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To Clamp, or Not To Clamp, This Is the Answer

By G. M. Morley, MB ChB FACOG

After reading many pages about cord clamping, most expectant parents will be confused about what to tell their doctor or midwife regarding cord clamping. The normal, healthy newborn with millions of years of experience in its genetic code, clamps its own cord, usually within two to four minutes of birth. After natural closure, the doctor’s cord clamp may be safely applied. How does one know that the child has clamped all of the three cord vessels?

  1. There are no pulsations in the cord. (The arteries are closed.)
  2. The child is breathing and is pink. (The heart is two sided; lungs are working.)
  3. The cord vein at the umbilicus is bloodless. (It is the largest of the three vessels.)

At this stage, with all vessels closed, the rest of the cord vein is often divided into sausage like segments of blood, while the arteries are white streaks.

The color of the child is best determined by the color of the lips and tongue. If these are blue or purple, the cord should not be clamped; a bluish color indicates that the heart has not yet converted from the fetal to the adult circulation. If a child is crying and blue, blood is not flowing through the lungs and is not absorbing oxygen; even if the cord is no longer pulsating, it should not be clamped as more placental blood transfusion through the cord vein may be needed to fill the lungs’ blood vessels. Uterine contraction or gravity will effect this.

All mammalian babies are naturally delivered downwards, and blood tends to run into the newborn from the placenta. Most human babies are delivered in bed, the best position being MacRoberts’ with the knees held up near the chin. The child should not be placed on the mother’s abdomen immediately, as this may cause blood to flow back into the placenta. Cord pulsations normally persist until the child is crying or breathing, and the child is in no danger of asphyxia while the cord is pulsating at over 100 beats per minute. Bulb suction clearing of the newborn’s mouth and nose is done with the child still attached to the placenta between the mother’s legs on the bed.

Everyone, of course, wants to hear that first cry that brings smiles to all the surrounding faces. Air in the lungs opens up the lung blood vessels. What makes babies cry when they are born?

Every child is born soaking wet, and on entering the planet’s atmosphere, water evaporates and the skin cools, and babies yell – as they do when they have cold, wet diapers on their bottoms. Grown men, on entering a cold shower, take a very deep breath and start to sing opera; on entering the cold world, wet babies do the next best thing, reflexively. At baptism, cold holy water on the head produces crying from the child and smiles on the relatives’ faces. A cold, wet sponge applied to a newborn will usually induce crying which fills the lungs with air and blood if the cord is open. An alcohol pad applied to the abdomen has the same effect. [1]

The politically correct method of resuscitation places the newborn in a warmer that simulates the inside of the uterus. This environment tells the child’s reflexes not to breathe and cry, and not to convert the heart to two sides as oxygen is available from the placenta. The only problem with this situation is that the placenta is not in the incubator, it usually has been thrown away, and there is no placental oxygen to keep the brain alive. For millions of years, newborns’ skins have cooled after birth. They have adapted to that problem very well by crying and yelling and making their mothers pick them up to keep them warm at the breast while the placental circulation has kept them warm and oxygenated in the interval. A newborn that is hypothermic (has a low temperature) is usually in hypovolemic shock following immediate cord clamping and is in need of a blood transfusion.

Never clamp the pulsating cord of a child that is not breathing and pink; if the child is slow to cry, put a cold diaper on its bottom or an alcohol pad on its abdomen. This usually is more effective and more natural than rubbing with towels or spanking the feet.

At cesarean section, the problem of cord clamping is more complicated. Uterine contraction seldom delivers the child and seldom transfuses the child immediately. Gravity also seldom transfuses the child which, when delivered, is usually placed on the mother’s abdomen above placental level; blood tends to flow back into the relaxed uterus. Landau kept the placenta and cord intact and hung up the placenta like an I.V. to give the child as much blood as it would accept. This produced very healthy newborns.[2] An alternative solution is to give pitocin I.V. during the cesarean delivery to contract the uterus so that blood is forced into the child soon after delivery. Having the uterus contracting or in labor before the cesarean is started helps the placental transfusion during and after delivery. The same parameters for cord clamping are then applied as for vaginal delivery. The cord may be safely clamped after:

  1. There are no pulsations in the cord
  2. The child is breathing and is pink
  3. The cord vein at the umbilicus (the largest of the three vessels) is bloodless.

If there is any doubt about these conditions, it is usually safe to leave the cord alone until the placenta is delivered.

There are few exceptions to the above; in general, there should be no interference with a vigorously pulsating cord that is filled with blood. Lack of breathing, however, should not be treated with complacency. Uterine contractions will eventually separate the placenta from the uterus and placental oxygenation will then cease. This may occur in as little as five minutes, and if the child is not breathing or crying within one or two minutes of birth despite placental transfusion, stimulation, and drugs to counter narcotics, efforts to ventilate the lungs such as bag-masking or even intubation should be started.

