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Ob/Gyne 3 > Module 8 : Doppler > Flashcards

Module 8 : Doppler Flashcards

1
Q

what are the 4 methods of fetal doppler assessment

A
  • continuous wave (non stress test)
  • pulsed wave doppler
  • colour doppler
  • power doppler
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2
Q

what technical parameter needs to be adjusted when doing doppler on baby

A
  • power
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3
Q

what three things are qualitatively analyzed

A
  • low of diastolic flow
  • reversal of diastolic flow
  • notching of venous flow
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4
Q

what velocities are increase as term approaches and why

A
  • diastolic velocities

- due to decreased placental resistance

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5
Q

why is it called semiquantitave analysis

A
  • difficult to control angle of incidence

- equations are all angle depenedant

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6
Q

what are the three ratios used to asses flow

A
  • pulsatility index PI = (S-d)/mean velocity
  • resistance index RI = (S-D)/S
  • systole/diastole ration = S/D
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7
Q

what causes and increase of PI

A
  • increase impedance
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8
Q

when will the S/D ratio become infinity

A
  • when diastolic velocity reaches zero
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9
Q

when will the RI become 1

A
  • when diastolic flow is zero
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10
Q

does the PI stay the same

A
  • no it continuous to show change even when diastolic flow is zero
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11
Q

how many waveforms should be measured to reduce error

A
  • 3 or more
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12
Q

when should we avoid performing doppler

A
  • during fetal breathing periods
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13
Q

how does the vascular resistance change during pregnancy

A
  • during embryonic period normal to have high resistance absent end diastolic flow
  • near end of 1st trim end diastolic flow appears
  • near end of pregnancy end diastolic velocity increases
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14
Q

what fetal vessels are routinely assessed

A
  • umbilical artery
  • ductus venosus
  • fetal cerebral vessels MCA
  • fetal aorta
  • umbilical vein
  • fetal IVC
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15
Q

how does the PI, RI, S/D ratios change in the UA during pregnancy

A
  • all decrease because diastolic flow increases
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16
Q

where are ratios higher when sampled in the cord

A
  • higher if measured at fetal end of the cord
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17
Q

what are abnormal umbilical artery findings

A
  • decreased or absent diastolic flow causes elevated RI and PI
  • reversed diastolic flow indicating severe fetal distress
  • RI > 0.72 is abnormal from 26 week onward
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18
Q

what are the indications for umbilical artery doppler

A
  • small for gestational age
  • hypertension in pregnancy
  • diabetes type 1
  • discordant growth in TTS
  • poor growth in both twins due to placental insufficiency
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19
Q

what is the normal flow in the umbilical artery

A
  • forward flow through all phases of the cardiac cycle
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20
Q

what is abnormal flow umbilical artery d

A
  • absent diastolic

- reversed diastolic

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21
Q

where is the fetal aorta sampled

A
  • descending aorta just Bove the diaphragm

- appearance is similar to umbilical artery

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22
Q

in which vessel is changes noticed earlier UA or ao

A
  • AO
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23
Q

when is the MCA sampled

A
  • asses for brain sparing effect with IUGR fetuses

- preferential flow to the brain results in an increased diastolic flow during fetal asphyxia

24
Q

what are the cerebral umbilical ratios

A

CU ratio = MCA PI/UA PI

- describes the relative impedance to blood flow between maternal and fetal circulation

25
Q

when is the CU ratio abnormal

A

MCA PI/ UA PI < 1

26
Q

how is the MCA doppler affected by immune hydrops

A
  • anemia causes increased systolic velocity due to decreased viscosity of the blood
  • > 1m/sec indicates an amnio
27
Q

how is the MCA sampled

A
  • slightly caudal from BPD
  • measure MCA that is closest to tansducer
  • must have MCA flow parallel to sound beam
  • sample at prox segmento of MCA
28
Q

why do we need to be conscious of transducer pressure when sampling the MCA

A
  • constant pressure from the transducer can cause a reaction similar to that of fetal distress so the blood will shunt to the brain
  • causing abnormal false positive
29
Q

how is umbilical vein flow changed during pregnancy

A
  • during embryonic period flow is pulsatile

- should not be pulsatile from 2nd trimester on

30
Q

what doe venous pulsation in the UV indicate for the fetus

A
  • poor prognosis

- CHF

31
Q

where is the ductus venous located and what si the normal flow

A
  • in fetal liver between left portal vein and IVC

- normal to see continuous biphasic flow

32
Q

what is abnormal flow in the DV

A

flow below the baseline

33
Q

why does the recipient twin in TTTS demonstrate flow below baseline and TR in the DV

