The essential functions of umbilical cord cannot be over emphasized. Therefore, any abnormal umbilical cord predisposes to rupture, mechanical failure, entanglement, disruption of labour, uterine malfunction, and premature labor.
What are abnormalities of umbilical cord?
Cord abnormalities are silent and invisible but can be diagnosed prenatally with meticulous ultrasound scan. Sometimes, may not be diagnosed until in labour/delivery. The followings are abnormalities with their accompanying risks:
False knots:
This is also known as Pseudoknots, resulting from merely a varicosity or redundancy of an umbilical blood vessel (usually the vein) within the cord substance and cannot be physically released in an intact cord. This cord anomaly has no clinical significance.
Nuchal Cords:
Dr. J. Selwyn Crawford of the British Medical Research Council in 1962 was first to define this as the condition in which the umbilical cord is wound at least once around the neck of the fetus. Simply, whenever a fetus’s umbilical cord crosses itself 360 degrees
around the neck, it’s called a nuchal cord.
This increases the risk for entanglement, fetal distress and neonatal depression, and possibly prolonged labour or even fetal death.
Thin or ‘lean” knot:
This is called Thin-cord syndrome which is characterised by reduced or completely absent Whartonʼs jelly.Whartonʼs jelly surrounding the three umbilical vessels offers a flexible protective layer against vessel compression, kinking and other mechanical forces, and hence, assuring the fetal blood supply and removal of metabolic waste products. With deficient or absent Wharton’s jelly, the umbilical cord is drastically exposed to dangers.
Thick knot:
Umbilical cord is naturally designed in a way to regulate blood flow. Therefore, the thickness of the cords can disrupt circulation.
Single umbilical artery (SUA):
This tends to cause disturbance in the fetal blood flow leading to fetal distress and stillbirth. SUA occurs in two forms: a helical form and a straight form.
The absent left or right umbilical artery is linked with increased risk of fetal abnormalities. SUA is found to be common in twins and diabetic pregnancies, and also with long cords and small placentas. Single umbilical artery may indicate kidney abnormalities.
Abnormal insertions of the cords: These may occur as:
- Battledore insertion of cord: This is the connection of the cord to the edge of the placenta. It is called a marginal cord insertion. If a marginal insertion is against the sacrum (lower backbone), there is increased risk of compression and fetal circulation disruption as the fetus descends into the pelvis. This leads to fetal distress and may call for an emergency C-section.
- Furcate cord insertion: This is when the cord does not connect to the placenta, but its branching elements do.
- Velamentous insertion of cord: This is a membranous insertion of the cord. When the membranous insertion is over the cervical opening, the risk of tearing and fetal blood loss is increased.
True Knots:
True knots is a rare cord anomaly occurring in 0.5% of all pregnancies. True knot is the abnormal twisting of the cord leading to disturbances in blood flow and it may be single, double, or triple. True knots are associated with hematomas.
Fetuses with true umbilical knots are at high increased risk of fetal hypoxemia and intrauterine death due to constriction of blood vessels.
Probably, true knots develop early in pregnancy when intrauterine space is available for excessive fetal movement
As the fetus grows, a true knot may tighten or tightening may occur at delivery when the umbilical cord undergoes traction. The constriction or hematoma development may lead to fetal hypoxia, neurologic impairment or fetal demise.
Etiologically, true knots are linked with conditions(risk factors) that allow for increased fetal movement including multigravidae, long cord length, male fetuses,small fetuses, monoamniotic twins and increased amniotic fluid(polyhydramnios).
Cord torsion:
Torsion is an anomaly of umbilical cord where twists are superimposed on the cord itself like an overly twisted telephone cord. Note that torsion is not a natural state of the umbilical cord and hence,torsioned cords must never be likening to naturally helical, coiled, or spiraled cords. Knots and nuchal cords do not usually accompany torsion, but they can be observed with torsion.
The harmful effect of torsion on the fetus ranges from heart failure to stillbirth owing to disrupted blood flow.
