Definition.—A dilatation of the pelvis and calyces of the kidney from an accumulation of urine, due to obstruction in some part of the ureters, bladder, or urethra.

Etiology.—Hydronephrosis may be congenital or acquired. When congenital, the constriction is usually due to malformation or defective development. Sometimes the ureter is attached at an acute angle, or the insertion may be quite high. Again, alterations in the lining mucous membrane may form a valvelike obstruction, or there may be a twisting of the ureter upon its axis. The dilatation has been found so great in some cases in the fetus as to form mechanical obstruction during labor. In the adult, the constriction of the ureter may be due to a tuberculous mass, or to malignant growths, or to pressure from tumors.

There may be stricture from ulceration of the ureter, or it may be due to a calculus. Cicatricial bands, the result of inflammatory adhesions, may be responsible for it; also thickening of the bladder walls from cystitis, enlarged prostate, and urethral stricture. In movable kidney, a twisting or flexion of the ureter may give rise to it. Pressure from a pregnant or displaced uterus as well as ovarian tumors may also produce the disease.

The enlargement may be so small as to escape detection during life, or it may be so enormous as to be mistaken for ascites.

Pathology.—While hydronephrosis may be unilateral or bilateral, it is usually confined to one kidney, its fellow member generally becoming hypertrophied. As the pelvis of the kidney dilates, the renal tissue, from pressure, atrophies, the papillae become flattened, the uriniferous tubules and glomeruli become smaller and finally disappear, or show as remnants in the walls of the cyst. The mucous membrane lining the pelvis and calyces becomes very much thickened by the growth of connective tissue forming the walls of the hydronephrotic sac, the size of which varies, sometimes becoming so large as to contain two or three gallons of fluid. The fluid contained in the sac in the early stage is urine; but as the disease progresses and the renal tissue atrophies, the secretion becomes more and more of the character of mucous membrane secretion. It is usually thin and colorless or yellowish in color, of low specific gravity, alkaline in reaction, and contains traces of urea, uric acid, various solids, and albumin. Where pus, epithelial and blood corpuscles, are present, the fluid becomes quite turbid. Hypertrophy of the left heart is a frequent complication.

Symptoms.—In the early stages, the symptoms are so obscured by the primary lesion as to be negative, and when due to pressure from tumors or cancer may never be recognized during life. When bilateral and congenital, hydronephrosis usually proves fatal in a few weeks, and has no characteristic symptoms.

After continuing for some time, the tumor enlarges, and the appearance of a visible or palpitating tumor in the region of the affected kidney is the first definite knowledge we have of the presence of the disease. With the further progress of the disease, there is distention of the hypochondriac region, which, when very large, may extend to the median line. The tumor shows considerable resistance, and at times distinct fluctuation. If on the left side, the tumor remains stationary on respiration; but if located on the right side, a deep inspiration gives the tumor a downward motion. Percussion gives a dull sound, though the tympanitic note of the colon is confusing unless we remember the characteristic sound.

The tumor may be mistaken for an ovarian cyst, or, in exaggerated cases, for ascites. Ovarian tumors, however, do not crowd the lumbar region so prominently, as a rule. Aspiration, however, in some cases, is the only means of determining the true character of the disease, and even this may not be positive, for in advanced cases of hydronephrosis the urinary salts may disappear, the fluid being sero-mucus in character.

In some cases the hydronephrosis is intermittent in character, the tumor mass suddenly disappearing with the discharging of a large quantity of fluids, this being followed by a gradually increasing tumor mass, with some gastric disturbance, intestinal derangement, constipation, or obstinate diarrhea. With the disappearance of the tumor, the general systemic symptoms also disappear, and the patient is comfortable for a time; but with each reappearance of the tumor, there is marked systemic derangement. Suppuration is announced by chills, irregular fever, sweats, small rapid pulse, nausea, and vomiting.

The cyst may rupture into the abdominal cavity, or, perforating the diaphragm, open into the lung.

Diagnosis.—The diagnosis of hydronephrosis is difficult, if not impossible, where the accumulation of fluid is small. With the appearance, in either lumbar region, of a tumor mass, with a gradual decline in the amount of urine voided, the disease would be suggested.

We have to differentiate between it and ovarian cysts, ascites, and splenic and hepatic tumors. To distinguish from solid tumors, the aspirating needle will be used. Aspiration may also aid in distinguishing an ovarian cyst, though, as already suggested, the fluid in advanced hydronephrosis may have changed to sero-mucus, in which case aspiration would not enlighten us. Ascites would be recognized by the uniform enlargement, the fluid filling both lumbar regions.

In pyonephrosis, there will be fever, night-sweats, and marked emaciation, which are generally absent in hydronephrosis.

Prognosis.—The prognosis is usually unfavorable, though where the disease is confined to one kidney and the accumulation remains small, the patient's life is rarely endangered. In the intermittent form, the disease may disappear after having existed for years. Where the sound kidney becomes involved from any cause, and ceases to perform its function, uremia is apt to follow, with fatal results. When the hydronephrosis is bilateral, the prognosis is always grave.

Treatment.—The treatment for hydronephrosis, save for the relief afforded to pain, or gastric and intestinal disturbances, will be almost entirely surgical. Massage has been highly recommended, and cases have been recorded where a cure has been effected by removing the obstruction. If practiced, however, it should be done by an experienced masseur, as there is danger of rupturing the ureter. When there is a large quantity of fluid in the sac, it may be removed by aspiration, and this repeated as often as it may accumulate; or an incision may be made down to the kidney and drainage obtained, and, if a calculus be present, the foreign body removed. Where badly diseased, the kidney may be removed, though this should only be done as a last resort, as the history of successful extirpation of the kidney is not such as to hope for great success. Where the hydronephrosis is intermittent, a well-applied pad and bandage may prove useful.

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