Purpose: Controversy still surrounds the treatment of the asymptomatic inguinal region in paediatric patients with a unilateral inguinal hernia. The concern is the development of a future metachronous contralateral inguinal hernia (MCIH) and therefore the need for a second operation. Our aim was to provide a current systematic review of the evidence for routine contralateral exploration, and identify potential at-risk groups.
Methods: Comprehensive review of the literature utilising broad search terms to identify all relevant publications. Precise inclusion and exclusion criteria to identify studies that included paediatric unilateral inguinal hernia repair without routine contralateral exploration.
Data analysis: Chi-square with Yates' correction or a Fisher's exact test as appropriate. Numbers needed to treat (NNT) calculated with 95% confidence intervals.
Results: A total of 7,130 titles and abstracts were screened and 61 studies included with data on 49,568 paediatric patients with a unilateral inguinal hernia fulfilling the inclusion criteria. 2,857 of these patients later developed a MCIH, revealing an overall risk is 5.76% (95% CI: 5.55-5.97%). The NNT for a MCIH is 18 (95% CI: 16.8-18) with 18 contralateral exploration required for the prevention of one MCIH. Patients <6 months at the time of the initial intervention were more likely to develop a MCIH; 183/1,470 (<6/12) versus 144/2,044 (≥6/12), P < 0.0001. As were patients with an original left-sided hernia; 815/6,739 versus 865/12,615, P < 0.0001. The NNTs for both of these groups were 9. There was no association with the gender of the patient; 888/14,480 (♂) versus 268/4,206 (♀), P = 0.37.
Conclusions: There is insufficient evidence to support the routine contralateral inguinal exploration in all paediatric patients presenting with a unilateral inguinal hernia. However, with patients presenting with an originally left-sided hernia or who are less than 6 months old, a parental discussion should occur about the possible benefits and risks of contralateral exploration.