Fetal Abdomen and Pelvis axial plane

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The three axial planes are in almost parallel orientation and include the axial plane in the upper abdomen, the axial plane in the mid-abdomen, and the axial plane in the pelvis.

Section Structure

1. Stomach
2. Liver
3. Rib

The second plane, the mid-abdomen plane, is obtained at the level of the cord insertion into the abdomen in order to confirm integrity of the anterior abdominal wall. It is important to note the absence of any abnormal hyperechoic or anechoic structures in the abdomen and pelvis as this may suggest the presence of fetal malformations. The kidneys can be occasionally seen in the posterior abdomen due to their increased echogenicity and due to the anechoic renal pelvis. It is often difficult however to see the kidneys in the first trimester on the transabdominal axial plane.

Section Structure

1. 6- Cord insertion

The third plane is obtained in the pelvis and demonstrates a normally filled urinary bladder. The length of the filled bladder (obtained in sagittal length) should be less than 7 mm. Color Doppler is added to this plane to demonstrate the two umbilical arteries surrounding the bladder and this is performed for three purposes:
(1) To confirm that the anechoic structure is the bladder, especially if the bladder is mildly filled-
(2) To confirm with color Doppler the closed anterior abdominal wall-
(3) To rule out a single umbilical artery, which can be associated with other fetal malformations.

Section Structure

1. 4- Bladder
2. 5- Two umbilical arteries
3. 6- Cord insertion