Sunday, May 24, 2009

Nuchal Cord Response

Taking up your post from NB:
K-“Besides, it is just incorrect to say that cord entanglement cannot prevent a vaginal birth. ”

E-I don’t recall saying that. My point was that nuchal cord is not an absolute indication for c-section.

I quote from your comment of Feb. 12 @ 2:30 p.m., "As I said in a previous reply, the cord does not prevent descent, except in the case of *extremely* short cords, which is very rare."

***
E -- (This is an aside, but why is it that when defending home birth, HCPs like to scoff at anecdotal evidence as “not reliable,” but it’s perfectly acceptable for HCPs to use anecdotal evidence to support that one time this super rare horror story birth accident happened and intervention was justified?)
I'm not sure what this is pertaining to, since I'm not sure what "HCP" means. Please elucidate.

However, you said, as quoted above, that the cord does not cause problems with descent, and then in your comment on Feb. 21 @ 3:11 pm, you said, "However, I can tell you this: of the literally hundreds of birth stories I have read/heard/been told in the last year, I have known exactly -1- case of a true cord length issue. Yours might well also be one of those rare cases, but you must understand why I am skeptical of all the many, many women who claim that theirs was also that 'one rare case.'"

You presented the anecdotal evidence from "hundreds of birth stories" as evidence that this woman was wrong; I merely presented anecdotal stories as evidence that cord entanglement may be more prevalent than you realize. And I particularly used home-birth stories, because you repeatedly lay all the blame for every type of fetal distress on epidurals, pitocin, and other interventions (and you throw in a few rare placental or umbilical cord problems for good measure). These stories that I referenced indicate that it is not merely interventions which can cause fetal distress, but that cord entanglement can as well, without so much as a whiff of Pitocin or a suggestion of an epidural.
*****
K - “In many instances, this was in home births that were transferred to the hospital, so you can’t blame doctors and interventions for causing the problem, the way you seem to do on your blog post and ensuing comments.”

E: "I don’t believe I ever blamed doctors for causing nuchal cords? And just because they had fetal distress and a nuchal cord does not mean one caused the other. Correlation does not equal causation. Considering 99% of the research out there shows that pitocin and epidurals can cause fetal distress, and that there is no relationship between the incidence of nuchal cords and negative outcomes, I think it is a fair assumption to say that in a medicalized birth in which there was fetal distress, the distress was most likely due to the medicalization."
I didn't say that doctors caused nuchal cords (although there is a study showing that induction is a risk factor for nuchal cord). The "problem" I was referring to was fetal distress (which in certain cases can be caused by cord entanglements, including nuchal cords), which you only ever say happens if the mom has had interventions such as Pit or epidural, or in the case of rare umbilical or placenta problems, but never due to a cord wrapped around the neck, no matter how tightly.

Also, it's not anywhere near 99% of the evidence that shows no causation -- particularly in the area of tight nuchal cords and Type B nuchal cords. Secondly, if you are going to make "a fair assumption" then clearly label it as your assumption, rather than saying things like, "Even more upsetting are the women who have suffered the tragedy of a stillborn baby, and have been told the reason the baby died was from a cord around the neck.THIS IS NOT TRUE." and "I'm sorry to tell you that you were misinformed." and "If you are a mother who was told your baby would have, or did, died due to nuchal cord, you were misinformed." Just because 99% of adult drowning accidents occur in swimming pools or other larger bodies of water does not mean that an adult cannot possibly drown in his own bathtub.
****
K- “Obviously, nuchal cords don’t always cause problems — they occur in up to 37% of births — but they can cause problems.”

E - "I would like to see some research that shows that?"
Here you go. It's long, and talks about all umbilical cord accidents, not merely nuchal cords, and include the following statements:

"Numerous published case reports since the CPP have described observations associated with witnessed UCA stillbirths. What is suggested by these reports is the fetus may not be dying suddenly. The fetus may have changes in blood supply due to cord compression that it adjusts to and compensates for several hours or days until it no longer can." [I rather suspect you will say that these are all UCAs, not just nuchal cords -- but where does the cord compression come into play prior to labor, since you say in your post, "The cord itself, however, is extremely strong, and unlikely to be compromised, except with a great amount of force." Where is the "great amount of force" that is applied to a baby that slowly dies over the matter of a few days? Oh, no, I forgot -- you declare that all babies that die do *not* die of nuchal cords nor of cord entanglements, but of other reasons. Cord compression can occur when the cord wraps around the baby at some point, including around the neck. To say that “oh, it’s cord compression because the cord is wrapped around the neck, but nuchal cord isn’t a problem” is a statement that is reminiscent of something Dr. Amy Tuteur might say. (If you don’t know to whom I’m referring, I’ll tell you that it’s not a compliment.)]

