True Knots: a Rare but Genuine Danger
There are two types of knots that can form in a baby’s umbilical cord: true knots and false knots.
False Knots (Pseudoknots)
On an ultrasound, any bulge or protuberance in the baby’s umbilical cord is likely to be a false knot. These “knots” are actually slight variations in the cord’s anatomy, usually formed by swollen blood vessels or an excessive covering of Wharton’s jelly.
Small pseudoknots are relatively common in pregnancies. They can’t be untangled (because it’s a formation inside the cord, not outside), but luckily, they have no clinical significance and do not present a danger to the baby.
Like the name, a true knot forms when the umbilical cord loops or interweaves around itself. They can form during pregnancy (when the baby’s active and moves around in the amniotic fluid) and during birth. By definition, these cords can be manually untangled because they’re knotted on the outside of the umbilical cord.
Cords knots occur in less than 2% of pregnancies. Most are relatively loose and don’t present a problem.
However, if your baby’s umbilical cord gets a knot early on, the baby’s growth and future movements can tighten the knot, squeezing off blood and oxygen to the baby. True knots get more dangerous the closer a baby gets to birth, and in a worse-case scenario can cause asphyxia, leading to brain damage or death. Tight knots have a mortality rate of 10%.
How Does the Umbilical Cord Get Knotted?
Early on in pregnancy, the baby has lots of room to move around the womb. As he does, he can loop and drag the umbilical cord into a knot. Doctors believe that most true knots are formed between 9–12 weeks of pregnancy—and, strangely enough, during labor! Some factors that seem to lead to the formation of true knots include:
- Older mother
- Male baby
- Small baby
- Active baby
- Long umbilical cord
- Excessive amniotic fluid in the sac
- Second or subsequent pregnancy
- Multiple babies in utero
During labor, knots are formed or tightened as the baby moves around, getting positioned for birth. Doctors should be on the lookout for any sign of fetal distress (non-reassuring fetal status), because that could indicate a tight knot.
Looking Out for Cord Knots
There is nothing mothers or doctors can do to prevent umbilical cord knots from forming, but keeping an eye on your baby’s movements can help.
Decreased fetal activity is usually the first sign that something’s wrong. If it’s an early-formed true knot, problems will show up around week 37—the baby won’t be as active, and may be in distress. The knot can stunt growth and development, and decrease the amount of blood flow to and from the baby.
If the knot forms during the birthing process, then the fetal heart monitor (cardiograph) should show an abnormal heart rate—and doctors can take appropriate steps to address it. C-sections are recommended to take the pressure off the true knot and get the baby out immediately, before he loses too much oxygen and irreversible damage sets in.
What More Can Modern Medicine Do?
Many cases of umbilical cord knots are not diagnosed before birth, despite the widespread use of ultrasound during pregnancy.
Doctors now know that mothers-to-be who have amniocentesis (a procedure where a small amount of amniotic fluid is withdrawn and tested for genetic defects), gestational diabetes, and hydramnios (excess amniotic fluid) are more likely to have cord knots. Early and thorough examination is the best prevention.
A National Institute of Health study recommends, “Four-dimensional and Color Doppler examination is very important to diagnose a true umbilical cord. To make a precise diagnosis a longer observation of the abnormality is necessary and its repeated confirmation by color Doppler and power Doppler. This diagnosis requires strict monitoring of fetal well-being during pregnancy and the delivery.”
Until all cord knots are easily diagnosable (and fixable), doctors and medical staff have to remain vigilant and look for this specific complication throughout pregnancy and birth! There is no excuse for negligence—not when the price is this high.
If Your Baby Was Harmed by an Umbilical Cord Knot
If your doctor or medical provider missed a true knot and your baby was born with an injury, you can contact Brown Trial Firm for a free consultation. Attorney Laura Brown has dedicated her time and energy to helping children and families who suffer from preventable medical mistakes.
- Radiopedia: False Knots
- DoveMed: True Knot of Umbilical Cord
- Pathology Outlines: Placenta Knots
- National Institutes of Health: True Umbilical Cord Knot
- National Institutes of Health: Diagnosis of True Umbilical Cord Knot