Improving prenatal detection of abdominal supraumbilical anomalies: The sonographic examination of fetal anechoic spaces of upper abdomen revisited

Abstract

Visualization of the axial plane of the fetal abdomen is mandatory to obtain abdominal biometry in the assessment of fetal growth in the second and third trimesters.The main anatomic landmarks that must be identified in this view include the fetal stomach and the intrahepatic portion of the umbilical vein, which are easily identifiable as they appear anechoic on ultrasound. The gallbladder is the other prominent anechoic structure in this plane. Focused study of the morphological characteristics of, and spatial relationship among, these three anechoic spaces is a simple technique to detect anomalies involving fetal upper abdominal organs. In this review, the sonographic features of those conditions that can be detected using this technique, which was termed the Fetal Examination of the Anechoic Spaces of upper abdomen Technique (FEAST), are classified and illustrated.

Fetal “Phrygian Cap” Gallbladder

“…9,[17][18][19] Recognition of a Phrygian cap as part of the differential diagnoses of other cystic masses of the fetal upper abdomen is also important to consider, and include choledochal cyst, hepatic cyst, and gallbladder duplication and septation. 11,13 Our small prenatal series shows that the Phrygian cap anomaly can be detected in a relatively higher number of fetal sonographic examinations if this condition is specifically looked for. This variant can only be identified when a focused examination of the fetal gallbladder including evaluation of its fundal region is performed.…”

“…14,15 On axial views, it typically appears as a pear-shaped anechoic structure located in the right upper abdominal quadrant, below the liver and to the right of the umbilical vein. 11,13,16 Color Doppler imaging can be helpful in the differentiation between the gallbladder and umbilical vein. 13 Routine evaluation of the gallbladder during obstetric ultrasound, however, is frequently neglected.…”

“…11,13,16 Color Doppler imaging can be helpful in the differentiation between the gallbladder and umbilical vein. 13 Routine evaluation of the gallbladder during obstetric ultrasound, however, is frequently neglected. 11 This is in spite of the various congenital and developmental anomalies that can affect this organ during fetal life [11][12][13] and which can have significant postnatal consequences in some cases.…”

“…At the time of sonographic evaluation of the fetal upper abdominal region, assessment of the gallbladder using the axial plane is always attempted at the time of abdominal circumference measurement, as previously described. 12,13 Differentiation between the gallbladder and umbilical vein is usually straightforward, although color flow imaging is used to recognize the umbilical vein in doubtful cases. Sonographic examination included the visualization of the gallbladder (yes or no), its position (to the right or left of the umbilical vein), its size (subjectively normal, small, or large), and its shape (straight, boomerang type or Phrygian cap type).…”

“…Ultrasound examinations at ≥20 weeks' gestation include assessment of the fetal anatomy and biometry, placenta and umbilical cord, and amniotic fluid volume. At the time of sonographic evaluation of the fetal upper abdominal region, assessment of the gallbladder using the axial plane is always attempted at the time of abdominal circumference measurement, as previously described 12,13 . Differentiation between the gallbladder and umbilical vein is usually straightforward, although color flow imaging is used to recognize the umbilical vein in doubtful cases.…”