Hydrocele is generally single, but some times occurs on both sides. It is commonly said to form more frequently on the left side than on the right. During the last few years I have registered the new cases of hydrocele coming under my notice in public and private practice. Of one hundred and ten cases of simple hydrocele, one hundred and four were single, and six double. Of the former sixty two occurred on the right side, and forty-two on the left. This result, which gives a decided predominance to the right side, does not agree with the observations of Velpeau, Gerdy, and Dujat, who found the disease to be more frequent on the left side. Hydrocele in young infants is usually single, and in my experience, more common on the right side. I have seen, however, a few cases of double hydrocele at this early period. When the fluid collected in the tunica vaginalis is attended with en largement of the testicle, the swelling is termed a hydro-sarcocele. This affection is generally consequent on chronic orchitis, but it is occa sioned by other morbid changes, malignant as well as innocent. In these cases the disease of the testicle is the original complaint and source of the irritation that excites an undue secretion from the tunica vaginalis.
Congenital hydrocele.— In simple hydrocele, the original communication between the ca vities of the peritoneum and of the tunica vaginalis is permanently obliterated ; but it sometimes happens that fluid accumulates around the testicle in cases in which the obliteration has not been completed, consti tuting the variety termed congenital hydrocele. The opening of communication between the two cavities is usually small in size, about sufficient to admit a crow's or goose's quill. There is rather a rare variety of congenital hydrocele, in which the testicle is retained in the abdomen or inguinal canal, while the peritoneum, prolonged for a short distance into the scrotum, forms the cyst containing the fluid which is covered only by the inte guments and superficial fascia.
Encysted hydrocele of the testicle. — In this form of hydrocele, fluid is effused into an ad ventitious cyst or cysts distinct from the sac of the tunica vaginalis. The cyst is Composed of a thin delicate serous membrane, and may be developed in three situations : I. beneath the visceral portion of the tunica vaginalis in vesting the epididymis ; 2. between the testi cular portion of the tunica vaginalis and the tunica albuginea, which are thus separated from each other ; 3. between the layers of the loose or reflected portion of the tunica vaginalis. The first is by far the most com mon situation, the two latter being very rare. These cysts are composed of a delicate serous membrane lined with tesselated epithelium, and the fluid contained in them differs from that of simple hydrocele in being perfectly limpid and colourless, and nearly free from albumen. In the cysts formed on the epi
didymis, the fluid, instead of being limpid, often presents an opaline opacity arising from the presence of spermatozoa.
1. Small cysts not larger than a pea, and even smaller, may frequently be found beneath the serous membrane covering the head of the epididymis, in which they produce a slight depression. In several instances I have seen as many as five and six perfectly distinct cysts connected with this part.
Sometimes one or two small cysts are so embedded in the substance of the epididymis, that they cannot be recognised without dis section. Though these minute cysts generally contain a limpid fluid, I have sometimes found them filled with fluid of a milky hue, and I have even observed matter like pus tinged with blood. These accidental cysts some times project the tunica vaginalis before them until they become so far separated from the epididymis, where they were originally deve loped, as to be attached only by a narrow peduncle formed by a contraction of the con necting tunica vaginalis. Such is the mode of development of those small pendulous pe dunculated cysts containing a limpid fluid often found hanging from the head of the epi didymis, which were erroneously supposed by Morgagni to be hydatids. I have on many occasions observed them in the different stages of their production. Thus I have seen a pedunculated cyst attached at one part, whilst close to it there was a cyst of a similar nature embedded in the substance of the epididymis. In other instances I have found the cyst very prominent, but still con nected by a broad attachment to the tunica vaginalis reflected over it, the membrane not having as yet contracted to form the narrow neck. In all these cases the prolongation of the tunica vaginalis investing the cyst could always be demonstrated by cautious dissec tion, and between the membrane and the cyst some minute red bloodvessels were generally seen ramifying. These pednuculated cysts never acquire a large size : I have seldom found them to exceed that of a currant. From the exposed situation of the testicle they are liable to be ruptured, the vestiges of them consisting of fimbriated folds of mem brane ; but this is not a common occurrence. I have seen the delicate peduncle by which the cyst was attached to the epididymis as long as three quarters of an inch. M. Gosselin states that small cysts are sometimes deve loped in the little appendage to the tunica va ginalis so often found connected with the upper part of the testicle.* This I have never seen.