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When performing umbilical cord Doppler, should you sample at the fetal insertion, placental insertion, or a free floating portion of the cord? I have heard different things and would like some clarification. The most recent article I have been able to find that states one or the other was published in 1999 by the Journal of Diagnostic Medical Sonography. It states that you should sample a free floating portion of the cord. Does anyone have any updated or more recent information on this topic?

Also, the same article speaks mostly about using S/D ratios to determine fetal outcome, however, Callen says that S/D ratios are being used less and less because if there is no end-diastolic flow the S/D ratio is no longer valid and that RI and PI are used more...mainly RI. Any information regarding this would also be appreciated!

If you read my first discussion, you will understand that my co-sonographer and I are just beginning to learn umbilical cord Doppler. Thanks for any help you can give us!

This is the link to the article that I referenced in this discussion:

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Replies to This Discussion

I read some reasons to place the sample near the placental insertion, one is the steadiness, the fetus does no "kick" the cord, so you can get better images and better doppler recording., Second, is being said that the data collected near the placental insertion it is more reliable.

There are times, many times, that you will find that the ideal sample is the one where the cord is free, is the one where you feel confident because you get a good cord view, and your doppler is clean with a nice spectral drawing

I use S/D Ratio; RI and PI, besides the study of fetal wellbeing can not depend on a single ratio you must see the entire picture.
Kerry, for some detailed discussion of Doppler sonography of the fetus and the umbilical cord, consider checking out the AIUM DVD/CD Rom "New Developments in Fetal Doppler Sonography." Topics on the disc include "Three-Dimensional Fetal Vascular Anatomy" (Dr Wesley Lee), "From Intrauterine Growth Restriction to Anemia: 2 Doppler Stories" (Dr. Giancarlo Mari), "Doppler Sonography of the Umbilical Artery" (Dr Alfred Abuhamad), and "Doppler Sonograhy of the Venous System" (Dr. Henry Galan).
I agree with Mario Perez. The placental end of the cord is the correct location: more stable, reproducible and really reflecting placental resistance as opposed to placenta + whichever portion of the cord between your sampling point and the placenta. Please, see

Abramowicz JS et al.: Doppler analysis of the umbilical artery. The importance of choosing the placental end of the cord. J Ultrasound Med. 1989 Apr;8(4):219-21.

This is not accepted by everyone and many do it differently (fetal insertion, free loop).
S/D is the simplest and most commonly used. The other indices are important when there is no end-diastolic velocity (AEDV) or reverse velocity (REDV) but many use S/D for routine and mention AEDV or REDV if this is the case.
I agree with Mario Perez, Kathi Borok, and Jacques Abramowicz. The literature reports different ways to sample the umbilical artery. The important point to remember is that the last part of the UA to experience deterioration such as reversed flow is the segment closest to the placental insertion site. Reversed flow at the placental insertion site reflects more severe disease (IUGR) than UA-RF measured in a free loop or at the abdominal insertion site.
we had two studies about S/D RATIO and site of umbilical artery for assessment---the results favored FREE LOOP and what Calan says-- PI & RI are better tahn S/D ratio.
I can send that studies (if needed).
one of these studies is
OBJECTIVE: .The objective of this study is to detect the Normal Umbilical artery S/D ratio in Pakistani women at 28 week and 36 week of Gestation at different sites i-e Fetal Insertion, Free loop and near Placental Insertion and to compare it with the previous studies. This study depends on practical scanning through which the data was collected in a data sheet. The study was conducted from June, 2003 to May. 2005.
METHOD: Two thousands (2000) patients of 28 week or 36 week Gestation for Umbilical artery assessment were scanned at,
►Afro-Asian Institute of Medical Sciences (AAIMS), Lahore – Pakistan.
RESULT: Total No of Patients of 28 week were 978 having S/D ratio at Fetal Insertion= 3.00 Free loop= 2.91 and Placental Insertion=2.8, while of 36 week were1022 having S/D ratio at Fetal insertion=2.36 Free Loop=2.38 and Placental insertion=2.31.
Umbilical artery S/D ratio decreases with advancing gestational age and is higher at fetal insertion as compared to Placental insertion.
CONCLUSIONS: Ultrasound is frequently available, non-invasive, inexpensive and easily assessable medical imaging modality. S/D ratio of Umbilical artery study is recommended to be assessed at 28 weeks and onward to discover the abnormality. Accurate assessment of S/D ratio at appropriate site can help us in early diagnosis of IUGR and other relevant abnormalities.

in my views s/d ratio/PI/RI at free floating umblical cord area doppler tracing is excellent because at placental site there are variations in umblical cord insertion in placenta which may be closely related to chromosomal disorders like trisomy 13/trisomy 18/trisomy 21/ with other malformations and IUGR and fluid irregularities create an error in S/D ratio and R/I and PIratio and at fetal insertion site there are many problems with fetuses like gastroschisis and omphalocele or umblical cord cyst which is difficult to accurately assess doppler spectrum of umblical artery cord around the neck also complicate accurate assessment so floating portion to assess umblical artery doppler waveform to see fetal distress is excellent site to assessthree parameters S/D ratio /PI/RI must be seen
I think free loop PI shall be the best choice.
i used to work for high risk perinatologist & I was required to do this in all 3 areas being discussed #1 free floating #2 placental insertion #3 fetal cord insertion, but havent worked there in years so not sure now


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