"Long umbilical cords (>70CM @ 4% of cords) are documented to be directly associated with poor fetal outcome and associated with UCA especially; fetal entanglement, true knots, (sometimes multiple) and torsion."

"Umbilical cord compression occurs when there is loss of slack and tension is created on the UCA ( regardless of loop numbers ). Case reports of single and multiple loops of nuchal cord have documented fetal compromise prenatally."

"Body loops and Extremity loops may be more common than previously reported. Vaginal delivery mechanics undo these points of cord compression probably before they can be observed. Prenatal documentation of occult cord compression would be needed to accurately determine how often the fetus is affected. The CPP reported no ill effects from cord body part entanglement (BP- UCA) in singletons. The issue may be that these fetuses are stillborn before labor and are not accounted for as labor related UCA or stillbirths with BP-UCA. These cases in some senarios are not recognized after birth because the compressed cord loop or segment is undone by the mechanics of birth. Four published studies were identified reporting specifically on BP-UCA other than the CPP. One reported a Body Loop incidence of @ <0.5%>failure of decent due to a nuchal cord and reports of consequences of tight nuchal cord illustrate the contribution of UCA to fetal morbidity.(306),(581) In human case reports UCA associated injuries documented are ; neurologic, cardiac, renal, pulmonary, gastrointestinal, hepatic, vestibular and ophthalmic. In one study, meconium and in another study, funisitis affected umbilical cord vessels (causing spasm?) leading to fetal ischemia and pulmonary injury."

"There may be risk of UCA associated stillbirth with cord length where excess length may predispose to cord compression. This may occur not only due to the absolute measurement of the cord but due to the relative amount of "slack". Therefore it does not matter for instance how many nuchal loops are present (one or five for example), but do the number of loops present create cord tension and compression. This lack of slack can lead to cord tension which may stimulate cord compression and umbilical artery spasm at the site of entanglement.(348),(349) Pathologic evidence for this has been noted in cases of skin grooving from cord entanglement.(10,Fig 5-14) Therefore if an umbilical cord is 45 cm long with a fundal placental insertion and the fetus has a nuchal cord, there may be a risk of nuchal cord compression depending on the fetal size. If the umbilical cord is 90 cm long attached to a low anterior placenta and there are 4 nuchal loops there may be enough slack so as not to create cord compression or restriction during labor. There may be an increased risk of stillbirth if the nuchal cord is looped vs hitched (Type A vs Type B- where type b forms knots once it slips over the fetal body) . Previous nuchal cord literature has not considered this detail. It takes a Type B nuchal cord to slip over the fetal body to form a knot. Once formed, it is not unusual to see case reports of a double nuchal cord and true knot at the fetal neck. The fetus rolled in response to the restricted circulation formed by the true knot. It developed 2 loops, created tension - lost slack and cinched the knot. An average 50 cm cord would only allow for 2 loops [10cm/loop-neck2x =20cm +10cm to umbilicus + 20cm to placental=50 cm]. There may be increased risk of UCA stillbirth when a combination of factors are present such as; thinness-marginal insertion-nuchal cord and true knot all in the same fetus."

"Fetal jerking movements and fetal hiccups may also be related to fetal blood flow disturbances especially cord compression. These maternal observations should be taken seriously.(355),(356),(357) Decreased fetal movement should be investigated with the objective to rule out umbilical cord entanglement and UCA especially in no risk patients.(358),(359),(360) Fetal breathing movements may be an indication of fetal well-being with gasping or absence of fetal breathing suggesting developing asphyxia." [Again, the cord entanglements, including nuchal cord, may cause cord compression. A nuchal cord by itself may not be inherently dangerous, but it may predispose to a much more dangerous condition. To say, “Well, I *said* that cord compression can cause a problem,” while ignoring the role that nuchal cords and body entanglements play in the development of cord compression is short-sighted, to say the least.]

