Background

Obstetric ultrasonography is used in radiology to assess pregnancy and fetal anatomy.

High demand exists for advanced 3D and 4D ultrasonography technologies from public and medical communities.

Obstetric ultrasonography evaluates pregnancy viability, anomalies, and fetal well-being. Basic understanding of targeted obstetric ultrasound examination is beneficial.

Ultrasonography utilizes sound waves for imaging, unlike CT and X-rays that use ionizing radiation.

Ultrasound bioeffects depend on mechanical index and thermal index.

The mechanical index indicates ultrasound potential to create temperature increases through bubble dynamics.

The thermal index indicates heat generation from sound waves in soft tissues to increase with extended static exams and Doppler ultrasound usage.

Indications

Pre-Existing Maternal Conditions

Maternal Infections

Abnormal Findings on Routine Ultrasound

Fetal Heart Concerns

Amniotic Fluid Abnormalities

Placental and uterine Abnormalities

Multiple Gestation Monitoring

Contraindications

Patient-Related Factors

Unstable Maternal Condition

Poor Acoustic Windows

Excessive Fetal Movement

Advanced Gestational Age

Ethical or Psychological Considerations

Outcomes

Identifying intra-uterine gestational sac in first trimester is priority through transvaginal or transabdominal.

A gestational sac appears by the fourth week via transvaginal ultrasound with the double decidual sign present in 85% of pregnancies.

Caution is essential to distinguish a gestational sac from a pseudo gestational sac in ectopic pregnancies.

Second- and third-trimester ultrasounds use transabdominal 3 to 5 MHz transducer.

Multiple-gestation exams assess chorionicity, amnionicity, fetal sex, fluid, and growth.

Equipment required

Ultrasound Machine

Transducers

Conductive Gel

Image Annotation Tool

Patient Preparation:

Apply a conductive gel to ensure optimal sound wave transmission in patient.

Informed Consent:

Ultrasound evaluates health, guides diagnosis, and determines follow-up actions.

Patient Positioning:

Place patient supine with slight left tilt for comfort and to prevent supine hypotension syndrome.

Position the patient supine with a slight left tilt and use pillows for comfort during late gestation.

Figure. Ultrasound with pregnancy obstetric of fetus

Systematic Scanning

Step 1: Survey of Fetus:

Perform an initial view of fetal anatomy to confirm gestational age, fetal lie, and position.

Step 2: Detailed evaluation of specific structures:

Focus on the area of concern using the following methos:

For Brain and Central Nervous System: Use axial and coronal planes to evaluate the ventricles, midline structures, and posterior fossa.

For Fetal Heart: Perform a four-chamber view to evaluate outflow tracts using color Doppler.

For Abdomen and Thorax: Check organ placement to assess anomalies like diaphragmatic hernia.

For Placenta and Umbilical Cord: Evaluate placental position and blood flow using Doppler studies.

Step 3: Monitor for Fetal Movement:

Observe fetal activity and movements during the scan for additional assessment of patient.

Complications:

Discomfort during the procedure

Anxiety or emotional distress

Fetal movement disturbance

Misinterpretation of results

References

Obstetrical Ultrasound During Pregnancy – NCBI Bookshelf

References

Obstetrical Ultrasound During Pregnancy – NCBI Bookshelf