Effectiveness of endoscopic totally extraperitoneal (TEP) hernia correction for clinically occult inguinal hernia (EFFECT): Study protocol for a randomized controlled trial

Background: Groin pain is a frequent complaint in surgical practice with an inguinal hernia being at the top of the differential diagnosis. The majority of inguinal hernias can be diagnosed clinically. However, patients with groin pain without signs of an inguinal hernia on anamnesis or physical examination provide a diagnostic challenge. If ultrasonography shows a hernia that could not be detected clinically, this entity is called a clinically occult hernia. It is debatable if this radiological hernia is the cause of complaints in all patients with inguinal pain. The objective of this study is to assess whether watchful waiting is non-inferior to endoscopic totally extraperitoneal (TEP) inguinal repair in patients with a clinically occult inguinal hernia. Methods: The EFFECT study is a multicenter non-blinded randomized controlled non-inferiority trial. Adult patients with unilateral groin pain and a clinically occult inguinal hernia are eligible to participate in this study. A total of 160 participants will be included and randomized to TEP inguinal hernia repair or a watchful waiting approach. The primary outcome of this study is pain reduction 3 months after treatment, measured by the Numeric Rating Scale (NRS). Secondary outcomes are quality of life, cost-effectiveness, patient satisfaction and crossover rate. Eight surgical centers will take part in the study. Participants will be followed-up for 1 year. Discussion: This is the first large randomized controlled trial comparing treatments for patients with groin pain and a clinically occult inguinal hernia. To date, there are no interventional studies on the effect of surgery or a watchful waiting approach in terms of pain or quality of life in this subset of patients. A trial comparing the outcomes of the two approaches in patients with a clinically occult inguinal hernia is urgently needed to provide data facilitating the choice between the two treatment options. If watchful waiting is not inferior to surgical repair, costs of surgical repair may be saved. Trial registration: The study protocol (NL61730.100.17) is approved by the Medical Ethics Committee (MEC-U) of the Diakonessenhuis, Utrecht, The Netherlands. The study was registered at the Netherlands Trial Registry ( NTR6835 ) registered on November 13, 2017.