The division of hernim into the incarcerated and strangulated, or into the acute and chronic forms of strangulation, however practically valuable if it inculcates a different mode of treatment for these affections, is yet pathologi cally incorrect if it supposes any analogy be tween them and the acute and chronic species of inflammation. An incarcerated hernia is not strangulated ; it is really in a condition re sembling irreducibility. I have before stated that in large and old hernim the neck of the sac generally becomes enlarged, and of course such a change of dimensions in the protruded viscera as is necessary to cause their strangulation will be proportionally less likely to occur. But hard and unwholesome and indigestible sub stanccs may gain admission into some of them and lodge there, for it must be recollected that the process of digestion cannot be very favora bly carried on in intestines thus protruded, placed in positions that will render it necessary that their contents must ascend against the in fluence of their own gravity, and deprived of the salutary pressure exercised by the walls of the abdomen on the viscera within it. If such a lodgment is formed, it will be the cause of future accumulation, and may occasion a deter mination of blood to the part or even inflam mation within it, thus gradually increasing its volume and leading it to a state that must end in strangulatiun. Undoubtedly, if the din-a lion of such a case is reckoned from the first occurrence of symptoms, which at that period are only those of indigestion, it will be an ex ample of a very chronic case of strangulated hernia ; but these two stages of the disease ought to be distinguished, for the treatment that would be judicious in the one might be injurious or destructive in the other. The in carceration of a hernia does not, moreover, ne cessarily involve its eventual strangulation, and this constitutes a vast difficulty in the case, for on the one hand few surgeons will advise an operation until there is an obvious and decided necessity for it, and on the other it is quite possible in a case of this description that the symptoms shall never be urgent, and yet the intestine be found in a state of actual spliace lus. I have seen a patient operated on in whom the hernia had been down and the bowels constipated for eighteen days. The intestine was completely mortified.
That strangulation which is most rapidly formed is the most severe in its symptoms and the most dangerous in its consequences, hut between these extremes there is every possible degree of intensity. A hernia has been gan grened in eight hours after protrusion. Mr. l'ott frequently mentions a single day as caus ing a most important difference in the ease, and I have found an intestine sphacelated on the day following the first occurrence of the dis ease; however, in general the case is not so quickly decided, although every moment of its duration is pregnant with danger. The change that is effected in the strangulated viscus next demands attention. Its altered condition has been always spoken of under the name of in flammation," not from want of a perfect and accurate knowledge of its pathology, but pro bably from the term appearing convenient and being hastily adopted by one writer from ano ther. Yet as it is not inflammation, the name is incorrect, and perhaps it has been injurious in leading practitioners to attempt a mitigation of the inflammation in the tumour, instead of the more obvious indication, a diminution of its size. The volume of a strangulated intes tine is always increased. In small hernim
(which in this respect can be more accurately examined) the intestine, on the sac being divi ded, starts up and swells out as if relieved from a compressive force. It always contains air, and if cut into, a small portion of dark-coloured serum will generally escape. Its colour, which is manifestly occasioned by an accumulation of venous blood, is at first of a reddish tint of purple, soon however changing to a coffee brown, and there is always more or less of serum within the sac, as in every other case of venous congestion. If unrelieved, dark and fibrous spots appear which are truly specks of mortification ; they very soon separate and allow a discharge into the sac of a quantity of putrid firces and horribly fetid gas. This done, the intestine either remains collapsed within the sae, or retires spontaneously into the abdomen.
In the meantime the parts covering the hernia become inflamed; in the first instance probably from sympathy with the deeper struc tures,afterwards obviously as an effort of nature to get rid of the putrid and sphacelated matter underneath. In the early stages the local symp toms are seldom very severe : the tumour is scarcely painful, and will permit reiterated at tempts at the reduction of the hernia, and en dure considerable pressure, whilst the abdomen may not be touched without intense suffering. In a little time, however, it becomes tense and tender to the touch, red, oedematous, and pitting under the finger, which leaves a white impres sion for a moment after it has been withdrawn. In fact, it is erysipelatous inflammation attack ing the coverings of the hernia, and its approach is often accelerated by handling the tumour or by repeated injudicious attempts to reduce it. This (if the patient lives sufficiently long) always terminates by the formation of one or more sloughs, on the separation of which the putrid coverings are thrown off, and the contents of the bowels being evacuated, the patient's life may be saved, but with the inconvenience and danger of an artificial anus at the groin. It is seldom that the efforts of nature are thus ca pable of procuring relief, the contents of the rupture being generally sphacelated, and incu rable mischief effected within the abdomen long before its external coverings shew any dis position to burst spontaneously. I think the condition of the sac has some influence on this external inflammation. In all cases it under goes a less injurious alteration of structure than the intestine contained within it, and is often found comparatively sound while the latter is in a state approaching to sphacelus. The supe riority of its vascular organization, its containing a greater quantity of blood, and moreover the volume of air always contained within the bowel, will explain this pathological difference; but the sac itself sometimes suffers from con gestion to a greater or less extent, and this, of course, in proportion to the degree of con striction fixed upon its neck. An old hernial sac, the neck of which is thickened and ac customed to its new position, and which is itself probably one of the chief causes of the stricture, will be less likely to suffer from an interrupted circulation than a recent protrusion just forced out through a narrow undiluted ring. It is in this latter case that the external structures ought to be the soonest engaged, and it has been in recent and acute cases of hernia that I have seen the earliest examples of super ficial inflammation.