Patologia
Ernia ventrale e laparocele

Descrizione
Irene Fiume, MD, PhD
Department of General, Oncologic and Vascular Surgery
Azienda Ospedaliera Ospedali Riuniti Marche Nord
Pesaro, Piazzale Cinelli n.4, 61121 PU
Italy
e-mail: irene.fiume@virgilio.it

Introduction
Spigelian hernia (SH) is the protrusion of the abdominal content or peritoneum through a congenital or acquired defect of the anterior abdominal wall fascia in correspondence of the Spigelian aponeurosis, along the semilunar line. Mostly, these hernias lie in the SH belt [1] in which, the weakest area is at the intersection between the semilunar and semicircular line, as the posterior rectus sheath is no longer present. The “weak triangular area” is delimited laterally by the semilunar line, superiorly by the semicircular line and, inferiorly, by the deep inferior epigastric vessels [1], above the Hesselbach’s triangle.

Anatomical definitions
Spigelian aponeurosis: part of the aponeurosis of the transverse abdominal muscle between the linea semilunaris laterally and the lateral edge of the rectus muscle medially.

Linea semilunaris: a vertical, curved structure that runs along the lateral edges of the rectus abdominis muscle in the anterior abdominal wall. It is the site of the union where the tendons of the lateral abdominal muscles (the external oblique, the internal oblique and the transversus abdominis muscles) meet the sheath surrounding the rectus abdominis muscle, also known as the rectus sheath. Linea semilunaris runs between the cartilage of the ninth rib and the pubic tubercle bilaterally. The ninth ribs are farther apart from each other when compared to the pubic tubercles, which are closer together, giving the linea semilunaris its curved shape [2].
Spigelian belt: a transverse zone of 6 cm located above the interspinal plane.
Semicircular line: also known as arcuate line or line of Douglas marks the caudal end of the posterior lamina of the aponeurotic rectus sheath. This line is found in the infraumbilical area and represent the anatomical transition, inferior to which, all the aponeurotic layers of the abdominal muscles, except the transversalis fascia, pass simultaneously anterior to the rectus abdominis muscle. At the caudal side of the semicircular line, the posterior side of the rectus abdominis muscle is covered only by the transversalis fascia and the peritoneum.
Rectus sheath: fibrous compartment that contains both the rectus abdominis muscles and the pyramidalis muscle that extends from the inferior costal margin and the costal cartilages of fifth to ninth ribs to the pubic crest. The fascial coverings of the external oblique, internal oblique, and transversus abdominis muscles comprise the rectus sheath [3].

Hesselbach’s triangle: limited by the inferior epigastric vessels, the rectus abdominis muscle and the inguinal ligament.

Epidemiology
SH is rare and account for only 0.1-2% percentage of occurrence. However, the risk of incarceration and strangulation is high due to the small size of the fascial defect [1, 4]. The hernia sac consists of extra peritoneal fat and peritoneum. Occasionally, the extra peritoneal fat is preceded by remnant bands from the transversalis fascia. Usually, SH contains small bowel or omentum. However, multiple intra-abdominal organs have been reported to have been found in the SH as large bowel, stomach, gallbladder, Meckel diverticulum, ovary, testis, leiomyoma of the uterus, and even bladder [1].

Clinical case report
75 year old man, BMI 24.9 kg/m2
Comorbidity: diabetes mellitus, benign prostatic hyperplasia
Previous surgery: open right inguinal hernia repair, open repair of strangulated left side SH with the hernia sac containing sigmoid loop with infarcted epiploic appendices, subsequently laparoscopic left side SH repair with intraperitoneal onlay mesh placement (IPOM) for recurrence
Proximate medical history: the patient presented to general surgery facility complaining right abdominal pain and discomfort. Physical examination demonstrated mild tenderness and a bulging of the right side. Abdominal ultrasound revealed an incarcerated SH containing vermiform appendix. CT scan confirmed the ultrasound diagnosis and ruled out other abdominal disease.

