Background: Tension of the abdominal wall in the inguinal region induced by Shouldice repair of an inguinal hernia is said to be responsible for elevated postoperative pain levels.
Patients and methods: In 20 patients we recorded the inguinal tensile strength during closure of the hernial gap using a wound retractor equipped with strain gauges. Postoperative pain levels were scaled using a visual analogous score, and correlated with the tensile strength of the inguinal abdominal wall together with peak flow and forced expiratory volume in 1 s (FEV1) 8, 24, and 48 h after the time of operation.
Results: Shouldice repair caused an average increase in inguinal tensile strength of 2.9 +/- 0.58 N (mean +/- SEM). The pain level expressed by active patients was twice the value obtained from resting patients (41.55 +/- 6.3% vs 20.81 +/- 7.1% 8 h after operation), but decreased slightly later on. Peak flow during forced expiration was depressed to about 80% of the control values, whereas the 1-s volume during forced expiration decreased only to 95% of the control value. We excluded any correlation between the recorded individual inguinal tensile strength or the changes in distance between the lateral edge of the rectus sheath and the base of the inguinal ligament and the postoperative pain level.
Conclusion: We failed to see any evidence for the hypothesis that higher inguinal tensile strength induced by Shouldice repair leads to an elevated level of postoperative pain. If there is any effect, it may be masked by other factors with a stronger influence.