Simulation and study of the geometric parameters in the inguinal area and the genesis of inguinal hernias

We are interested in studying the genesis of a very common pathology: the human inguinal hernia. How the human inguinal hernia appears is not definitively clear, but it is accepted that it is caused by a combination of mechanical and biochemical alterations, and that muscular simulation plays an important role in this. This study proposes a model to explain how some physical parameters affect the ability to simulate the region dynamically and how these parameters are involved in generating inguinal hernias. We are particularly interested in understanding the mechanical alterations in the inguinal region because little is known about them or how they behave dynamically. Our model corroborates the most important theories regarding the generation of inguinal hernias and is an initial approach to numerically evaluating this affection.     

Simulation and study of the behaviour of the transversalis fascia in protecting against the genesis of inguinal hernias

Simulating the muscular system has many applications in biomechanics, biomedicine and the study of movement in general. We are interested in studying the genesis of a very common pathology: human inguinal hernia. We study the effects that some biomechanical parameters have on the dynamic simulation of the region, and their involvement in the genesis of inguinal hernias. We use the finite element method (FEM) and current models for the muscular contraction to determine the deformed fascia transversalis for the estimation of the maximum strain. We analysed the effect of muscular tissue density, Young's modulus, Poisson's coefficient and calcium concentration in the genesis of human inguinal hernia. The results are the estimated maximum strain in our simulations, has a close correlation with experimental data and the accepted commonly models by the medical community. Our model is the first study of the effect of various biological parameters with repercussions on the genesis of the inguinal hernias.     

Sliding indirect inguinal hernia

From 2 per cent to 5 per cent of all indirect inguinal hernias are of the sliding variety. (Sliding hernias are those in which part of the wall of the sac is formed by a viscus.) The proportion of sliding hernias is even higher in the aged. Hernias of this kind are found almost exclusively in males and usually on the left side. Preoperative diagnosis is not essential if the surgeon can recognize the lesion at operation and knows how to repair it properly. The LaRoque technique in which the peritoneal cavity is entered above the internal ring allows accurate definition of the pathological anatomy and effective repair of the hernia. It should be used in all true sliding indirect inguinal hernias.     

Peritoneal fine structure of inguinal hernia: a scanning electron microscope study

Mesothelial cells of the normal human peritoneum of the anterior abdominal wall are covered with numerous surface microvilli. These cells become partially denuded inside the sacs of direct and indirect inguinal hernias and so lose the protective property the microvillar covering may impart on them. These mesothelial cells of hernial sacs also acquire an extensive surface coat of fibrin-like material, presumably due to the loss of that protective property, which may as a result subject them to adhesions. There is a considerable collagen build-up in the subserosal fibrous tissue of sacs of both direct and indirect inguinal hernias. Such a build-up is at variance with the accepted current surgical concept which suggests a defect in collagen synthesis, rather than a build-up, as the cause of direct hernia.     

Comparison of the plasma and hernia sac tissue copper levels in direct and indirect inguinal hernia patients

Although the inguinal hernia is among the most commonly encountered and well-described health problems all over the world, the etiology is still controversial. The aim of this study was to compare the plasma and hernia sac tissue copper levels in direct and indirect inguinal hernia patients. Plasma and hernia sac tissue copper levels obtained from patients operated under spinal anesthesia with primary direct (group I, n = 55, 45 male, mean age = 45.68 yr) and indirect (group II, n = 55, 40 male, mean age = 38.57 yr) hernias were detected by atomic absorption spectrophotometer. Significantly lower plasma and hernia sac tissue copper levels were detected in group I in comparison to group II (p < 0.001). Both plasma and hernia sac tissue copper levels were significantly lower in males when we compare the patients according to their sex characteristics, including both direct and indirect hernia groups (p < 0.05 and p < 0.01, respectively). Age was not a significant factor. The plasma and hernia sac tissue copper levels were significantly lower in direct hernia patients in comparison to indirect hernia patients. Copper is a cofactor of lysyl oxidase, an important enzyme in collagen tissue metabolism, so there might be a defect in the collagen synthesis of direct hernia patients because of the decreased activity of the lysyl oxidase. Further investigations are necessary to clarify this concept.     