Surgical technique
The patients underwent laparoscopy with placement of three trocars (a 5 mm sovraumbilical trocar for the telescope, a 10 mm trocar in left flank for the introduction of the stapler and the mesh, and a 5 mm trocar in ipogastrium) avoiding the area of the previous repair of the left SH. The hernia defect containing the incarcerated appendix was visualized. After being reduced into the abdominal cavity, the appendix appeared congested and covered by the thickened hernial sac but there were no sign of ischemia and purulent peritonitis. Appendectomy and resection of the sac were then performed and the defect was addressed clearing off the peritoneum and the preperitoneal adipous tissue up to 5-6 cm from the edges. The defect was measured by the introduction of a sterile ruler (the size of the defect was less than 2 cm). No closure of the defect was carried out. An expanded polytetrafluoroethylene mesh (Gore® Dualmesh®, W.L. Gore & Assoc., Flagstaff, AZ, USA) was shaped of adequate size in order to obtain an overlap of about 5 cm per side and introduced into the abdominal cavity. The pneumoperitoneum was reduced to 8-9 mmHg and the fixation of the mesh was obtained using laparoscopic tackers and cyanoacrylat glue. A careful inspection of the deep ring and the identification of the angle of doom and the triangle of pain was done before fixation of the tacks to avoid injury to the testicular vessels, duct deferens, inferior epigastric vessels, iliac vessels, (the structures of the inverted Y) and the lateral cutaneous nerve of the thigh, the femoral branch of the genitofemoral nerve and the femoral nerve (crossing the triangle of pain). The cyanoacrylat glue was used to fix the part of the mesh closest to the internal inguinal ring. No intraoperative or postoperative complications occurred and the discharge was on day 2. Pathological examination revealed a chronic appendicitis.

Discussion points
1) SHs often have a narrow fascial defect and may be intra-parietal hernias, meaning that the hernial content may not lie below the subcutaneous fat but penetrate between the muscles of the abdominal wall [5]. Therefore, these hernias may be misdiagnosed at clinical examination and have an increased risk of incarceration and strangulation. Laparoscopic exploration, when feasible, is fundamental to evaluate the inflammation degree and the possibility of carrying out a mini-invasive treatment.
2) SHs may be primitive o secondary to previous trocar insertion [6, 7]. In the present case, four years earlier, the patient had undergone laparoscopic IPOM repair for recurrent left side SH. It is difficult to say if the right side SH was primitive or secondary to previous trocar insertion as the skin scar was barely visible.
3) In emergency setting, the risk of wound infection must be carefully considered before mesh positioning. In this case, we used the IPOM repair with an expanded polytetrafluoroethylene mesh given the absence of any abdominal effusion and phlegmonous appendicitis.
4) The IPOM method is the most popular type of repair among the laparoscopic methods of SH repair, including trans-abdominal preperitoneal (TAPP) and totally extra-peritoneal (TEP) mesh placement repair. IPOM technique is usually a quick procedure and less demanding. However, tack fixation may result in disastrous drawbacks [8, 9]. In particular, it is necessary to consider the risk of damage of anatomical vascular and nervous structures surrounding the internal inguinal ring given its proximity to the Spigelian belt. Therefore, before positioning of the tacks, a careful inspection of the inguinal region and the identification of the anatomical landmarks, Hasselbach triangle, triangle of pain and triangle of doom, is mandatory. As was shown in a previous report of the Literature, the technique to partially fix the mesh with cyanoacrylat glue was adopted, in order to reduce the number of tacks near the inguinal ring and the epigastric vessels [10].
5) The approximation of the hernia defect was not carried out for two reason: the small size of the defect and consequently the low risk of post-operative seroma, and to avoid tension and alteration of the muscle-tendon dynamics of the abdominal wall at this level in close proximity to the internal inguinal ring. Furthermore, because of the anatomic nature of SH, the abdominal wall is stable and provides reasonable support after the incorporation of a mesh [11,12].
6) The presence of vermiform appendix within the hernial sac is peculiar. The presence of vermiform appendix within the inguinal hernia is named Amyand’s hernia after, in 1735, Amyand described the first case of incarcerated inguinal hernia, containing a perforated appendix, in an 11-year-old boy [13]. Femoral hernia containing the appendix was named De Garengeot hernia after Rene Jacques Croissant De Garengeot first described in 1731 a case of femoral hernia, containing a non-inflamed appendix [14]. Although rare entity, a classification of Amiand’s hernia have been described in order to improve management [15]. This last point of discussion is precisely aimed at underlining the importance of giving a name to the SH containing appendix. The search for scientific literature on the subject would become rapid and immediate so as to obtain all the necessary information on the optimal management of this uncommon pathology.
The proposal of an acronym and a classification for the severity of this condition could be useful to face the reason for the lack of data and consequently of study designs.
The acronym VAISAD (vermiform appendix in Spigelian aponeurosis defect) is readily and easily applicable to refer this type of hernia.
The table presents a classification proposal based on the severity of the inflammation of the vermiform appendix contained in SH and on its reducibility into the abdominal cavity by laparoscopic traction.
By applying this acronym and the proposed classification in clinical studies, a larger database could be obtained to guide surgeons towards the surgical treatment in relation to the gravity of inflammation and applying the most recent minimally invasive innovations in the treatment of hernial pathology.

