This study did not observe significant differences between TEP and TAPP in the proportion of postoperative complications, acute postoperative pain, chronic inguinal pain, and hernia recurrence. However, operative time and hospital stay were longer in the TAPP group, while conversion to open surgery was higher in the TEP group.
The laparoscopic approach in inguinal hernia repair is a valid alternative to traditional open repair [15, 25]. However, despite the recommendations of international guidelines, the utilization rates are variable, 38% in the USA [26], 23% in England [27] and 5.7% in Spain [28]. The use rate of laparoscopy for bilateral inguinal hernia repair in Spain in 2019 was 23% [29].In our study, we observed a significant increase in the use of laparoscopic access for bilateral hernia repair, reaching 94% in 2020.
TEP and TAPP are the two most used laparoscopic procedures for inguinal hernia repair. Most previous studies have not identified advantages between the two laparoscopic techniques [25, 30]. The main difference between TEP and TAPP is the access route to the preperitoneal space. For many groups, TEP is more attractive as it reproduces the access route of the open preperitoneal repair without accessing the abdominal cavity and avoids the risk of intra-abdominal organ injury [3]. In contrast, other groups prefer TAPP as it has an access route more similar to conventional laparoscopy for other pathologies and the advantage of exploring both inguinal regions [31].
Visceral and vascular injuries are the most important intraoperative complications of inguinal hernia repair. It has been described that visceral injuries are more frequent in TAPP than in TEP, reporting an incidence of 0.21% [5, 13]. Vascular lesions, especially inferior epigastric artery lesions, are more common in TEP [32, 33], and 0–3% incidence has been reported [22, 34]. Our study reported no intraoperative complications in bilateral inguinal hernia repairs by TEP and TAPP.
Accidental tears of the peritoneum, bleeding, and adhesions have been reported as the main causes of conversion from laparoscopic repair to open surgery [35, 36]. Previous studies describe a higher incidence of conversion to open surgery in TEP [22, 37]. For anatomical orientation and identification of structures, it is necessary to create an adequate preperitoneal space that allows correct mesh placement and control of complications such as injury to the inferior epigastric artery [37]. The higher conversion rate in TEP could be explained by the greater difficulty in creating and maintaining a wide preperitoneal space, which is worsened by adhesions from previous preperitoneal surgery and tears of the peritoneum [35, 36]. We found six cases of conversion to open surgery in TEP and no conversion in TAPP, a result similar to that reported in previous studies.
The operative time reported in some studies was longer in TEP [20, 24], while other authors report that the operative time is longer in TAPP [20, 38]. These differences can be explained because the operative time depends on the type of hernia, the patient's condition, and the surgeon's experience [23, 39]. We must remember that these studies were conducted in unilateral hernias; a recent randomized trial in bilateral hernias reported that operative time was longer in TEP [22]. Our study found that the operative time was longer in TAPP. Self-adhering mesh and a balloon dissector to create the preperitoneal space in TEP could decrease operating time. In TAPP, using conventional mesh fixed with glue and subsequent suturing of the bilateral peritoneum increased operating time. In addition, we observed a significant decrease in operative time in both surgical techniques in the study period, which was greater in TEP. At the beginning of the study, the surgical teams had no previous experience in laparoscopic hernia repair; however, the team that performed TEP was made up of two surgeons, and the team that performed TAPP was made up of three surgeons, which could explain the differences.
Differences between TEP and TAPP in common postoperative complications such as hematoma, seroma, wound infection, and urinary retention analyzed in two systematic reviews and meta-analyses were not statistically significant [23, 40]. In a recent meta-analysis, TEP was associated with a lower risk of genital edema, and TAPP repair with a lower risk of seroma formation [41]. A likely explanation could be that TAPP has more surgical space, which facilitates inversion of the transversalis fascia and fixation, associated with a lower incidence of seroma [42]. In our study, the differences in postoperative complications were not significant. When performing multivariable analysis, we observed that the type of technique used was not associated with the presence of complications.
The reported results of the differences in hospital stay between the two techniques are very diverse, probably because it depends on various factors such as age, complication rate, postoperative pain, social factors, educational factors, and trust in the surgeon [43, 44]. A randomized trial found no significant difference in hospital stay between TAPP and TEP in bilateral inguinal hernia repair [22]. In our study, the length of hospital stay was shorter in TEP, and ambulatory surgery was greater in TEP. The shorter operative time reported in the TEP group could be a favorable factor for the greater use of outpatient surgery in these patients and reduce their hospital stay. The current recommendation is to use outpatient surgery for inguinal hernia repair, regardless of the technique [15]. In recent years there has been an increase in the percentage of inguinal hernia repairs performed as outpatient surgery [45]. The use of laparoscopy in repairing a bilateral inguinal hernia would increase the use of outpatient surgery by reducing pain and complications compared to open surgery.
Some studies report less early postoperative pain in TEP [21, 24, 46]. However, a recent systematic review found no difference in postoperative pain between TEP and TAPP [47]. Using tacks to fix the mesh and close the peritoneum increases postoperative pain, so glue or self-fixing mesh is recommended [14, 48]. Some authors suggest that postoperative pain is greater in TAPP than in TEP, mainly due to the use of tacks [25, 49]. In our study, self-fixing meshes were used in TEP and glue to fix the mesh in TAPP, and we found no differences in postoperative pain between the two techniques.
Previous studies have found no differences between TEP and TAPP in chronic pain and hernia recurrence [23, 24, 47, 48, 50]. The reported incidence of recurrence of laparoscopic repair is similar to that of open repair [51, 52]. The main causes of recurrence after laparoscopic repair are incomplete dissection, mesh size that is too small, and improper mesh position or migration [53]. Using a mesh of at least 10 x 15 cm, proper surgical technique, and training can significantly reduce the recurrence rate [14, 15]. When we performed a multivariable analysis, we found no association between the type of laparoscopic technique chosen and chronic pain or hernia recurrence.
The limitations of this study are its retrospective design, the small number of cases because we only included bilateral hernias, the performance of laparoscopic techniques (TEP and TAPP) by two different teams of surgeons, the non-assessment of costs and the postoperative follow-up period that was not more than one year. However, its strengths are being one of the few studies that specifically analyzes the results of TEP and TAPP in bilateral inguinal hernia repair, the similarity of the groups analyzed, and the similar experience of surgical teams in inguinal hernia repair by laparoscopy.