Comparison of direct and indirect inguinal hernia

The differentiation of a direct from indirect inguinal hernia is not vital; management is similar for both.

A direct inguinal hernia protrudes directly forwards when the patient stands up whereas the indirect hernia shows a more oblique route downwards towards the scrotum. A hernia which goes into the scrotum is always indirect. The direct hernia appears as a symmetric, circular swelling at the external ring, i.e. medial to the femoral artery, whereas the indirect hernia is seen as an elliptical swelling.

From the superficial ring, an indirect hernia reduces superiorly then superolaterally. A direct hernia reduces superiorly then posteriorly.

The reduced indirect hernia can be controlled by pressure over the internal ring, classically with a single finger, but a reducible, direct hernia cannot.

On standing, the direct hernias appears immediately whilst the indirect hernia takes time to reach its full size. Similarly, on lying down, direct hernias disappear immediately whilst there is a delay before the reducible indirect retracts fully. This is due to the relatively large orifice of the direct hernia compared to that of the indirect one. This also explains the greater propensity of the indirect hernia to strangulate and that its defect is not always palpable. For a direct hernia, the defect may be palpable superior to the pubic tubercle.

Direct hernias are always acquired and are rare in children. They are more common in males.

At operation, the direct hernia passes medially to the inferior epigastric vessels whilst the indirect hernia passes laterally to these.