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Presentation 11MCA Doppler .pdf
- 1. Fetal surveillance Doppler Middle cerebral artery ( MCA)
- 2. Middle cerebral artery — largest branch from internal carotid artery. — low resistance high capacitance vessel . —it received 7 ٪ of the cardiac output . — increase end diastolic f low occurs in MCA as the response to hypoxia. — peak systolic velocity increased in fetal anemia .
- 3. MCA indications — IUGR after abnormal umbilical Doppler. — suspect fetal anemia ; RH isommnization Or hydrops. — MCDA twins.
- 4. Fetal MCA ( when) -MCA can be easily demonstrated by color Doppler in transverse fetal head position. — At 28- 32 weeks when- umbilical A Doppler is abnormal due to placental insu ff iciency . — At any time of gestation when fetal anemia is suspected . —normal waveform characterized by high systolic velocity and low diastolic volume resulting Inhigh pI >1.45 — in fetal hypoxia vascular tone is increased in MCA/ Resulting in increased diastolic volume . and reduced PI values.
- 5. Steps of MCA Doppler ( how) - the fetal head is f ixed - Transverse view of the head at the level of BPD . Slightly tilting the prob caudally ,, posterior to the thalmi 0r towards the base of skull until the butter f ly shape of suprasellar cisterns appears. - - zoom at the area of the greater wing of the sphenoid bone( hyper echoic bone) -we can see the pulsation of the vessels before applying the color Doppler . - activate the color Doppler the circle of wiils appears . — The MCA Appears as-a small running vessel anterolateral . Then apply the PW ,the most accurate measurement when the Doppler beam is parallel to vessel ,that means the angle of insinuations = zero or less than 30 - and the gate = 1 mm
- 6. MCA ( How) Normal MCA wave form characterized by peak systolic wave and low end diastolic f low
- 7. MCA by Power Doppler ( PD ) - By power Doppler no need to adjust the angle - MCA is easily identi f ied by PD
- 8. Normal MCA waveform Normal MCA waveform at f irst trimester ( no diastolic f low) Normal MCA waveform At second and third trimester
- 9. Middle cerebellar artey Umbilical artery graph — The MCA is opposite of the umbilical artery . Abnormal UA PI above 95th percentile. . Abnormal MCPI below the 5th percentile
- 10. Brain sparing — with hypoxia there’s cerebellar vasodilation to keep supplying the brain by oxygen And nutrients ( redistribution) So initially the diastolic f low may be in normal range — when the vasodilation ability is exhausted as with fetal acidosis ) the resistance start to increase again . In sever hypoxia the diastolic f low is reversed which is crtical Event for the fetus and proceeds fetal death. Normal Brain sparing Dilated cerebral arteries in order to perverse brain supply
- 11. Causes of reversed diastolic Flow in MCA —- Often due to fetal head compression by prob —impending fetal death — cardiac anomalies
- 12. MCA ( fetal anemia) —measurement of peak systolic velocity ( PSV) Is a non invasive method for the fetal anemia diagnosis . Why — in FA the cardiac output increases and blood viscosity decreases leading to increased f low to the brain Resulting in elevation of peak systolic velocity. Fetal anemia Normal MCA wave
- 13. Cerebro placental ratio —CPR is measured from 18 - 40 weeks. -CPR has a great sensitivity than assessing umbilical artery and cerebral artery Doppler PI in isolation. - CPR=MCAPI / UAPI it is abnormal when less than 1.08 or less than 5th percentile of gestational.age. —abnormal ratio is associated with abnormal prenatal outcome .
- 14. MCA tips — MCA peak systolic velocity was e ff ective for accurate diagnosis of fetal anemia And avoided 70% of invasive procedures — redistribution in hypoxemic fetus may lead to transient decrease in PI then its increased with worsening of hypoxemia . - cerebro placental ratio ( CPR) is more sensitive than MCAD 'or umbilical AD alone .