Imaging the fetal abdominal aorta and IVC

Important points to consider whilst imaging two of the fetal great vessels namely abdominal aorta and IVC. 

1. Ultrasound imaging of the abdominal aorta and inferior vena cava (IVC) is a crucial part of a comprehensive fetal anatomy scan, typically performed at around 20 weeks of gestation.

2. The abdominal aorta is the main artery that carries blood from the heart to the lower body, while the IVC is the main vein that returns blood from the lower body to the heart. Imaging these structures can help detect potential abnormalities that may affect fetal development and health.

3. One important aspect to observe in the ultrasound imaging of the abdominal aorta and IVC is the size of these vessels. Abnormalities in vessel size may indicate a problem with blood flow or an underlying condition, such as an aneurysm or stenosis (rarely seen).

4. Another important aspect to observe is the presence of any blood clots or blockages in these vessels. These can restrict blood flow and potentially cause complications for the fetus. However, this is very rare in fetus. 

5. The sonologist must also observe the structure and location of the abdominal aorta and IVC. For example, a malpositioned aorta or IVC may suggest other anomalies or abnormalities that require further investigation.

6. The ultrasound imaging may also be used to evaluate other surrounding organs, such as the kidneys and liver, which may be affected by any abnormalities in blood flow to and from the lower body.

7. Overall, ultrasound imaging of the abdominal aorta and IVC is a critical part of the fetal anatomy scan, as it can help identify potential problems and allow for early intervention and treatment. 

Abdominal aorta in 20 weeks fetus:

The aorta seen entering the fetal abdomen:

Abdominal aorta and IVC seen side by side:

IVC seen entering right atrium:

Branches of abdominal aorta: Renal arteries and common iliac arteries:

What are the major branches of the abdominal aorta in a 20 weeks fetus?

During fetal development, the abdominal aorta gives rise to several important branches that supply blood to different organs and tissues. Here are some of the important branches of the abdominal aorta that can be visualized during ultrasound imaging:

Celiac artery: This is the first branch of the abdominal aorta and supplies blood to the liver, spleen, and stomach. Not always seen adequately. 

Superior mesenteric artery: This artery arises from the anterior surface of the abdominal aorta just below the celiac artery and supplies blood to the small intestine, cecum, and ascending colon. Again difficult to image on fetal ultrasound. 

Renal arteries: The left and right renal arteries arise from the lateral aspects of the abdominal aorta just below the superior mesenteric artery and supply blood to the kidneys. These are easily imaged, as seen in the ultrasound and color Doppler images above. 

Inferior mesenteric artery: This artery arises from the anterior surface of the abdominal aorta just above the bifurcation into the common iliac arteries and supplies blood to the descending colon, sigmoid colon, and rectum. Difficult to identify on routine ultrasound imaging. 

Common iliac arteries: The abdominal aorta bifurcates into the left and right common iliac arteries, which supply blood to the pelvis and lower extremities. These are easily seen as the terminal branches of the abdominal aorta. See images above. 

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Sonography of fetal abdomen