There are two types of inguinal
hernia,
direct and
indirect, which are defined by their relationship to the
inferior epigastric vessels.
Direct inguinal hernias occur medial to the inferior epigastric vessels when abdominal contents herniate through a weak spot in the fascia of the posterior wall of the inguinal canal, which is formed by the
transversalis fascia.
Indirect inguinal hernias occur when abdominal contents protrude through the
deep inguinal ring, lateral to the inferior epigastric vessels; this may be caused by failure of embryonic closure of the
processus vaginalis. In the case of the female, the opening of the
superficial inguinal ring is smaller than that of the male. As a result, the possibility for hernias through the inguinal canal in males is much greater because they have a larger opening and therefore a much weaker wall through which the intestines may protrude. Inguinal hernias, in turn, belong to groin hernias, which also includes
femoral hernias. A femoral hernia is not via the inguinal canal, but via the
femoral canal, which normally allows passage of the common
femoral artery and vein from the pelvis to the leg. In
Amyand's hernia, the content of the hernial sac is the
appendix. In
Littre's hernia, the content of the hernial sac contains a
Meckel's diverticulum. Clinical classification of hernia is also important, according to which the hernia is classified into • Reducible hernia: can be pushed back into the abdomen by putting manual pressure on it. • Irreducible/Incarcerated hernia: cannot be pushed back into the abdomen by applying manual pressure. Irreducible hernias are further classified into • Obstructed hernia: is one in which the lumen of the herniated part of the intestine is obstructed. • Strangulated hernia: is one in which the blood supply of the hernia contents is cut off, thus leading to ischemia. The lumen of the intestine may be patent or not.
Direct inguinal hernia The direct inguinal hernia enters through a weak point in the
fascia of the
abdominal wall, and its sac is noted to be medial to the
inferior epigastric vessels. Direct inguinal hernias may occur in males or females, but males are ten times more likely to get a direct inguinal hernia. A direct inguinal hernia protrudes through a weakened area in the
transversalis fascia near the
medial inguinal fossa within an anatomic region known as the inguinal or
Hesselbach's triangle, an area defined by the edge of the
rectus abdominis muscle, the
inguinal ligament and the inferior epigastric artery. These hernias are capable of exiting via the
superficial inguinal ring and are unable to extend into the
scrotum. When a patient develops a simultaneous direct and
indirect hernia on the same side, it is called a
pantaloon hernia or
saddlebag hernia because it resembles a pair of pants with the epigastric vessels in the crotch, and the defects can be repaired separately or together. Another term for pantaloon hernia is '''Romberg's hernia'''. Since the abdominal walls weaken with age, direct hernias tend to occur in the middle-aged and elderly. This is in contrast to indirect hernias, which can occur at any age, including the young, since their etiology includes a congenital component where the inguinal canal is left more patent (compared to individuals less susceptible to indirect hernias). Additional risk factors include chronic constipation, being overweight or obese, chronic cough, family history and prior episodes of direct inguinal hernias. An
indirect inguinal hernia results from the failure of embryonic closure of the
deep inguinal ring. In the male, it can occur after the
testicle has passed through the deep inguinal ring. It is the most common cause of groin hernia. A
double indirect inguinal hernia has two sacs. In the male fetus, the
peritoneum gives a coat to the testicle as it passes through this ring, forming a temporary connection called the
processus vaginalis. In normal development, the processus is obliterated once the testicle is completely descended. The permanent coat of peritoneum that remains around the testicle is called the
tunica vaginalis. The testicle remains connected to its blood vessels and the vas deferens, which make up the
spermatic cord and descend through the inguinal canal to the scrotum. The deep inguinal ring, which is the beginning of the inguinal canal, remains as an opening in the fascia transversalis, which forms the fascial inner wall of the spermatic cord. When the opening is larger than necessary for passage of the spermatic cord, the stage is set for an indirect inguinal hernia. The protrusion of the peritoneum through the
internal inguinal ring can be considered an incomplete obliteration of the processus. In an indirect inguinal hernia, the protrusion passes through the deep inguinal ring and is located lateral to the inferior epigastric artery. Hence, the conjoint tendon is not weakened. There are three main types • Bubonocele: In this case, the hernia is limited to the inguinal canal. • Funicular: here, the processus vaginalis is closed at its lower end just above the epididymis. The content of the hernial sac can be felt separately from the testis, which lies below the hernia. • Complete (or scrotal): here, the processus vaginalis is patent throughout. The hernial sac is continuous with the tunica vaginalis of the testis. The hernia descends to the bottom of the scrotum, and it is difficult to differentiate the testis from the hernia. In females, groin hernias are only 4% as common as in males.
Indirect inguinal hernia is still the most common groin hernia for females. If a woman has an indirect inguinal hernia, her internal inguinal ring is patent, which is abnormal for females. The protrusion of the peritoneum is not called "processus vaginalis" in women, as this structure is related to the migration of the testicle to the scrotum. It is simply a hernia sac. The eventual destination of the hernia contents for a woman is the
labium majus on the same side, and hernias can enlarge one labium dramatically if they are allowed to progress.
Medical imaging A physician may diagnose an inguinal hernia, as well as the type, from
medical history and
physical examination. For confirmation or in uncertain cases,
medical ultrasonography is the first choice of imaging, because it can both detect the hernia and evaluate its changes with for example pressure, standing and
Valsalva maneuver. When assessed by
ultrasound or cross sectional imaging with
CT or
MRI, the major differential in diagnosing indirect inguinal hernias is differentiation from
spermatic cord lipomas, as both can contain only fat and extend along the inguinal canal into the scrotum. On axial
CT, lipomas originate inferior or lateral to the cord, and are located inside the
cremaster muscle, while inguinal hernias lie anteromedial to the cord and are not intramuscular. Large lipomas may appear nearly indistinguishable as the fat engulfs anatomic boundaries, but they do not change position with coughing or straining. •
Femoral hernia •
Epididymitis •
Testicular torsion •
Lipomas • Inguinal
adenopathy (
lymph node swelling) • Groin
abscess •
Saphenous vein dilation, called
saphena varix • Vascular
aneurysm or
pseudoaneurysm •
Hydrocele •
Varicocele •
Cryptorchidism (
undescended testes) == Management ==