How Dangerous Is an Umbilical Cord Around the Neck?

Umbilical cord around the neck is very common in obstetric clinics, accounting for about 20% to 25% of total births. The cause is related to too long umbilical cord, small fetus, excessive amniotic fluid and frequent fetal movement. Most of them are around the neck for 1 to 2 weeks, and it is rare for more than 3 weeks, and the literature reports up to 9 weeks. The umbilical cord has a compensatory stretch, loose winding has little effect on the fetus, tight winding and multiple turns can affect the fetal blood supply, and there is a risk of changing the fetal heart, perinatal hypoxia, asphyxia and even death. In fact, the key factor affecting the prognosis is not the number of laps around the neck, but the length of the umbilical cord left around the neck. If it is only about 1 week but the relative length is too short, it can still cause a painful ending. Due to the relative shortening of the umbilical cord, it is not uncommon for the fetal exposure to decline after labor, and umbilical hernia, uterine inversion, placental abruption, and umbilical cord rupture are not uncommon. Occurred in a single amniotic sac twin is more dangerous.

Basic Information

English name

nuchal cord

English alias

cord around neck, circular of umbilical cord

Visiting department

Obstetrics and Gynecology

Common causes

Umbilical cord is too long, small fetus, too much amniotic fluid, frequent fetal movement

Common symptoms

Fetal heart changes, perinatal hypoxia, etc.

Contagious

no

Causes of umbilical cord around the neck

When the umbilical cord is too long, the fetus is too small, too much amniotic fluid, and fetal movement is frequent, umbilical cord around the neck is prone to occur. When the umbilical cord is wrapped around the fetal body, and the fetus passes through the umbilical collar to form a true knot, it is very likely to cause lack of blood supply to the fetus, resulting in ischemia and hypoxia. Umbilical cord prolapse easily occurs when the exposed part of the fetus cannot be connected. Mostly due to abnormal fetal position, high fetal head, or cephalopelvic disproportion, too small fetus, too much amniotic fluid, too long umbilical cord. The reason for the umbilical cord around the neck: The umbilical cord around the neck is related to the length and fetal movement, such as more automatic eye rotation or external inversion of the fetus can cause it. The umbilical cord around the neck of a full-term child for one week requires an umbilical cord length of 18-20cm. The more perimeters around the neck, the longer the umbilical cord, but short umbilical cords can also occur around the neck.

Because umbilical cord around the neck is very common, it does not mean that the umbilical cord around the neck means a high-risk pregnancy, but you need to be aware of the adverse effects of the umbilical cord around the neck on the perinatal child. Perinatal morbidity and mortality can be significantly increased; strengthening prenatal and postnatal fetal monitoring, and choosing the right delivery method can reduce perinatal perinatal perinatal mortality and mortality.

Umbilical cord around neck examination

B-ultrasound is the only way to diagnose umbilical cord around the neck, but the accuracy of ultrasound diagnosis is not completely reliable. Even an experienced sonographer may misdiagnose or miss the umbilical cord around the neck. Doppler ultrasound can provide hemodynamic information of umbilical vessels, including parameters such as blood flow velocity, resistance index, pulsatility index, etc., and provide a strong basis for judging whether the fetus with umbilical cord around the neck has intrauterine distress.

Scanning technique

Routine inspection When the umbilical cord is suspected to be wound, the probe is scanned along the longitudinal axis of the carcass, and the probe is rotated to both sides. With this part as the axis, slide the probe as much as possible for an arc scan. Compensation scans are performed on the upper and lower sides.

2. Ultrasound performance

There is a dent on the surface of the fetus. One week is a "U" type, and two weeks is a "W" type. It can be arranged in parallel or overlapped for more than two weeks. The skin indentations have different manifestations. The umbilical cord extends rearwardly and laterally at this part. When it is determined that the umbilical cord is wound, if the umbilical cord is floating and is at a distance from the surface of the carcass, and there is a tortuous floating umbilical cord echo in other parts, it means that the winding is loose. The umbilical cord is close to the winding part, the amniotic fluid is not easy to detect and the umbilical cord echoes, or the umbilical cord is stretched and pulled, it should be regarded as too tight or the umbilical cord is too short.

