Hernial sac hystology of the inguinal hernias: identification of smooth muscle fibers and their relation with the blood vessel

Abstracts

OBJECTIVE: To study the correlation between the blood vessels and the smooth muscles in the hernial sac. MEHTODS: 250 surgeries were done to correct inguinal hernias, in children and adults from two months to 75 years old, from March 2002 and February 2003. A hundred ninety two hernial sacs were isolated in 184 surgeries and only eight patients were treated of bilateral inguinal hernia. They were excluded the patients with inguinal hernia which did not have hernial sac during the surgeries and the adult women cause there was no material. From these 184 cases, 90 patients were chosen aleatorialy to make this analysis. They were distributed as follows: 30 male children, 30 female children and 30 male adults. RESULTS: The vessels were present in all groups with a media of 11 vessels per field. The smooth muscle fibers were present in some cases and the horizontal distance was in media 0,1665µ and the vertical 0,1378µ in the adult group with a media of 4,5 isle of smooth muscle fibers, in the child male group the horizontal distance was 0,135µ, the vertical 0,190µ and the isle, 5,35. In the child female group, the horizontal distance was 0,052µ, the vertical 0,037µ and the median number of isles, 4,75. CONLCUSION: The majority of smooth muscles fibers would be proper of the hernial sac independent of the smooth muscles fibers of the blood vessels.

Hernia; inguinal; Histology; Muscle; smooth; Muscle fibers

OBJETIVO: Estudar a relação dos vasos sanguíneos e as fibras de músculo liso presentes no saco herniário. MÉTODOS: Foram realizadas 250 operações para correção de hérnia inguinal em crianças e adultos de dois meses a 75 anos, no período de julho de 2002 a fevereiro de 2003. Foram isolados 192 sacos herniários em 184 procedimentos e somente oito pacientes foram tratados com hérnia inguinal bilateral. Foram excluídos os pacientes que não apresentavam saco herniário durante as operações, e nas mulheres por não haver material. Destes 184 casos, foram escolhidos, aleatoriamente, 90 pacientes para realização desta análise distribuídos em três grupos: 30 adultos masculinos, 30 crianças do gênero feminino e 30 crianças do gênero masculino. RESULTADOS: Os vasos sanguíneos estavam presentes em todos os campos estudados com uma média de 11 vasos por campo. As fibras de músculo liso estavam presentes em alguns casos e tanto na distância horizontal quanto na vertical com a arteríola escolhida, não apresentavam nenhuma relação. CONCLUSÃO: As fibras de músculo liso são próprias do saco herniário e não relacionadas com as dos vasos sanguíneos.

Hérnia inguinal; Histologia; Músculo liso; Fibras musculares

ORIGINAL ARTICLES

Hernial sac hystology of the inguinal hernias: identification of smooth muscle fibers and their relation with the blood vessel

Artur Laizo ACBC–MG^I; Rafael Silveira Vasconcelos^II; Ângela Maria Gollner^III; Alcino Lázaro da Silva, ECBC – MG^IV

^IMSc in Surgery, School of Medicine of the Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil

^IIPhysiotherapist, Universidade Presidente Antônio Carlos (UNIPAC), Juiz de Fora, MG, Brazil

^IIIAssociate Professor, Universidade Federal de Juiz de Fora, MG, Brazil

^IVProfessor Emeritus, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil

Correspondence address

ABSTRACT

OBJETIVE: To study the correlation between the blood vessels and the smooth muscles in the hernial sac.

METHODS: 250 surgeries were done to correct inguinal hernias, in children and adults from two months to 75 years old, from March 2002 and February 2003. A hundred ninety two hernial sacs were isolated in 184 surgeries and only eight patients were treated of bilateral inguinal hernia. They were excluded the patients with inguinal hernia which did not have hernial sac during the surgeries and the adult women cause there was no material. From these 184 cases, 90 patients were chosen aleatorialy to make this analysis. They were distributed as follows: 30 male children, 30 female children and 30 male adults.

RESULTS: The vessels were present in all groups with a media of 11 vessels per field. The smooth muscle fibers were present in some cases and the horizontal distance was in media 0,1665µ and the vertical 0,1378µ in the adult group with a media of 4,5 isle of smooth muscle fibers, in the child male group the horizontal distance was 0,135µ, the vertical 0,190µ and the isle, 5,35. In the child female group, the horizontal distance was 0,052µ, the vertical 0,037µ and the median number of isles, 4,75.

CONCLUSION: The majority of smooth muscles fibers would be proper of the hernial sac independent of the smooth muscles fibers of the blood vessels.

Key words: Hernia, inguinal. Histology. Muscle, smooth. Muscle fibers.

INTRODUCTION

Inguinal hernias will always be a subject of study and a reason for the enhancement of surgical techniques. It is estimated that 10% of the hernia operations performed each year are aimed at repairing recurrent hernias. Approximately 40% to 50% of recurrences take place in the first postoperative year, which implies faulty technique or repair method¹.

