Indirect Inguinal Hernia  

 

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Indirect Inguinal Hernia

Etiology

Inguinal HerniaAn indirect inguinal hernia is considered mainly to be a congenital lesion.  It is denoted “indirect” because the bowel and peritoneum do not herniate directly through a weakness in the abdominal wall.  Rather, the bowel and peritoneum move through a patent processus vaginalis (hence it being a congenital defect) and into the scrotum.  This also lends to the analogy that “in”-direct hernias extend “in” through the internal ring.  As such, they technically protrude lateral to the inferior epigastric vessels.

The hernia itself consists of a sac of peritoneum extending through the internal ring, antero-medial to the spermatic cord in males (or round ligament in females), through which omentum or bowel can traverse.

The larger the defect and extension into the scrotum, the higher the risk of incarceration and/or strangulation.

Risk Factors

Probably the largest single risk factor for developing an inguinal hernia is being male.  Men are almost 10 times more likely to develop an inguinal hernia than females.  Other factors (which mainly lead to an increased pressure in the lower abdomen) put the general population at risk.  They include:

bulletFamily History:  There is an increased risk of hernia with a close family history
bulletCertain Medical Conditions:  Cystic fibrosis, or conditions associated with a chronic cough increase the risk of developing a hernia
bulletSmoking:  Like cystic fibrosis, a chronic cough increases risk
bulletChronic Constipation:  Excessive straining over time can lead to hernia
bulletExcess Weight & Pregnancy:  Increases risk by weakening and placing stress on lower abdominal muscles
bulletPast History:  Having one hernia puts you at risk of having another

Clinical Presentation

Palpating an inguinal hernia

Indirect inguinal hernias typically cause a bulge in the groin (at the top of or within the scrotum) and usually with increased abdominal pressure.  The bulge may or may not be painful.  By palpating the inguinal canal and asking the patient to cough while standing, one can usually elicit the hernia.  In fact, one can often times palpate an inguinal hernia without invaginating the scrotum (as is typically taught in medical school).  Rather, by placing one's fingers over the inguinal canal and asking the patient to cough, one can often feel the bulge against the lower abdominal wall.  As indirect and direct hernias are unreliably differentiated by physical exam alone, the need to invaginate the scrotum to feel into the inguinal canal is often more uncomfortable to the patient, than revealing to the physician.  Rarely, palpation is not even necessary, as the hernia is large enough to be visualized.

Indirect inguinal hernias are the most common type of hernia encountered.  Virtually any patient under the age of 25 presenting with hernia will have an indirect hernia.  They are more prevalent in men (the male to female ratio being about 9:1).  This is because, during their descent, the testicles and blood vessels pass through the inguinal canal, making the opening from the abdomen less likely to close completely. 

  Direct   Indirect     Femoral    
Men 40%   50% 10%
Women   Rare 70% 30%
Children   Rare All Rare

Because indirect hernias originate through the deep inguinal ring, there is an increased risk that bowel can slip into the canal, become swollen and engorged, and become trapped outside the abdomen.  This is known as incarceration, and is the second leading cause of bowel obstruction (second only to adhesions from previous surgery).  Bowel can remain incarcerated for long periods of time without leading to strangulation, however, if the entrapment of bowel becomes so severe as to compromise blood flow, strangulation ensues with the risk of bowel necrosis.  Strangulation, therefore, is a surgical emergency.

Treatment of Hernias