Disorders of the Umbilicus

INTRODUCTION

A stark contrast exists between the physiologic importance of the umbilicus during development and after birth. During development, the umbilicus functions as a channel allowing blood flow between the placenta and fetus. It also serves an important role in the development of the intestine and the urinary system. After birth, once the umbilical cord falls off, no evidence of these connections should be present. Nevertheless, umbilical disorders are frequently encountered in pediatric surgery. These disorders range from the very common umbilical hernia to infections such as omphalitis, which can be life threatening. Most patients with umbilical problems present with a mass or drainage from the umbilicus. An understanding of the anatomy and embryology of the abdominal wall and umbilicus is important to identify and properly treat these conditions.

History of the Procedure: The embryology of the umbilicus and the developmental basis for surgical abnormalities has been well described for more than one hundred years. Umbilical hernias, abdominal wall defects, umbilical polyps and drainage, and omphalomesenteric remnants are well described. Methods of management in some disorders, such as treating umbilical granulomas with silver nitrate, have changed little over the last century. In the early 1900s, umbilical hernia repair was a challenging procedure. Spontaneous closure of these hernias and preservation of the appearance of the natural umbilicus were recognized. Today, umbilical hernia repair is one of the most common procedures performed by pediatric surgeons.

Problem: Patients with umbilical disorders present with drainage, a mass, or both. Most umbilical disorders result from failure of normal embryologic or physiologic processes. Unusual umbilical anatomy, such as a single umbilical artery or abnormal position of the umbilicus, may be associated with other congenital anomalies or syndromes. Masses of the umbilicus may be related to lesions of the skin, embryologic remnants, or an umbilical hernia. Masses associated with the skin include dermoid cysts, hemangiomas, and inclusion cysts. Umbilical drainage is associated with granulomas and embryologic remnants.

Delayed separation of the umbilical cord: The umbilical cord usually separates from the umbilicus 1-8 weeks postnatally. Topical antimicrobials are usually applied after delivery, followed by isopropyl alcohol until cord separation. Delayed separation may signify an underlying immune disorder.

Umbilical granuloma: Granulation tissue may persist at the base of the umbilicus after cord separation. The tissue is composed of fibroblasts and capillaries and can grow to more than 1 cm. Umbilical granulomas must be differentiated from umbilical polyps, which do not respond to silver nitrate cauterization.

Umbilical infections: Patients with omphalitis may present with purulent umbilical discharge or periumbilical cellulitis. Although infections may be associated with retained umbilical cord or ectopic tissue, in the past, infections were often related to poor hygiene. Current aseptic practices and the routine use of antimicrobials on the umbilical cord have reduced the incidence to less than 1%. Cellulitis may become severe within hours and progress to necrotizing fasciitis and generalized sepsis.

Omphalomesenteric remnants: Persistence of all or portions of the omphalomesenteric duct can result in fistulas, sinus tracts, cysts, congenital bands, and mucosal remnants. Patients with mucosal remnants can present with an umbilical polyp or within an umbilical cyst.

Urachal remnants: The developing bladder remains connected to the allantois through the urachus. Remnants of this connection include a patent urachus, urachal sinus, and urachal cyst. Umbilical polyps can also be observed in association with a urachal remnant.

Umbilical hernia: Umbilical hernias result when persistence of a patent umbilical ring occurs. Umbilical hernias may close spontaneously, but many require surgical repair.

Frequency: The frequency of the many different umbilical disorders varies. Umbilical infections are now identified in less than 1% of hospitalized newborns.

Umbilical hernias are commonly identified in early infancy; however, most close spontaneously. No sex predilection exists. The incidence at age 1 year ranges from 2-15%. Incidence is increased in infants who are black and in infants with low birthweight, Down syndrome, trisomy 13, trisomy 18, or Beckwith-Wiedemann syndrome.

Etiology: The development of the anterior abdominal wall depends on differential growth of embryonic tissues . As the embryo grows, the yolk sac is divided into an intracoelomic portion and an extracoelomic portion. The intracoelomic portion becomes the primitive alimentary canal and communicates with the extracoelomic portion through the vitelline duct, also known as the omphalomesenteric duct. This communication is lost at 5-7 weeks' gestation. Persistence of part or all of this connection results in omphalomesenteric anomalies.

In the third week of gestation, the yolk sac develops a diverticulum, the allantois, which grows into the body stalk . As the distal hindgut and the urogenital sinus separate, the developing bladder remains connected to the allantois through a connection called the urachus. Persistence of this communication leads to urachal remnants. Subsequently, the yolk and body stalks fuse to become the umbilical cord. Development of the abdominal wall narrows the umbilical ring, which should close before birth. Persistence of the umbilical ring results in an umbilical hernia.

