Ultrasound Flashcards
What is the purpose of advanced ultrasound techniques in obstetrics?
Advanced ultrasound techniques go beyond routine scanning, providing more detailed information to guide clinical management. They offer deeper insights into fetal development, maternal health, and potential pregnancy complications.
What is Doppler ultrasound, and what does it assess?
Doppler ultrasound measures blood flow velocity through blood vessels to assess fetal and maternal circulation, placental function, and complications like fetal growth restriction (FGR), pre-eclampsia, and intrauterine hypoxia.
What are the types of Doppler ultrasound, and what do they assess?
Umbilical Artery Doppler: Assesses placental blood flow and detects placental insufficiency and fetal distress.
Middle Cerebral Artery Doppler: Evaluates brain circulation and monitors fetal anemia and FGR.
Uterine Artery Doppler: Early detection of pre-eclampsia and placental insufficiency.
Ductus Venosus Doppler: Evaluates blood flow from the umbilical cord to the fetal heart in suspected fetal compromise.
What is 3D ultrasound used for?
3D ultrasound creates three-dimensional images of the fetus, helping detect facial abnormalities, visualize abnormal fetal positions, and provide clearer images for parents.
How does 4D ultrasound differ from 3D ultrasound?
4D ultrasound adds a time element to the 3D image, providing a “live” view of the fetus in motion, including breathing, swallowing, or facial expressions. It’s used for bonding, reassurance, and detecting some fetal anomalies.
What is the purpose of elastography in obstetrics?
Elastography measures tissue stiffness and is used to assess cervical stiffness (predicting preterm labor) and placental stiffness (linked to placental perfusion issues like pre-eclampsia and IUGR).
What is 3D/4D Doppler imaging?
3D/4D Doppler imaging combines Doppler ultrasound techniques with 3D/4D imaging to assess fetal and placental blood flow, identifying complex fetal conditions like congenital heart defects and brain abnormalities.
What is high-resolution ultrasound, and when is it used?
High-resolution ultrasound uses higher frequency transducers for greater detail in visualizing small structures and abnormalities, often used in early pregnancy to detect fetal anomalies such as neural tube defects or heart defects.
What is fetal echocardiography used for?
Fetal echocardiography examines the fetal heart to detect structural heart defects, using high-resolution ultrasound and Doppler to assess blood flow, valve function, and conditions like tetralogy of Fallot.
What is advanced placental imaging used for?
Advanced placental imaging assesses placental structure, position, and function. It includes placental mapping to detect abnormalities and Doppler imaging to assess blood flow for signs of insufficiency that could lead to fetal growth restriction.
What is the purpose of Amniotic Fluid Index (AFI) and 3D Amniotic Fluid Mapping?
AFI: Measures the amount of amniotic fluid to assess risks of oligohydramnios or polyhydramnios.
3D Amniotic Fluid Mapping: Provides precise visualization of fluid distribution around the fetus to identify areas of concern, such as fetal urinary tract anomalies.
What is the role of ultrasound in evaluating the cervix?
Ultrasound is used to predict preterm labor by measuring cervical length and detecting abnormalities like a shortened cervix or cervical funnel, which increases the risk of preterm birth.
What procedures can be guided by ultrasound in obstetrics?
Amniocentesis: Genetic testing through amniotic fluid collection.
Chorionic Villus Sampling (CVS): Prenatal diagnostic test for chromosomal abnormalities.
Fetal Biopsy: Genetic analysis for suspected genetic disorders or mosaicism.
How does ultrasound help predict pregnancy complications?
Ultrasound monitors factors like cervical length for preterm labor, uterine artery blood flow for pre-eclampsia, and fetal growth for intrauterine growth restriction (IUGR), guiding early interventions.
How can advanced ultrasound techniques be integrated with other imaging modalities?
Advanced ultrasound can be combined with MRI or CT to provide a more comprehensive evaluation, particularly in complex fetal anomalies or maternal conditions, such as evaluating the brain in suspected CNS abnormalities like spina bifida.