In the surgical management of inguinal hernias, there were numerous attempts at reinforcement over the centuries up to contemporary times, when synthetic prostheses appeared. They afford the benefit of reinforcement, but are foreign bodies and, as such, give rise to rejection and extrusion problems once in a while².

In an attempt to reconcile the need to prevent rejection – a common occurrence with synthetic prostheses – with producing a satisfactory reinforcement, trials and research studies have been undertaken over the last decades on the use of analogenous hernial sacs. Within that line of research, smooth muscle fibers were histologically detected in the hernial sac. It is well-know that those fibers cannot possibly originate from contamination of abdominal smooth muscle. Their origin has not yet been elucidated. Could it be by cell differentiation? Stem cells? Originated in the vascular endothelium? Migrated from smooth muscle along the testicular descent process? Many are the questions that, once correctly responded, could lead to a closer understanding of hernial pathophysiology.

A number of materials have been developed, for instance, for the reinforcement of the abdominal wall in hernia repair surgery in adults, such as artificial meshes, and there are studies using the hernial sac itself for reinforcement of that region^1,3.

Long overlooked⁴, this peritoneal sac produced by the protrusion of organs from the interior of the abdomen is now the object of studies whose aim is to identify the structures that can be found therein, especially the vasculature and its relation to smooth muscle fibers^5-7.

The objective of this study was to conduct a histological analysis and assess the distance between the smooth muscle fibers and the vascular component occurring in the hernial sacs of direct, indirect and recurrent inguinal hernias, in different age ranges and in both sexes.

METHODS

The study was approved by the Research Ethics Committee of the Universidade Federal de Juiz de Fora, as were the data collection and the research work.

The patients were operated on at the Hospital Municipal Dr. Mozart Geraldo Teixeira, Juiz de Fora, MG, Brazil. Two hundred-fifty operations for the repair of direct, indirect and recurrent inguinal hernias were performed on children from two months to 12 years of age, and adults over 12 years to 75 years of age, in the period from July 2002 through February 2003. The hernia specimens were submitted for histological examination.

The sacs from the indirect hernias were removed entirely.. Regarding the direct hernias, it was decided to remove part of the neck of the sac in view of the surgical technique used. The specimens were excised and submitted for anatomopathological study, fixed in 10% formalin, and histopathological examination was undertaken using the hematoxylin-eosin and Gomori Trichrome staining techniques.

The patients who were found to have no hernial sac, due to their anatomy or hernia type, were excluded from the study.

From the 184 patients with hernial sacs, 90 were randomly chosen for the study and distributed thus: 30 male children, 30 female children and 30 male adults. The distance was measured from islands of muscle to an artery that was selected based on its size. For each specimen, an artery of similar caliber was sought, subsequently centered in the field of view, and the existing vessels and islands were then histologically counted. The distance between that artery and the islands of smooth muscle fibers was measured, and in most cases no relation was found between them .

With regard to the statistical analysis, Spearman's and Pearson's methods were chosen since the distribution of the data was not symmetric.

RESULTS

The presence of blood vessels in the specimens was significant: in the adult group, vessels were found in all fields, with a mean of 11 vessels per field; in the male child group, 10.5; and the mean was 10.8 for the number of vessels in the female child group.

When fibers of smooth muscle were observed in the adult group, the mean horizontal distance from the selected vessel to the island of fibers was 0.1665 µ, while the mean vertical distance was 0.1378 µ. The mean number of islands of those fibers was 4.5 per field, while the mean number of vessels was 10.83.

In the male child group, the mean horizontal distance from the vessel to the island of smooth muscle fibers was 0.135 µ, and the vertical distance was 0.190 µ. A mean of 5.35 islands per field was found, while the mean number of vessels was 10.5.

Regarding the female child group, the mean horizontal distance was 0.052 µ, the mean vertical distance, 0.037 µ, the mean number of vessels was 10.8 and a mean of 4.75 islands was found.

Through statistical analysis, it was found that some correlations were significant (P<0.05), while others were not. However, all signaled a positive correlation: as the distance from the vessel increases, the number of islands tends to increase as well. Spearman's correlation coefficient test was more sensitive in this case, since those variables did not exhibit a normal distribution (Tables 1 and 2).

DISCUSSION

The purpose of demonstrating the distance relationship between the smooth muscle tissue and the vasculature is part of a line of research started in 1971 by Lázaro da Silva⁸ from the histological study of hernial sacs with the aim of identifying their components. Since that time, the following have been identified: fibrous tissue³, loose and dense connective tissue, collagen fibers types I and II (reticular and elastic), adipose tissue, fibroblasts, myofibroblasts, mesothelium and smooth muscle^7,9-11.

