almost invariably congenital, the hydronephrosis is often not noticed until several months or even years have elapsed from birth. The mother then observes that the abdomen is enlarged, and that the chief swelling is limited to one side of the belly. Her attention being thus directed to the child's abdomen she finds that this progressively in creases in size, and a medical practitioner is consulted.
The tumour is a painless one and forms a soft elastic swelling in the situation of the kidney. The cyst sometimes reaches a large size, and may cause great inconvenience by its weight, or interfere with respiration by pressing upwards against the diaphragm. The lumbar region on the affected side is then seen to be prominent as the child lies on his face, and fluctuation is transmitted freely from the front to the back. In a ease re corded by Dr. Hillier—a child three years and a half old—the swelling filled the whole abdomen, and five pints of clear non-albuminous fluid were withdrawn by tapping. Sometimes an escape of some of the retained fluid occurs from time to time, and the size of the tumour may thus undergo marked variations. If the accumulation be due to an impacted calculus, attacks of nephritic colic may occur, with bloody urine. If both kidneys are affected, and the escape of fluid is entirely prevented, the child may die with symptoms of urremia. Such a condition is of course incompat ible with life, and if it be a congenital one, the child is generally stillborn.
Diagnosis of Renal have first to satisfy ourselves that the tumour is due to enlargement of the kidney, and then to ascertain the nature of the swelling. In order to arrive at an accurate diagnosis, a careful examination of the abdomen is of course indispensable ; so that if the child is fretful and unmanageable, crying and contracting his abdom inal walls, he should be put under the influence of an anaesthetic.
A rounded mass in which no edge can be detected, situated in the region of the kidney, and little affected by respiration ; one which does not dip into the pelvis, but passes upwards to the liver or spleen and backwards into the lumbar region—such a tumour is in all probability an enlarged kidney. Renal tumours may be confounded with tumours of any other abdominal organ, or indeed with a swelling anywhere within the abdominal cavity.
On the right side the renal enlargement must be distinguished from a tumour of the liver. The latter rises and falls with respiration, and will be noticed to lie close up under the ribs so that the fingers cannot be passed between 'its upper border and the diaphragm. Moreover, a hepatic tumour
is rarely covered by a coil of intestine ; and on careful manipulation the edge can usually be detected. This, of course, at once excludes the kidney, for a kidney, whether enlarged or not, is rounded in all directions.
On the left side a splenic tumour must be excluded. Enlargements of the spleen are very common in children, but they can never be mistaken for a kidney by a careful observer. An enlarged spleen lies very super ficially ; its position is markeclly influenced by respiration ; it is freely movable ; it has a distinct edge towards the middle line, in which the notch can usually be felt, and its upper border passes upwards beneath the ribs.
On eitter side the renal tumour may be mistaken for a mass of enlarged glands, a psoas abscess, fmcal accumulations, and, in girls, ovarian enlarge ments.
Enlarged glands lie very deeply against the spine, and have to be felt for with care. They are only slightly movable. Still, palpation alone may be insufficient to distinguish a swelling of this kind from an enlarged kidney. By attention, however, to the general symptoms, we may usually arrive at a conclusion. A kidney only slightly enlarged from sarcoma pro duces no impairment of the general health ; while caseous glands, suffi ciently large to be detectable by the touch, are associated with a history of ill-health or of more or less interference with nutrition. The patient has usually suffered from attacks of diarrhoea, and may perhaps have signs of chronic ulceration of the bowels. In such a case he would look ill even although the bowels were not actually loose.
A psoas abscess, like a renal tumour, occupies the region of the loins and extends forwards into the belly. It is, however, placed more deeply than a tumour of the kidney, and cannot be so easily felt. Little informa tion is to be derived from the presence of fluctuation in the swelling ; for this is difficult to ascertain in a psoas abscess, and a sarcomatous kidney conveys a sense of pseudo-fluctuation which is often very deceptive. A far more important distinction is that furnished by the actual position of the mass, for a renal tumour reaches far higher in the abdomen than an abscess. Moreover, the latter is distinctly tender on pressure, while the kidney tumour is quite painless. Lastly, in psoas abscess, although there may be no curvature of the spine, careful examination will often discover the existence of disease of the vertebue (see page 185).