What are the ethical considerations when using advanced ultrasound techniques?
Informed consent is crucial for invasive procedures like amniocentesis. Counseling parents about abnormal findings and their implications, as well as providing follow-up, is important for appropriate management and decision-making.
What are the safety considerations for ultrasound during pregnancy?
No ionizing radiation: Uses sound waves instead of X-rays.
What are the thermal and mechanical effects of ultrasound?
Sound waves can produce heat or cause tissue vibration.
How do modern ultrasound machines ensure safety?
They operate within safe limits to avoid harm.
What are the safety guidelines for using ultrasound in pregnancy?
Use only when medically indicated.
Minimize exposure time and use the lowest power settings (ALARA principle).
What is the purpose of an early pregnancy ultrasound?
To confirm pregnancy and differentiate between intrauterine and ectopic pregnancy.
How is gestational age determined in early pregnancy ultrasound?
By measuring Crown-Rump Length (CRL).
Why is early pregnancy ultrasound used in case of bleeding or pain?
To rule out miscarriage or ectopic pregnancy.
What is assessed during early pregnancy ultrasound to check pregnancy viability?
Presence of fetal heartbeat and fetal growth.
How is multiple pregnancy assessed in early ultrasound?
By determining chorionicity and amnionicity.
What does an ultrasound show in suspected molar pregnancy?
It helps identify abnormal trophoblastic tissue.
What is the first visible structure in early pregnancy ultrasound?
The Gestational Sac (GS), seen at ~4.5–5 weeks.
How does the Gestational Sac (GS) appear on ultrasound?
A round, anechoic structure within the endometrium.
What is the normal growth rate of the Gestational Sac (GS)?
The mean sac diameter (MSD) grows ~1 mm/day
When is the Yolk Sac (YS) visible on ultrasound?
At around 5 weeks.
What does the Yolk Sac (YS) confirm?
It confirms an intrauterine pregnancy.
When is the Fetal Pole visible on ultrasound?
At around 5.5–6 weeks.
What does the Fetal Pole represent?
It represents early fetal tissue.
When is the fetal heartbeat visible on ultrasound?
From around 6 weeks.
What is the normal heart rate at 6 weeks?
100–120 bpm.
What is the normal heart rate after 6 weeks?
120–180 bpm.
What is the most accurate method for dating early pregnancy?
Crown-Rump Length (CRL) measurement.
What is the accuracy of Crown-Rump Length (CRL) measurement?
±5–7 days.
What measurement is used when the fetal pole or yolk sac is not visible?
Gestational Sac Diameter (MSD).
How is Gestational Sac Diameter (MSD) calculated?
MSD = (length + height + width) / 3.
What are the signs of an ectopic pregnancy?
Empty uterus with positive β-hCG.
Adnexal mass or free fluid in the pelvis.
What ultrasound technique is used for better visualization in cases of suspected ectopic pregnancy?
Transvaginal ultrasound.
What criteria indicate a non-viable pregnancy in case of miscarriage?
No fetal pole in a GS >25 mm (anembryonic pregnancy).
No fetal heartbeat when CRL >7 mm.
What are the signs of incomplete miscarriage?
Retained products of conception.
What features are suggestive of a molar pregnancy?
Snowstorm or cluster-of-grapes appearance.
No visible fetus in complete mole.
What are the characteristics of transabdominal ultrasound?
Non-invasive.
Requires a full bladder in early pregnancy.
Limited resolution for early findings.
What are the advantages of transvaginal ultrasound?
Provides better resolution of early pregnancy structures.
Useful for diagnosing ectopic pregnancy or miscarriage.
How can early ultrasound help in multiple pregnancies?v
Confirms chorionicity (number of placentas) and amnionicity (number of sacs).
Identifies complications like twin-twin transfusion syndrome (TTTS).
What is the discriminatory zone for ultrasound in early pregnancy?
Gestational sac becomes visible when β-hCG >1500–2000 IU/L.