A fetal ultrasound (sonogram) is an imaging technique that uses sound waves to produce images of a fetus in the uterus. Fetal ultrasound images can help your health care provider evaluate your baby's growth and development and monitor your pregnancy. In some cases, fetal ultrasound is used to evaluate possible problems or help confirm a diagnosis.
The first fetal ultrasound is usually done during the first trimester to confirm the pregnancy and estimate how long you've been pregnant. If your pregnancy remains uncomplicated, the next ultrasound is typically offered during the second trimester, when anatomic details are visible. If a problem is suspected, a follow-up ultrasound or additional imaging tests, such as an MRI, might be recommended.
There are two main types of fetal ultrasound exams:
Transvaginal ultrasound. With this type of fetal ultrasound, a wandlike device called a transducer is placed in your vagina to send out sound waves and gather the reflections. Transvaginal ultrasounds are used most often during early pregnancy. This type of ultrasound also might be done if a transabdominal ultrasound didn't provide enough information.
Transabdominal ultrasound. A transabdominal fetal ultrasound is done by moving a transducer over your abdomen.
Various other types of transabdominal ultrasounds are available, including:
Specialized sonographic evaluation. This type of exam might be needed in specific circumstances, such as when a fetal abnormality is known or suspected. In this situation, a more detailed evaluation can provide additional information about the abnormality.
3D ultrasound. This exam provides a two-dimensional display of three-dimensional data. This type of ultrasound is sometimes used to help health care providers detect facial abnormalities or neural tube defects.
Doppler ultrasound. A Doppler ultrasound measures slight changes in the ultrasound waves as they bounce off moving objects, such as blood cells. It can provide details about a baby's blood flow.
Fetal echocardiography. This exam provides a detailed picture of a baby's heart. It might be used to confirm or rule out a congenital heart defect.
2. • RECENT ADVANCES IN FETAL IMAGING HAVE BEEN THE RESULT OF TECHNOLOGICAL
ACHIEVEMENTS IN SONOGRAPHY AND MAGNETIC RESONANCE IMAGING, WITH DRAMATIC
IMPROVEMENTS IN RESOLUTION AND IMAGE DISPLAY. BOTH 3- AND 4-DIMENSIONAL
ULTRASOUND IMAGINGS HAVE CONTINUED TO EVOLVE, AND DOPPLER APPLICATIONS HAVE
EXPANDED.
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3. ULTRASOUND
• THE REAL-TIME IMAGE ON THE ULTRASOUND SCREEN IS PRODUCED BY SOUND WAVES PASS
THROUGH LAYERS OF TISSUE, ENCOUNTER AN INTERFACE BETWEEN TISSUES OF DIFFERENT
DENSITIES, AND ARE REFLECTED BACK TO THE TRANSDUCER.
• DENSE TISSUE SUCH AS BONE PRODUCES HIGH-VELOCITY REFLECTED WAVES, WHICH ARE
DISPLAYED BRIGHTLY ON THE SCREEN.
• FLUID GENERATES FEW REFLECTED WAVES AND APPEARS DARK OR ANECHOIC.
• HIGHER-FREQUENCY TRANSDUCERS YIELD BETTER IMAGE RESOLUTION, WHEREAS LOWER
FREQUENCIES PENETRATE TISSUE MORE EFFECTIVELY.
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4. SAFETY
• SONOGRAPHY SHOULD BE USE TO GAIN ONLY NECESSARY INFORMATION
-AS LOW AS REASONABLY ACHIEVABLE-
• PROLONGED UTZ EXPOSURE MAY EFFECT BRAIN CELL MIGRATION.
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5. 1ST TRIMESTER SONOGRAPHY
• BEFORE 14 WKS GESTATION
• EARLY PREGNANCY CAN BE EVALUATED USING TRANSABDOMINAL OR TRANSVAGNAL UTZ
• CROWN-RUMP LENGTH(CRL) IS THE MOST ACCURATE BIOMETRIC PREDICTOR , SHOULD BE
OBTAINED IN SAGITTAL PLANE
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7. NUCHAL TRANSLUCENCY (NT)
• NUCHAL TRANSLUCENCY EVALUATION IS A COMPONENT OF 1ST TRIMESTER ANEUPLOIDY
SCREENING BETWEEN 11-14 WKS .
• IT PRESENTS THE MAXIMUM THICKNESS OF SUBCUTANEOUS TRANSLUCENT AREA BETWEEN
THE SKIN AND SOFT TISSUE OVERLYING THE FETAL SPINE AT THE BACK OF NECK.
• WHEN NUCHAL TRANSLUCENCY IS INCREASED, RISK FOR FETAL ANEUPLOIDY AND
STRUCTURAL ANOMALIES IS INCREASED.
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11. 2ND AND 3RD TRIMESTER SONOGRAPHY
• THERE ARE 3 TYPES OF EXAMINATIONS
• 1. STANDARD
• 2. SPECIALIZED
• 3. LIMTED
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12. • 1. STANDARD
• TO EVALUATE FETAL ANATOMICAL STRUCTURES
• MAY BE ADEQUATELY ASSESSED AFTER APPROXIMATELY 18 WKS
2nd AND 3rd TRIMESTER SONOGRAPHY
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14. • 3. LIMITED
• PERFORMED TO ADDRESS A SPECIFIC CLINICAL QUESTION SUCH AS AMNIONIC FLUID VOLUME
ASSESSMENT, PLACENTAL LOCATION OR EVALUATION OF FETAL PRESENTATION OR VIALILITY
2nd AND 3rd TRIMESTER SONOGRAPHY
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15. FETAL BIOMETRY
• DERIVES TO ESTIMATED GESTATIONAL AGE FROM CROWN-RUMP LENGTH AND FETAL WEIGHT
FROM MEASUREMENT OF BIPARIETAL DIAMETER, HEAD AND ABDOMINAL CIRCUMFERENCE, AND
FEMUR LENGTH.
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17. AMNIOTIC FLUIDS
• THE VOLUME SHOULD BE EVALUATE EVERY 2ND AND 3RD TRIMESTER UTZ
• CAN BE ASSESSED FROM 16 WKS ONWARD
• AMNIOTIC FLUID INDEX IS A MEASUREMENT OF
• THE SINGLE DEEPEST VERTICAL FLUID POCKET (NORMALLY BETWEEN 2-8CM)
• THE SUM OF THE DEEPEST VERTICAL POCKETS FROM EACH OF 4 UTERINE QUADRANTS
• NORMAL RANGES BETWEEN 8-24CM
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18. NORMAL AND ABNORMAL FETAL ANATOMY
• BRAIN
• EVALUATION IS INCLUDES 3 AXIAL VIEWS
• 1. TRANSTALAMIC VIEW: TO MEASURE BIPARIETAL DIAMETER AND HEAD CIRCUMFERENCE
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19. NORMAL AND ABNORMAL FETAL ANATOMY
• BRAIN
• EVALUATION IS INCLUDES 3 AXIAL VIEWS
• 2. TRANSVENTRICULAR VIEW
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20. NORMAL AND ABNORMAL FETAL ANATOMY
• BRAIN
• EVALUATION IS INCLUDES 3 AXIAL VIEWS
• 2. TRANSCEREBELLAR VIEW
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