Morphometric analysis of inguinal canals and rings of human fetus and adult corpses and its relation with inguinal hernias

Abstracts

OBJECTIVE: To evaluate the anatomical differences of fetus and adults concerning the inguinal region of male gender, as well as the presence of possible morphological basis for the higher incidence of inguinal hernias in the right side in both groups. METHODS: Twenty human stillborn fetuses and twenty in natura adult male corpses were dissected in order to compare the length of the inguinal canals, the longer diameter of the deep and superficial inguinal rings in both sides of each corpse, and the presence or not of overlap between the deep and superficial rings. RESULTS: No statistically significant differences were observed in both groups regarding the measures of the deep and the superficial rings, as well as the inguinal canals, when in comparison to the respective contralateral anatomical structures of each specimen. Nevertheless, there was a statistically significant difference between the diameter of homolateral inguinal rings, once the superficial ring was longer than the deep ring in fetus (p=0.0002) and adult corpses (p<0.0001). The ratio inguinal canal/height showed to be statistically different between both groups (p<0.0001), since the inguinal canal in fetus is shorter than in adults. It was also observed overlapping of homolateral superficial and deeper inguinal rings in two fetuses, but none in adults. CONCLUSION: Morphometric analysis of the inguinal canals and rings does not justify the higher incidence of hernias in the right side in the male gender.

Inguinal canal; Inguinal hernia; Regional anatomy; Fetus

OBJETIVO: Avaliar as diferenças anatômicas na região inguinal de fetos e adultos do gênero masculino, assim como a existência de uma possível base morfológica para a maior incidência de hérnias inguinais à direita em crianças e adultos. MÉTODOS: Foram dissecados 20 fetos natimortos e 20 cadáveres humanos adultos in natura, todos do gênero masculino, comparando-se o comprimento do canal inguinal, o maior diâmetro dos anéis inguinais superficial e profundo em ambos os lados de cada cadáver e a existência ou não de superposição entre os anéis superficial e profundo. RESULTADOS: Não foram observadas, nos dois grupos, diferenças significativas na comparação das medidas dos anéis profundos e superficiais, assim como dos canais inguinais, com seus respectivos contralaterais em cada espécime. Entretanto, houve diferença significativa entre os diâmetros dos anéis inguinais homolaterais, sendo o anel superficial maior do que o profundo nos fetos (p = 0,0002) e nos cadáveres adultos (p < 0,0001). A razão canal inguinal/altura mostrou diferença significativa entre os grupos (p<0,0001), evidenciando que o canal inguinal em fetos é relativamente mais curto que em adultos. Foi observada, também, superposição dos anéis inguinais superficial e profundo ipsilaterais em dois fetos, porém não houve em nenhum dos adultos. CONCLUSÃO: A morfometria dos canais e anéis inguinais não justifica a maior incidência de hérnia do lado direito no gênero masculino.

Canal Inguinal; Hérnia inguinal; Anatomia Regional; Feto

ORIGINAL ARTICLE

Morphometric analysis of inguinal canals and rings of human fetus and adult corpses and its relation with inguinal hernias

Carlos Manoel de Oliveira Figueiredo^I; Sônia Oliveira Lima^II; Sebastião Duarte Xavier Júnior^III; Caroline Baptista da Silva^IV

^IMedical student, Universidade Federal de Sergipe, SE, Brazil

^IIPhD, Coordinator, Discipline of Clinical Surgery, Department of Medicine, Universidade Federal de Sergipe, SE, Brazil

^IIIPediatric surgeon, Hospital Universitário de Sergipe, SE, Brazil

^IVMedical student, Universidade Federal de Sergipe, SE, Brazil

Correspondence address

ABSTRACT

OBJETIVE: To evaluate the anatomical differences of fetus and adults concerning the inguinal region of male gender, as well as the presence of possible morphological basis for the higher incidence of inguinal hernias in the right side in both groups.

METHODS: Twenty human stillborn fetuses and twenty in natura adult male corpses were dissected in order to compare the length of the inguinal canals, the longer diameter of the deep and superficial inguinal rings in both sides of each corpse, and the presence or not of overlap between the deep and superficial rings.

RESULTS: No statistically significant differences were observed in both groups regarding the measures of the deep and the superficial rings, as well as the inguinal canals, when in comparison to the respective contralateral anatomical structures of each specimen. Nevertheless, there was a statistically significant difference between the diameter of homolateral inguinal rings, once the superficial ring was longer than the deep ring in fetus (p=0.0002) and adult corpses (p<0.0001). The ratio inguinal canal/height showed to be statistically different between both groups (p<0.0001), since the inguinal canal in fetus is shorter than in adults. It was also observed overlapping of homolateral superficial and deeper inguinal rings in two fetuses, but none in adults.

CONCLUSION: Morphometric analysis of the inguinal canals and rings does not justify the higher incidence of hernias in the right side in the male gender.

Key words: Inguinal canal. Inguinal hernia. Regional anatomy. Fetus.

