The overall incidence of hydroceles is hard to estimate, as many may be clinically occult. The best evidence may come from ultrasound scanning, which is highly sensitive to the presence of fluid collections. In the ultrasonographic study of normal men, a small amount of fluid between the layers of the tunica vaginalis is usually seen around the upper pole of the testis and the head of the epididymis.7 It is not uncommon to see 1 to 2 mm of fluid within that potential space, but more than 2 mm is consistent with the diagnosis of a hydrocele.9 It seems reasonable to assume that such small hydroceles, whether idiopathic or hernia-associated, could easily be missed on a routine physical examination of the scrotum.
Hypothetically, after traumatic perforation such as that occurring during vasectomy, a hydrocele could become smaller, remain the same, or enlarge. Spontaneous sclerosis after accidental perforation and drainage with obliteration of the space could occur, or there might be no clinical change. Irritation from surgical trauma could cause enlargement due to fluid production or hemorrhage.
At least in the short term, each of these possibilities occurred in our case series (Table). Case 4 had a nodular swelling associated with sonographic evidence of hydrocele that was clinically gone at 10 days. Case 3 remained normal on examination at 4 days. Case 7 reported transient swelling that was not evident by 19 days. Cases 1, 2, 5, and 6 had evidence on examination of swelling consistent with at least transiently increased hydrocele fluid. None of these patients, however, perceived any long-term increase in size of hydrocele when contacted by telephone at least 3 months later.
Hernias and hydroceles often occur together. Both are caused developmentally by the failure of fusion and obliteration of the processus vaginalis. A hydrocele can occur anywhere along the spermatic cord and can simulate a hernia or a tumor of the cord. The secanbe differentiated clinically by trans-illumination of the mass or by ultrasonography.10 In this series 3 of the 7 vasectomy-associated hydrocele perforations occurred in patients who had previously had herniorrhaphies on the same side.
Although most hydroceles are idiopathic, the potential association with testicular cancer should be considered. Approximately 10% of testicular neoplasms have an associated hydrocele.9 It is infrequent, but possible, that a new hydrocele is the first presentation of testicular cancer. This is most common in adults with large nonseminiferous tumors.7 Seminomas account for 40% to 50% of malignant testicular tumors and are more common in patients aged 30 to 40 years, the ages when most men have vasectomies.9 Testicular cancer is rare, causing only 1% of cancer in men; however, it is the most common cancer in young men, with an average age of 32 years at diagnosis.11
When a hydrocele develops in a young man without apparent cause, evaluation of the testicle and epididymis should be performed to rule out cancer or infection. This may be an indication for ultrasonography, particularly if a palpable mass does not transilluminate, indicating a possible solid mass.12
There may be different frequencies of occult hydrocele perforation when different techniques are used (traditional or no-scalpel vasectomies). This could be addressed by a larger prospective study to determine the actual frequency of hydroceles, comparing physical examination findings, technique used, and occurrence of perforation at the time of vasectomy.
Conclusions
The incidence of hydrocele perforation accompanying vasectomy was 7 of 150 patients (4.7%) in our study. In 6 of the 7 patients the hydrocele was not clinically apparent before the vasectomy, and in the patient where the diagnosis was made before the procedure, it did not seem to extend either clinically or by ultrasound into the area of the scrotum where a vasectomy is performed.
It is likely that the incidence of hydroceles in all patients is actually higher than 4.7%, since there is no reason to suspect that other undetected hydroceles would always be perforated during vasectomy; they would remain undetected unless they enlarged. The vast majority of small hydroceles are likely to be congenital, idiopathic, and associated with hernias.
Some testicular cancers are associated with hydroceles almost 10% of the time, and the age of presentation of many of these cancers overlaps with the common ages when men undergo vasectomies. Because testicular cancer is so rare and hydroceles so common, however, the mere presence of a hydrocele probably portends very little additional risk of undetected cancer when discovered incidentally during a vasectomy.
It seems prudent, however, to reexamine such patients carefully postoperatively. Scrotal masses that fully transilluminate are reassuring, because they suggest simple hydrocele. Patients with masses that do not transilluminate and may be associated with the testicle should be offered evaluation with scrotal ultrasonography or urology consultation. For any patient with persisting palpable scrotal masses, instruction in testicular self-examination and periodic physician reassessment should be considered as well.