Umbilical Hernia

Introduction

An umbilical hernia is one of the commonest abdominal wall defects occurring in young children. An umbilical hernia is detected as a bulge seen and/or felt at the belly button or umbilicus. The abdominal content may protrude outside the abdominal cavity through the defect in the abdominal wall at the site of the umbilicus.

Incidence:

Almost 10-20% of the children have an umbilical hernia. Boys and girls are equally affected. It is found more often (20-30%) in African-American children and 4% in white children. Incidence is more in infants with prematurity, low birth weight, congenital hypothyroidism, Down syndrome, trisomy 13, trisomy 18, trisomy 21, Hurler's syndrome, Beckwith-Wiedemann syndrome, or children requiring peritoneal dialysis.¹

Patho-physiology for umbilical hernia:

The umbilical region is involved in very complex activities in intra-uterine life. In the embryonal stage, a wide-open communication exists between the yolk sac and primitive gut. During fetal development in the womb, the mid-gut from the baby is herniated outside the body in the yolk sac at 32 days, the rotation of the gut takes place. This physiological umbilical hernia remains till 9th weeks and in the 10th week, the intestines return back to the abdominal cavity. In 3rd trimester, the aperture around the umbilical vessels and urachus narrows. In the post-natal stage, the umbilical ring is formed when the mesoderm of muscle and fascia around the umbilical vessels and urachus contracts. An umbilical hernia is caused by the failure of closure of the umbilical ring.²

Clinical Anatomy of umbilical hernia:

The umbilical ring (fibro-muscular ring) is a wide defect in the abdominal wall. The actual fascial defect varies in size, ranging from 1 to 4 cm. The ring is anteriorly bordered by linea alba, laterally by the rectus sheath, and posteriorly by umbilical fascia and peritoneum (Figure 1). When the abdominal content (bowel and/or mesenteric fat) herniates through the ring, they are covered with peritoneum. (Figure 2). The extent of the skin protrusion is not indicative of the size of the umbilical defect. So it is important to reduce the content of the hernia and palpate for the actual size of the ring.^1,2

Figure 1: Schematic diagram of abdominal wall layers in health.

Figure 2: Schematic diagram of umbilical hernia and its relation to abdominal wall layers

Signs and symptoms:

Children with umbilical hernia present early in life as a bulge in the umbilicus. The bulge becomes more prominent after crying or coughing or straining. Otherwise, they are asymptomatic and it rarely causes pain. The sac may content a loop of bowel that is easily pushed back into the abdomen or some peritoneal fat.^1,2

Investigations

An umbilical hernia is a clinical diagnosis. No special investigations are required to diagnose this condition. If any complications are present then a USG abdomen or CT abdomen may be performed.

Management:

The use of pressure dressing or other devices to keep the hernia in a reduced state does not help in the early closure of the umbilical hernia. It may result in skin irritation and not advisable.

Surgical repair:

Most of the umbilical hernias are repaired by direct closure of the defect. Unlike in adults, prosthetic placement is not required.

The most common method for surgical repair is as follows:

• A small transverse infra-umbilical incision is made
• The hernia sac is identified and dissected free from the dermis
• Excision of the hernia sac
• Closure of the fascial defect in a transverse fashion using non-absorbable sutures.

Umbilical defects more than 3 cm are called as Huge Umbilical hernias.⁴

Complicated hernias are more common with smaller defects.

Common complications after surgeries:

Postoperative morbidities are seen in 2% of patients, which consist of superficial wound infection, hematoma, and seroma. Recurrence may be seen in up to 2% of the patients which is treated with reoperation.⁵

Complications:

Incarceration, strangulation, bowel obstruction, erosion of the overlying skin, and bowel perforation are rare events in infants and small children. The risk of incarceration increases significantly with smaller umbilical ring 0.5 cm to 1.5 cm.³

Prognosis:

Most umbilical hernias do not pose any problem. By 2 years of age, 80% of the umbilical hernias close spontaneously and do not require any surgical corrections.

Defect more than 1.5 cm generally does not close spontaneously. Surgical corrections should be considered in large umbilical hernia, beyond 4 years of age and incarcerated hernia. The umbilical hernia is closed before the school-going age.^1,2,3