Echogenic Bowel

Excerpt

Fetal echogenic bowel is one of the soft markers detected on the prenatal ultrasound. Fetal echogenic bowel is defined as an increased echogenicity of the fetal bowel, which is noted on the prenatal ultrasound. It can be detected in the fetal ultrasound as a hyperechoic and well-defined area in the lower abdomen of the fetus. An associated focus of shadowing may suggest calcification. In the third trimester, this can be a normal finding representing meconium in the bowel of the fetus. However, when fetal echogenic bowel is detected in the second trimester, it can be associated with several fetal disorders.

Typically, the echogenicity is compared with the surrounding fetal iliac bone, although it can also be compared with the fetal lung or liver. Fetal echogenic bowel can occur as focal, multifocal, or diffuse.

The most widely accepted grading system for fetal echogenic bowel compares the echogenicity of the fetal bowel with that of the fetal iliac crest. This classification was developed by Slotnick et al. It is outlined as follows:

1. Grade 1: mildly increased- less echogenic compared to the bone

2. Grade 2: moderately increased- the same echogenicity as the bone

3. Grade 3: pronounced increased- more echogenic than the bone.

The grading system is dependent on the subjective assessment of the sonologist and thus can be associated with significant inter and intra-observer variability. Furthermore, the transducer frequency and grading can affect this scoring. With the advancement of technology and the availability of high-frequency transducers, echogenic findings can be exaggerated, leading to an overdiagnosis of the fetal echogenic bowel. Hence, the recommendation is to use a lower frequency transducer (<5 MHz) at a lower gain setting.