Hernia indd

Inguinal canal anatomy
The inguinal canal lies between the superficial and deep inguinal 
rings. The deep ring lies deep to the mid-inguinal point (which is 
half way between symphysis pubis and anterior superior iliac spine). 
The superficial inguinal ring is located within the external oblique 
aponeurosis, immediately above the crest of the pubis. Anteri-
orly and posteriorly the inguinal canal is bordered by the external 
oblique aponeurosis and the transversalis fascia respectively. The in-
ferior border is the inguinal ligament and the superior border is the 
conjoint tendon (the lower fibres of internal oblique and transversus 
abdominis). In men, the inguinal canal contains ilio-inguinal nerve, 
the genital branch of the genitofemoral nerve and the spermatic 
cord. In women, it contains the round ligament 
(1)
.
Direct inguinal hernia
Femoral canal anatomy: 
Femoral hernias occur in the femoral canal. The anterior border is 
the inguinal ligament. The posterior border is the pectineal liga-
ment. The medial border is the lacunar ligament, the lateral border 
is the femoral vein.
Inguinal hernia
50% of all abdominal wall hernias are indirect inguinal hernias and 
a further 25% are direct inguinal hernias 
(1,2)
. Inguinal hernias, there 
is protrusion of abdominal contents through the inguinal canal 
towards the scrotum or labia. In indirect hernias, intraperitoneal 
contents herniate through the internal inguinal ring (lateral to the 
inferior epigastric vessels) into the inguinal canal. Direct inguinal 
hernias arise medial to the inferior epigastric vessels and do not pass 
through the internal inguinal ring. Instead they travel through an 
acquired defect in transversalis fascia of the Hesselbach triangle.
An indirect inguinal hernia in a child is considered a congenital 
hernia because it requires an open processus vaginalis. This type is 
more common in males due to a predisposition for the process vagi-
nalis to remain patent after testicular descent. Direct inguinal her-
nias (often bilateral) are commonly seen in 30-40 year old men 
(6)
.
US is the first line in clinically indeterminate or recurrent inguinal 
hernias. Postural techniques and Valsalva maneuver are useful in 
differentiating true inguinal hernias from fat in the inguinal canal 
and normal movement of the spermatic cord. Comparison with the 
contra lateral side is essential not only for review of the normal anat-
omy but because inguinal hernias are bilateral in up to 20% of cases.