The pathogenesis of Amyand’s hernia associated acute appendicitis remains controversial. Previous studies indicated that muscle contractions or other sudden increases in intra-abdominal pressure might compress the appendix, resulting in inflammation [11, 12]. Moreover, an extraluminal obstruction of the appendix usually causes appendicitis due to pressure in the hernia neck rather than intraluminal obstruction [10, 11]. In our study, we presented six cases with Amyand’s hernia, in which two had normal appendix and four had inflamed appendix. The different operative methods and outcomes of six patients would provide a reference for the treatment of Amyand’s hernia.
A definitive preoperative diagnosis of Amyand's hernia is rare since the diagnosis is usually made during surgery. Physical examinations, laboratory examinations, and imaging examinations are not always helpful for the differential diagnosis of Amyand's hernia. With respect to imaging examinations, CT scanning can facilitate the diagnosis of Amyand's hernia. However, CT is usually not the first choice for an uncomplicated inguinal hernia [13]. Therefore, the diagnosis of Amyand's hernia will be missed at that time. Sonography has been reported as a valuable examination in the preoperative screening of Amyand’s hernia since it is cheap and convenient for painful patients [14, 15]. Moreover, the suspected lesion can be further validated by CT. However, a preoperative diagnosis of Amyand's hernia based on ultrasound alone depends on the proficiency of the operator and, for that reason, remains a relatively unreliable imaging modality to accurately diagnose Amyand’s hernia [16]. Therefore, laparoscopic surgery can function as a diagnostic and therapeutic approach. Recently, a systematic review indicated that CT was the definitive diagnostic modality in patients with preoperative diagnosis.[17] In our six cases, four patients were diagnosed with appendicitis and inguinal hernia by CT whereas two patients were diagnosed with inguinal hernia by ultrasonography. However, the diagnosis of Amyand’s hernia of these patients was obtained during surgery. In our opinion, CT imaging can facilitate the diagnosis of inguinal hernia but it is difficult to diagnose Amyand’s hernia. As shown in Fig. 1, the density of the appendix is similar to that of the intestine and the identification of the appendix within the hernia is made after surgery. Therefore, CT is limited for the definite diagnosis of Amyand’s hernia. The diagnosis of Amyand’s hernia should be made by laparoscopy or laparotomy.
Losanoff and Basson have described four subtypes of Amyand’s hernia and recommend different treatments (Table 4) [8]. Amyand’s hernia with a normal appendix is classified as type I whereas type II-IV includes acute appendicitis. Therefore, Case 3 and 6 in our study were classified as type I Amyand’s hernia and other cases were defined as type II. Generally, the primary management for Amyand’s hernia with a non-inflamed appendix is hernia repair without appendectomy [7, 18, 19, 20]. Some clinicians believe that this will decrease the occurrence of postoperative complications because appendectomy will convert a clean surgery into a clean-contaminated surgery. Also, the remaining appendix can be further used to replace the extrahepatic biliary tract, perform urinary diversion, or conduct Malone procedure [21, 22]. Furthermore, during appendicectomy, surgical manipulations in the base of the caecum may lead to the recurrence of inguinal hernias caused by the detachment of the deep inguinal ring [23]. Moreover, surgical manipulations involving the appendix might trigger secondary acute inflammation [22, 23]. However, these potential complications are minimized when the operation is performed laparoscopically [21, 22]. Shaknovsky et al. reported the successful treatment of an adult patient with type I Amyand’s hernia after applying the Robotic platform Da Vinci Surgical System with 3D high-definition imaging [24]. Of the six cases included in this study, the treatment of Case 3 and 6 was tension-free mesh repair without appendicectomy, which was consistent with the recommendation. As for other cases with type II Amyand’s hernia, Case 1 and 5 received appendicectomy without tension-free mesh repair, which was consistent with the recommendation. However, for Case 2 and 4 who had inflamed appendixes, the surgeons performed appendectomy and tension-free mesh repair and patients did not develop postoperative infections. This may be due to postoperative antibiotics and pelvic drainage.
Table 4
Four types of Amyand’s Hernia
Classification
|
Description
|
Surgical management
|
Type 1
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Normal appendix with an inguinal hernia
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Hernia reduction, mesh repair, appendectomy in young patients
|
Type 2
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Acute appendicitis within an inguinal hernia, no abdominal sepsis
|
Appendectomy through hernia, primary endogenous repair of hernia, no mesh
|
Type 3
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Acute appendicitis within an inguinal hernia, abdominal wall, or peritoneal sepsis
|
Laparotomy, appendectomy, primary repair of hernia, no mesh
|
Type 4
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Acute appendicitis within an inguinal hernia, related or unrelated abdominal pathology
|
Manage as types 1 to 3 hernia, investigate or treat second pathology as appropriate
|
Prosthetic mesh is typically contraindicated in patients with an inflamed or perforated appendix because of the increased risk for wound and mesh infections [9]. Besides, a recent study suggested that mesh repair should be conducted after removal of the appendix regarding an inflamed appendix without perforation or abscess. As for the perforated appendix, the synthetic mesh repair should be avoided. Moreover, mesh repair should be deferred if the inguinal canal had severe inflammation [17]. In our view, mesh repair is recommended when a non-inflamed appendix is discovered during herniorrhaphy. When acute appendicitis exists in the hernia sac, the surgeon should perform the appendicectomy and tension-free hernia repair. In our study, the appendix of Case 4 is inflamed but not perforated, therefore, the mesh repair is applicable in this case. Case 1, 2, and 5 have perforated appendix, in which Case 1 and 5 do not receive mesh repair whereas Case 2 receives mesh repair. Since Case 2 did not develop postoperative infections, the application of the drainage tube and antibiotics may be helpful for the prevention of infections. Besides, the surgeon did not perform hernia repair in Case 5 because of the serious infection of the inner ring. In this case, it is better to perform two-stage surgery or one-stage reopen hernia repair. However, additional studies are required to determine the optimal surgical approaches for these patients.