6. Pressure upon the ureter from without, as by tumors and constricting bands (pelvic adhesions). The gravid and retrodisplaced uterus, uterine and ovarian neoplasms, and similar condi tions causing compression or traction and obliteration of the lumen of the ureter, are found in this class.
Case of intermittent hydronephrosis depending upon an acute bending of the ureter in its upper portion. Braun (Wiener med. Woch., July 19, '90).
Case of ingninal hernia where the hernial sac contained a knuckle of pro lapsed ureter, marked hydronephrosis resulting as a consequence. P. Reiehel (Centralb. f. Chin, Aug. 13, '92).
Case of cancer of the uterus which caused complete obliteration of the left ureter and almost complete obliteration of the right. The ureter was moderately and the pelvis enormously dilated, the latter forming a large pocket; the kid ney itself appeared to be but slightly involved. On the left side, where there was complete obstruction of the ureter, there was almost no hydronephrosis. Frumussaine (Bull. de la Soc. Anat., No. 10, '93).
Aberrant renal vessels considered as a cause of bydronephrosis, as seen in four cases. In two of these veins and in the other two arterial branches were the aberrant vessels. N. Pitt (Brit. Med. Jour., Apr. 21, '94).
Hydronephrotie kidney in which the obstructive cause was a small branch of the renal artery, which crossed the ureter a short distance from the insertion of the latter into the pelvis, causing an angle in the course of he ureter and produc ing obstruction. Coats (Glasgow Med. Jour., May, '94).
7. Diseases and tumors of the blad der that involve the ureteral orifices, particularly carcinoma, or that cause re tention, as prostatic enlargement. S.
Case of double hydronephrosis due to obstruction of the ureters at point of entrance into the bladder by the thick ening and infiltration of the bladder walls from vaginal and uterine cancer. Street (So. Med. Record, Mar., '90).
Case in which the cause of hydrone phrosis was a fibrous perivesical thick ening at the point where the ureter en ters the trigone. Martin (Montreal Med. Jour., Feb., '94).
Traumatic hydronephrosis may he due (1) to serious injury, with rupture and consecutive stricture of the ureter; (2) to an extravasation of blood about the kidney and ureter; (3) to a blood-clot obstructing the ureter; (4) to displace ment, by the traumatism, of a calculus, which lodges in the ureter; (5) to dis placement of the kidney and closure of the ureter. P. Wagner (Schmidt's Jahr
bficher, Apr., '94).
Pathology. — The cyst caused by a dilatation of the pelvis of the kidney, often assuming the shape of the latter, may become very large, containing as much as several gallons of fluid. The external appearance of the walls may be lobulated, particularly in medium-sized sacs; the interior, however, shows only partial septa projecting from the walls into the cavity of the sac, as a rule. Ac cording to the site of the obstruction one or both ureters may also be dilated, and if, as is usual, one kidney is involved, its fellow is often hypertrophied. Marked enlargements cause displacement of the adjacent abdominal organs.
Atrophy of the renal tissues results and is proportionate to the size of the tumor or dilatation. Accumulated liquid causes flattening and atrophy of the papillge and gradually of the tubules and glomeruli, and in extreme cases rem nants only of the renal structure remain in the walls of the hydronephrotic cyst. In the renal parenchyma (medullary and cortical) there is a growth of connective tissue, a chronic nephritis with degener ation and atrophy of the renal cells. The mucous membranes lining the pelvis and calyces first become thinned, and later thickened, by the growth of con nective tissue, thus forming a dense sac wall.
If hydronephrosis is complete,—that is, if the urethral outlet is wholly im pervious,—only a moderate dilatation of the kidney occurs, since atrophy of the nephritic tissue, under such circum stances, speedily ensues, thus putting an end to the secreting process. If, how ever, the hydronephrosis is incomplete, great dilatation eventually takes place, since in the latter condition hypertro phy rather than atrophy of the paren chyma is the rule. Albarran and Legueu (La Semaine Mod., Apr. 30, '92).