The surgical repair of inguinal and femoral hernias

This paper is based on 15,000 hernia repairs performed by the author at the Shouldice Hospital, Toronto. Experience with more than 75,000 consecutive herniorrhaphies performed in this hospital from 1945 to 1970 is reviewed in four parts — statistics, including recurrence rates; the management of the patient with a primary uncomplicated hernia, emphasizing in particular the preoperative phase, the sedation given, the local anesthetic used in 95% of cases and the postoperative phase; the technique of repair of a primary inguinal hernia; and a review of experience with primary and recurrent femoral hernias, emphasizing the different problems in men and women, and describing the technique of femoral repair.     

Bilateral Hernias in the Female

An experience with 216 bilateral hernias in female patients is reviewed. The condition is rare, occurring only once in every 250 patients admitted for a hernia repair. Bilateral primary indirect inguinal hernias were the most frequent type. Bilateral primary femoral hernias were quite rare while bilateral primary direct inguinal hernias were even more uncommon. Other rare bilateral combinations are briefly described. The incidence in children is given.Etiological factors are discussed, emphasizing the strong posterior wall of the inguinal canal in females.Two per cent of patients developed a recurrent hernia; one per cent of hernias recurred. No recurrence following a bilateral primary indirect inguinal hernia repair and no “femoral” recurrence following inguinal repair were recorded.     

Genital oedema in patients treated by continuous ambulatory peritoneal dialysis: an unusual presentation of inguinal hernia.

Four patients receiving continuous ambulatory peritoneal dialysis presented with scrotal or labial oedema but no detectable cough impulse. Two of the patients later developed clinical evidence of inguinal hernia, and in the other two inguinal hernias were found at operation. These cases suggest that genital oedema occurring in a patient receiving continuous ambulatory peritoneal dialysis is a sign of a small inguinal hernia which may not be detectable clinically.     

Herniography in symptomatic patients following inguinal hernia repair.

Patients with symptoms at the site of a previous inguinal hernia repair may constitute a diagnostic dilemma. The usefulness of herniography in the assessment of these patients was evaluated at 54 symptomatic sites in 46 subjects. Ten persistent or recurrent hernias were shown by herniography, only 2 of which were definitely detected on physical examination. The herniogram was normal at 44 sites, of which, on physical examination, 5 were equivocal and 1 was diagnosed as a definite hernia. On the unoperated-on or asymptomatic side, a total of 14 hernias were shown herniographically. Of these hernias, 8 were not detected on physical examination. Herniography was found to be more sensitive than physical examination in detecting hernias at the symptomatic, previously operated-on sites, as well as at the unoperated-on or asymptomatic sites. When a herniogram provides corroborative evidence that hernia has not recurred, the need for reexploration may be eliminated.     

Risk of incarceration of inguinal hernia among infants and young children awaiting elective surgery

Background

We determined the rate of incarceration of inguinal hernia among infants and young children waiting for elective surgery and examined the relation to wait times. We also explored the relation between wait times and the use of emergency department services before surgery.

Methods

We used linked data from administrative databases to identify infants and children less than 2 years of age who underwent surgical repair of an inguinal hernia between Apr. 1, 2002, and Mr. 31, 2004. We determined the rate of hernia incarceration during the wait for surgery and stratified the risk by patient age and sex. We used logistic regression analysis to examine factors associated with hernia incarceration and wait times.

Results

A total of 1065 infants and children less than 2 years old underwent surgical repair of an inguinal hernia during the study period. The median wait time was 35 days (interquartile range 17–77 days). Within 30 days after diagnosis, 126 (11.8%) of the patients had at least 1 emergency department visit; 23.8% of them presented with hernia incarceration. The overall rate of hernia incarceration was 11.9%. The rate was 5.2% with a wait time of up to 14 days (median time from diagnosis to first emergency department visit), as compared with 10.1% with a wait time of up to 35 days (median wait time to surgery) (p < 0.001). Factors associated with an increased risk of incarcerated hernia were age less than 1 year (odds ratio [OR] 2.07, 95% confidence interval [CI] 1.32–3.23), female sex (OR 1.75, 95% CI 1.04–2.93) and emergency department visits (1 visit, OR 2.73, 95% 1.65–4.50; ≥ 2 visits, OR 3.77, 95% CI 1.89–7.43). Children less than 1 year old who waited longer than 14 days had a significant 2-fold risk of incarcerated hernia (OR 1.92, 95% CI 1.11–3.32).

