Nephralgia is apt to be confounded with colic ; and as we have seen colie pass into enteritis, so the nephritis which follows is liable to be confounded with inflammation of the bowels. The presence of sympathetic affection of the testicle, or the appearance of blood in the urine, would be sufficient to prevent any mistake In diagnosis ; but these are often absent, and dysuria is a common effect of inflammation of the bowels: we have, then, no better guide than the history of its commencement on one side of the loins, and not in the abdomen.
Rheumatic affections may also be confounded with nephralgia; but, apart from the suddenness of the incursion, and the constancy and severity of the pain, when the kidney is affected, they may be distinguished by their more general distribution, and especially by the circumstance, that the pain of a rheumatic affection is only felt on movmg, or at least is very greatly aggravated by it.
Sometimes we have reason to believe that an attack of nephralgia has nothing to do with calculus at all, but is merely a form of gout, when the bowels are loaded, and the urine secreted is highly acid and irritating: in such circum stances there may be no unusual frequency in the calls to empty the bladder, as the secretion is scanty, and the irritation of the kidney less intense.
§ 2. Absce88.—Sometimes directly traceable to an attack of nephritis with a well-marked history, this condition of the kidney is not unfrequently met with in practice, without any distinct precursory symptoms: no doubt there must be some degree of inflammation before pus is formed, but it is to be remembered that the inflammation is often of the strumous kind, and then the evidence of its existence is necessarily obscure. In either case the pus may make its way externally, through the loins, or may be discharged by the bowels, or be voided in the urine. The first of these terminations is to be recognized by the position and size of the swelling which accompanies it: a small abscess in the loins leads us to inquire after previous attacks of nephralgia, or to look for the presence of albumen in the urine ; a larger one is much more probably connected with disease of bone : it is a mis take to suppose that the pus discharged by an abscess of the kidney has any urinous odor. In the second form, the diagnosis may be aided by calculi being passed by the rectum along with the pus : if the history of the case show that affection of the kid ney had existed prior to the appearance of pus in the stools, and there be no indication of ulceration of the mucous membriine of the intestine, it is highly probable that it proceeds from abscess of the kidney. When pus forms in consequence of local perito
nitis, there is very generally a history of pain somewhere or other to point out the locality in which the inflammation had been going on, and we are left to judge from probabilities only, when there is no such history obtained.
The third mode of discharge is the most common, especially in the strumous abscess. The attention of the patient is first arrested by the frequency of the calls to empty the bladder : the total quantity of the urine in the twenty-four hours is not increased, and it is turbid when passed, depositing a white sediment on standing. It is acid, and it remains slightly opaque; the sediment is not dissolved by heat or acid, but, on the contrary, both of these reagents increase the turbidity, and the decanted fluid gives a distinct precipitate of albumen. The sediment is in greet part dissolved by boiling with alkali, and the fluid becomes ropy; under the microscope abundant globules of pus are seen. If these characters are permanent, we may be certain that we have to do either with abscess of the kidney, or with that form of nephritis which gives rise to suppuration in the calyx—pyelitis, as it is called ; and I do not know that in any case we can positively affirm which of the two is *sent. Some idea of its nature may be gained from the relative amount of the pus, and still more from the persistence of the disease.
Catarrh of the baldder (I 6) is at times liable to present similar features ; but there are two grand distinctions, which must ever be borne in mind. When the suppuration takes place in the kidney, the urine usually continues acid, and is not ammoniacal when passed ; the pus itself remains unchanged, and has not become ropy or mixed with phosphates ; the triple phosphate especially, which is so common in cystitis, is rarely seen in such circumstances ; still more, in consequence of the disease of the kidney, the urine is albumi nous in a much greater degree than can be attributed merely to the amount of albumen contained in the liquor puris which is mixed with it. The con glomeration of the pus-globules into masses, or lines, as seen under the mi croscope, may be taken as proof of commencing change in their structure, and so far may be regarded as evidence that the bladder is the seat of the affection rather than the kidney. An abscess must be of considerable size before any such chemical changes can take place.