A
  • volume overload

- getting too much blood

34
Q

what is the purpose of ductus venosus

A
  • regulator of oxygen to the fetus

- half of the blood returning from the placenta is directed through the DV

35
Q

how do we obtain ductus venosus flow

A
  • level of AC
  • colo doppler of umbilical vein
  • sweep posterior towards fetal spine
  • locate a turbulent flow vessel
36
Q

what are the points of the DV wave

A
  • first peak = PSV
  • second peak = rapid filling of ventricles
  • A wave = atrial contraction (reversal abnormal)
37
Q

what is the flow in the IVC

A
  • triphasic close to the heart
  • becomes biphasic further from heart
  • measure below diaphragm
  • PI increase with fetal hypoxia/asphyxia
38
Q

what are 2 ominous signs for hypoxia in the fetus

A
  • reversed flow in the umbilical artery

- increased diastolic flow in the MCA

39
Q

what do the abnormal dopplers mean

A
  • indicate placental resistance is rising due to loss of small vessels
  • loss of perfusion in placenta
  • UV flow is decreased causing hypoxia
40
Q

when is uterine artery doppler warranted

A
  • is PAPP-A low and abnormal when uterine doppler will be performed later
41
Q

what is the normal PI in the uterine artery

A
  • PI < 1.2

- notching is abnormal

42
Q

what are three reasons doppler is perform in gynaecology with EV

A
  • persistent trophoblastic disease
  • neoplasia or tumours
  • AV fistulas
43
Q

what is the normal Uterine artery RI

A

< 0.4

44
Q

what uterine abnormalities can cause low resistance flow

A
  • endo carcinoma

- uterine leiomyoma

45
Q

what should we look for with doppler in ovarian torsion

A
  • look for color flow

- spectral doppler performed as well

46
Q

what are the doppler characteristics of ovarian neoplasia

A
  • RI < 0.4
  • PI < 1
  • increased diastolic flow
  • non specific to whether ovarian mass is bengin or malignant
  • corpus luteal doppler may mimic neoplasm flow
47
Q

what does ovarian doppler vary with

A
  • menstrual cycles
    + increases in P and F decrease during ovulation
  • ovary with dominant follicle
    + decrease PI and RI reflect decreased vascular impedance and an increase in flow in ovary with dominant follicle
  • inactive ovary
    + low or absent end diastolic flow
  • pregnancy
48
Q

how is the flow different in malignant vs benign ovarian neoplasm

A
  • malignant = central flow

- benign = peripheral flow

49
Q

what is postpartum ovarian vein thrombophlebitis

A
  • inflammation of vein caused by clot
  • rare
  • associated with post partum, malignancies, PID
  • increased risk of C-section patients
50
Q

what is Virchows triad

A
  • hyper coagulability in pregnancy
  • venous stasis
  • vessel damage due to uterus expanding and contracting
51
Q

which ovarian vein is more common to contain clot adn what will it look like

A
  • right t
  • dilated hypoechoci tube lacking color or spectral doppler flow
  • asses IVC
52
Q

what are the DDX of ovarian thrombus

A
  • appendicitis
  • fibroids
  • nephrolithiasis
  • ovarian torsion
  • tube-ovarian abscess
53
Q

what are the cause of pelvic congestion

A
  • unknown
54
Q

what are the symptoms of pelvic congestion

A
  • chronic dull pelvic ache

- pain ( premenstual, mesntual, postcoital, perineal)

55
Q

what is pelvic congestion associated with and what exam is gold standard for diagnosis

A
  • lower extremity varies, multiparty

- venogram

Ob/Gyne 3 (10 decks)

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