Table of Contents  

Eltayeb and Salih: Clinical differentiation between direct and indirect hernias – is it a clinical necessity or a medical dogma?

Introduction

How to differentiate clinically between direct and indirect hernias is one of the clinical skills most commonly taught in medical schools. The knowledge is passed from one medical generation to the next. The emphasis placed on the skill by surgical textbooks13 and the fact that it is frequently tested during clinical examinations at various levels confer on the skill an importance that might not be justified. We carried out a literature search for evidence on the accuracy of, and need for, such differentiation.

The search strategy was limited to the English-language literature and we searched the following databases, with the stated results:

  • PubMed: Open search. ‘Hernia, Inguinal/diagnosis’ [Mesh] AND (English [Lang] AND jsubsetaim[text]). A total of 325 articles were retrieved.

  • MEDLINE: Open search. Direct Inguinal Hernia and Indirect Inguinal Hernia limit to (English language and ‘core clinical journals (aim)’). A total of 86 articles were retrieved.

  • MEDLINE 1966-10/03 using the OVID interface. [exp electric injuries OR exp burns, electric injuries.mp OR electrocution.mp] AND [exp monitoring, physiologic OR monitoring.mp]. Search retrieved 102 papers, of which 96 were irrelevant.

Only 27 of all articles retrieved were relevant and were examined in detail. The remainder were about various diagnostic tools or therapeutic approaches.

Discussion

A number of clinical tests to differentiate between direct and indirect inguinal hernias have been taught and practised for decades.13 Surprisingly, it is only in recent decades that some authors have questioned the accuracy and value of these tests in clinical practice.412 Ralphs et al.4 and Cameron5 were the first to challenge the accuracy of such clinical tests. American textbooks,12 in contrast to British textbooks,13 have pointed to the equivocal value of such differentiation.

Although physical examination has been shown to be more accurate in diagnosing indirect inguinal hernia than direct hernia, the combined accuracy is around 70%,4,6,14 although Moreno-Egea et al.9 reported an accuracy of 85%. This led to the use of modern diagnostic radiological tools [e.g. ultrasound, colour duplex scanning (CDS), computerized axial tomography (CAT) and magnetic resonance imaging] to examine diagnostic accuracy.68,11,1517 Djuric-Stefnovic et al.7 reported that ultrasound showed an accuracy of 96% in determining the type of inguinal hernia while Truong et al.18 reported a sensitivity of 82.3% and specificity of 98.9%. The use of CDS was found to improve the diagnostic accuracy with a sensitivity of 90% and specificity of 86%.6

Subsequently, CAT, claimed to be the best available diagnostic radiological tool despite certain limitations, was used.19,20 Various techniques have been used in order to decrease these limitations, and improve diagnostic accuracy, for example changing position,2123 performing a Valsalva manoeuvre22 and use of the relation of the hernia to the pubic tubercle.17,24,25

From the results from all the above clinical and radiological diagnostic tests it becomes evident that all of them have limitations. Therefore, to move forward, it is logical to ask why we need to differentiate between inguinal hernias. The answer comes from guidelines (e.g. RCSE 1993) and studies that show direct hernias to be less likely to strangulate, therefore permitting a more liberal approach to conservative treatment.6,26

It follows that, if a conservative approach is not to be entertained, then attempts at differentiation will be of no clinical value, as both types require the same operation. However, in the current era of laparoscopic surgery some surgeons have renewed interest in differentiating inguinal hernias as they claim that indirect hernias are more difficult to treat laparoscopically, consequently, requiring more laparoscopic expertise.9,16

Conclusion

It is clear from the above that it is not always necessary to differentiate between inguinal hernias. If the need for such differentiation arises, then physical examination is not accurate. In this case, CAT or ultrasound, which is more widely available, could be used to improve diagnostic accuracy.8,15,27 Clinical differentiation of inguinal hernias may continue to be of limited academic value for teaching applied anatomy to undergraduate medical students but other than that it is more of a medical dogma than a clinical necessity.

Acknowledgement

The author is indebted to Miss Marilyn Basilica for typing the manuscript.

References

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2. 

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Cameron A. Accuracy of clinical diagnosis of direct and indirect inguinal hernia. Br J Surg 1994; 81:250. http://dx.doi.org/10.1002/bjs.1800810231

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Cherian P, Parnell A. The diagnosis and classification of inguinal and femoral hernia on multisection spiral CT. Clin Radiol 2008; 63:184–192. http://dx.doi.org/10.1016/j.crad.2007.07.018

18. 

Truong SN, Pfingsten F, Dreuw B, Schumpelick V. Value of ultrasound in the diagnosis of undetermined findings in the abdominal wall and inguinal region. Inguinal Hernia Repair/Expert Meeting on Hernia Surgery, 1994, St Moritz, Switzerland, pp. 29–41.

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Højer A, Rygaard H, Jess P. CT in the diagnosis of abdominal wall hernias: a preliminary study. Eur Radiol 1997; 7:1416–18. http://dx.doi.org/10.1007/s003300050309

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Miller PA, Mezwa DG, Feczko PJ, Jafri ZH, Madrazo BL. Imaging of abdominal hernias. Radiographics 1995; 15:333–47. http://dx.doi.org/10.1148/radiographics.15.2.7761639

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Markos V, Brown E. CT herniography in the diagnosis of occult groin hernias. Clin Radiol 2005; 60:251–6. http://dx.doi.org/10.1016/j.crad.2004.02.013

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Suzuki S, Furui S, Okinaga K, Sakamoto T, Murata J, Furukawa A, Ohnaka Y. Differentiation of femoral versus inguinal hernia: CT findings. Am J Roentgenol 2007; 189:W78–83. http://dx.doi.org/10.2214/AJR.07.2085

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Delabrousse E, Michalakis D, Sarliève P, Paratte B, Rodière E, Kastler B. Value of the pubic tubercle as a CT reference point in groin hernias. J Radiol 2005; 86(6–C1):651–4.

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Kettlewell M. Lumps in the groin and scrotum. Br J Hosp Med 1973; 9:724–30.

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Burkhardt JH, Arshanskiy Y, Munson JL, Scholz FJ. Diagnosis of inguinal region hernias with axial CT: the lateral crescent sign and other key findings. Radiographics 2011; 31:E1–12. http://dx.doi.org/10.1148/rg.312105129




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