Turners: Conflicting info on ovaries, coarctation, PDA

[alicealicealice]

Hi,
I was wondering if anyone could clear up the following info about Turners. Pathoma, UWorld, Wikipedia, and USMLERx don't seem to agree on this commonly tested topic and its frustrating.
1) Ovaries:
U world says "In turners, the ovaries develop normally during fetal life. However lack of paternal X chromosome causes loss of follicles by age 2."
Pathoma says: "Hypoplasia is a decrease in cell production during embyrogenesis, resulting in a relatively small organ (e.g. streak ovary in Turner syndrome)."

2) Coarctiation +/- PDA +/- Bicuspid:
All over the place it seems. Bicuspid is more likely/less likely, coarctation is Preductal, postductal (or there is no such thing since everything is periductal), with PDA, without PDA, presenting as lower extremity cyanosis as a baby vs notching of the ribs as an adult...

Sorry I can't be more specific, I've read numerous sources, and to get the q's right it seems more like a guessing game on what the exam writer believes rather than any verifiable fact. Any guidance in how to think about turners in terms of answering questions on the USMLE would be appreciated.

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[ChessMaster3000]

Hi,
I was wondering if anyone could clear up the following info about Turners. Pathoma, UWorld, Wikipedia, and USMLERx don't seem to agree on this commonly tested topic and its frustrating.
1) Ovaries:
U world says "In turners, the ovaries develop normally during fetal life. However lack of paternal X chromosome causes loss of follicles by age 2."
Pathoma says: "Hypoplasia is a decrease in cell production during embyrogenesis, resulting in a relatively small organ (e.g. streak ovary in Turner syndrome)."

2) Coarctiation +/- PDA +/- Bicuspid:
All over the place it seems. Bicuspid is more likely/less likely, coarctation is Preductal, postductal (or there is no such thing since everything is periductal), with PDA, without PDA, presenting as lower extremity cyanosis as a baby vs notching of the ribs as an adult...

Sorry I can't be more specific, I've read numerous sources, and to get the q's right it seems more like a guessing game on what the exam writer believes rather than any verifiable fact. Any guidance in how to think about turners in terms of answering questions on the USMLE would be appreciated.

well I have never heard the Patent Ductus Arteriosus thing with Turners. As for coarctation, that should be preductal since it is infantile. And bicuspid is definitely more likely. Again, I havent heard of any associations with PDA, if you could point to sources or questions youve seen that in it would be helpful. I agree with pathoma's version of the pathogenesis, and I would bet that step 1 writers will as well

 

[alicealicealice]

Thanks. I got the PDA thing from pathoma, his point is that becasue it si likely to be infantile and preductal, there usually is a PDA:

Also, I can figure out the above from a vignette, but the ovary things are such a contrast: completely normal development in UWorld vs Hypoplasia in Pathoma? I agree hypoplasia makes more sense.

 

[ChessMaster3000]

Thanks. I got the PDA thing from pathoma, his point is that becasue it si likely to be infantile and preductal, there usually is a PDA:

Also, I can figure out the above from a vignette, but the ovary things are such a contrast: completely normal development in UWorld vs Hypoplasia in Pathoma? I agree hypoplasia makes more sense.

the image didn't load. regardless, I am practically positive the classic pathophysiology of turner's is hypo/aplasia during embryogenesis. that is why the ovaries are considered "streak". I feel like sometimes UW reads a case report or something like that and bases an entire question on it.

 

[Transposony]

This is what I understand:

1. In Turner syndrome, ovaries develop normally but by age of 2 yrs there is increased loss of follicles due to absence of second X chromosome.
“menopause before menarche”.
So, UW is correct.

2. The coarctiation is preductal and the the valve is Bicuspid.
Cyanosis v/s Rib notching is easy to explain: In infancy it is cyanosis since the baby has not yet developed the collateral circulation via aorta proximal to coarctation>Subclavian>internal mammary (dilation of intercostal artery is responsible for rib notching) >superior epigastric > Inferior epigastric>External iliac>Femoral.