Interpretation

A wait time for surgery of more than 14 days was associated with a doubling of the risk of hernia incarceration among infants and young children with inguinal hernia. Our data support a recommendation that inguinal hernias in this patient population be repaired within 14 days after diagnosis.Inguinal hernias in infants and young children are a result of a failure of the processus vaginalis to close.¹ Once diagnosed, an inguinal hernia should be promptly repaired on an elective basis to prevent the risk of hernia incarceration. Incarceration occurs in about 12% of infants and young children with an inguinal hernia. The incidence is highest (approaching 30%) among infants (< 1 year old).² Boys who experience incarceration of an inguinal hernia have a 30% risk of testicular atrophy that may affect future fertility.³Many countries are struggling with long wait times for elective surgical procedures.^4–6 To date, research has been skewed toward examining wait times for surgery and other medical or diagnostic care in adults.^7–10 Prolonged wait times for surgery to repair hernias have not been associated with adverse outcomes in adults,¹¹ but the effect of prolonged wait times in children has not been well studied.^1,12We conducted this study to examine the relation between wait times for elective surgery and the risk of incarceration of inguinal hernia in infants and young children. We also explored the relation between wait times and the use of emergency department services before surgery.     

The large inguinal ring: its significance in the diagnosis of inguinal hernia

A large external inguinal ring is often reported by a medical examiner as a "potential hernia." This finding may cause the subject to be denied job opportunities and may make him apprehensive about many normal activities. The author believes that unless a sac is present and is causing symptoms that necessitate surgical relief, the term hernia should not be used, regardless of how it is qualified. The ordinary intraabdominal stresses due to coughing, sneezing, etc. increase intraabdominal tension more than heavy lifting, except with loads of nearly the body's own weight. The lifetime effect of such stresses can contribute to the development of a direct hernia, but most of these cannot be eliminated.     

Genetic analysis of the TBX1 gene promoter in indirect inguinal hernia

Inguinal hernia is a common disease, most cases of which are indirect inguinal hernia (IIH). Genetic factors play an important role for inguinal hernia. Increased incidences of inguinal hernia have been reported in patients with 22q11.2 microdeletion syndrome, which is mainly caused by TBX1 gene mutations. Thus, we hypothesized that altered TBX1 gene expression may contribute to IIH development. In this study, the human TBX1 gene promoter was genetically analyzed in children with IIH (n = 100) and ethnic-matched controls (n = 167). Functions of DNA sequence variants (DSVs) within the TBX1 gene promoter were examined in cultured human fibroblast cells. The results showed that two heterozygous DSVs were found, both of which were single nucleotide polymorphisms. One DSV, g.4248 C>T (rs41298629), was identified in a 2-year-old boy with right-sided IIH, but not in all controls, which significantly decreased TBX1 gene promoter activity. Another DSV, g.4199 C>T (rs41260844), was found in both IIH patients and controls with similar frequencies (P > 0.05), which did not affect TBX1 gene promoter activity. Collectively, our data suggested that the DSV within the TBX1 gene promoter may change TBX1 level, contributing to IIH development as a rare risk factor. Underlying molecular mechanisms need to be established.     

Genome-wide association study using deregressed breeding values for cryptorchidism and scrotal/inguinal hernia in two pig lines

Background

Cryptorchidism and scrotal/inguinal hernia are the most frequent congenital defects in pigs. Identification of genomic regions that control these congenital defects is of great interest to breeding programs, both from an animal welfare point of view as well as for economic reasons. The aim of this genome-wide association study (GWAS) was to identify single nucleotide polymorphisms (SNPs) that are strongly associated with these congenital defects. Genotypes were available for 2570 Large White (LW) and 2272 Landrace (LR) pigs. Breeding values were estimated based on 1 359 765 purebred and crossbred male offspring, using a binary trait animal model. Estimated breeding values were deregressed (DEBV) and taken as the response variable in the GWAS.