Newborn Resuscitation

A very depressed baby may not respond to cold and stimulation, and artificial ventilation may be needed. It is extremely important that placental oxygenation and placental transfusion be maintained (the cord should NOT be clamped) during resuscitation. If heart tones disappear during delivery and the child has no heartbeat at birth, all available cord blood should be milked into the child; this may re-start the heart. If the heart rate is very slow at birth, the child should be lowered below the level of the placenta to allow gravity to fill the child with oxygenated blood from the placenta.

There are two rare situations when the cord should be clamped immediately:

  1. Bleeding from a ruptured cord at birth.
  2. Following a very "dry" birth when the cord and placenta contain little blood.

The first is usually very obvious and is quickly stopped by closing the bleeding cord between finger and thumb. All blood in the cord should be milked (stripped) into the child and the cord clamped immediately. This same treatment is used at cesarean section for placenta previa when the placenta has to be incised to deliver the baby.

The second, following oligohydramnios (no fluid around the baby), results in a very dehydrated newborn in very poor condition, usually heavily meconium stained. In these cases, the cord is visibly quite empty, and the vessels may appear as three thin streaks of blood due to cord vessel narrowing. In both the above cases, placental transfusion is not available, and immediate clamping is needed for insertion of a catheter into the umbilical vein for immediate transfusion of fluids and blood volume expanders. A neonatologist who is familiar with what normally occurs with a child’s cord and placenta immediately after normal birth is best qualified to handle these situations. Amnioinfusion (replacement of amniotic fluid) during labor may alleviate the second condition to a great extent before birth.

Neonatologists may demand immediate clamping for timely ventilation at the resuscitation table; however, timely presence of the neonatologist at the delivery or operating table is much more appropriate, especially with meconium contamination of the airway.

DeLee (long tube) suction to clear the mouth, esophagus and naso-pharynx is done before delivery of the shoulder. After birth, with placental respiration intact and with an assistant positioning the apneic child, the vocal cords are readily visualized without panicked haste; an umbilical cord pulse rate of over 100 indicates adequate oxygenation, and removal of carbon dioxide by the placenta delays the first inspiratory gasp and allows tracheal clearing of meconium. [3] When ventilation is established, the child with an adequate blood volume rapidly turns a ruddy pink color; placental oxygenation avoids any asphyxia.

Immediate clamping of the apneic newborn causes complete asphyxiation until the lungs function, and rapid build up of CO2 hastens the first gasp that aspirates meconium. Without placental transfusion, adequate establishment of the pulmonary circulation may not occur; [4] without blood flow to absorb oxygen, ventilation is futile. Very low five minute Apgar scores and neurological deficits [5] result from immediate clamping and failed resuscitation. [6]

If any physician cannot believe that the child clamps its own cord very well, the following exercise should convince any doubting Thomas. After the above three parameters for cord closure are well established, and before placing the clamp on the cord, try to strip some blood from the cord next to the umbilicus into the child; it is very difficult to do so and the high pressure may rupture the cord vein. The child’s clamp has effectively stopped the contracting uterus and gravity from giving the child too much blood. Now strip blood away from the umbilicus for about six to eight inches; that segment of vein will remain empty – no blood is flowing from the child. Cut the cord (without clamping) six inches from the umbilicus. The cord will not bleed. The child’s clamp is keeping the right amount of blood in the child to make the lungs work. Even though the child’s clamp has millions of years of experience and guarantees behind it, the doctor will feel more comfortable if he now puts a clamp on those three large blood vessels that are not bleeding. That clamp does no harm.

Natural cord closure is a complex event that prepares the child for a healthy start to life outside the womb; good obstetrical care should preserve and ensure natural cord closure; it should not disrupt the process. Three clinical criteria are enumerated above which indicate that the cord vessels are closed and that the lungs are functioning. A cord clamp may be safely applied after these criteria are in place.


References:

  1. Charles D. Meigs M.D Professor of Obstetrics, Jefferson College. Philadelphia Practice of Midwifery, Second Edition. Page 192. C.H. Kay & co, Pittsburgh 1842
  2. Landau DB. Hyaline membrane formation in the newborn: hematogenic shock as a possible etiological factor. Missouri Med 1953; 50: 183.
  3. Oh, W. Walgren, G. Hansen, JS. Et al. The effects of placental transfusion on respiratory mechanics of normal term newborn infants. PEDIATRICS 1967; 40:6-12
  4. Morley, GM. LETTERS. OBSETERICS & GYNECOLOGY Vol.97 No. 6, June 2001, 1024-1026
  5. Thorngren-Jerneck, K. et al. A population-based study of one million live births. OBSTERICS & GYNECOLOGY Vol. 98, No, 1, July 2001. 65-70
  6. Morley, GM. LETTERS. OBG MANAGEMENT, May 1999, p.102-109

©Copyright George M. Morley, MB ChB March 8, 2002

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