Bilateral vs Unilateral Inguinal Hernia Repairs With an Asymptomatic Inguinal Hernia in Bilateral Hernias

BACKGROUND

Groin hernia repair is one of the most common surgical procedures with approximately 20 million repairs performed annually in the world. In Sweden, over 18.000 groin hernia operations are prospectively registered annually in the Swedish Hernia Register (SHR). Over the past 30 years, the SHR has achieved a national completeness and data validation level of 98%. By creating a database of over 400.000 operations, the SHR has had a large impact on improving the quality of hernia surgery in Sweden as well as internationally.

There are mainly two important outcomes following a groin hernia repair that could impair the patient's quality of life; recurrence and chronic pain - both of them retained from the SHR and being main quality predictors for groin hernia repair in Sweden.

The prevalence of bilateral groin hernias has been reported up to 22%, while the prevalence of an asymptomatic contralateral groin hernia in patients with symptomatic unilateral groin hernia has been estimated to around 15%. Around 30% of all asymptomatic groin hernias are predicted to become symptomatic and require a future repair.

Chronic pain following groin hernia repair has been described to have a rate somewhere in the range of 10-15 % after a groin hernia repair. However, some studies have reported disturbing incidences up to 30-60 %, confirming that chronic pain is an unfortunate problem that impairs patients' quality of life.

The conditions of an asymptomatic groin hernia and an occult groin hernia may sometimes be exchangeable in the literature. However, it is important to distinguish the definitions from each other.

Earlier studies has suggested that simultaneous prophylactic repair of an asymptomatic contralateral hernia may prevent a repeat procedure in the future and without any significant side effects of patient recovery to daily life. In a randomized controlled trial from 2006, it was demonstrated that a repair of an asymptomatic groin hernia has little effect on the rate of long-term chronic pain for patients. It has proposed that repairing an asymptomatic contralateral groin hernias is associated with more benefits than risks for both the patient and for the society.

In contrast to the above-mentioned advantages of patients with bilateral groin hernias undergoing a simultaneous prophylactic repair of the asymptomatic contralateral groin hernia, some suggest that it is likely that there can be an increase in operation-time and prolonged immediate postoperative pain in these patients compared to those that only have their symptomatic unilateral groin hernia repaired. From earlier studies, it could confirm that the short-term postoperative pain was higher for bilateral repairs compared to unilateral repairs at 2 weeks postoperative control, but this difference resolved by 6 weeks after surgery. Previous reports indicate no significant differences between unilateral hernia repairs compared to bilateral repairs considering length of hospital stay, postoperative complications or duration for returning to daily activity.

The European Hernia Society (EHS) guidelines recommend laparo-endoscopic repair for bilateral groin hernias if it is feasible and in agreement with the patients, but a routine's exploration of the contralateral groin is only suggested for the TAPP approach (transabdominal preperitoneal repair) and not for repairs performed through TEP (total extra-preperitoneal repair). EHS also state that although most patients with asymptomatic groin hernias will develop symptoms and need a future surgery, watchful waiting for an asymptomatic inguinal hernia is safe since the risk of hernia complications is low.

An important withdrawal with previous studies is that it is not possible to predict whether the patients were operated laparoscopically because of bilateral symptoms, or if occult bilateral groin hernias were detected due to the laparoscopic approach.

The incidence and treatment of an asymptomatic contralateral groin hernia in patients with bilateral groin hernias have therefore been debated on in the past decades. The majority of bilateral hernias are operated laparoscopically and we are facing an increasing trend. Despite the high prevalence of bilateral groin hernias and asymptomatic contralateral groin hernias, there is currently no proper consensus on the timing of repair of the asymptomatic contralateral groin hernia.

Therefore, the study aim, with this large multicenter register- randomized controlled trial via a national highly validated Swedish register, to investigate the outcomes of asymptomatic contralateral groin hernias in patients with bilateral groin hernias.

AIM

The aim is to investigate the differences in the outcome of chronic pain, reoperation, peri - and postoperative complications and patient satisfaction between laparo-endoscopic bilateral inguinal hernia repair with an asymptomatic contralateral groin hernia versus a laparo-endoscopic unilateral inguinal hernia repair without repairing the asymptomatic contralateral groin hernia in bilateral inguinal hernias in adults. Additionally, we aim to study the prevalence of future elective and emergency hernia repair of the unrepaired asymptomatic contralateral inguinal hernia.

The chronic pain, reoperation, peri - and postoperative complications and patient satisfaction is hypothesized to be equal between bilateral inguinal hernia repairs with an asymptomatic contralateral inguinal hernia compared to unilateral symptomatic inguinal hernia repairs.

STUDY OBJECTIVES

The exposure Method of repair, containing two groups of allocation repairs;

Bilateral repair (exposure - intervention arm) Unilateral repair (unexposure - standard arm)

Primary outcome PROM - Patient-reported chronic pain 1 year after surgery

To compare chronic pain 1 year after surgery between laparo-endoscopic bilateral inguinal hernia repair with an asymptomatic contralateral inguinal hernia (bilateral arm) versus a laparoscopic unilateral inguinal hernia repair (unilateral arm) without repairing the asymptomatic contralateral inguinal hernia in bilateral groin hernias in adults.

Secondary outcomes See these under outcome measures.

