Chapter 89 Hernia (Inguinal) and Hernia Repair
PATHOPHYSIOLOGY
An inguinal hernia is generally the result of a patent processus vaginalis caused by congenital weakness or failure of the processus vaginalis to close. Normally the layers of the proximal portion of the processus vaginalis atrophy around the eighth month of gestation, and the peritoneal cavity is then closed off from the inguinal canal. Failure of the processus vaginalis to close allows abdominal fluid or contents (such as intestine) from the abdominal cavity to enter the inguinal ring and possibly the scrotum.
A communicating hydrocele is present if only fluid from the peritoneal cavity enters the scrotal sac. Although present at birth, the hernia may not be detected for several weeks, until enough abdominal pressure is built up and opens the sac. The child is initially seen with an intermittent lump or bulge in the groin, the scrotum, or the labia. It becomes prominent with intraabdominal pressure such as that resulting from crying or straining. Contents of the hernia sac usually can be reduced with gentle pressure. Surgical repair (herniorrhaphy) is usually performed on an outpatient basis. Early repair eliminates the risk of incarceration.
INCIDENCE
1. Of full-term newborns, 3.5% to 5% will have an inguinal hernia. Incidence of bilateral hernias approaches 50% in premature and low birth weight infants. The majority of infantile inguinal hernias are diagnosed in the first month of life.
2. If premature infants, incidence ranges from 9% to 11% and as high as 30% in very low birth weight infants.
3. Incidence is highest during infancy (more than 50%), with the remaining cases generally occurring before 5 years of age.
4. Boys are affected more frequently than girls at a ration of 5:1 or 6:1.
5. Sixty percent of hernias occur on the right side, 30% on the left side, and 10% bilaterally.
