title: The degree to which the size and side of an inguinal hernia is predictive of a hernia on the other side.
abstract: BACKGROUND
  The indication for contralateral exploration in patients with a unilateral inguinal hernia and the implications of a contralateral patent processus vaginalis have been the subject of much debate during recent decades. The aim of this study was to investigate whether the size and side of the hernial sac on the side of presentation are predictive for the operative appearance of the processus vaginalis/hernial sac on the contralateral side.
  
  
  METHODS
  All primary herniotomies performed by the Christchurch-based paediatric surgical service were reviewed. Patients who developed a contralateral hernia after unilateral repair were identified. In a random subset of patients who had bilateral exploration for unilateral hernias, the size of the clinical hernial sac was plotted against the size of the contralateral patent processus vaginalis/hernial sac (when present) as assessed at the time of open surgery.
  
  
  RESULTS
  Overall, 2,124 unique patients underwent herniotomies in the period reviewed, and 44 (3.8%) metachronous contralateral hernias were identified. Girls were not at greater risk than boys of developing a metachronous hernia. There was a positive correlation between the size of the clinical hernial sac and the size of the contralateral processus vaginalis/hernial sac. There was no significant relationship between the original presenting side and the development of a metachronous contralateral hernia.
  
  
  CONCLUSIONS
  It is not possible to predict reliably which patients who present with a unilateral hernia would benefit from bilateral exploration, although the size of the hernia has a positive correlation with the size of the contralateral processus vaginalis/hernial sac. Those with "massive" hernias on the presenting side were more likely to have "large" contralateral hernial sacs, but how many of these would subsequently become symptomatic remains uncertain.
authors.affiliation: Christchurch Hospital, Christchurch, New Zealand.
authors.forename: H D E
authors.initials: HD
authors.lastname: Vogels
authors.forename: C J P
authors.initials: CJ
authors.lastname: Bruijnen
authors.forename: S W
authors.initials: SW
authors.lastname: Beasley
authors.forename: R T
authors.initials: RT
authors.lastname: Blakelock
authors.forename: K
authors.initials: K
authors.lastname: Maoate
mesh_terms: D005260:Female; D005544:Forecasting; D006552:Hernia, Inguinal / Q000601:surgery*; D006801:Humans; D007223:Infant; D008297:Male