I don’t really expect you to respond to all of the above individually, although some of the above quotes go directly against some of what you have said in either your post or your comments. The rest, well, I expect you will dismiss it as “not being proof that nuchal cords cause problems”; and to that I say, perhaps not, but it’s an awful lot of circumstantial evidence to just dismiss out of hand. Particularly when nuchal cords may cause problems so rarely that the current studies just haven’t been large enough to show it. But case studies can.
Here is one case study. Yes, the baby did not die in utero, but that was because of prompt action in removing the baby from his oxygen-deprived state. Had the doctors not intervened, the baby would have been stillborn.

And here is a pdf, with the following statements:
“The number of infants killed by their umbilical cords is unknown. The National Center for Health Statistics does not have enough data to determine this. Possibly as few as 4,000 deaths per year or as many as 8,000 deaths per year involve umbilical cord complications. The important point here is these infants are normal; they are normal, but they are dead.
“Some researchers believe that cord accidents do not cause death. However, Dr. Arnold Lillien explains this may not be correct….

“The effect of a body loop is cord compression. Tight loops have made impressions on the skin of the fetus and can restrict fetal movement in the uterus. Loops around the extremity can affect circulation of the extremity and cause damage to a foot or a hand. Circulation disturbances can sometimes form blood clots in the arteries, vein, or placenta. These events can change the oxygen supply to the fetus and cause growth disturbances or death…" [Although you cast doubt that a fetus can strangle itself with its umbilical cord because it wouldn't have the strength to, I wonder how you would explain this.]

“Combinations involving fetal umbilical cord insertion site hematomas (vessel rupture) have been observed. These hematomas were associated with nuchal loops, true knots, and midcord hematomas. These particular combinations suggest an umbilical cord subject to stretch mechanisms, possibly tearing the umbilical vein near its insertion…" [In plain language, nuchal loops/cords may cause insertion site problems. So while you blame insertion site problems for certain problems including stillbirth, you may be ignoring the reason the insertion site had a problem to start with, including nuchal cord.]

“Many of these combinations go unnoticed simply because no one is looking for them. When blockage occurs with cord compression mechanisms, one of the clues left behind is edema (a build up of fluid) of the cord. It is not unusual, for example, to have a nuchal cord with proximal cord edema suggesting mild episodes of blood flow disturbance but not enough to cause death. In addition, it is not unusual for these combinations to cause fetal heart rate changes severe enough during labor to cause an emergency C-section…” [So, in these cases, it doesn't lead to IUFD/stillbirth, because the doctors saved the baby. What would you have them do, let the baby die?]

“Body and extremity loops, one of the more difficult mechanisms to observe, may be a significant cause of fetal decompensation. Anecdotal reports have described extremities damaged by tight loops. The ability of these loops to injure an arm or leg but not cause fetal death is difficult to determine. Stillbirths are observed with multiple loops around ankles, necks, and bodies; yet it is difficult to determine which compressed segment caused death….”
Again – without the nuchal cord or other body entanglement, there likely would have been no cord compression.

*****
E – “Nuchal cord was not proven to be the cause of fetal demise in those cases, but was the only clinically significant (i.e. “not textbook”) thing about the birth.”
Yet you have also dismissed the statement of one of your commenters who said that the autopsy on his baby showed that the fetal demise was caused by nuchal cord. It was proven then, yet you still did not accept that proof.

Let me bring in another example: uterine rupture. What are the causes of it? What increases the likelihood of it? Studies uniformly show that uterine ruptures are most likely to happen in women who have had a previous C-section, particularly if they receive drugs to induce or augment their labors. Studies also show that unscarred uteri can also rupture, if the women are given induction/augmentation drugs. I would have to check the studies again, but I daresay that over 99% of all uterine ruptures take place in a scarred uterus and/or with induction/augmentation drugs. But you would be wrong to say that uterine ruptures *only* happen in induced/augmented labors, and/or *only* happen in women who have had a C-section. The incidence of such things happening is very rare – too rare for most studies to show, which is where case studies come in. I read a case of a woman who had no previous surgery, no female issues of any kind, who in her first pregnancy had her uterus rupture before she even made it to term. No scar, no pitocin, no cervidil, no prepidil, no misoprostol, no labor – in short, no risk factors whatsoever for uterine rupture, yet her uterus still ruptured. It is certainly rare, and her case may be the only documented case (so, one in a billion, perhaps, maybe a trillion?), but just because several large studies that looked at a hundred thousand women didn’t catch a case like hers doesn’t mean they don’t exist and are completely impossible for them to happen. Rare, yes. Unlikely, yes. Impossible – no! The rarer the event, the larger the study needs to be to catch it. Or else, a case study can be done documenting the singular event.


