An umbilical hernia is a protrusion, bulge, or projection of an organ or part of an organ through the body wall such as the abdominal wall. The word derives from the Greek, meaning “bulge,” or "offshoot.” in general, umbilical hernias tend to have a narrow neck, which increases the risk of strangulation and incarceration. The majority of umbilical hernias in adults are indirect and may occur either above or below the umbilicus.
The cause of a true umbilical hernia (congenital type) is a failed closure of the umbilical ring during gestation that ultimately results in a central defect in the linea alba. This defect is prevalent in infants and young children. Skin and subcutaneous tissue only cover an umbilical hernia itself, but the underlying fascial defect allows protrusion of abdominal contents such as omentum or possibly intestines. Umbilical hernias are smaller than one centimeter in size that present at the time of birth usually will close spontaneously by four to five years of life. Most of these cases do not warrant early surgical repair. In some cases, the umbilical hernia is large enough that the protrusion is blighting and disconcerting to both the child and the family, which would then warrant early repair.
Umbilical hernias in adults are usually acquired and are more common in women or patients with increased intra-abdominal pressure as in pregnancy, obesity, ascites, or chronic abdominal distention. This is due to the presence of a single midline aponeurotic decussation as compared to the normal decussation of fibers from all three lateral abdominal muscles.
The incidence of umbilical hernias ranges from 10% to 25% and is increased in females; specifically African American children and low-birth-weight babies. Umbilical hernias also are associated with several congenital syndromes and medical conditions such as hypothyroidism, mucopolysaccharidosis, Down syndrome, Beckwith–Wiedemann syndrome, and exomphalos–macroglossia syndrome.
During fetal development, the abdominal wall is formed by four separate embryologic folds: cephalic, caudal, and right and left lateral, respectively.
Each fold is composed of somatic and splanchnic layers. The folds then develop towards the anterior center portion of the coelomic cavity (i.e., the hollow, fluid-filled cavity lined by an epithelium derived from mesoderm in humans) and ultimately join to form a large umbilical ring that surrounds the following structures:
These structures are enclosed by the outer layer of amnion. The entire unit, itself, comprises the umbilical cord.
During the time between fifth and tenth weeks of gestation, the intestinal tract undergoes rapid growth with protrusion of the abdominal content outside the abdominal cavity, usually within the proximal portion of the umbilical cord. This is followed by a gradual re-entry of the abdominal cavity and then the ultimate narrowing of the umbilical ring which completes the process of abdominal wall formation as fetal development concludes.
Failures of each fold will lead to different congenital disabilities at birth. For example, failure of the cephalic fold to close will usually result in sternal defects (i.e., congenital absence of the sternum). If the caudal fold fails to close, this will often result in exstrophy of the bladder or possible exstrophy of the cloaca.
Disruption of the central migration of the lateral folds will lead to a defect called omphalocele. Omphalocele is a condition that leads to the inability of the abdominal contents to be reduced back into the abdomen, resulting in a large hernia covered by a peritoneal sac. In comparison to gastroschisis, thought initially to be a variant of omphalocele, this possibly results from isolated intrauterine vascular insult leading to an abdominal wall defect to the right of the umbilical cord.
Umbilical hernias are generally asymptomatic protrusions of the abdominal wall. Parents or physicians typically note them shortly after birth. All families of babies with an umbilical hernia should be counseled about signs of incarceration, which is rare in umbilical hernias and more common in smaller (1 cm or less) than larger defects. Incarceration presents with abdominal pain, bilious emesis, and a tender, hard mass protruding from the umbilicus. This constellation of symptoms mandates immediate exploration and repair of a hernia to avoid strangulation. More commonly, the child is asymptomatic, and treatment is governed by the size of the defect, the age of the patient, and the concerns that the child and family have regarding the cosmetic appearance of the abdomen. Most defects close spontaneously by the age of two. When the defect is small and spontaneous, closure is likely, and most surgeons will delay surgical correction until five years of age. If closure does not occur by this time or a younger child has a very large or a symptomatic hernia, it is reasonable to proceed to repair.
Adults who are symptomatic typically present with a large hernia (loss of domain), skin color changes consistent with incarceration, thinning of the overlying skin, or uncontrollable ascites and should have a hernia repair. Spontaneous rupture of umbilical hernias in patients with ascites can result in peritonitis and death.
In children, bowel incarceration or strangulation is extremely rare and is the only absolute indication for urgent surgical repair. Relative surgical indications take into account the two factors most often associated with a decreased likelihood of spontaneous closure: age greater than three to five years and fascial defect size greater than 1.5 cm to 2 cm. Some surgeons also recommend elective repair when there is a need for general anesthesia during concurrent minor otolaryngologic, orthopedic, or other procedures.
In adults, careful examination of the entire abdominal wall, especially around scar/previous incisional, is warranted. Patients should be examined in the standing and supine positions (to determine the size of a hernia +/- Valsalva maneuver) to determine the edges of the fascial defect. Ultrasound and CT with PO/IV contrast are good adjunct imaging modalities and usually best reserved for obese patients.
Surgical repair for an uncomplicated umbilical hernia is done under general anesthesia as an outpatient procedure. After local anesthesia, a small curvilinear incision is made into the skin crease of the umbilicus, and the sac is dissected free from the overlying skin as well the fascial defect to ensure not abdominal content are present prior repair of the fascial defects. The fascial defect is repaired with absorbable, interrupted sutures that are typically placed in a transverse plane. The skin is closed using subcuticular sutures, either monocryl or vicryl. The postoperative recovery is usually uneventful. Recurrence is uncommon, but often seen in children with elevated intra-abdominal pressures.
In adults, small defects are closed primarily after separation of the sac from the overlying umbilicus and surrounding fascia. Defects greater than 3 cm are closed using prosthetic mesh. Currently, no prospective data have conclusively found clear advantages of one technique over another.
Options for mesh implantation include bridging the defect and placing a preperitoneal underlay of mesh reinforced with suture repair. The laparoscopic technique requires general anesthesia and is reserved for large defects or recurrent umbilical hernias.
Complications related to surgery
For most patients, the prognosis is excellent. However, recurrences have been reported in adults chiefly due to faulty technique.
Umbilical hernias are common in clinical practice. Because these hernias have a high risk of incarceration, surgery is recommended in all patients. A multidisciplinary team approach is necessary to avoid the morbidity of an umbilical hernia. Once the surgeon is completed, the nurse should educate the patient on the importance of losing weight and avoiding heavy lifting. A dietary consult should be made to educate the patient on a healthy diet. Once the healing is done, the patient should be encouraged to join a physical therapy program and lose weight. This is vital in preventing a recurrence. Most patients with an umbilical hernia have a good outcome, but despite advances in treatment with a mesh, recurrences do occur in about 1-3% of cases.