What is the natural history of hydrocele?

Natural History of Hydrocele

Overview

Most congenital hydroceles in infants resolve spontaneously within 18-24 months without intervention, while acquired hydroceles in older children and adolescents have lower but still significant spontaneous resolution rates. 1, 2

Age-Specific Natural History

Infants (0-12 months)

• Spontaneous resolution occurs in 62.7-94.3% of cases depending on age at presentation, with earlier presentation associated with higher resolution rates 3, 4
• The prevalence of patent processus vaginalis (the anatomical basis for communicating hydroceles) decreases from 80% in term male infants to 33-50% by age 1 year 2
• Mean time to resolution is approximately 5 months for infants presenting before 12 months of age 4
• Communicating hydroceles (those with fluctuation in size) can still resolve clinically in 62.7% of cases without surgery, contrary to traditional teaching that all require immediate repair 3

Toddlers (12-24 months)

• Spontaneous resolution occurs in 65% of cases presenting between 12-24 months 4
• Average time to resolution from presentation is 17 months in this age group 4
• This represents a critical observation period, as most guidelines recommend waiting until 18-24 months before considering surgical intervention 1

Children Over 2 Years

• Approximately 33% of hydroceles presenting after age 2 years still achieve spontaneous resolution, though this is lower than in younger children 4
• For non-communicating hydroceles specifically in children over 1 year, 76% resolve completely with conservative management 5
• Average time to resolution for non-communicating hydroceles is 5.6 months (median 3 months, range 1 day to 24 months) 5

Type-Specific Natural History

Communicating Hydroceles

• These result from a patent processus vaginalis maintaining open communication between the peritoneal cavity and tunica vaginalis 2
• The estimated risk of developing an inguinal hernia is 25-50% in patients with patent processus vaginalis 2
• In one series, only 6% progressed to hernia during observation, and importantly, none experienced incarceration 3
• Despite the communicating nature, 62.7% still resolved without surgery by mean age 11.7 months 3

Non-Communicating Hydroceles

• These represent an imbalance between fluid production and reabsorption without peritoneal communication 6, 7
• 76% resolve completely with conservative management, 6% decrease in size, and 14% remain stable 5
• Resolution is independent of hydrocele size 5
• An observation period of 6-12 months is appropriate before considering surgical repair 5

Factors NOT Affecting Resolution

• Age at presentation (within pediatric range) does not significantly affect resolution rates 3
• Gestational age at birth (including prematurity) does not impact resolution 3
• Size of hydrocele does not predict likelihood of resolution for non-communicating types 5
• Bilateral versus unilateral presentation does not alter natural history 3

Impact on Testicular Development

• Conservative management does not adversely affect testicular size or growth (14.4 mm vs 14.5 mm before and after observation, p=0.483) 4
• This finding supports extended observation periods without concern for testicular damage 4

Risk of Complications During Observation

• Hernia incarceration is extremely rare during observation periods, with zero cases reported in one series of 110 patients 3
• Only 2 patients with apparent resolution subsequently developed recurrence with hernia 3
• The low complication rate supports initial conservative management over immediate surgical intervention 3

Clinical Implications

The natural history data strongly support initial observation for most pediatric hydroceles, particularly those presenting before age 2 years. Even communicating hydroceles, traditionally thought to require surgery, have substantial spontaneous resolution rates. The key is distinguishing hydroceles from inguinal hernias, which require prompt surgical repair 1, 2. An observation period of 18-24 months for infants and 6-12 months for older children is well-supported by natural history data showing continued resolution throughout these timeframes 1, 5, 4.