Pathophysiology: Failure of the normal obliterative processes of the vitelline duct and the urachus leads to abnormal communications or cysts. Retention of components of the umbilical cord can also produce a mass or drainage.

A patent umbilical ring at birth is responsible for most umbilical hernias. The umbilical opening is usually reinforced by the attachments of the median umbilical ligament, the obliterated urachus, the paired medial umbilical ligaments, the obliterated umbilical arteries inferiorly, and is more weakly reinforced superiorly by the round ligament and the obliterated umbilical vein.

Richet fascia, derived from the transversalis fascia, covers the ring. The peritoneum covers the innermost portion of the ring. Variability in the attachment of the ligaments and the covering by Richet fascia may predispose some children to developing umbilical hernias. However, many children undergo spontaneous closure in the first few years of life. The pressure exerted on the umbilical skin, even when a small

umbilical defect is present, can result in marked stretching of the skin and a proboscis appearance .

Clinical: Umbilical infections can occur because of an embryologic remnant or poor hygiene. Traditionally, gram-positive organisms, such as Staphylococcus aureus and Streptococcus pyogens, were identified most commonly. Gram-negative and polymicrobial infections are seen today, especially in rapidly progressing cellulitis and necrotizing fasciitis.

Umbilical granulomas appear as 1-mm to 1-cm, pink, friable lesions at the base of the umbilicus. They produce variable amounts of drainage that can irritate the surrounding skin. An umbilical polyp is brighter red than a granuloma and represents retained intestinal or gastric mucosa from the vitelline duct.

The presentation of omphalomesenteric remnants depends on the specific type of defect. If a communication persists from the terminal ileum to the umbilicus, intestinal contents or stool can be observed leaking from the umbilicus. Prolapse of intestine through an omphalomesenteric fistula can also be observed. The drainage from a fistula that does not communicate with the ileum is variable; it may be clear, bloody, or purulent. Cystic remnants may become infected and manifest with pain and swelling.

The presentation of urachal remnants also is variable. Clear drainage from the umbilicus is characteristic of a urachal fistula. Drainage of urine from the umbilicus may suggest bladder outlet obstruction and warrants further investigation. A urachal sinus manifests with drainage that can be clear or purulent. A urachal cyst is usually discovered as a painful mass between the umbilicus and suprapubic area when it becomes infected. Pain and retraction of the umbilicus during urination may suggest a urachal anomaly.

Patients with umbilical hernias present early in life with bulging at the umbilicus. The swelling is most prominent when the infant or child is crying or straining. Umbilical hernias usually are asymptomatic and rarely cause pain. The skin can become severely stretched, which may be alarming to parents and physicians. Parents often mention that the child plays with the redundant skin. 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 in adults with umbilical hernias.

Patients with umbilical infections can present with drainage from the umbilicus, swelling, and redness. Cellulitis may progress rapidly and lead to necrotizing fasciitis. Necrotizing fasciitis is characterized by abdominal distention, tachycardia, purpura, leukocytosis, and other signs of sepsis despite antibiotic therapy.

INDICATIONS

Small umbilical granulomas usually respond to silver nitrate application. Large umbilical granulomas or those that persist after silver nitrate treatment require surgical excision.

Omphalomesenteric remnants and urachal remnants require surgical excision. The precise diagnosis often is not confirmed until surgery is performed and the anatomy of

the umbilicus is established.

The diameter of the umbilical ring defect is predictive of spontaneous closure. The length of the protruding skin is not prognostically significant. Umbilical hernias with ring diameters less than 1 cm are more likely to close spontaneously than those with ring diameters more than 1.5 cm. Surgery is indicated for all symptomatic umbilical hernias. Incarceration, strangulation, skin erosion, and bowel perforation are indications for immediate surgery. Similarly, patients presenting with pain should be repaired on an elective basis.

Asymptomatic umbilical hernias should be monitored until the child is aged 4-5 years to allow spontaneous closure, especially if the ring defect is small. Because umbilical hernias with larger defects (ie, >1.5 cm) are unlikely to close spontaneously, surgery can be performed at an earlier age. Similarly, closing umbilical hernias with large ring defects is reasonable if the child is having a general anesthetic for another procedure, such as an inguinal hernia repair. Considering surgery in younger children who have a large protrusion of the umbilical skin that is causing distress to the parents is also reasonable.

Necrotizing fasciitis and gangrene of the umbilical skin requires emergency surgical debridement and can be life saving.