Precautions for ultrasound diagnosis of umbilical cord around the neck:

(1) The time of umbilical cord around the neck for ultrasound diagnosis should be selected before labor. The closer to birth, the more reliable the result (97% accuracy). The umbilical cord wound due to fetal activity before 30 weeks of pregnancy can be released or re-wound by itself (80% accuracy).

(2) It is found that the signs of umbilical cord around the neck are accompanied by fetal bradycardia or irregularity, which indicates fetal distress and urgent measures should be taken in time.

(3) Display the long-axis section of the fetal neck and back as clearly as possible during the examination. The cross-section of the neck should try to include both sides of the neck and the ventral side, and look for umbilical cord crossing.

(4) The probe should not be pressed against the abdominal wall during the scan to prevent the amniotic fluid around the fetal neck from being squeezed and reduced, which will affect the diagnosis.

(5) The neck U-shaped impression should be distinguished from the V-shape formed by skin folds at the junction of the neck and shoulders of slightly fat fetuses, and attention should be paid to the near-field accumulation and the prevention of artifact interference.

(6) The presence of U-shaped indentations on the neck and back and color blood flow are not sufficient to confirm the diagnosis. To be sure at the same time colored blood flow or W-shaped impression on the ventral side of the fetus. Because the umbilical cord can be passed around the cheek, anterior orbit and shoulder, not around the neck.

(7) When the pregnant woman is in the lying position, it is not easy to distinguish the umbilical cord around the neck due to less amniotic fluid. The standing position scan can be used instead. The gravity relationship causes the amniotic fluid to accumulate below the amniotic cavity to form a sound transmission window.

Umbilical cord around neck diagnosis

With the popularity of B-ultrasound, this technology is often due to the prenatal diagnosis of umbilical cord winding. In addition, the method of electronic fetal heart monitoring can also help diagnose the existence of umbilical cord winding problems, especially during labor, frequently listening to the fetal heart , Or fetal heart rate monitoring, can know in time whether the fetus is in a dangerous situation, the doctor can make timely judgments based on this information and decide how to deal with it.

Umbilical cord treatment and monitoring

Routine monitoring

The monitoring of the umbilical cord around the neck is consistent with normal pregnancy monitoring, and does not need to cause too much panic. Pregnant women also need regular checkups, and learn to count fetal movements. When there are too many or too few fetal movements, they should go to the hospital in time for examination. Routine listening to the fetal heart is not recommended for pregnant women because normal or abnormal changes in the fetal heart require professional analysis. Listening to the fetal heart on its own often causes excessive misunderstanding, psychological anxiety, and unnecessary intervention.

2. Delivery method

Umbilical cord around the neck is not an indication of cesarean section. Because the incidence of umbilical cord around the neck is high, it does not mean pathological conditions. Intensive monitoring during labor will not increase the prevalence of fetuses / babies with umbilical cord around the neck.

You can confirm the diagnosis of umbilical cord pressure on the body of the fetus by B-ultrasound, check whether the entanglement affects the health of the fetus, and observe the change of the fetal heart rate by electronic fetal monitoring. , It should be considered that the umbilical cord is pulled and squeezed. The treatment of umbilical cord winding is mainly based on the progress of the labor process and the degree of impact of the winding on the fetus. At the beginning of the labor process, the fetus already has hypoxic manifestations, and cesarean section should be performed immediately. When the abnormality is discovered in the second stage of labor, the fetus should be delivered quickly. When the umbilical cord is found to be too tight, it should be clamped and cut off immediately.

3. Other progress

In the second trimester of pregnancy, the resistance index of the middle cerebral artery (MCA) and umbilical artery (UA) of the umbilical cord around the neck is better than the resistance index. It is of important clinical value to make a diagnosis before distress.