A 55-year-old man comes to the office due to swelling in his groin that he first noticed 2 weeks ago. Physical examination shows a bulge above the inguinal ligament that increases in size when the patient is asked to cough. He is referred to a surgeon and scheduled to undergo elective laparoscopic hernia repair. Which of the following landmarks will best aid the surgeon in distinguishing an indirect from a direct inguinal hernia?
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Inguinal hernias are located above the inguinal ligament and are much more common in men. The inferior epigastric vessels are clearly visible on the anterior abdominal wall during laparoscopic hernia repair and can be used as a landmark to distinguish between direct and indirect inguinal hernias.
Indirect inguinal hernias occur due to failure of the processus vaginalis to obliterate, allowing abdominal contents to protrude lateral to the inferior epigastric vessels through the deep (internal) inguinal ring. The abdominal contents follow the path of the inguinal canal and may exit through the superficial (external) inguinal ring into the scrotum.
Direct inguinal hernias occur due to weakness in the transversalis fascia that allows abdominal contents to protrude medial to the inferior epigastric vessels into the Hesselbach triangle. Compared to indirect inguinal hernias, direct hernias are less prone to incarceration due to their wide neck. It is also uncommon for them to descend into the scrotum as there is no direct path through the abdominal fascia.
(Choice A) The femoral vein runs directly lateral to femoral hernias, which protrude below the inguinal ligament into the femoral canal.
(Choice C) The pectineal ligament (inguinal ligament of Cooper) forms the posterior border of the femoral ring and would be located behind a femoral hernia that protrudes through the ring.
(Choice D) The rectus abdominis muscle sheath forms the most medial aspect of the Hesselbach triangle, which is the site of protrusion for direct inguinal hernias. Because both direct and indirect inguinal hernias lie lateral to the rectus abdominis muscle sheath, it would not be useful for distinguishing these two types of hernia.
(Choice E) Indirect inguinal hernias follow the path of the spermatic cord (or uterine round ligament) as it courses through the deep (internal) inguinal ring.
(Choice F) The transversalis fascia is the site of weakness in a direct inguinal hernia and lies posterior to indirect inguinal hernias as they extend through the inguinal canal.
Educational objective:
The inferior epigastric vessels are useful as a landmark during laparoscopic hernia repair to classify the type of inguinal hernia. Indirect inguinal hernias protrude through the deep inguinal ring into the inguinal canal lateral to the inferior epigastric vessels. In contrast, direct inguinal hernias protrude through Hesselbach's triangle medial to the inferior epigastric vessels.