METHOD

Study design The study is a register-based randomized controlled multicenter trial with patients that have bilateral inguinal hernias whereas one of the hernias (called the contralateral groin hernia) is asymptomatic. Patients are either randomized to a repair undergoing laparo-endoscopic bilateral inguinal hernia repair of both hernias or only a laparo-endoscopic unilateral inguinal hernia repair of the symptomatic inguinal hernia. The name of the trial is; the BILAP HERNIA Trial. Inclusion, randomization and follow-up will be conducted through a national register; the Swedish Hernia Register (SHR). At each participating unit, all patients who fulfill the inclusion criteria and none of the exclusion criteria will be invited in the study. After oral and written consent, the patients will be included in study. They will be given a question about pain to answer before surgery and this will be recorded in their baseline characteristics. Patients are then randomized intra-operatively through the SHR to one of the allocation arms. During operation all patient and hernia characteristics are filled in prospectively by the operation-team in SHR according to the SHR register, forming the patients CRF (Clinical Research Form). 1 year after surgery, all participants will be sent out a PROM questionnaire according to the incorporated routine in the SHR including questions addressing chronic pain and patient satisfaction.

The Swedish Hernia Register The Swedish Hernia Register (SHR) has near national coverage of surgical units across Sweden. More than 98% of all groin hernia operations from 90 surgical units performed in Sweden are registered in the SHR. It is a nationwide database of more than currently 400,000 groin hernia procedures. Procedures are recorded prospectively by the surgeon during the operation and patients are identified using a personal identity-number, unique for each citizen in Sweden. The SHR is linked to the Swedish population registry to obtain accurate follow-ups. 10% of the aligned surgical units are checked independently each year. Validity of the SHR has been reported to be 98 % correct variables and a 97 % cover rate for procedures in the participating units, demonstrating that the SHR is a highly validated register.

PROM questionnaire Between 2012 and 2018 a questionnaire assessing patient-reported outcome measures (PROMs) was sent out 1 year after surgery to all patients that had undergone a groin hernia repair from units participating in the SHR. The previous response rates have approximately been up to 72%. The distributed questions are extracted from the Inguinal Pain Questionnaire (IPQ)19 and is a short-form questionnaire. A short-form questionnaire has shown to be exchangeable to the longer original version of IPQ20. This provides the unique opportunity to determine prospective collected patient-reported pain outcomes through a register. Studies reflecting the results of surgeons not specialized in hernia surgery are lacking today on assessing pain patients between different method of repairs, and especially on a large number of unselected hernias. This routine, by sending out PROM 1 year to all patients that has been undergone a groin hernia repair has now in 2025 again been incorporated in the SHR and will continue forward to be. The PROM questionnaire consists today of more questions. The population-based SHR offers a unique possibility to study this through a randomized controlled trial and send out the questionnaire again within a trial. Patients are followed from operation to re-operation, death or migration. Due to the personal identity-number, unique for each citizen in Sweden, patients can be followed until a reoperation for recurrence or pain and if a future elective or emergency repair has been done and registered within the framework of the SHR.

Definition of a symptomatic and asymptomatic inguinal hernia A symptomatic inguinal hernia is defined as a clinical detectable reducible bulge (very small or large) in the groin above the inguinal ligament with symptoms of bulging, pain and discomfort.

An asymptomatic inguinal hernia is defined as a clinical detectable reducible bulge (very small or large) in the groin above the inguinal ligament where the patient has no symptoms of bulging, pain or discomfort. In some cases, the patients have not even noticed their asymptomatic hernia.

If preoperative imaging detects an inguinal hernia but the patient does not exhibit a clinically identifiable hernia during examination, this situation is not classified as an asymptomatic hernia. Preoperative imaging is not always reliable for diagnosing hernias, and clinical examination remains a critical component in assessment.

Selection of the study population All adult patients referred for a groin hernia to outpatient clinical are eligible to the study and screened for inclusion. An unaware asymptomatic contralateral groin hernia might be present in the outpatient clinic after examination by the surgeon. Patients randomized to only a unilateral hernia repair will be followed-up through the register to investigate both the risk of emergency hernia repair and the risk of a future elective repair of the asymptomatic not repaired hernia.

Inclusion criteria • Elective laparo-endoscopic surgery of bilateral primary inguinal hernia in both men and women above and 18 years old, whereas one of the hernias is asymptomatic in a surgical center that perform \> 50 laparo-endoscopic groin hernia repairs per year.

Exclusion criteria

• See study protocol

Femoral hernias According to current guidelines, patients with femoral hernias (groin hernias below the inguinal ligament) are recommended for surgery whether they are symptomatic or asymptomatic. This is due to literature report

• Risk of reoperation due to recurrence of the hernia repair [Time frame: 2, 5 and 10 years after surgery]
• Perioperative complications (safety) [Time frame: Intraoperatively during surgery]
• Postoperative complications (safety) [Time frame: 30 days after surgery]
• Rate of future elective hernia repair of the unrepaired asymptomatic contralateral inguinal hernia [Time frame: 1, 2, 5 and 10 years after surgery]
• Rate of future emergency hernia repair of the unrepaired asymptomatic contralateral inguinal hernia [Time frame: within 2 years after surgery]
• Rate and characteristics of found femoral hernias in the total study population [Time frame: Intraoperatively during surgery]
• Operation time of surgery [Time frame: Intraoperativley during surgery]
• Patient-reported satisfaction 1 year after surgery via PROM [Time frame: 1 year after surgery]