INTRODUCTION

Annually, 20 million inguinal hernias are operated worldwide, which represents a large proportion of the interventions in general surgery¹. This condition is more frequent in males of all age groups, and occurs more commonly on the right side^2-4. Even though several techniques have been described for the treatment of inguinal hernias⁵, they still represent a permanent surgical challenge^6,7.

Congenital inguinal hernias affect approximately 1% to 3% of the general population. They are considered the most frequent surgical condition in children of all ages, the indirect type being the most common^7-10. Inguinal hernia repair is one of the procedures most frequently performed by the pediatric surgeon¹¹.

In the present study, the measurements of the anatomical structures (morphometry) of the inguinal canals and rings of human stillborn fetuses and adult cadavers of the male gender were analyzed, and comparisons were made between groups. The objectives of this study were to investigate a possible anatomical basis for the greater incidence of right inguinal hernias in male children and adults, as well as to establish a correlation with the surgical techniques via inguinal herniotomy used for the treatment of those hernias in both groups.

METHODS

The study used 20 human stillborn fetuses preserved in 10% formalin obtained from the Human Anatomy laboratories of the Universidade Federal de Sergipe and Universidade Tiradentes, Aracaju, SE, Brazil, with a gestational age over 30 weeks, and 20 fresh adult cadavers obtained from the Instituto Médico Legal (Forensic Medicine Institute) of Sergipe. The groups were of the male gender and no disease existed in the inguinal region.

Length (height) and age were recorded for both groups. Gestational age was estimated by Capurro's somatic method¹². For the adults, the age was recorded based on the identity cards, or, if lacking, on the coroner's estimate.

On dissection, the length of the inguinal canal and the greater diameter of the superficial and the deep inguinal ring on both sides of each cadaver were measured with the aid of a 5X loupe and a caliper. The length of the inguinal canal was defined as the distance between the superficial and the deep inguinal rings. The existence of overlapping between the superficial and the deep inguinal ring on each side of all specimens was investigated. Overlapping occurred when the distance between the vertical axes (parallel to the midline) of the rings was equal or inferior to 1 millimeter.

Means and standard deviations were calculated for all height measurements and the results were statistically analyzed through Student's t-test at the level of significance of p<0.05. The inguinal rings were compared unilaterally (the superficial with the deep ring) and bilaterally (each ring with its contralateral homologous structure) in all studied specimens. The inguinal canal was compared with its contralateral homologous structure and the quotient "mean of inguinal canal length (right and left)/height" was calculated for each specimen. The results of that ratio were compared between the groups.

The present study was approved by the Research Ethics Committee of the Universidade Federal de Sergipe under protocol 072/2003.

RESULTS

The mean gestational age of the stillborn fetuses (group 1) was 36.9 weeks (range, 30.6-42.6 weeks) and the mean length was 42.5 cm (range, 30.0-55.5 cm). In the adult cadavers (group 2), age ranged from 18 to 68 years (mean, 35.1 years) and length (height), from 1.60 m to 1.78 m (mean, 1.70 m).

No significant differences were found in either group when the deep and superficial ring measures, or the inguinal canal measures, were compared with those of their respective contralateral structures in each specimen. However, there was a significant difference between the diameters of the homolateral inguinal rings, as the superficial ring was wider than the deep ring in the fetuses (p = 0.0002) and in the adult cadavers (p < 0.0001) (tables 1 and 2).

Overlapping of the superficial and deep inguinal rings was found in two fetuses (7.5%). In one of them, overlapping was bilateral, while in the other fetus it only occurred on the right side. No such overlapping was found in any of the adult cadavers.

The ratio inguinal canal/height showed a significant difference between groups 1 and 2 (p<0.0001), an evidence that the inguinal canal is relatively shorter in fetuses than in adults.

DISCUSSION

In children, despite the fact that an inguinal hernia usually occurs because of persistent patency of the processus vaginalis², the permanence of that structure does not necessarily imply the occurrence of a congenital inguinal hernia¹³. The higher incidence of that condition on the right side could be explained, in part, by differences in the dimensions of the inguinal canals and rings between the two sides. Although no significant differences were observed in the morphometric evaluation of those structures, some anatomical particularities of the fetuses in relation to the adult cadavers were found. The former exhibited shorter inguinal canals, in addition to overlapping of the ipsilateral external and internal inguinal rings, albeit infrequent (7.5%). According to Tanyel et al.¹⁴, the inguinal canal remains short until the age of two years, when it starts to grow linearly. Those characteristics warrant the repair of inguinal hernias by inguinal herniotomy in children without opening the aponeurosis of the external oblique muscle¹⁵. In adults, the opening of that aponeurosis is a mandatory step in the surgical repair of hernias by inguinal herniotomy¹⁶.

In the two groups, the superficial ring was wider than the homolateral deep ring both on the right side and on the left. However, the inguinal canal and its rings did not differ in relation to the contralateral homologous structures for the same specimen. Save further studies, the morphometry of the inguinal canals and rings does not explain the higher incidence of right-sided hernias in males.

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Publication Dates

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

History

• Accepted
  15 Jan 2009
• Received
  10 Jan 2008