*****
E – “I did not mention it by type, but Type B is a type involving knots, which I did indicate was problematic. Any type of cord compromise, be it knots, compression, or insertion issues, can result in negative outcomes. But a simple nuchal cord is not a “compromise,” and therefore no cause for concern.”
Type B does not always manifest as a knot – for the umbilical cord to knot, there first has to be a Type B loop around the baby somewhere, and then the baby moves out of it. If it tightens around the baby at a place where the baby cannot move it off of him (for instance, it’s too tight to move down across the trunk or up over the head), so a Type B nuchal cord may not knot, but may tighten around the neck and compromise the baby.

Further, knots and compression are or can be caused by nuchal cords.


Your problem, which somebody already pointed out, is that you have focused on what studies have to say, without considering the possibility that studies may not be able to present the whole picture, but only part of the picture – and perhaps a very small part, if it is not enough magnitude. What you are doing may be analogous to finding a study tracking 1000 drivers aged 55-65 for 3 months, finding that none of them died in a car wreck, and then concluding that nobody ever dies in a car wreck. Then, when people tell you of their personal experience of family members dying in a car wreck, you say, “I hate to tell you this, but that is impossible. People that age are more likely to die of heart attacks, strokes, and cancer, so what really happened is that your father had a heart attack which caused him to lose control of the car, causing the wreck, and he was dead before he hit the pavement.” You can see in this case that the conclusion is manifestly wrong, because you know that people do die in car wrecks, even if that study didn’t show it, because it was too small.

Or perhaps this hypothetical study did have some people die in car wrecks, but the rate of death in the “car wreck” cohort was the same in the “no wreck” cohort, perhaps due to a problem in the study design, or the group size was too small, or an unmatched group, or perhaps that people who died in a car wreck happened to be those who would have been at risk for dying of a heart attack the following week. Just because they would have died of something had a car wreck not killed them first does not mean that they did not die of a car wreck.

*****

Now, going back to one of your comments: “In the first study you listed, the Miser study, it was concluded, "his study suggests that nuchal cords occur commonly, but are rarely associated with significant neonatal morbidity or mortality." Which proves my point in the first place.”

Actually, you have said repeatedly that nuchal cords pose NO problem, but this study shows that they CAN cause problems. Certainly, nuchal cords are common – no one disputes that! Certainly, nuchal cords “are rarely associated with significant neonatal morbidity or mortality” (and I would add stillbirth) – BUT THIS MEANS THAT SOMETIMES THEY ARE associated with significant neonatal mortality or morbidity.

What you are doing is saying that because a simple nuchal cord poses no problems, therefore no nuchal cord poses problems, and that is an oversimplification. Do nuchal cords pose as much threat as many people commonly believe? No. Is nuchal cord fear overstated and overblown? Absolutely. Does the fact that people are one thousand times as scared of nuchal cords as they ought to be (most of which are simple and loose and pose no problem to the baby at any time), mean that there is *never* a problem with a nuchal cord? Absolutely not.

5 comments:

Emily said...

Okay, you got me. There are hundreds of variations on the nuchal cord scenario, and I can't possibly account for every single one of them, so to say that death by nuchal cord is impossible is hyperbole at best, and insensitive and illogical at worst.

So we should c-section all women who have any kind of cord anomaly, because we can't possibly know which ones will be the 1 in a million rare case that kills their baby with a cord wrapped around the little toe.

(Yes, I'm being a teeny sarcastic.)

Look, the fact is, NO ONE knows what killed those babies. It is assumed a nuchal cord killed them because it was the only event of clinical significance present, but the fact that it is so common in births generally speaking just doesn't make sense that that could be the cause.

You're right, though, it could be. But if we go around worrying about the fraction of a fraction of a fraction of rare freak accidents that occur in pregnancy, labor, and delivery, we will have every woman in bed rest in the hospital for 9 months and sectioned at 37 weeks.

I GET IT. I chose to speak in hyperbole to prove a point. And my point was, nuchal cord *in general* is no cause for concern.

Kathy said...

