Doppler Applications in OBGYN Flashcards
Which vessels supply blood to the pelvic organs?*
internal iliac arteries/hypogastric arteries
The doppler of which arteries help predict IUGR?*
Umbilical artery, middle cerebral artery, uterine artery
The diastolic notch is best described as?*
Early diastolic flow reduction
Diastolic notch is a prognostic value only after?
24 wks GA
What is the Doppler criterion that provides the best indicator of diastolic runoff into distal vascular bed?*
Pulsatility index
During menses, what happens to the spiral arteries and endo?
constrict; sheds
Impedence and resistance ______ during the periovulatory and luteal phase
decrease
Doppler ultrasound is standard in the evaluation of?
high-risk pregnancies
What is an example of the audible acoustic Doppler effect?
siren of an ambulance as it moves toward and away
Pitch (frequency) is higher ______ the receiver
towards
Pitch (frequency) is lower ______
from the receiver
away
What happens when high frequency sound interacts with RBCs?
Rayleigh scattering
Color Doppler allows you to evaluate?
Direction and velocity of blood flow
The Doppler frequency shift is _____ when it is away from the transducer
negative
The Doppler frequency shift is _____ when it is toward the transducer
positive
What are the variables of the Doppler formula that are under sonographer control?
incident frequency (selected Probe) and Doppler angle (Probe position and steering)
What are the variables of the Doppler formula that are not under sonographer control?
Speed of sound (medium) and velocity of moving RBCs
How can you correct aliasing?
reduce depth (decrease baseline) or increase PRF (transducer frequency)
Aliasing occurs when what limit is exceeded?
Nyquist limit
The Doppler angles should be less than?
60 degrees
What happens when the Doppler angle is at 0 degrees?
reliability of the Doppler signal increases
What happens when the Doppler angle is at 90 degrees?
reliability of the velocity measurement is unreliable
What are the hemodynamic parameters assessed with doppler ultrasound?*
presence of flow, pulsatility of flow, direction of flow
How does arterial flow appear?
pulsatile highs and lows
How does venous flow appear?
slow and phasic
True or False: Doppler can differentiate normal vs abnormal
false
Ovarian torsion is more common in ovaries with?
a mass
How does ovarian torsion appear sonographically?*
whirlpool sign enlarged, free fluid, absent flow, mass common
A ring of fire sign can indicate?
ectopic pregnancy or corpus luteum cyst
GTD demonstrates what flow?*
high amplitude and low resistance
RPOC demonstrates what flow?
enhanced blood flow
Where can the uterine artery be found?*
at the level of the cervix
Estrogen allows _____ resistance blood flow in the uterus
low
Progesterone allows ______ resistance blood flow in the uterus
high
A postmenopausal uterus demonstrates ______ resistance bloow flow
high
A uterus with hormone replacement therapy (HRT) demonstrates _______ resistance blood flow
low
A diastolic notch can predict?
poor fetal outcome (more resistance, compromised flow)
As pregnancy progresses, the umbilical artery resistance should?*
decrease
The middle cerebral artery is dopplered to assess?
IUGR and anemia
What is brain sparing? What results from it?
blood shunts to brain when there is inadequate flow; small abdomen
Fetal anemia can be shown by?
high peak systolic velocity
What is supine hypotensive syndrome (SHS)?
IVC is compressed and mom cannot breathe properly
How can you correct SHS?
Roll mom onto her left side
How do flow patterns change as the uterus cycles towards menstruation?*
resistance decreases