Results

Heritability estimates were equal to 0.26 ± 0.02 for cryptorchidism and to 0.31 ± 0.01 for scrotal/inguinal hernia. Seven and 31 distinct QTL regions were associated with cryptorchidism in the LW and LR datasets, respectively. The top SNP per region explained between 0.96% and 1.10% and between 0.48% and 2.77% of the total variance of cryptorchidism incidence in the LW and LR populations, respectively. Five distinct QTL regions associated with scrotal/inguinal hernia were detected in both LW and LR datasets. The top SNP per region explained between 1.22% and 1.60% and between 1.15% and 1.46% of the total variance of scrotal/inguinal hernia incidence in the LW and LR populations, respectively. For each trait, we identified one overlapping region between the LW and LR datasets, i.e. a region on SSC8 (Sus scrofa chromosome) between 65 and 73 Mb for cryptorchidism and a region on SSC13 between 34 and 37 Mb for scrotal/inguinal hernia.

Conclusions

The use of DEBV in combination with a binary trait model was a powerful approach to detect regions associated with difficult traits such as cryptorchidism and scrotal/inguinal hernia that have a low incidence and for which affected animals are generally not available for genotyping. Several novel QTL regions were detected for cryptorchidism and scrotal/inguinal hernia, and for several previously known QTL regions, the confidence interval was narrowed down.

Electronic supplementary material

The online version of this article (doi:10.1186/s12711-015-0096-6) contains supplementary material, which is available to authorized users.     

How accurately can direct and indirect inguinal hernias be distinguished?

An inguinal hernia was clinically diagnosed as direct or indirect by paired surgeons of 134 occasions. When compared with the findings at operation the hernia was correctly diagnosed in 60 of 78 observations when it was indirect and in 33 of 56 when it was direct. The level of accuracy does not warrant continuing the practice of attempting to distinguish one type of inguinal hernia from another.     

High Incidence of Scrotal Hernias in a Closed Colony of FVB Mice

Although inguinal hernias are rarely reported to occur in mice, a high incidence of scrotal hernias was observed in a closed breeding colony of FVB/N mice. Unilateral or bilateral hernias occurred in more than 20% of the male mice in the colony that were available for necropsy over 3 inbred and 1 outcross generations; no female mice were affected. Organs commonly present within the hernial sac included the cecum and seminal vesicles. Hernias did not adversely affect the fertility or lifespan of the affected male mice. Although the condition was heritable, no clear pattern of transmission was evident.During development, the testes descend from the abdominal cavity through the inguinal canal and into the scrotum, guided by the processus vaginalis. In primates and carnivores, the processus vaginalis is largely or entirely obliterated during late gestation.¹³ When correct closure fails to occur, a hernial sac may travel through the deep inguinal ring to create an inguinal hernia.¹⁶ Protrusion of a hernial sac containing abdominal organs into the scrotum results in scrotal hernia, a severe and potentially dangerous form of inguinal hernia. In rodents, the inguinal canal is very short and the processus vaginalis remains patent throughout life, allowing the testes to pass freely between the scrotum and abdomen.¹³ Despite this potential pathway for herniation of abdominal organs, scrotal hernias have rarely been reported to occur in laboratory mice.Spontaneous inguinal hernias have rarely been reported in either male or female mice. Inguinal hernias occur in intact but not castrated male mice treated with estrogenic compounds and in intact female mice treated with testosterone or bearing testicular grafts.^1,2,10 Both male and female C57BL/6 mice that fail to express fibulin 3 develop multiple large hernias, including inguinal hernias.¹⁴ In these mice, herniation occurs at the myopectineal orifice, through the external inguinal ring. Female mice transgenic for insulin-like factor 3 develop inguinal hernias with 100% penetrance.¹¹ A recent report described a high incidence of lateral femoral hernias in an inbred colony of FVB/NHsd mice; the condition predominantly affected female mice.¹⁵ This phenomenon was attributed to genetic drift in a closed colony. We now report on another situation in which many hernias were noted in inbred FVB/N mice. In the present case, scrotal hernias occurred in a high proportion of FVB/N mice maintained in a closed breeding colony.     