However, the exact mechanism(s) of cardiac abnormalities are not yet known due to the fact that it is highly variable which part of the X chromosome is active/not active since there are many variations due to mosaicism, lyonization, structural abnormalities of the X chromosome (deletion of the short arm, isochromosome of the long arm etc). So, the phenotypic abnormalities will depend on the type of "partial" monosomy. Hence the confusion.

My suggestion for USMLE is to stick with UW.

 

[ChessMaster3000]

This is what I understand:

1. In Turner syndrome, ovaries develop normally but by age of 2 yrs there is increased loss of follicles due to absence of second X chromosome.
“menopause before menarche”.
So, UW is correct.

2. The coarctiation is preductal and the the valve is Bicuspid.
Cyanosis v/s Rib notching is easy to explain: In infancy it is cyanosis since the baby has not yet developed the collateral circulation via aorta proximal to coarctation>Subclavion>internal mammary>superior epigastric (which is responsible for rib notching) > Inferior epigastric>External iliac>Femoral.

However, the exact mechanism(s) of cardiac abnormalities are not yet known due to the fact that it is highly variable which part of the X chromosome is active/not active since there are many variations due to mosaicism, lyonization, structural abnormalities of the X chromosome (deletion of the short arm, isochromosome of the long arm etc). So, the phenotypic abnormalities will depend on the type of "partial" monosomy. Hence the confusion.

My suggestion for USMLE is to stick with UW.

why would the superior epigastric arteries anastomose with the inferior epigastric? They are trying to supply the intercostal arteries

 

[Transposony]

why would the superior epigastric arteries anastomose with the inferior epigastric? They are trying to supply the intercostal arteries

That's normal anatomy i.e. collateral circulation.
In other words, throughout the body there are anastomosis between various arteries to keep the blood supply going in case there is a blockage in one artery (with few exceptions like renal, splenic artery etc which are end arteries).
When a blockage happens the corresponding collateral arteries enlarges to supply the area rendered ischemic by the blockage.
In coarctation, since there is a narrowing of the aorta the collateral circulation dilates which is seen as rib notching (due to dilation of intercostal artery).
In essence this is effectively a connection between aorta above the narrowing and below the narrowing.

http://www.springerimages.com/Images/RSS/1-10.1007_s00276-003-0096-z-0

The anatomic and functional continuity between the internal thoracic artery and the inferior epigastric artery is well recognized and is known to supply blood to the lower body in coarctation and atherosclerotic and iliac disease

 

[ChessMaster3000]

That's normal anatomy i.e. collateral circulation.
In other words, throughout the body there are anastomosis between various arteries to keep the blood supply going in case there is a blockage in one artery (with few exceptions like renal, splenic artery etc which are end arteries).
When a blockage happens the corresponding collateral arteries enlarges to supply the area rendered ischemic by the blockage.
In coarctation, since there is a narrowing of the aorta the collateral circulation dilates which is seen as rib notching (due to dilation of internal mammary artery).
In essence this is effectively a connection between aorta above the narrowing and below the narrowing.

http://www.springerimages.com/Images/RSS/1-10.1007_s00276-003-0096-z-0

so youre saying there is normally an anastomosis between sea and iea, correct?

 

[Transposony]

so youre saying there is normally an anastomosis between sea and iea, correct?

Exactly.
Just like hundreds of named and unnamed collateral circulations e.g around hip joint, around elbow joint, around shoulder joint etc.

A crude analogy- when there is a traffic jam on a major road you (or your GPS) always finds an alternative route to reach you destination. Those alternative roads always existed.

 

[alicealicealice]

Thanks guys/girls. I tired to fix the images above.
I guess i was initially confused about how a coarctation could ever go undetected at birth since it seems you would either (1) become symptomatic after DA closes or (2) have a PDA. But I guess "adult" coarctation is really just a lesion that wasnt severe enough to be picked up eary and is found incidentally or becomes symptomatic later.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1769162/
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1769162/table/t1/

Also, in seperate UW question I just did, the vignette gave a Turners phenotype and asked what further evaluation would reveal. The answer was "Absent ovaries." From the answer: "Patients with turner syndrome have a variable degree of ovarian dygenesis (including complete absence) with many having effectively no ovarian function. Their ovaries are sometimes referred to as streak gonads when there is minimal amount of connective tissue with no or minimal follicles."
That is pretty contradictory to the declaration that "ovaries develop normally in fetal life," the direct quote from the UW question in my OP. I got it wrong because I said to myself: the ovaries aren't absent, they're streaked! But I see how you can make an argument for their positions.

