Definition.—A suppurative inflammation of the perinephritic tissues.
Etiology.—Perinephritis may be primary or secondary. The secondary, which is far more common, is due to an extension of a suppurative inflammation from neighboring parts. It may be from caries of the spine, from suppurative appendicitis, abscess of the liver or bowel, pelvic cellulitis, or an extension from the pelvis of the kidney, or of the entire kidney, or from the ureter; also from tubercular or cancerous deposits in the kidney. It may also be secondary to the more septic of the infectious fevers, such as typhoid, small-pox, diphtheria, pyemia, and kidney affections.
The primary cause is due to sudden exposure and to blows and contusion of the loins.
Pathology.—The suppurative process usually begins in the loose tissue behind the kidney. There may be multiple purulent foci in the early stage, though usually they merge into one large abscess. The abscess wall is soft, shreddy, and ragged where the suppurative process has been rapid, and thick, smooth, and fibrous when more chronic in character.
As the pus accumulates, there is bulging in the region of the kidney, and when very large the liver is crowded on the right side, or the spleen on the left. Burrowing downward along the psoas muscle, it points in the groin, or works its way into the perineum, scrotum, or vagina. It may perforate the peritoneum, the colon, or the bladder. Extending upwards, the diaphragm may be penetrated, and the pus discharged into the pleura or lungs.
The pus is usually very offensive; sometimes fecal in character, owing to its close relation to the bowel, of an urinous odor, the result of infiltration of urine.
Where the disease is of long standing, the fatty capsule may become firmly adherent to the true capsule of the kidney by bands of fibrous tissue.
Symptoms.—The first pronounced symptom is usually pain and tenderness on the affected side between the ribs and the crest of the ilium. At other times rigors, followed by fever of an intermittent character, are the first symptoms announcing the presence of an abscess. As the suppurative process advances, the skin over the affected side becomes red, edematous, and painful, the patient lying on the back, with the legs flexed to a void tension.
Where large nerves are pressed, the pain is severe, extending down the thigh and into the testicle or labium. Fluctuation can usually be elicited on palpation. There is loss of appetite, nausea and vomiting, and all the symptoms of septic poisoning.
Should the abscess rupture into the peritoneal cavity, symptoms of acute peritonitis suddenly develop. If it empties into the lung, it is expectorated from the bronchi, while k is passed w^ith the feces and urine when it opens into the colon or bladder.
Diagnosis.—There are certain characteristic symptoms that will make the diagnosis comparatively easy. The bulging over the affected kidney, the skin being red, edematous, and sensitive to pressure, the urine free from blood, pus, and casts, unless the kidney be involved, and finally the use of the exploring needle, render the diagnosis positive. In pyelitis, the urine contains pus, blood, and casts, while in hydronephrosis the pain and tenderness are absent, and the exploring-needle reveals water instead of pus.
Prognosis.—This depends somewhat upon the vigor of the patient and the point at which the abscess is directed. If externally, and the abscess is freely drained, the outlook is quite favorable, but if it empties into the peritoneum or the lung, the prospect is unfavorable, and when into the bladder or bowel it is also quite grave.
Treatment.—In the early stage, rest in bed, with the proper sedative and echinacea, the sulphites, chlorates, or mineral acids as the antiseptics, will be the proper internal medication. As soon as the abscess is discovered, free drainage is at once instituted. The longer the delay in making a free incision, the greater becomes the septic poisoning, and the less hope there is for the patient.