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Variations, Placentas, and Cords

Posted Nov 14 2012 9:00am
Yes, as you have probably guessed, I love placentas , cords , and all of the things about pregnancy and birth that most people will think are a little 'icky'. Just like with birth though, every cord and placenta carries their own characteristics and variations. Since I handle a large number of placentas (as a doula, midwife assistant, and placenta encapsulationist), I get to see lots of different types of placentas. I have seen all of the variations we are going to discuss, and it never fails to astound me how perfectly that normal, natural, physiological labor and birth is designed, even when confronted with variations like the ones we will be looking at in this post.

As I stated in an earlier post, the placenta is a vascular organ. The word placenta comes from the Latin for “cake”. It is the only organ that is grown to be temporary, and sheds itself after its primary use is finished. Placental development and circulation begins 3 weeks after implantation. There is both a fetal and a maternal component to the placenta, so it is actually a product both of conception and the mother’s body as well. The placenta attaches to the baby through the umbilical cord. The cord inserts into the placenta via the chorionic plate. On the fetal side of the placenta, vessels branch out over the surface and divide to form a network covered by a thin layer of cells. On the maternal side, these villous tree structures are grouped into lobules called cotyledons.

As I stated in an earlier post, normally, an umbilical cord has two arteries and one vein and, at term, is around 22-24 inches long. These are all wrapped up in a beautifully plump, purple, rich cord of three. Surrounding, insulating, and protecting everything is a substance called Wharton's Jelly . The arteries return deoxygenated, nutrient-depleted blood from babe to the placenta, where it will be reoxygenated and replenished with vital nutrients to be recirculated through the one vein back to babe again. Wharton's Jelly is a substance that, when exposed to extreme changes in temperature, begins to expand and, as a result, occludes and collapses the vein and arteries... physiologically clamping the cord within an average of 5-20 minutes after birth. Wharton's Jelly contains a great many types of stem cells. The umbilical cord is attached to the placenta 'on the fetal side, usually in the center of the placenta.

Some variations to the placenta and cord can include
Marginal, or Battledore, Insertion - whereas the cord usually implants more central to the body of the placenta, Battledore Insertion refers to a marginal (along the edge) insertion to the placenta. (you can also see some infarcts on the placenta body).

Kristin Beckedahl of
Velementous Insertions are a variation where the cord doesn't implant into the body of the placenta at all, but instead implant into the membrane, trailing through them to the placenta. This is more likely to occur in older women, women with diabetes mellitus, and smokers.
Furcate Insertion refers to the absence of Wharton's Jelly, a protective coating, before it inserts into the placenta.

Circummarginate placenta is the term used when a thin ring of fibrous tissue surrounds the placenta on the babies side, like a halo.

Similarly, but not the same, a circumvallate placenta is when the membranes themselves double back over the babies side of the placenta, and the chorionic plate is too small. Unfortunately I don't  have a picture to correspond with this one.

Succenturiate, or Bi-Lobed, Placenta is when a portion of the placenta is separate from the rest of the placenta, with trailing vessels running between the two through the sac.

True Knot. Now, this one is just really REALLY cool. In most instances, a true knot is A knot; this one was knotted 5 times. A true knot is when babies movements result in a truly knotted cord.

False Knot refers to a small outgrowth on the cord where the vessels twist through them before realigning in the main cord again.

Placenta Infarction is simply dead tissue. Infarcts result from no blood supply to that particular part ofthe placenta. Small infarcts are expected around the due date, as they show the placenta is aging and baby is due to be born. Large infarcts are associated with hypertension.

  • Battledore Insertion - The cord is more prone to compromise, which is why it is in the best interest of baby to leave the water intact as long as possible, refrain from the use of labor stimulating drugs and herbs, and refrain from cord traction in the third stage of labor (placenta delivery).
  • Velamentous Insertion - There is a definite increase in risk for baby during labor and birth due to the fact that the vessels run, unprotected, through the thin sac. They are at a greater risk for tearing, thrombosis, and compression.  AROM has a higher chance of nicking/tearing through one of the vessels, causing massive hemorrhage, whereas SROM will usually occur at another location other than the vessel implantation site.
  • Furcate Insertion - Because they don't have the protection of the Wharton's Jelly, furcate insertions have a higher incidence of thrombosis and tearing. One way to reduce the risk of tearing is to refuse cord traction in the third stage of labor and to keep the bag of water intact as long as possible during labor. 
  • Circummarginate placenta there is a slight increased risk of placental abruption from circummarginate placenta, but again, can be reduced by not artificially starting or speeding up the process, as well as not forcing the delivery of the placenta in 3rd stage.
  • Succenturiate Placenta - there is an increased risk of postpartum  hemorrhage and retained placenta, which is why careful and patient management of third stage is very important. Judicious use of fundal pressure, oxytocic medications, and cord traction.
  • True Knot - True knots, in and of themselves, do not pose a large risk to baby. Wharton's jelly and the length of the cord will normally allow for minimal risk. When there are other variations, like additional cord anomalies, short cords, induced and augmented labor, or an extremely tight knot, baby may experience heart decelerations and be at risk. The best management is to monitor baby during labor and not try to induce or augment labor.
  • False Knot - This varicosity is a non-issue for labor and birth and doesn't affect labor/birth/baby in any way.
  • Infarct - Small, medium, and large infarcts are a non-issue. Extremely large ones can result in placental blood flow insufficiency, which can compromise babies health, with or without labor. 
  • Calcium Deposits - They can be a result of too much calcium in the diet prenatally (think habitual Tum's consumption), although they are also attributed to smoking in pregnancy or an aging placenta. This does not normally cause any issues in pregnancy and labor/birth unless there is an abnormally large amount of calcification that might restrict blood flow through the placenta or cause the placenta to detach prematurely or in pieces postpartum. If it is going to be an issue that might require induction, other indicators would include lower amniotic fluid, and IUGR, among others. Also, patience with third stage will reduce the risk of the placenta coming out in pieces. 
 As I said before, I have seen a lot of placentas and a lot of variations. Risks occur rarely when the  body and design of labor and birth is trusted and respected. As birth attendants, we should honor normal, natural, physiological labor and birth in as many cases as possible, so as to minimize risk and assure to not compound any risk already present.

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