The detection of smooth muscle fibers was incidental and, since it was a new finding, not reported in the literature, elicited questions that are being answered throughout the various studies that constitute the research¹².

Tanyel¹³ hypothesized on the role of those fibers in the tissue, postulating that it was the increase in hernial sac resistance, since it exhibits poor elasticity. The origin of the smooth muscle fibers was another question. Were they dependent on the musculature of the vessel, given their proximity? How to explain the islands of fibers that lie away from vessels or even their abundance in regions with less vascularization? Could the origin of those muscles be through myogenesis or by muscle satellitosis originated in the vascular smooth muscle fibers? Pucci¹⁴, in 1986, suggested the occurrence of muscle neogenesis.

In 2000, Barbosa analyzed the presence of those fibers in the hernial sac of adults and children and found that there was no significant difference concerning the site of biopsy in the sac – proximal, medial or longitudinal to the internal inguinal ring –, and he also demonstrated that the difference between men and women or adults and children was not important⁶. In the present study, there was no significant difference between groups either.

In the present study, it was observed that most islands found in the fields examined were isolated from the smooth muscle fibers of the arterial vessel. Furthermore, it was found that there are fields with plenty of vessels without smooth muscle fibers, as opposed to fields where various islands can be seen, yet few vessels. Therefore, the fibers were found to be proper to the hernial sac, independent of the vessel.

Another question arises: one might wonder if the good outcome of using hernial sacs in the reinforcement of hernias is due to the presence of fibers of smooth muscle providing elasticity and tensile strength to the hernial sac.

In summary, the presence of fibers of smooth muscle in the hernial sac was proper to the peritoneal tissue, unrelated to the vessels.

REFERENCES

• 1. Silva AL. Hérnias da parede Abdominal. Rio de Janeiro: Atheneu, V. 1, 1997.
• 2. Netto AC. Clínica cirúrgica. 4Ş ed. São Paulo: Sarvier; 1994.
• 3. Escalante JR, Diogo Filho A, Andrade JI. Tratamento de hérnias incisionais volumosas pela técnica de Alcino Lázaro da Silva. Rev Col Bras Cir. 1983; 10(1):24-8.
• 4. Miller GG, McDonald SE, Milbrandt K, Chibbar R. Routine pathological evaluation of tissue from inguinal hernias in children is unnecessary. Can J Surg. 2003; 46(2):117-9.
• 5. Adriani AC. Avaliação histológica do saco herniário de hérnias inguinais [dissertação]. Florianópolis (SC): Universidade Federal de Santa Catarina; 2000.
• 6. Barbosa CA. Histopatologia do saco herniário da hérnia inguinal indireta e do peritônio parietal em adultos e crianças, estudo qualitativo da sua musculatura lisa [dissertação]. Belo Horizonte (MG): Universidade Federal Minas Gerais.
• 7. Barbosa CA, Amaral VF, Lázaro da Silva A. histopatologia do saco herniário da hérnia inguinal indireta e do peritônio parietal em adultos e crianças: estudo qualitativo da sua musculatura. Rev Col Bras Cir. 2000; 27(4):183-8.
• 8. Lázaro da Silva A. Plástica com saco herniário na correção das hérnias incisionais. Hospital. 1971; 79(1):129-34.
• 9. Ross MH, Reith EJ, Romrell LJ. Tecido conjuntivo. In: Histologia: texto e atlas. 2Ş ed. São Paulo: Panamericana; 1993. p. 85-115.
• 10. Faria LP, Lázaro da Silva A, Rocha A. Hérnias incisionais medianas e paramedianas: estudo do saco herniário à microscopia óptica (mesotélio, tecido conjuntivo frouxo e denso com presença de fibras colágenas, reticulares e elásticas). Rev Col Bras Cir. 1996; 23(4):187-91.
• 11. Lázaro da Silva A, Brasileiro Filho G, Ferreira AP. Patologia do saco herniário. In: Lázaro da Silva A. Hérnias. 1Ş ed. São Paulo: Roca; 1992. p. 1226-040.
• 12. Lázaro da Silva A. Pesquisa em hérnia. Rev Col Bras Cir. 1989; 16(4):191.
• 13. Tanyel FC, Müftüoglu S, Dagdeviren A, Kaymaz FF, Büyükpamukcu N. Myofibroblasts defined by electron microscopy suggest the dedifferentiation of smooth muscle within the sac walls associated with congenital inguinal hernia. BJU Int. 2001; 87(3):251-5.
• 14. Pucci JA. El uso del saco herniário autógeno como refuerzo en la plástica de hérnias inguinales. Cien Med. 1986;1(1):35-42.

Publication Dates

• Publication in this collection
  09 Nov 2009
• Date of issue
  Aug 2009

History

• Accepted
  17 Jan 2009
• Received
  23 Oct 2008