Table 1. VAISAD hernia classification

Type State of appendix
1a Normal-slightly congested, reducible
1b Normal-slightly congested, not reducible
2a Phlegmonous appendicitis, reducible
2b Phlegmonous appendicitis, not reducible
3a Perforated appendicitis, reducible
3b Perforated appendicitis, not reducible
4a Appendicular abscess or inflammatory mass with ileocecal involvement need for extensive resection, reducible
4b Appendicular abscess or inflammatory mass with ileocecal involvement need for extensive resection, not reducible

References
[1] Skandalakis PN, Zoras O, Skandalakis JE, Mirilas P. Spigelian hernia: surgical anatomy, embryology, and technique of repair. Am Surg (2006), vol. 72, pp. 42-48,
[2] Nassereddin A, Sajjad H. Anatomy, Abdomen and Pelvis, Linea Semilunaris. In: StatPearls. Treasure Island (FL): StatPearls Publishing (2021), vol. 26.
[3] Sevensma KE, Leavitt L, Pihl KD. Anatomy, Abdomen and Pelvis, Rectus Sheath. In: StatPearls. Treasure Island (FL): StatPearls Publishing (2021), vol. 28.
[4] Rankin A, Kostusiak M, Sokker A. Spigelian hernia: case series and review of the literature. Vis Med(2019), vol. 35, 133–136.
[5] Srivastava KN, Agarwal A. Spigelian hernia: a diagnostic dilemma and laparoscopic management. Indian J Surg (2015), vol. 77, 35-37.
[6 Ussia A, Imperato F, Schindler L, et al. Spigelian hernia in gynaecology. Gynecol Surg (2017), vol. 14, 8.
[7] Kamel A, Abdallah N, El-Sandabesee D. Spigelian hernia following laparoscopy. J Obstet Gynaecol (2012), vol. 32, 310-311.
[8] Barnes TG, McWhinnie DL. Laparoscopic Spigelian Hernia Repair: A Systematic Review. Surg Laparosc Endosc Percutan Tech (2016), vol. 26, 265-270.
[9] Wilson P, Hickey L. Laparoscopic transabdominal preperitoneal (TAPP) groin hernia repair using n-butyl-2-cyanoacrylate (Liquiband®Fix8™) for mesh fixation and peritoneal closure: learning experience during introduction into clinical practice. Hernia (2019), vol. 23, 601-613.
[10] Moreno-Egea A, Campillo-Soto Á, Morales-Cuenca G. Which should be the gold standard laparoscopic technique for handling Spigelian hernias? Surg Endosc (2015), vol. 29, 856-862.
[11] Barnes TG, McFaul C, Abdelrazeq AS. Laparoscopic transabdominal preperitoneal repair of spigelian hernia-closure of the fascial defect is not necessary. J Laparoendosc Adv Surg Tech A (2014), vol. 24, 66-71.
[12] Fernández-Moreno MC, Martí-Cuñat E, Pou G, et al. Intraperitoneal Onlay Mesh Technique for Spigelian Hernia in an Outpatient and Short-Stay Surgery Unit: What's New in Intraperitoneal Meshes? J Laparoendosc Adv Surg Tech A (2018), vol. 28, 700-704.
[13] Amyand C. Of an inguinal rupture, with a pin in the appendix coeci, incrusted with stone, and some observations on wounds in the guts. Philosophical Transactions (1835), vol. 39, 1735–1736.
[14] dG RJC. Traite des operations de chirurgie. Paris: Huart (1731) 369–371.
[15] Losanoff JE, Basson MD. Amyand hernia: a classification to improve management. Hernia (2008), vol. 12, 325-326.