Absent umbilical cords:
This is a rare cord anomaly. If the umbilical cord does not develop, the fetus can develop but can be malformed. The fetus is directly attached to the placenta at the abdomen and usually develops defects. Fetuses without cords have been born by C-section. Without an umbilical cord, life is usually not possible.
Short cord (<40):
A short cord has found to be associated with increased risk for fetal malformations, umbilical vein and arteries to tears, which can lead to hematomas (vessel rupture of the cord, fetal distress and death, stillbirth risk especially with relatively short cords which can be more heightened in the presence of other factors like toxemia, maternal labor and delivery complications, including retained placenta, uterine inversion(inside out and a medical emergency) can occur from traction on a short cord, placental abruption and prolonged labour due to poor fetal descent seen in short cord accruing operative vaginal delivery (forcep, vacuum extractions or even cesarean section).
Short cords and cigarette smoking tend to result in small babies, called IUGR
(intrauterine growth retarded).
Moreover, restricted fetal movements and when they occur, may predispose the cord vessels to compression/constriction, thrombosis, hemorrhage, or hematoma formation.
Relatively short cords interfere with the mechanics of labor and delivery while exhibiting changes in fetal heart rate patterns. Short cord is believed to be associated with placental trisomy 16.
Long cord (>60):
Excessive lengthy cords are found to be associated with cord entanglements around the neck and body, cord prolapse (slip out of the womb),
emergency deliveries and fetal thrombotic vasculopathy in the placenta, fetal death and increased risk of neurological complications.
Long cords can enter the fetal mouth acting as ”pacifier” or the fetus handles the cord like a toy. This may result in cord blockage during the sucking and handling thereby affecting the fetus.
Risk factors associated with long umbilical cords: Naturally, male cords tend to be longer than female cords, and term vertex fetuses may have longer lengths than term breech fetuses (with the duration of presentation unknown).
Multigravida cord length may be longer than primigravida cord length (the first pregnancy having a shorter length than the third, this may imply more room for movement-tension or more blood supply/hormone production/fetal and maternal weight gain).
Multifetal pregnancies may have fetuses with discordant lengths and shorter lengths than singletons.
Patent urachus:
This results in fistulous or abnormal connection of the bladder with umbilicus.
Variable umbilical cord-vessel number: These are rare though reports had shown presence of four vessels,five vessels,
fused cords in twins, and two-vessel cords which are associated fetal conditions.
Hematoma of the umbilical cord:
This is due to bleeding into the substance
of the umbilical cord which can be spontaneous, iatrogenically induced, traumatic self-induced, or secondary to an umbilical cord defect. Hematomas can result from the umbilical artery or umbilical vein obstruction. Cord hematoma impairs proper perfusion of the fetus via the umbilical vessels.
Bleeding cord:
This is not really a cord anomaly. It occurs either because the cord was forcefully pulled, or loosened clamp or haemorrhagic disease of the newborn due to vitamin K deficiency . This can lead to death if not properly managed urgently.
Omphalitis:
This is an infection of the umbilicus and/ or surrounding tissues primarily occurring during the neonatal period.
It may result from contacts of the umbilical cord with excreta predisposing to microbial invasion, especially E. Coli. Omphalitis may be characterized by foul smelling drainage.
Management of Omphalitis
Treatment of omphalitis involves the following:
- Get swab for culture and sensitivity test.
- Broad spectrum antibiotics can be instituted while waiting for the result of the test. Combination of parenterally administered antistaphylococcal penicillin and an aminoglycoside antibiotics (e.g gentamicin) is commonly prescribed for uncomplicated omphalitis. Or use of intravenous antimicrobial therapeutic agents like clindamycin or metronidazole.
- When results come, treat according to sensitivity. If the infection is severe, refer to expert care.
- Observe cord care as explained above.
- Maintain adequate nutrition for the baby.
Other cord abnormalities
These anomalies include umbilical artery angioma/aneurysm,umbilical teratoma,Wharton’s jelly cyst,cord entanglement, bifurcation of the blood vessels, and tumors in Wharton’s
jelly. Most of these cord anomalies are rare, but when they occur, can disrupt vessels and blood flow.