Hydrocele

A hydrocele is an abnormal collection of serous fluid between the two layers of tunica vaginalis of testis. It can either be congenital or acquired.

Congenital hydrocele results from failure of processus vaginalis to obliterate. During development, the testes are formed retroperitoneally in the abdomen and proceed to descend into the scrotum via the inguinal canal in the third gestational week. This descent of the testes into the scrotum is accompanied by a fold of peritoneum of the processus vaginalis. Normally, the proximal portion of processus vaginalis gets obliterated while the distal portion persists as the tunica vaginalis covering the anterior, lateral, and medial aspects of the testes. The tunica vaginalis is a potential space for fluid to accumulate, provided the proximal portion of processus vaginalis remains patent and results in free communication with the peritoneal cavity, leading to congenital hydrocele.

Hydroceles are divided into two types: primary and secondary.

1. Primary Hydrocele: The processus vaginalis of the spermatic cord fuses at term or within 1-2 years of birth, thus obliterating the communication between the abdomen and scrotum. The distal portion, however, remains patent as the tunica vaginalis covers the testis, creating a potential space where fluid accumulation within it can lead to hydrocele formation. Depending upon the site of the obliteration of processus vaginalis, there are four types of primary hydrocele.1. Congenital Hydrocele: This occurs when processus vaginalis is patent and communicates with the peritoneal cavity. This communication allows the movement of peritoneal fluid but is too small to allow the intra-abdominal contents to herniate through.2. Infantile Hydrocele: In this case, processus vaginalis gets obliterated at the level of the deep inguinal ring. However, the portion distal to it remains patent and allows fluid accumulation.3. Encysted Hydrocele of the Cord: Both the proximal and distal portions of processus vaginalis get obliterated while the central portion remains patent and fluid accumulates within it.4. Vaginal Hydrocele: Processus vaginalis remains patent only around the testes, and, as fluid accumulates, it renders the testes impalpable.

1. Secondary Hydrocele: This usually occurs as a result of an underlying condition, such as infection (filariasis, tuberculosis of the epididymis, syphilis), injury (trauma, post-herniorrhaphy hydrocele), or malignancy. This type of hydrocele tends to be small, with the exception of secondary hydrocele due to filariasis, which can be very large.