The term hernia is used to describe a weakness or defect of the abdominal wall, through which abdominal contents can protrude. It is important to note the distinction between the hernia defect and hernia contents, as surgical repair is generally more concerned with the former, with a few exceptions. Abdominal wall defects arise at areas of weakness in the abdominal wall. These areas include sites of previous surgery, the umbilicus, as well as areas of weakened abdominal and/or flank musculature such as in lumbar hernias.1
Patients may unknowingly have an abdominal wall or fascial defect that only becomes apparent after intraabdominal or preperitoneal contents pass through the hernia defect. This is especially true of umbilical hernias, which are the most common type of ventral abdominal hernia.2
The umbilicus is a natural area of weakness in the anterior abdominal wall. Located in the linea alba, it is technically a scar, located at the point of passage of the umbilical vessels through the abdominal wall while in utero. The fascial edges of the hernia develop by the third week of gestation, with the umbilical cord developing by week five. The extra-abdominal rotation of the intestine occurs between the sixth and tenth weeks of gestation, with fascial defect fusing thereafter. A hernia occurs after this area fails to close or later stretches and reopens as an adult. These hernias have been documented as early as the ancient Egyptians, with the first known repair occurring in the first century AD by Celsus. The first series of primary suture repairs were reported by Mayo in 1901,3 a technique that largely remains consistent today for small defects.
A wide estimated range of neonatal incidence exists for umbilical hernias. In Caucasian babies, the reported incidence is 10% to 30%. For unknown reasons, the incidence in African-American children is higher. Prematurity and family history of umbilical hernia are known risk factors.
The vast majority of congenital umbilical defects close as infants grow into early childhood. In fact, once children are entering school age, only about 10% of previously diagnosed defects remain on physical exam. For this reason, most pediatric surgeons recommend deferring repair for uncomplicated umbilical defects. The current recommended age for surgical repair in the pediatric literature is at least 2 to 3 years, with many surgeons advocating for even later.
Umbilical hernias diagnosed in adulthood tend to be acquired in nature, and therefore it is more difficult to establish a true incidence. A female predominance exists, with a female:male ratio of 3:1. Also, medical comorbidities or physiologic factors that increase intraabdominal pressure confer a higher incidence of umbilical hernia.2 These include pregnancy, obesity, abdominal ascites, chronic obstructive pulmonary disease, or persistent bowel distension or obstruction. In the adult patient, hernia formation seems to be ...