Indications for Doppler Flow Velocimetry During Pregnancy
Thursday, June 05, 2008
Kenneth F. Trofatter, Jr., MD, PhD
Doppler flow velocimetry (DFV) is a noninvasive method to assess resistance to, and velocity of, blood flow using ultrasound technology. In pregnancy, it has been proven to be a valuable adjunct to fetal assessment because often DFV abnormalities will precede detectable fetal abnormalities of growth, amniotic fluid, and placental insufficiency and can help assess the severity of fetal compromise when these abnormalities are suspected.
The principles underlying the most common indications for DFV are as follows:
Under normal conditions, the placenta offers little resistance to fetal and maternal blood flow, even during diastole (i.e., between heart beats); and, there is no preferential blood flow to the brain as reflected in normally high resistance, especially from late midtrimester on, at the expense of perfusion of other organs...
Under abnormal conditions, blood flow to the placenta may be reduced and accompanied by increased resistance to perfusion (fetal and/or maternal) and/or there is preferential blood flow to preserve ‘essential’ organs such as the brain (‘brain-sparing effect’) as manifested by low resistance Doppler patterns to these organs and eventually reduced perfusion (fetal blood flow redistribution) of ‘nonessential’ organs such as the kidneys.
Some factors that lead to aberrations in DFV patterns include:
• Abnormalities in placentation or of the umbilical cord
• ‘Placental insufficiency’ regardless of fetal size
• Fetal anemia resulting from maternal isoimmunization, viral infection (e.g., parvovirus B19 and CMV), twin-twin transfusion syndrome, fetal-maternal hemorrhage…
• Chromosomal abnormalities
• Cardiac and intracranial malformations
When indicated, DFV evaluation of the following may contribute valuable information with regard evaluation of the pregnancy, but should be performed by individuals trained and experienced in the performance and interpretation of the results:
Maternal:
Uterine arteries
Fetal:
Umbilical arteries
Middle cerebral arteries
Ductus venosus
Umbilical vein
Common indications for Doppler flow velocimetry studies include:
• Abnormalities of growth (both intrauterine growth restriction(IUGR) and excessive fetal growth (macrosomia)
• Fetal anomalies (e.g., cystic hygromas, cardiac, thoracic, diaphragmatic, neural tube, renal, and abdominal wall)
• Fetal hydrops
• Oligohydramnios (decreased fluid) and polyhydramnios (increased fluid)
• Poor OB history (e.g., preeclampsia, IUGR, previous stillborn…)
• Known maternal risk factors: hypertension, preeclampsia, diabetes, autoimmune disorders (overt and subclinical), thrombophilias (acquired and genetic)
• Abnormal maternal serum screening (e.g. elevated MSAFP and/or increased risk for fetal chromosomal abnormality)
• Multiple gestation
• Maternal trauma (fetal-maternal hemorrhage)
• Suspected placental abruption
• Known maternal isoimmunization
• Exposure to parvovirus B19
In recent years, DFV has become the primary means of screening related to fetal anemia. This is done by evaluating the peak systolic velocity (PSV) in the fetal middle cerebral artery. Its negative predictive value is so high that it has obviated the need for, and the expense of, repetitive invasive procedures when there is known maternal isoimmunization, Parvovirus B19 exposure, or other potential causes of severe fetal anemia such as trauma or placental abruption or placenta previa that might lead to fetal-maternal hemorrhage or fetal blood loss.
It is also the primary means of ruling out fetal anemia as a cause of hydrops fetalis and it is the mainstay in the assessment of multiple gestations as a means of screening and staging possible twin-to-twin transfusion syndrome. DFV of the fetal ductus venosus in early pregnancy has also proven useful in the identification of fetuses at risk for chromosomal abnormalities and major congenital heart defects. DFV of the branch pulmonary arteries can help predict the risk of fetal pulmonary hypoplasia in cases of premature and prolonged rupture of membranes.
DFV is no longer considered ‘experimental’ and it has become a ‘standard of care’ in the hands of specialist in Maternal-Fetal Medicine for the evaluation and management of complicated pregnancies.
