Inguinal hernia surgery : aspects on chronic pain and contralateral repair

Inguinal hernia is common, and the only permanent treatment is surgical repair. Approximately 16,000 hernia repairs are performed annually in Sweden. Optimized surgical technique including mesh prosthesis decreases the prevalence of recurrences and the main outcome measurement is today chronic postoperative inguinal pain (CPIP). CPIP prevalence is often reported as 10-30%. The wider use of endo-laparoscopic surgical technique has slightly decreased the prevalence of CPIP and has also offered the opportunity to perform a bilateral inguinal hernia repair, as well as exploration for occult hernias in the contralateral groin, during one procedure without additional incisions. Considering the large number of patients with CPIP it is vital to better understand the etiology and causes for the development of CPIP. It is also of interest to evaluate the benefits and risks to an extended laparoscopic procedure such as a bilateral prophylactic hernia repair. In Paper I, the aim was to explore if surgical postoperative complications increased the risk for CPIP in a long-term cohort study. Participants responded to the Inguinal Pain Questionnaire (IPQ) regarding postoperative groin pain 8 years after inguinal hernia repair. Responses to the questionnaire were matched with data regarding self-reported postoperative complications after open inguinal hernia repair. A total of 170 patients (17.9%) reported persistent groin pain and 29 patients (3.0%) reported severe persistent groin pain. Severe pain in the preoperative or immediate postoperative period was a significant risk factor while increasing age was negatively correlated to the risk for chronic groin pain. In Paper II, the aim was to develop and evaluate a condensed version of the IPQ. The IPQ is a standardized and validated instrument for assessing CPIP after groin hernia surgery. The Short- Form Inguinal Pain Questionnaire (sf-IPQ) comprises two main items extracted from the IPQ. Four hundred patients with groin hernia repairs were recruited from the Swedish Hernia Register (SHR) and were sent the IPQ, sf-IPQ and the Short-Form McGill Pain Questionnaire (SF-MPQ) three years after hernia repair. Correlation, consistency, and agreement were seen between the IPQ and sf-IPQ despite a systematic difference in level of pain score. The forms appeared to provide similar responses for parameters assessed by both instruments, though the sf-IPQ may be a more sensitive instrument. In Paper III, the aim was to analyze if specific postoperative complications constitute predictors for the risk of developing CPIP using a population-based prospective cohort of 30,659 patients operated for groin hernia 2015–2017 included in the SHR. Registered post-operative complications were categorized into hematomas, surgical site infections (SSI), seromas, urinary tract complications, and acute post-operative pain. A questionnaire enquiring about groin pain was distributed to all patients 1 year after surgery. Acute postoperative pain was a strong predictor for CPIP following both open anterior and endo-laparoscopic hernia repair. SSI and hematoma were predictors for CPIP following open anterior hernia repair. In Paper IV, the aim was to investigate the incidence as well as the factors predictive for a subsequent hernia repair on the contralateral side following a primary unilateral hernia repair. Participants were recruited from the SHR. 151,297 patients operated with a unilateral groin hernia repair using open and endo-laparoscopic technique, during 2007-2019, were studied. There were 7.4% registered contralateral hernia repairs with a median time to contralateral repair of 2.7 years. Significant predictors for a subsequent contralateral hernia were, male sex, high age, medial inguinal hernia, combined inguinal hernia, hernia defect size >1.5 cm, and a repair on the left side. Endo-laparoscopic repairs and obesity were associated with a lower incidence of a later contralateral repair. In conclusion, patient reported CPIP is a significant negative outcome following groin hernia repair that needs to be evaluated continuously. The sf-IPQ can be recommended as an evaluation tool in daily clinical practice. The postoperative complications: postoperative severe pain, hematomas, and SSI were associated with CPIP. These predictors may be related to surgical technique. Considering the relatively low incidence of subsequent contralateral hernia repairs, a routine extended exposure of the contralateral groin or a prophylactic contralateral repair cannot be recommended considering the risk for surgical complications and associated CPIP