My point is that we should neither scare women into worrying about the tiny possibility that something might happen (we might as well worry about an asteroid strike), nor should we completely dismiss every fear as completely unfounded. There is a balance that can be reached - truth that will alleviate the almost paralyzing fear of nuchal cord without going so far into the other ditch of saying it never happens. Interventions are overused; but that doesn't mean that every use of them is unwarranted or unnecessary.

No, we don't need to section every woman, nor every woman with a known or suspected cord anomaly. But if a baby has a known cord anomaly or body entanglement (including NC), or if (like me) the mother declines ultrasound, then it would make sense for the mother to be more strongly urged to do kick counts and to be more vigilant in those last weeks before birth. It might have saved my friends' daughter's life.

Sometimes, it is assumed that NC was the cause of death without being proven. My friends declined to have their daughter autopsied to know for sure; I wish they had, just in case it was something else. It may be that she died of some sort of prenatal SIDS, and the NC was just incidental. We don't always know the cause of death; but sometimes we can. I agree that sometimes doctors jump too quickly to "NC caused death" without really knowing for sure. But just as SIDS is assumed to be something along the lines of the baby gradually losing more and more oxygen until it finally succumbs to death, so too can SADS (sudden antenatal death syndrome) be due to low oxygen intake. The reasons for both are largely unknown, but that doesn't mean that all of the factors are unknown and unknowable. For instance, researchers have shown that certain factors (breastfeeding, sleeping on the back, having a pacifier, having a fan on in the room, etc) reduce the risk of SIDS - and implementing the famous "Back to Sleep" campaign has reduced the rate of SIDS. It hasn't eliminated it, but it has reduced it. Yes, NC in general is usually not a problem - just as putting a baby to sleep on his tummy is usually not a problem. (Both my kids were tummy sleepers, fwiw.) But research has shown that a greater percentage of babies who sleep on their tummies than on their backs will die of SIDS. Just because most babies will not die of SIDS when they sleep on their stomachs does not mean that no babies won't; and just because most babies won't die of SIDS when they sleep on their stomachs doesn't mean that somehow sleeping on their stomachs didn't cause their death somehow.

Not every NC causes fetal demise or brain damage. But if 90% of stillborn babies have NCs, while only 20-25% of live-born babies do, then, much like breastfeeding vs. bottle-feeding in SIDS, NCs can be reliably looked at as a factor in stillbirth. Perhaps not because the cord was around the neck, per se, but because the cord was wrapped around the body at some point, causing cord compression and compromising fetal oxygen.

The problem is, there are too many factors involved in death - of any kind - to say with 100% certainty most of the time that this or that factor was *the* thing that caused it. Take AIDS, for instance. Most people don't really die of AIDS, but of complications due to the AIDS virus. In a similar fashion, babies may not be dying "of NC" per se, but it may be a contributing factor in their deaths, or it may have been the thing that started the cascade that ultimately led to their deaths.

What can be done? Not much beyond monitoring (such as kick counts), and then possibly wise intervention should the situation call for it. That's something for the doctors and parents to undertake, using the best information they have, to make the best choice they can.

Anonymous said...

Kathy... I must thank you for defending the idea that we cannot say that nuchal cords do not cause any problems. I lost my firstborn son at 35 weeks due to one and I can promise you that my next child (due in December of this year - a year after my last son) will be born by c-section at 37 weeks after extensive monitoring throughout the pregnancy. I will take the risk of whatever the c-section and early delivery brings for the hope that I will have a living baby. Thank you for defending those of us who have had this happen to us. I hate to think there is someone spreading the idea that this never actually causes death. It just gives women false hope that this cannot happen to them. Thank you again...

Kathy said...

Anonymous,

One of the reasons why I am so passionate about this is that a friend of mine likewise lost her first baby due to a nuchal cord entanglement or strangulation. On her due date.

I understand your fears for this pregnancy, and wish you peace for the remainder of this pregnancy.

Undoubtedly, one of the "extensive monitoring" things you will be doing is kick counts towards the end of pregnancy, since many mothers of stillborn babies (or mothers of babies who were born by necessary emergency C-section, like my friend Sheridan, noticed a decrease of movement, which was an indication that their babies were compromised. (I mostly include this information in case anyone reads afterwards, and wants to know what can be done.)

I am sorry for your loss.

Emily Heizer Photography said...

I would rather have an emergency c-section than risk being that one in a million whose child dies.

Sorry, my child's life is more important than being right.