Umbilical knot

definition

The umbilical cord knot is a dreaded complication during pregnancy and delivery. Increased childlike movement in the womb can twist or knot the umbilical cord.

In the umbilical cord, blood vessels run from mother to child and back again. As a result, the child is supplied with oxygen and nutrients from the mother and metabolic products from the child are transported away via the maternal blood. The umbilical cord is built up in a spiral to prevent the blood vessels from kinking. In most cases, umbilical cord knots are only loosely wound, which does not affect blood flow.

If the umbilical cord is continuously and strongly pulled, as is the case with childbirth, the knot can pull itself and thus severely limit or completely interrupt the care of the child. In the worst case, an umbilical cord knot leads to the death of the child in the womb. A symptomatic (= contracted) umbilical cord knot is an absolute emergency and an emergency caesarean section must be performed immediately.

How common is there an umbilical knot?

The umbilical cord knot is a very dreaded complication in obstetrics. A distinction is made between a single looping, which occurs in 20% of all births and usually does not cause any complications, and a multiple looping of the umbilical cord, which occurs in <1% of births, the risk of complications is significantly increased here.

A real umbilical cord knot is found in 1-2% of all births. This occurs when the baby slips through a loop in the umbilical cord while making the movements.

causes

An umbilical cord knot usually results from strong childlike movements in the womb. The amount of amniotic fluid also plays a major role. At the end of pregnancy, 800-1500ml of amniotic fluid should surround the child.

If the amount of amniotic fluid is over 2000ml one speaks of a polyhydramnios (amniotic fluid addiction).The child has more space to move around and to turn around the umbilical cord, which can lead to knots. Another risk factor is a longer umbilical cord, which has more leeway and the child can even wrap around it several times.

diagnosis

An umbilical cord knot may be seen on ultrasound in the form of a larger swelling. Most of the time, however, it goes undetected during pregnancy and is only noticed when it becomes symptomatic.

During pregnancy, the kinking of the umbilical cord leads to an insufficient supply of the child, which is noticeable in the child's decreased movements. In this case, a CTG check must be carried out immediately. In the CTG (cardiotocography = recording of the child's heart sounds and maternal contractions) one can see a decrease in the child's heart rate (bradycardia). However, a falling heart rate can also have other causes.

If there is a suspicion of an umbilical cord knot, the blood flow in the umbilical cord or placenta and in the child can be measured with the help of Doppler sonography, thus showing constrictions. The diagnosis of umbilical cord nodes can ultimately only be made after birth.

These symptoms can be used to identify an umbilical node

If a real umbilical cord knot occurs, the child is acutely insufficiently supplied with oxygen (hypoxia). This represents an absolute emergency situation.

The fetal organism cannot compensate for this condition for a long time and reacts quickly with a change in heart rate. Typically, the fetal heartbeat is 140-160 beats per minute. At the beginning there may be an increase in heart rate> 160 beats per minute (tachycardia), but in the course the cardiac output decreases rapidly and bradycardia develops <110 beats per minute (decrease in heart rate).

It is the same with the child's movements. The child reflexively tries to get into a position in which it receives better care. However, in the case of an umbilical cord knot, this can even cause the knot to deteriorate and tighten. With persistent undersupply, the child's movements gradually decrease until it no longer moves.

Treatment / therapy of an umbilical cord knot

The umbilical cord has a spiral structure so that if there is a loose knot, the blood flow in the vessels is usually not affected. In this case, no acute therapy needs to be initiated.

The knot cannot be loosened from the outside and in the rarest cases the knot loosens by itself. The child must therefore be closely monitored with the help of a CTG and ultrasound.
If the child is mature, early induction must be considered. The birth should only be carried out by caesarean section, as in a spontaneous birth the knot is tightened by pulling on the umbilical cord.

An external twist should not be used if an umbilical cord knot is suspected, as further movement of the child can tighten the knot. Once the umbilical node becomes symptomatic, i.e. the child's heart rate drops, therapy must be initiated immediately.

An emergency caesarean section (Caesarean section) must be performed immediately. Due to the squeezed umbilical cord, the child does not receive any oxygen-rich blood from the mother; this condition leads to severe under-supply within a few minutes, which has serious consequences, especially for the development of the child's brain. If a real umbilical cord knot is suspected, the pregnant woman is immediately taken to the operating room and general anesthesia is initiated.

As soon as the mother sleeps, the child is born via an abdominal incision. The child is cut off by the mother and can develop its lungs and take in oxygen by screaming vigorously or by assisted ventilation.
Depending on which week of pregnancy the birth was initiated or how long the lack of oxygen lasted, the newborn may need further intensive medical treatment. In any case, the child must be carefully examined by a pediatrician and monitored for several days.

Read more about: Caesarean section

These can be the long-term consequences of an umbilical cord knot

The child is supplied with oxygen and nutrients by the mother via the vessels that run in the umbilical cord. If the vessels are squeezed off, there is an acute undersupply. The child's brain in particular is very sensitive to a lack of oxygen. Serious brain damage or even intrauterine (in the uterus) death of the unborn child can occur.

If the supply is permanently limited, there are considerable growth delays, organ malformations e.g. Heart defects with subsequent cardiac insufficiency or kidney malformations and kidney failure.
In addition, the risk of necrotic enterocolitis, a severe inflammation of the bowel, increases after birth. In severe cases, parts of the intestine must be removed.

The risk of sudden infant death syndrome, neurological diseases such as epilepsy or psychological diseases such as attention deficit disorder (ADHD) or eating disorders also increases.

This is how you can prevent an umbilical cord knot

Umbilical cord knots cannot be prevented or strengthened from the outside. If a number of risk factors are present, regular checks may reveal the formation of an umbilical cord knot and the monitoring of the unborn child can be intensified.

In the rarest of cases, however, an asymptomatic lump can be discovered during the preventive medical check-ups. Most lumps remain symptom-free until birth. You do not need to do without exercise or sport.

What is a false umbilical cord knot?

A false umbilical cord knot is a looping of the vessels within the umbilical cord or a local thickening of the umbilical cord (Wharton's jelly), which resembles a knot on ultrasound. With a wrong umbilical cord knot, however, the blood flow is not restricted and there is no undersupply. Therapy does not have to be initiated and the birth can take place naturally.