很多，但在溃破之余，疼痛消除，毒邪泄出。如果胃气旺盛、能进食的患者，往往不到十天就能痊愈。那些经过十天甚至更长时间仍不愈合的，大多是因为失治导致的坏证，未必都是病情本身难以治疗。
如果在刚溃破时，脓液本来就不多，却清澈如水，或者浑浊腻滞、晦暗无光，像黑豆汁，又像污泥浆，这就一定是气血长期衰弱，正气不敌邪气，无力化生脓液的表现。结合患者的形色来看，无不表现为形体枯槁，面色脱失，肌肉消瘦，脉象细弱。如果患者胃气尚佳，可以投用滋补药物，或许还能指望转败为胜。但如果邪气未清，或者胃纳也已疲惫，难以进行补益治疗，那么即使有卢医、扁鹊那样的神医，也难以在无何有之乡挽回元气。
如果脓液浊而稠浓，且色泽鲜明，这是气火有余，适宜投用清热理气的药物。即使脓液质地不稠，颜色白或黄，纯净莹洁的，也必然是顺证。如果脓色像青色、像绿色，稀薄不浓，这是因为蕴酿多日，蒸酿导致质地变薄。如果有脓液中兼杂瘀血，颜色紫黑成块，说明血络也被腐蚀，血液从络脉中溢出，积存而成瘀血。如果有脓液中混杂着鲜血，就是络脉中的血液与脓液一同泄出。如果脓血不分，形色不纯，已有正气虚弱、邪气盛实的忧虑。如果脓血不稠，颜色杂乱不一，或淡白如粉浆，或污浊如秽水，这是正气不充，不能托毒透泄的现象。日久拖延，多有变化。严重的则呈现紫黯晦滞，像降香磨成的汁液，混杂着污泥；又像腐败的猪肝，捶打成烂酱；或者气味腥秽恶臭，颜色黑白难名状，像井底的淤泥，像沟渠中的积污，分不清是脓、是血、是水还是浆，这种不可名状的状况，说明正气已不存在，血肉的质地已经变成异物，都是不治之证。
When a sore or ulcer (Yang illness) suppurates, it produces foul matter and emits a putrid odor. Those who are fastidious naturally recoil from it, fearing contamination, and it might seem unnecessary to record in writing or analyze its color and form. Nevertheless, observing color to differentiate syndromes is essential among the Four Diagnostic Methods (Inspection, Auscultation-Olfaction, Inquiry, Palpation). Both pus and serous fluid are brewed from flesh and blood; they can be used to assess the strength or decline of the constitution and to determine whether the disease condition is mild or severe. With experience and insight, one can judge by a single glance, so how can one ignore discussing this and proceed muddledly? Therefore, regarding the consistency of pus, it should be thick rather than thin. Thick and dense pus indicates that the patient's Yuan Qi (Original Qi) must be robust; thin and watery pus indicates that the patient's Ben Zhen (Fundamental Essence) must be weak.
If pus forms internally and remains un-drained for a long time, especially if the opening is deep and large with prolonged brewing, its quality will often not be thick. Once drained, if it flows freely like water, with a clear luster and no offensive odor, it remains a standard, favorable presentation, not a sign of collapse. In cases where the cavity is deep and pus abundant, there will inevitably be interspersed necrotic tissue, resembling pig fat membranes or clumps of dregs. This represents the blood collaterals and fascia within the muscle that have not completely decomposed, flowing out with the pus.
After the rupture of major lesions, for two to three days, there will typically be a continuous flow of clear, thin pus. In severe cases, necrotic tissue may occasionally discharge spontaneously. (If the necrotic tissue is massive and blocks the rupture site, pus drainage will be obstructed, swelling will not subside, and pain will persist; measures must be taken to ensure complete removal.) Although the opening is large and pus volume is high, after rupture, pain ceases and toxins are expelled. If the Stomach Qi is strong and appetite is good, recovery is often achieved in less than ten days. Cases that do not heal after ten days or more are mostly due to mismanagement leading to deteriorated conditions, not necessarily because the disease itself is difficult to treat.
However, at the moment of initial rupture, if the pus is scant yet clear as water, or turbid, greasy, and dull like black bean juice or muddy slurry, it indicates long-term deficiency of Qi and Blood, where Zheng Qi (Upright Qi) cannot overcome the pathogen, lacking the power to generate pus. Correlating with the patient's appearance, one invariably sees emaciation, loss of luster, wasting of muscles, and a fine, faint pulse. If Stomach Qi remains adequate, tonifying treatments may be administered, offering hope for turning defeat into victory. But if pathogens remain uncleared, or Stomach intake is exhausted, making supplementation difficult, then even masters like Lu Dan and Bian Que would find it hard to restore Yuan Qi from nothingness.
If the pus is turbid, thick, and bright in color, it indicates excess Qi and Fire, requiring clearing and regulating therapies. Even if the pus is not thick, but white or yellow, pure and translucent, it is still a favorable progression. If the pus is greenish or bluish and thin, it results from prolonged brewing causing the quality to become thin. If pus contains mixed blood stasis appearing as purple clots, it indicates corrosion of blood collaterals, with blood leaking out and accumulating as stasis. If fresh blood is mixed with pus, it signifies that blood from the collaterals is discharging together with the pus. If pus and blood are indistinguishable and impure in form and color, there is concern for deficiency of Zheng Qi and excess of pathogens. If pus and blood are not thick, with mixed colors—either pale white like flour water or filthy like sewage—it indicates insufficient Zheng Qi, unable to push out toxins. Prolonged delay often leads to changes. Severe cases present as dark purple and dull, like ground agarwood juice mixed with mud, or like rotten liver pounded into paste. The odor may be fishy, foul, and repulsive, while the color is black and white beyond description, like well-bottom silt or ditch filth, indistinguishable as pus, blood, water, or serum. Such indescribable states indicate the absence of Zheng Qi, where flesh and blood have transformed into foreign matter; these are incurable conditions.