Synonyms.—Consecutive Nephritis; Pyelonephritis; Pyonephrosis.

Definition.—Primarily, an inflammation of the pelvis of the kidney, though the contiguous renal tissue soon becomes involved, with varied results.

Etiology.—The most frequent cause is the irritation arising from foreign bodies, especially from renal calculi, whose roughened surfaces may destroy the mucous membrane. The finer calculi, gravel, or even uric acid sand, may be sufficiently irritating to produce the disease.

The decomposition of retained urine in the pelvis, due to obstruction of the ureter, either from growths or foreign bodies. The extension upwards from urethritis or cystitis, especially v/here there is gonorrheal infection.

Cancer and tuberculosis of the kidney, and more rarely parasites, as the echinococcus, distoma, etc.; also irritating diuretics, as cubebs, cantharides, turpentine, copaiba, oil of sandal-wood, and mustard. The infectious fevers may also give rise to pyelitis, especially diphtheria, scarlet fever, small-pox, typhoid and typhus fever.

Enlarged prostatic tumors, stricture, and phimosis may also be responsible for this disease.

Pathology.—In the early stage and in the mildest forms of pyelitis, the catarrhal, the mucous membrane is swollen, of a dark-red color or ecchymotic, and covered with a viscid mucus or muco-pus. A turbid urine, which contains pus and epithelial cells, is found in the pelvis of the kidney.

In the most severe forms, the mucous membrane is of a brownish-red, increased in thickness, the veins being enlarged and tortuous, and is covered with a thick, purulent secretion. The submucous tissue, and sometimes the entire wall of the pelvis, becomes infiltrated with serum, and a purulent inflammation and ulceration occur, with an extension into the kidney structure—pyelonephritis. Renal abscesses are thus distributed throughout the organ, or there may be but one abscess. Following the more severe infectious fevers there may be a diphtheritic inflammation, with the formation of a false membrane and sloughing of the pelvis, and sometimes severe hemorrhages occur. Where the pelvis of the kidney or the ureter is obstructed for a long time, distention of the pelvis, and sometimes the calyces of the entire kidney, takes place, resulting in atrophy of the tissue and converting the organ into a sac filled with serous or purulent material—hydronephrosis and pyonephrosis.

Following severe cystitis, there may be acute suppurative inflammation of the kidney, the so-called surgical kidney. This is usually bilateral pyelitis, and unilateral when the result of a calculus.

Symptoms.—The symptoms of a primary lesion may so obscure the disease that there will be no characteristic symptoms to suggest pyelitis. In simple catarrhal cases, there will be pain and tenderness over the affected kidney, slight fever, frequent desire to micturate, though the urine is scanty and more or less turbid, acid in reaction, and contains a few pus cells, some mucus, more rarely red blood-corpuscles, and if pus is abundant there will be albumin.

In chronic pyelitis and pyelonephritis, scanty secretion of urine is rare, and not infrequently it is increased to three or four times the normal quantity, due, as suggested by Senator, to the diminished absorption of water from the urine in the medullary substance and to compensatory hypertrophy of the sound portions of the affected kidney and of the well kidney, as well as to cardiac hypertrophy.

In the more severe cases, the pain is often severe, extending down the ureters. Deep pressure reveals marked soreness. The urine is dark in color, owing to the presence of red blood-corpuscles. Pus cells and mucus are abundant, and transitional epithelial cells are found, though this may be from the bladder or sound kidney. If there be obstruction of the ureter, either from a calculus, clotted blood, or a plug of mucus, the urine becomes clear from the sound kidney, to become again turbid with pus-cells when the obstruction gives way.

In suppurative pyelitis, there will be rigors, followed by fever, the chills occurring with such regularity that the case is often mistaken for malaria; later the fever may assume the hectic type, and the rigors disappear. At times the fever assumes a typhoid type, though diarrhea and tympanites are not a marked symptom.

As the disease progresses, the symptoms are those of pyemia, the patient losing flesh and strength.

In the chronic form, especially where there is extensive inflammation, the kidneys may become enormously distended, and distinct fluctuation may be observed.

Diagnosis.—A careful history of the case is important in determining causes that lead to this lesion. The character of the urine, which should be examined frequently, is also an important diagnostic feature. Tubercular pyelitis will be recognized by finding tubercular bacilli in the urine and the presence of tubercular foci in the other parts. Calculous pyelitis is sometimes quite difficult to recognize, though a history of renal calculi is quite suggestive, and if crystals of uric acid or oxalate of lime be more or less continuously present, the diagnosis is quite certain.

It is sometimes quite difficult, if not impossible, to differentiate suppurative pyelitis from cystitis; the chief points to be remembered are, that in pyelitis the urine is acid and the pain in the lumbar region, while in cystitis the urine is ammoniacal and the pain is in the bladder. In the female, by catheterization of the ureters, we determine not only the source of the pus but the kidney affected.

The presence of a fluctuating tumor in the region of the kidney would signify pus, though it may be extremely difficult to decide between perinephric abscess and pyelitis, although the edema about the loins and but little if any pus in the urine would suggest the former.

Prognosis.—This depends largely upon the form of the disease. Where tubercular, it is unfavorable, though the pus may become encysted, caseate, and finally calcify, the patient recovering.

In those cases that come on during fevers, or in the catarrhal case, the patient usually recovers. The calculus variety, tending as it does to chronicity and eventually to suppuration, is very apt to terminate fatally from exhaustion.

Treatment.—This will necessarily depend largely upon the producing cause and the type of the disease. Thus when due to cystitis, our attention must be directed to the bladder; if urethral irritation or prostatic troubles are responsible, these must be corrected; if due to a calculus, the treatment will, in the main, be that for nephrolithiasis. When the infectious fevers have preceded the disease, there is usually more or less sepsis to combat, and antiseptics will be indicated. The treatment, therefore, is symptomatic, meeting- the conditions as they arise.

Pure water should be taken freely, and infusions of the milder diuretics, such as marshmallow, polytrichum, triticum repens, etc. Apis, gelsemium, rhus tox., and eryngium will be called for according to well-known indications.

Where there is suppurative conditions, echinacea, baptisia, potassium chlorate, and the mineral acids will be used. Where the tongue is broad and thick, with fullness of tissue and puffiness under the eyes, the acetate or citrate of potassium will give good results. Where the pain is intense, despite the use of hot fomentations, hot-water bottles, cupping, etc., morphia will be used hypodermically. Should there be active fever, aconite, veratrum, jaborandi, and like remedies will be indicated. Should there be fluctuation in the lumbar region, with accompanying symptoms of pus, surgical intervention will be necessary.

The diet will consist of sweet milk, malted milk, buttermilk, whey, and plenty of pure water.

The Eclectic Practice of Medicine, 1907, was written by Rolla L. Thomas, M. S., M. D.