Oh well. Thanks for you help.

 

[alicealicealice]

double post

 

[ChessMaster3000]

Thanks guys/girls. I tired to fix the images above.
I guess i was initially confused about how a coarctation could ever go undetected at birth since it seems you would either (1) become symptomatic after DA closes or (2) have a PDA. But I guess "adult" coarctation is really just a lesion that wasnt severe enough to be picked up eary and is found incidentally or becomes symptomatic later.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1769162/
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1769162/table/t1/

Also, in seperate UW question I just did, the vignette gave a Turners phenotype and asked what further evaluation would reveal. The answer was "Absent ovaries." From the answer: "Patients with turner syndrome have a variable degree of ovarian dygenesis (including complete absence) with many having effectively no ovarian function. Their ovaries are sometimes referred to as streak gonads when there is minimal amount of connective tissue with no or minimal follicles."
That is pretty contradictory to the declaration that "ovaries develop normally in fetal life," the direct quote from the UW question in my OP. I got it wrong because I said to myself: the ovaries aren't absent, they're streaked! But I see how you can make an argument for their positions.

Oh well. Thanks for you help.

Yeah, just try not to overthink it. Its tough for sure. The way I like to think of it is, if I myself wrote the question I would have worded it like X, but is it reasonable that somebody else will be thinking the same thing and word it like Y? If the answer is yes, then that is the correct answer."

 

[Transposony]

Thanks guys/girls. I tired to fix the images above.
I guess i was initially confused about how a coarctation could ever go undetected at birth since it seems you would either (1) become symptomatic after DA closes or (2) have a PDA. But I guess "adult" coarctation is really just a lesion that wasnt severe enough to be picked up eary and is found incidentally or becomes symptomatic later

I can see the images and now understand your confusion.

Infantile (Predutal) coarctation: You already know that everyone is born with a PDA. Now in predutal coarctation, the newborn can have either of the two scenarios:

1. Either, the coarctation is not severe enough at birth to cause symptoms till ductus arteriosus starts closing.

2. Or, the coarctation is severe and ductus arteriosus remains patent in order to perfuse the lower extremity with mostly deoxygenated blood (differential cyanosis).
This will eventually lead to RVH if untreated since RV is now pumping against PVR.

Adult (postductal) coarctation: The coarctation is not severe enough to cause symptoms but as the body grows the limited perfusion cannot keep up with the demand (lower body is slowly outgrowing it's limited blood supply). Therefore, to compensate the body starts developing collateral circulation (leads to rib notching) over many years. There comes a stage at which even the collateral circulation has reached it's limit (especially at times of high demand like running etc) and only then the patient becomes symptomatic.
This will eventually lead to LVH if untreated.
Hope this helps.

 

[ChessMaster3000]

I can see the images and now understand your confusion.

Infantile (Predutal) coarctation: You already know that everyone is born with a PDA. Now in predutal coarctation, the newborn can have either of the two scenarios:

1. Either, the coarctation is not severe enough at birth to cause symptoms till ductus arteriosus starts closing.

2. Or, the coarctation is severe and ductus arteriosus remains patent in order to perfuse the lower extremity with mostly deoxygenated blood (differential cyanosis).
This will eventually lead to RVH if untreated since RV is now pumping against PVR.

Adult (postductal) coarctation: The coarctation is not severe enough to cause symptoms but as the body grows the limited perfusion cannot keep up with the demand (lower body is slowly outgrowing it's limited blood supply). Therefore, to compensate the body starts developing collateral circulation (leads to rib notching) over many years. There comes a stage at which even the collateral circulation has reached it's limit (especially at times of high demand like running etc) and only then the patient becomes symptomatic.
This will eventually lead to LVH if untreated.
Hope this helps.