RELEVANT ANATOMY AND CONTRAINDICATIONS

Relevant Anatomy: During development, the embryonic disk is in contact with the yolk sac anteriorly. As the embryo grows and differential growth of tissues leads to the folding appearance of the embryo, the ventral attachment of the yolk sac narrows.

The intracoelomic portion of the yolk sac becomes the primitive alimentary canal and attaches to the extracoelomic portion through the vitelline duct. The allantois buds from the hindgut and grows into the body stalk. The yolk stalk and the body stalk eventually fuse to become the umbilical cord.

As the abdominal wall forms, the umbilical ring is narrowed. The vitelline and umbilical vessels, vitelline duct, and allantois should be absent in the umbilicus at term . Residual tissue leads to remnants that require surgical intervention.

During exploration for a sinus or fistula, all structures, including the round ligament, median, and medial umbilical ligaments, must be identified . An omphalomesenteric or urachal sinus or fistula must be dissected back to its origin in the ileum or bladder, respectively .

Contraindications: No specific contraindications to surgery exist for umbilical disorders, and timing of surgery depends on the general medical condition of the infant or child.

WORKUP

Lab Studies:

Routine laboratory tests are not needed in healthy children undergoing umbilical hernia repair or excision of omphalomesenteric or urachal remnants.

Infants with necrotizing fasciitis can be extremely ill, and umbilical cultures and blood cultures are needed. Frequent hematologic, electrolyte, and blood gas analyses may be needed.

Imaging Studies:

Radiography is not indicated in most children with umbilical disorders. Umbilical hernias are diagnosed by means of physical examination. Fistulography or sinography may be performed if a definitive opening is observed within the umbilicus. Ultrasonography is helpful when a mass is present.

Fistulography can be performed by injecting water-soluble contrast medium into the opening at the base of the umbilicus. If the track is blind-ended, the child has a sinus; if it enters the intestine or bladder, a fistula is present.

Ultrasonography may be useful in identifying cysts of the umbilicus. It is especially useful to evaluate for a urachal cyst, which most commonly appears as a mass between the umbilicus and suprapubic area.

Plain radiography may be useful in children with omphalitis. Air in the subcutaneous tissue or muscle planes is an ominous sign.

Cystography or cystoscopy may be indicated to identify bladder outlet obstruction in children draining frank urine from a urachal fistula. However, recent studies suggest that, in most cases, history and ultrasonography are sufficient for the diagnosis.

Histologic Findings: The histology of umbilical remnants depends on the tissue of origin and may reveal intestinal or gastric mucosa. Examination of urachal remnants shows transitional or columnar epithelium.

TREATMENT

Medical therapy: Medical therapy is indicated only when infection is present. For omphalitis or necrotizing fasciitis, broad-spectrum antibiotics are needed. Antibiotics are also administered for acute infection of omphalomesenteric and urachal remnants. Surgical drainage is also needed.

Many umbilical hernias close spontaneously; currently, no medical therapy exists to hasten this process.

Silver nitrate application to umbilical granulomas is usually successful. One or more applications may be needed. Care must be taken to avoid contact with the skin. Silver nitrate can cause painful burns. Large granulomas and those growing in response to an umbilical fistula or sinus do not resolve with silver nitrate and must be surgically

excised.

Surgical therapy: Surgical therapy is the mainstay of treatment for large umbilical granulomas, omphalomesenteric remnants, urachal remnants, umbilical gangrene and necrotizing fasciitis, and umbilical hernias that are symptomatic or do not close spontaneously.

Often, surgery on the umbilicus is performed for a mass or drainage without a specific preoperative diagnosis. Surgical principles include identification of all structures of the umbilicus, excision of urachal or omphalomesenteric remnants, closure of the umbilical ring, and preservation of the natural appearance of the umbilicus.

If acute infection with an abscess is present, prompt surgical drainage is required. In most cases, definitive surgical resection of the underlying lesion is needed several weeks following the initial infection.

Wide surgical debridement of the umbilicus and abdominal wall can be life saving in patients with necrotizing umbilical infections.

Preoperative details: Most umbilical procedures can be performed on an elective basis, and surgery should be scheduled when the child is in his or her usual state of health. The exceptions are infants with necrotizing infections and those with stool draining from the umbilicus, indicative of an enteric-umbilical fistula.

A mechanical bowel preparation is not needed. Perioperative antibiotics are used for sinuses and fistulas. Antibiotics are not needed for umbilical hernia repairs.

