During development

During development, the embryonic disk is in contact with yolk sac anteriorly. As the embryo grow and differential growth of tissues leads to the folded appearance of the embryo. The attachment of the yolk sac narrows and the intracoelomic portion of the yolk sac becomes the primitive alimentary canal and attaches to the extracoelomic portion by the vitelline duct. The allantois buds from hindgut and grows into the body stalk. Yolk stalk and the body stalk eventually fuses and forms the umbilical cord.
The umbilical cord contains two umbilical arteries, the vein, the rudimentary allantois, the remnant of the omphalomesenteric duct and a gelatinous substance called Wharton jelly. The sheath of the umbilical cord is derived from the amnion. The muscular umbilical arteries contract readily, but the vein does not and retains fairly large lumen after birth. Long cord of length more than 70 cm increases the risk of true knots, wrapping around fetal parts, cord prolapse. Straight untwisted cords are associated with fetal distress, anomalies and intrauterine fetal demise.
When the cord sheds off after birth, portions of these structures remain in the base .The blood vessels are functionally closed but anatomically patent for 10-20 days. The arteries become the lateral umbilical ligaments; vein, the ligamentum teres and the ductus venosus, the ligamentum venosum. During this interval, the umbilical vessels are potential portals of entry for infection. The cord usually sloughs within 2 weeks. Delayed separation has been associated with bacterial infection.
A single umbilical artery is present in about 5-10/1000 births & 35-70 in twin births. About 30% of infants with single umbilical artery have congenital abnormalities, usually more than one. Many such infants are stillborn or die shortly after birth. Trisomy 18 is one of the more frequent abnormalities. As many of them may not be apparent on physical examination, it is important that at every delivery the cut cord and the maternal and fetal surfaces of the placenta be inspected.
Patency of the omphalomesenteric duct may be responsible for intestinal obstruction, intestinal fistula with fecal or bilious draining, prolapse of the bowel, a polyp or Mekel diverticulum. The management is surgical excision of the anamoly. A persistent uracus is due to failure of closure of the allantoic duct and is associated with bladder outlet obstruction. Patency is suspected in case of clear or light yellowish urine like discharge is observed from the umbilicus. Symptoms include drainage a mass or cyst, abdominal pain, local erythema or infection. Urachal anomalies should be investigated by ultrasound and cystogram. The management is surgical excision.
The normal complete cord length in a full term baby is approximately 55 cm long. Abnormally short cords are associated with antepartum abnormalities, fetal hypotonia, oligohydramnios, uterine constraint and with increased risk of complications of labor and delivery for both mother and infant.
Single umbilical artery or abnormal position of the umbilicus such unusual umbilical anatomy is generally seen associated with congenital anomalies in the baby. Omphalocele and gastroschisis are the common abdominal wall defects associated with the umbilicus. Masses of the umbilicus associated with the skin include dermoid cysts, hemangiomas, and inclusion cysts. Umbilical discharge is also sometimes seen in granulomas and embryologic remnants.
The following should be noted:
• Delayed separation of the umbilical cord – The umbilical cord usually separates from the umbilicus 1-2 weeks after birth; topical antimicrobials, isopropyl alcohol is applied till the cord separates; delayed fall may signify an underlying immune disorder and sepsis.
• Umbilical granuloma- After separation of the umbilical cord some granulation tissues may persist at the base of the umbilicus. The fibroblasts and capillaries and can grow to more than 1 cm and it must be differentiated from umbilical polyps or granulomas secondary to a patent urachus, both of which does not respond to cauterization of silver nitrate .
• Umbilical infections – Patients with omphalitis may present with purulent umbilical discharge or peri-umbilical cellulitis. The infections may be associated with retained umbilical cord or ectopic tissue, they were often, related to poor hygiene but current aseptic practices and the routine use of antimicrobials on the umbilical cord have reduced the incidence to less than 1%.The cellulitis may become severe and rapidly progress into necrotizing fasciitis and generalized sepsis, which requires urgent attention and management.
• Omphalomesenteric remnants – Persistence of portions of the omphalomesenteric duct can result in fistulas, sinus tracts, cysts and congenital bands. The patients with mucosal remnants can present with an umbilical polyp or an umbilical cyst.
• Urachal remnants – The developing urinary bladder remains connected to the allantois through the urachus, and remnants of this connection include a patent urachus, urachal sinus, and urachal cyst. Umbilical polyps and granulomas can also be observed in association with aurachal remnant.
• Umbilical hernias – Persistence of a patent umbilical ring leads to umbilical hernias. Most of the umbilical hernias close or resolve spontaneously, but few of them require surgical correction.