Paediatric Urology

7. HYDROCELE

7.1. Epidemiology, aetiology and pathophysiology

Hydrocele is defined as a collection of fluid between the parietal and visceral layers of the tunica vaginalis [242]. In males, congenital hydrocele is based on failed obliteration of the processus vaginalis between the inguinal canal and scrotum. Similarly, although rarer, hydrocele can occur in females with failed obliteration of the canal of Nuck - a protrusion of peritoneum in the female inguinal canal. There are various types of congenital hydrocele. In communicating hydrocele, intraperitoneal fluid passes into the scrotal tunica vaginalis due to persisting patency of the processus vaginalis (PPV). This must be differentiated from inguinal hernia, in which the processus vaginalis is wide enough to allow passage of abdominal viscera or omentum [242]. If obliteration of the processus vaginalis occurs with focal patency of the mid-portion, a hydrocele of the cord occurs. The exact time of spontaneous closure of the inguinal processus vaginalis is not known. Processus vaginalis is present in approximately 80-94% of newborns and in 20% of adults [243]. Scrotal hydroceles without associated patency of the inguinal processus vaginalis may be encountered in newborns [244]. However, such noncommunicating hydroceles are often acquired and based on an imbalance between the secretion and reabsorption of lymphatic fluid, and thus can be found secondary to minor trauma, testicular torsion, epididymitis, varicocele operation (due to ligation of the lymphatics) or may appear as a recurrence after hydrocele repair. In rare cases, a hydrocele may have an intra-abdominal component, positioned ventral or dorsal to the bladder: the so-called abdominoscrotal hydrocele (ASH). This is considered a scrotal hydrocele with an hourglass-shaped extension reaching into the abdomen via the inguinal ring. Abdominoscrotal hydrocele may be associated with testicular dysmorphism related to increased pressure [245,246].

7.2. Diagnostic evaluation

The classic description of a communicating hydrocele is that of a hydrocele that fluctuates in size and is usually related to ambulation. Communicating hydrocele may be diagnosed through history-taking and physical investigation. The presence of contralateral disease should be addressed during the initial consultation [243]. Transillumination of the scrotum provides the diagnosis in the majority of cases, bearing in mind that fluid-filled intestine and some prepubertal tumours may transilluminate as well [247,248]. In hydroceles, the swelling is smooth and usually not tender. If there are any doubts about the character of an intrascrotal mass or if the testis is not palpable, scrotal US, which has nearly 100% sensitivity in detecting intrascrotal lesions, should be considered. Doppler US studies help to distinguish hydroceles from varicocele and testicular torsion, although these conditions may also be accompanied by a hydrocele [249]. Presence of ASH is suggested by a tense hydrocele or palpable abdominal extension upon compression of the scrotal part of the hydrocele and can be confirmed by US [246].

7.3. Management

Conservative management
In the majority of infants, observation is warranted at least within the first twelve months due to the tendency of spontaneous resolution [250]. The rate of resolution decreases with age, with 92% resolution below one year old and 43% above three years [251,252]. Initial observation poses little risk, as progression to hernia is rare and does not result in incarceration [250]. There is no evidence that hydrocele risks testicular damage [252]. In acquired hydrocele suggestive of a non-communicating hydrocele, there is still a reasonable chance of spontaneous resolution (75%), and expectant management of six to nine months is recommended [253]. In ASH, the rate of spontaneous resolution appears lower, although it has been reported [254]. In exemption to the above, the suspicion of a concomitant inguinal hernia or underlying testicular pathology necessitates early surgery [255]. In other cases, initial conservative treatment may reduce the number of procedures without increasing morbidity, however, persistence of hydrocele is an indication for surgical correction.

Surgical treatment
In the paediatric age group, surgical correction consists of inguinal ligation of the patent processus vaginalis via inguinal incision with the distal stump being left open. In hydrocele of the cord, the cystic mass is excised or unroofed [248,256,257]. In expert hands, the incidence of testicular damage during hydrocele or inguinal hernia repair is very low. Laparoscopic hernia repair with percutaneous ligation of the patent inguinal processus vaginalis is a minimally invasive alternative to open inguinal herniorrhaphy [258,259]. In line with these techniques, various laparoscopic techniques for hydrocele correction have been described. No technique appears to be superior [243].

Laparoscopic correction of a contralateral patent processus may be considered, however, a recent meta-analysis found insufficient evidence to recommend this for inguinal hernia [243] and hydrocele was not reported. The incidence of patent contralateral processus appears much higher than the percentage of children developing metachronous hernia (63% vs 8%) [243]. Thus, to prevent metachronous inguinal hernia, the number needed to treat is relatively high (NNT = 18) [260]. For acquired, noncommunicating hydrocele, the scrotal approach (Lord or Jaboulay/Winkelmann technique) is used.

In ASH, most case series describe resection of the abdominal component, which is connected to the scrotal, but not to the inguinal processus vaginalis. The incidence of complications for this procedure is higher than in regular hydrocele repair [254] and can result in testicular loss and atrophy, causing some to question if resection is necessary [246,254]. Larger series are needed to assess optimal management. Testicular dysmorphism may recover following surgery [245]. Sclerosing agents should not be used due to the risk of chemical peritonitis in communicating processus vaginalis [248].

7.4. Summary of evidence and recommendations for the management of hydrocele