Labels: Doppler flow velocimetry, fetal hydrops, isoimmunization, IUGR, oligohydramnios, polyhydramnios
7 Comments:
At Wed Jun 11, 03:00:00 AM 2008,
Health Point said…
Cigarette smoking is one of the important preventable hazards which cause premature deaths. One study shows that more than 2.4 million deaths per annum are caused by this smoking. Smoking itself causes several chronic disorders. Hence, smoking while pregnant puts both mother’s and child’s life and health, both in danger.
At Mon Jun 16, 11:51:00 AM 2008,
Anonymous said…
Hi Dr. T, I posted this question already (I think) so forgive me if it is a repeat. I've posted to you before in connection with my 28 week loss (with no answers after extensive texting) after a healthy full term pregnancy. I always find your opinions thoughtful. I continue looking for answers. In your post on Doppler Flow studies, you list maternal "autoimmune disorders (overt and subclinical)" as an indication for doing such studies. Does this refer to the testing for such things as anti-nuclear antibodies, natural killer cells, embryotoxicity. I done some research and it sems to me that Reproductive Immunologists generally conduct this type of testing - but it seems quite rare (almost fringe medicine). Is that what you're referring when you reference maternal autoimmune disorders? I am considering having the testing done but am uncertain because the treatment for such a disorder (IVIG or prednisone) seems ot come with some risks. Thanks for reading.
At Mon Jun 16, 05:34:00 PM 2008,
Kenneth F. Trofatter, Jr., MD, PhD said…
To anonymous June 16: I was thinking more in terms of common autoimmune disorders such as systemic lupus, Sjogren's syndrome, rheumatoid arthritis, and autoimmune thyroidits, etc, as well as antiphospholipid antibodies, lupus anticoagulants, anti-beta2-glycoprotein-1 and the like. There are some patients who have a signifcant ANA titer and perhaps a strong family history of autoimmune problems, but don't yet quite meet the clinical criteria for the diagnosis of an autoimmune disease, but are certainly at risk for these. Some of these women will have an abnormal immune response to pregnancy and should be watched carefully abnormalities of placentation. Thanks for writing and I hope this helps a little. Dr T
At Wed Jul 02, 09:05:00 AM 2008,
irma said…
i'm on my period and i notice this morning while rubbin my lower abdomen cuase of my soarness a lump which surprised me because i didn't have it before,then while i kept rubbin and pressing to feel what is it, it disapears then i feel it isn't right or my bodys playin tricks on me ,then i'm thinking if it's possible i'm pregnant during my period ,or a tumor but i don't think tumors would move from where it's growing then i feel air (gas) inside of me and i feel the same lump again and i tell my boyfriend to feel it and while he feels it pressing on it for a while he tells me i should check that and then he says the lump disapears and that he don't feel it anymore.i have two kids and i made sure i had an operation to not have anymore kids 7 years ago,after the operation i asked if it's posible getting pregnant and they told me i closed fabric 99.8% so i would like to know what could it be cause i don't have any symptons ( just a wierd feelin on my right nipple )but would like to know anyway till i get a hold of a doctor.
At Thu Jul 03, 07:27:00 PM 2008,
Kenneth F. Trofatter, Jr., MD, PhD said…
To Irma July 2: If the "lump" in your abdomen is moving, it probably is gas. But there are some bad reasons you could have "gas" like that as well. go see your doctor. I'm pretty good at what I do, but I cannot diagnose problems like yours over the internet!!!!! Dr T
At Thu Jul 03, 09:08:00 PM 2008,
cat said…
hi dr T i have been reading your site and have lernt enough to do more research. my 10 month ultarsound read that there is a curvilinear anechoic region with an anterior posterio measurement of 4mm on the posterior head/neck. i understand that ch size makes a difference and that septated tends to have a highr rate of sever disorder & aneuploidy and miscarrage. i am waiting for a 15 mo ultrasound and then my dr and i will talk about other test. i hope to do the cvs right away and the amneocentesis as well.
two questions- what do you make of the shape of the ch. is this a preliminary to being septated or too hard to tell. the other question is does amnio give the same info as the cvs what should i push for for hapening right away as far as diagnostic- both, one or the other, and is there annother test i should know about.
thanks cat
At Sat Jul 12, 08:26:00 PM 2008,
Kenneth F. Trofatter, Jr., MD, PhD said…
To cat: Go with the CVS. That should tell you whether or not the baby has a chromosomal abnormality and then you will not need the amniocentesis. Dr T
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