Excessive sac pressures: the pathogenesis and innocence of hydroceles in children

Objective To determine whether paediatric hydroceles result entirely from a small-calibre patent processus vaginalis, allowing free communication betw een the abdominal cavity and hydrocele sac, or whether there are other mech anisms. Patients and methods Twenty-five hydroceles were studied prospectively in 2 4 boys (aged 18-132 months). Consent for the intraoperative measurements wa s obtained before surgery. The hydrocele was repaired under general anaesth esia with endotracheal intubation, using a standard approach, taking care n ot to open the sac during mobilization. Intra-abdominal pressures during su rgery were measured indirectly via a nasogastric tube after gastric decompr ession. The pressure in the sac was measured via a 20 G intravenous cannula inserted via a purse-string suture. The relative pressure was then calcula ted by subtracting the intra-abdominal from the sac pressure, The effects o f age and laterality were evaluated. Results The median (range) intra-abdominal, sac and relative pressures were 8 (2-18), 11 (3-30) and 4 (3-30) cmH(2)O, respectively. The sac pressure i n the sac was greater than the intra-abdominal pressure in 17 of 25 (68%; P =0.004) patients. Age or laterality had no significant influence on any of the pressures. Conclusions These results suggest that in a significant proportion of hydro celes in children the pressures are higher than the intra-abdominal pressur e. Therefore, they cannot be explained simply as a freely communicating, na rrow-calibre processus. In addition, the pressures may reach levels which a re potentially damaging to the testis.