Doppler Ultrasound

Question 1

Doppler ultrasound Assesses flow in what blood vessels?

Answer 1

umbilical artery, aorta, middle cerebral arteries, uterine arteries
-used to diagnose and assess congenital heart abnormalities

Question 2

advantages and disadvantages of ultrasound

Answer 2

advantage: non-invasive, affordable
disadvantages: penetration limitations 1) bone 2) air, must look for acoustic window,

Question 3

Waveform Parameters

Answer 3

Period- single wave cycle
amplitude- peak pressure or height of wave, represents loudness of wave
wavelength- distance traveled during a single cycle
frequency- number of times the wave is repeated per second expressed in hertz
velocity- speed of wave, 1540 m/sec in soft tissue,
two factors: type of material, temp of material

Question 4

Acoustic impedance

Answer 4

resistance that matter presents to the ultrasound beam

Question 5

two types of transducers in fetal heart monitors

Answer 5

directional- selectively process signals corresponding to motion toward or away from the transducer

ranged- allows the operator to select distances from transducer from which signals will be processed

Question 6

Antepartum monitors

Answer 6

conception to before delivery, only external monitoring capabilities such as ultrasound and external pressure

Question 7

Intrapartum Monitors

Answer 7

during delivery an labor to monitor uterine contractions strength, frequency and duration and how FHR responds to uterine contractions

Question 8

Average FHR

Answer 8

140 bpm

Question 9

Baseline Variability

Answer 9

normal irregularity of cardiac rhythm and single most important feature for the assessment of fetal status

Question 10

Uterine Contractions

Answer 10

duration: 30 to 60 seconds
frequency: 3 to 5 min
intensity: 50 to 75 mmHg

Question 11

External Monitoring Methods

Answer 11

FHR- Doppler ultrasound, Phonocardiography- acoustically sensitive microphone, detection of sounds emitted by fetal heart, Abdominal ECG- two signals- Large- maternal ECG and small- fetal ECG

Question 12

Internal monitoring Methods

Answer 12

FHR- Spiral Electrode- two plastic tubes with spiral tip and metal piece insulated from spiral tip and bathed in amniotic fluids and vaginal fluids and metal plate is attached to the maternal thigh to act as a reference elecrode

Question 13

Pressure monitoring- Intrauterine Catheter

Answer 13

records pressure of the amniotic fluid trapped in the uterus