This is sort of related, but in terms of "differential cyanosis" I have only ever associated that with PDA. But I think I saw one question where it was actually caused by the coarctation. Is it possible that isolated coarctation (with a closed ductus) can cause differential cyanosis? That wouldn't make sense to me as the blood would only be coming from the left circulation. Perhaps the question implied there was also a PDA with the coarc, but my question really centers around differential cyanosis in the absence of a pda

 

[alicealicealice]

This is sort of related, but in terms of "differential cyanosis" I have only ever associated that with PDA. But I think I saw one question where it was actually caused by the coarctation. Is it possible that isolated coarctation (with a closed ductus) can cause differential cyanosis? That wouldn't make sense to me as the blood would only be coming from the left circulation. Perhaps the question implied there was also a PDA with the coarc, but my question really centers around differential cyanosis in the absence of a pda

Thanks for your help @Transposony and @ChessMaster3000
@ChessMaster3000 Check out UWorld QID 32 whichd eals with differential cyanosis.
The take home point, as also explained by transposony:
1) If severe, Coarct can cause differential cyanosis in infancy if a PDA is also present. (One can make the argument that a severe coarct is what is causing the DA to stay open). These patients need to be treated surgically or they will die of CHF.
2) Therefore a coarctation in a child and adult can present as limited lower extremity exercise tolerance (in addition to blood pressure disparity) but NOT as differential cyanosis (you need a shunt for cyanosis, and there is no shunt present, just obstruction and a collateral system that can no longer keep up).
3) As you stated, differential cyanosis in a child (not an neonate) is most suggestive of an (isolated) PDA that has reversed its shunt flow.
4) Shunt reversals from TOF and septal defects will present with full body cyanosis (distinguishing them from PDA shunt reversal)

 

[Transposony]

This is sort of related, but in terms of "differential cyanosis" I have only ever associated that with PDA. But I think I saw one question where it was actually caused by the coarctation. Is it possible that isolated coarctation (with a closed ductus) can cause differential cyanosis? That wouldn't make sense to me as the blood would only be coming from the left circulation. Perhaps the question implied there was also a PDA with the coarc, but my question really centers around differential cyanosis in the absence of a pda

You are right. There cannot be differential cyanosis without PDA in coarctation of the aorta.

However, there are other causes of differential cyanosis where the cyanosis involves lower or upper body (reverse Differential Cyanosis) depending on the defect.
It is important to understand that there has to be a connection between right side of heart with left side of heart (ASD, VSD, PDA) in order for the newborn survive to have the cyanosis.

Following are the various causes of differential cyanosis depending on the congenital defect.

Lower body cyanosis:

Coarctation of the aorta

Interrupted aortic arch (Just like Coarctation of the aorta but instead of coarctation there is complete obstruction of aorta)

Persistent pulmonary hypertension with PDA (Eisenmenger syndrome due to untreated ASD/VSD etc))

Infradiaphragmatic Total anomalous pulmonary venous return (TAPVR)

Upper body cyanosis (aka Reverse Differential Cyanosis):

Transposition of the great vessels (TGV)

SupradiaphragmaticTAPVR

 

[alicealicealice]

Thanks. Never heard of the distinctions between TAPVR location, going to need to look that up. Why would TGV (assuming shunt via, say, a VSD) not cause full body cyanosis? You have two parallel circulations mixing thorough the shunt; what happens once it leaves through the transposed aorta that would cause it to preferentially affect the upper body?

 

[ChessMaster3000]

Thanks. Never heard of the distinctions between TAPVR location, going to need to look that up. Why would TGV (assuming shunt via, say, a VSD) not cause full body cyanosis? You have two parallel circulations mixing thorough the shunt; what happens once it leaves through the transposed aorta that would cause it to preferentially affect the upper body?

Yeah, how is all TAPVR not supradiaphgramatic?

 

[Transposony]

TAPVR can be supradiaphgramatic or infradiaphgramatic depending on the drainage of the pulmonary veins:

1. Drainage to right atrium

2. Drainage to right common cardinal system
(SVC or azygous vein)

3. Drainage to left common cardinal system
(Left innominate vein or coronary sinus)

4. Drainage to umbilical-vitelline system
(Portal vein, ductus venosus, and so on)

It is not high yield but good for understanding CVS embryology.

Some good references:

http://www.hci.utah.edu/eihg/perinatal/reprogen/research/tapvr/

http://emedicine.medscape.com/article/899491-overview