Difference between Inguinal Hernias

Herniation of abdominal viscera can occur in one of several weak aspects of the abdominal wall (e.g. inguinal,femoral , umbilical, or diaphragmatic). Inguinal hernias are the most common of the abdominal hernias and occur more frequently in males due to the inherent weakness of the male inguinal canal. Inguinal hernias occur superior to the inguinal ligament. 

Two types of Inguinal hernias are described :

Indirect inguinal hernias: Indirect hernias result when abdominal contents protrude through the deep inguinal ring lateral to the inferior epigastric vessels. After passing through the inguinal canal and superficial ring, the viscera can  continue and coil in the scrotum. Indirect hernias follow the route taken by the testis and are found with in the spermatic cord. They are covered by the three layers of spermatic fascia.

Direct inguinal hernias: During a direct inguinal hernia, the abdominal contents will protrude through the weak area of the posterior wall of the inguinal canal medial to the inferior epigastric vessels (in the inguinal [Hesselbach's triangle]). Direct hernias rupture through the posterior wall of the inguinal canal and area usually found on the surface of the spermatic cord and bulge at the superficial ring. They may be covered by only the external layer of spermatic fascia.

Note: 

• That both Direct and Indirect hernias may exit through the superficial ring but only Indirect hernias pass through the deep ring.

• Direct hernias are found medial to the inferior epigastric vessels, and Indirect hernias occur lateral to the inferior epigastric vessels.

Clinical correlate

• Inguinal (Hasselbach's) Triangle : 

Direct inguinal hernias usually pass through it

Lateral border: Inferior epigastric vessels

Medial border: Rectus abdominis muscle

Inferior border: Inguinal ligament

• A persistent process vaginalis often results in a congenital indirect inguinal hernia.

• A collection of serous fluid in the tunica vaginalis form a hydrocele resulting in an enlarged scrotum. A hydrocele does not reduce in size when the patient is lying down.

• Inguinal hernias pass above the inguinal ligament 

• Femoral hernias pass below the inguinal ligament.

Femoral hernias: most often occur in women,