Intraoperative details: General anesthesia is used. The child is placed supine. The abdomen should be prepared widely with antiseptic solution and draped in standard fashion. Omphalomesenteric and urachal remnants can usually be approached through the umbilicus without the need for additional incisions. Alternatively, an infraumbilical incision may be used. An infraumbilical incision is used for umbilical hernias.

During exploration of the umbilicus, all structures must be identified. The umbilical vein (round ligament), the umbilical arteries (medial umbilical ligaments), and the urachus (median umbilical ligament) must be identified . A patent vitelline duct must be traced to its origin and divided . If a Meckel diverticulum is present, it is excised. Similarly, the urachus should be traced to its origin and divided. Broad-based connections of the urachus and bladder are closed in 2 layers. The umbilical fascia is closed with interrupted suture. The umbilical skin is then closed. Attempts should be made to create a natural-appearing umbilicus. Antibiotic ointment and a light dressing can be applied to the incision.

If an abscess is identified preoperatively or found intraoperatively, an incision and drainage procedure is indicated. Definitive resection should be delayed.

Umbilical hernias are approached through an incision in the infraumbilical crease. Dissection is carried down to the level of the fascia. The hernia sac is identified at its base and encircled. Contents from the hernia sac should be reduced. The sac is then disconnected from its attachment with the umbilicus.

Care is taken to avoid injury to contents within the hernia sac and to the umbilical skin. Opening the anterior surface of the sac may help to avoid injury to the bowel. The sac is resected down to the level of the fascia. The umbilical fascia is closed with interrupted absorbable suture. The wound should be inspected and meticulous hemostasis achieved. The umbilicus is tacked down to the fascia with an interrupted suture. The subcutaneous tissue is reapproximated with a few interrupted sutures, and the skin is closed with a subcuticular stitch. Bupivacaine can be injected for postoperative analgesia. The skin is cleaned, and Steri-Strips are applied. A pressure dressing may be used for large hernias to prevent a postoperative hematoma or seroma.

Routine umbilicoplasty, ie, removal of excessive umbilical skin, generally is not needed. In most cases, a redundant umbilicus appears more natural than a neoumbilicus. Several techniques can be used for extremely protuberant umbilical hernias. A simple technique is to invert the umbilicus over a finger so that the undersurface is exposed. The skin is then incised circumferentially so that a 1- to 2-cm rim of umbilicus remains. The umbilical skin defect is reapproximated from within the umbilicus and tacked down to the fascia.

For necrotizing fasciitis, wide surgical debridement of the umbilicus and preperitoneal structures, skin, fat, muscle, and fascia back to healthy bleeding tissue is required. A silo or fascial patch may be needed.

Postoperative details: Most umbilical hernia repairs and excision of umbilical remnants can be performed as outpatient procedures. For incisions within the umbilicus, antibiotic ointment should be applied twice a day for 3-4 days. Pressure dressings may be removed in 24-48 hours.

Feedings can be initiated when the child recovers from the anesthetic. Incisions are generally kept dry for 3 days. No activity restrictions are indicated for infants and small children. Older children should avoid heavy activity for one week.

Most children need only acetaminophen for pain, especially when bupivacaine has been used.

Follow-up care: Children undergoing umbilical surgery must be seen in the surgery clinic 2-6 weeks following surgery or sooner if problems occur.

COMPLICATIONS

Complications of any surgery include intraoperative or postoperative bleeding. Bleeding problems are rare during umbilical surgery. A postoperative hematoma may occur when a large cavity is left following umbilical hernia repair.

Infection of the incision also is rare; however, if infection is present, treatment with antibiotics is indicated. Opening of the incision to drain an abscess may also be needed. Drainage following umbilical exploration and excision may indicate infection or retained embryologic tissue.

Recurrent umbilical hernias are very rare.

Silver nitrate can cause painful burns to the umbilical skin.

OUTCOME AND PROGNOSIS

The outcome for infants and children with umbilical hernias and embryologic remnants generally is excellent. In most cases, no long-term problems occur.

In contrast, in most series, omphalitis leading to necrotizing fasciitis is associated with a high mortality rate, up to 80%. Necrotizing fasciitis can also lead to portal venous thrombosis and portal hypertension.

FUTURE AND CONTROVERSIES

Debate remains regarding the timing for umbilical hernia repair, and the true instance of complications related to umbilical hernias in adults is not known. Most surgeons agree that, in most cases, small hernias can be monitored safely. Although spontaneous closure does occur, large hernias with large fascial defects are less likely to close on their own, and continued stretching of the umbilical skin may make closure more difficult. Therefore, many surgeons advocate earlier repair in these children. Others argue that umbilical hernias should be monitored until children are aged 5 years.