The long-term effect of mesh bioprosthesis in inguinal hernia repair on testicular nitric oxide metabolism and apoptosis in rat testis

Polypropylene mesh is the most widely used material in inguinal hernia repair. Although polypropylene mesh is known as an inert material, it is experimentally proven that mesh generates a chronic inflammatory tissue reaction. The aim of the present study was to investigate the long-term effects of polypropylene mesh material used in inguinal hernia operations on testicular function, testicular nitric oxide (NO) metabolism and germ cell-specific apoptosis in rats. The study comprised 40 male rats that were randomly allocated into two groups. In group 1, the left spermatic cord was elevated and a 0.5 x 1 cm polypropylene mesh was placed behind the left inguinal spermatic cord and group 2 consisted of the sham-operated controls. Blood samples were taken at 6 months preoperatively and postoperatively after to assess luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels for hormonal evaluation. Testicular NO was evaluated by the Griess method, apoptosis by a TUNEL method and inducible nitric oxide synthase (iNOS) and endothelial NOS (eNOS) expressions by immunohistochemical staining. Mild (+) eNOS expression was observed in all specimens. Mild (+) iNOS expression was only detected in ipsilateral testis of the mesh-implanted study group. Apoptotic cells were not detected in any samples. We are of the opinion that long-term polypropylene mesh implantation has no effect on testicular hormonal function and only a limited effect on nitric oxide levels and this effect is not sufficient to cause apoptosis in testis that could lead to infertility. It seems that mesh implantation is a reliable method in inguinal hernia repair; however, further work is required by more sensitive methods to fully elucidate the potential testicular damage.     

Marlex? Mesh in Incisional and Inguinal Herniorrhaphy

Marlex® mesh was used in 31 cases of inguinal herniorrhaphy and in 15 cases incisional herniorrhaphy in a five-year period. In 14 of the inguinal and six of the incisional cases the hernias were recurrent. Marlex® mesh was used in one case to reenforce the transthoracic repair of eventration of the diaphragm, and in another to reenforce the transthoracic repair of an esophageal hiatal hernia.There were no recurrences. In one case after inguinal herniorrhaphy the mesh was removed because of persistent drainage. Wound infections occurred in two patients with incisional herniorrhaphy, and two others had the accumulation of serous fluid subcutaneously necessitating aspiration of fluid.     

Antimicrobial resistance of Escherichia coli isolates from broiler chickens and humans

Background

Inguinal hernias are usually caused by a congenital defect, which occurs as a weakness of the inguinal canal. Porcine β-glucuronidase gene (GUSB) was chosen as functional candidate gene because of its involvement in degradation of hyaluronan within gubernacular tissue during descent of testes. Since a genome-wide linkage analysis approach has shown evidence that two regions on porcine chromosome 3 (SSC 3) are involved in the inheritance of hernia inguinalis/scrotalis in German pig breeds, GUSB also attained status as a positional candidate gene by its localization within a hernia-associated chromosomal region.

Results

A contig spanning 17,157 bp, which contains the entire GUSB, was assembled. Comparative sequence analyses were conducted for the GUSB gene locus. Single nucleotide polymorphisms (SNPs) located within the coding region of GUSB were genotyped in 512 animals. Results of transmission disequilibrium test (TDT) for two out of a total of five detected SNPs gave no significant association with the outcome of hernia in pigs.

Conclusion

On the basis of our studies we are able to exclude the two analyzed SNPs within the porcine GUSB gene as causative for the transmission of inguinal hernia.     

Outpatient Adult Inguinal Hernia Repair

Repair of adult inguinal hernia has been done on an outpatient basis at our surgical facility for the past six years. In 616 consecutive repairs, complications have been remarkably few: one patient was electively admitted to hospital, two hernias have recurred and one patient needed to be catheterized. Patient acceptance has been enthusiastic.