ECHINOCOCCIC CYST. — In this dis order there is a history of close associa tion with dogs; the size of the tumor constant and slowly increasing; urea is not demonstrable in aspirated fluid. In fluid removed by puncture the echino coccus-booklets, shreds of membrane, and sodium chloride are found. A mov able kidney is not detectable. The urine is constant in amount. Recurrences do not occur.
Additionally, hydronephrosis must be distinguished by exclusion from ovarian cyst, cystic kidney, and tumors of the spleen, liver, and gall-bladder. It is some times necessary to detect the tympanitic band, to evacuate the colon by the intro duction of air, and this, coupled with a chemical examination of the fluid ob tained on exploratory puncture, will suf fice in most cases. With reference to ovarian cyst, it is to be recollected that a slight amount of urea is sometimes found.
Etiology.—The principal factor in the production of dilatation of the pelvis of the kidney is chronic or prolonged ob struction, caused by occlusion of the ureter, either congenital or acquired. Probably from 20 to 35 per cent. of the cases are congenital (Roberts). The former cases are due to obstruction in duced by a defective development or malformation of the ureter of one or both sides, usually the latter.
An instance of hydronephrosis, occur ring in a young man, in which there seems to be a congenital factor of causa tion. The tumor apparently followed a fall, but when the patient was but a day or two old the father had had occa sion to call the. attention of the physi cian to the enormous size of his abdo men. and this had never entirely disap peared. The tumor at the present time was of enormous size, filling up the whole right side of the abdomen, the hypogastrium, and a part of the left iliac fossa. Lannois (Lyon Med., Nov. 30. '110).
In many eases hydronephrosis develops during intra-ut erine life. The specimen illustrated in Fig. 1 was obtained from an infant which survived its birth a few days. Only one kidney was present. Dissection clearly indicated that me chanical obstruction of some kind inter fered with the flow of urine through the vesical orifice of the ureter. In Fig. 2
is shown an example of narrow acting as cause. Bland Sutton (Clip. .Tour., July, '97).
There may be atresia, a valve-like formation, or an acute (oblique) inser tion of the ureter into the kidney.
Apart from hydronephrosis caused by renal calculi, the most common form of obstruction capable of determining hy dronephrosis is a valve-like projection which occludes the upper end of the pelvis of the kidney or one of its divi sions. Fenger (Annals of Surg., June, Excessive dilatation has occasioned more or less mechanical difficulty during labor. The causes, both predisposing and exciting, of the acquired cases are varied, and may be conveniently grouped in tabular form as follows: 1. Sex, women being more often subject to hydronephrosis than men, especially those having borne children. 2. Age; apart from the congenital cases, hydro nephrosis is most common in middle and advanced. life. 3. Impacted calculi in the ureter or renal pelvis. 4. Disease of the ureteral walls, as inflammatory thick ening and cicatrical stenosis from ulcers. 5. Flexion and twisting of the ureter, as _from movable kidney.
The usual cause for intermittent hy dronephrosis is a floating kidney which, when displaced, causes a kink in the ureter, thus arresting the evacuation of urine until the organ slips back into place again. Most of these cases of intermittent hydronephrosis eventually become permanent, owing to inflamma tory changes which often result in bands of adhesions, thus fastening the kidney in its displaced position. Terrier and Baudouin (Revue de Chin, Sept., Oct., Dec., '91).
Hydronephrosis produced in the dog. four out of eight times, simply by sep arating the kidney from its attachments. Tuflier (La Semaine XW., Dee. 1, '93).
Simple hydronephrosis considered as due, in many instances, to an inherited tendency, often associated with more or less malpocition or mobility of the kid ney. Cramer (Centralb. f. Chin, Nov. 24. '94).