Echogenic bowel

Echogenic bowel is often described as being ‘brighter than bone’ on ultrasound. It is most commonly seen in the lower abdomen of the fetus, and can be a normal finding that disappears before birth, with no adverse short- or long-term outcomes.

Genetic considerations for echogenic bowel include chromosome anomalies and cystic fibrosis. Other recognised associations include:

• fetal infections, such as cytomegalovirus, which can be diagnosed by testing the blood of the mother and/or performing amniocentesis for microbiological assessment;
• cases in which bleeding occurs into the amniotic fluid and the baby subsequently swallows the blood products;
• intrauterine growth restriction; and
• bowel obstructions or meconium peritonitis.

Chromosome conditions

When a baby has more or fewer chromosomes than expected, many organs and systems can be affected. Echogenic bowel is associated with aneuploidy, and around 15% of fetuses with Down syndrome (trisomy 21) will be diagnosed with echogenic bowel.

Cystic fibrosis

Cystic fibrosis is a genetic condition in which the lungs and digestive system get congested with mucus, and the vans deferens is missing or blocked for most affected men. The genetic variant that causes it affects the body’s ability to make or direct the CFTR protein, which assists with the movement of salt and water in and out of cells.

As cystic fibrosis is an autosomal recessive condition, both parents will be offered a blood test to assess their carrier status. Around 3% of babies found to have echogenic bowel during the anatomy scan (the 20-week screening scan) will have cystic fibrosis.

Echogenic bowel is typically diagnosed during the 20-week screening ultrasound scan if the fetal intestine appears brighter than expected.

Echogenic bowel in isolation is not an inherited condition. If it has a genetic cause, however, appropriate counselling should be given for the consideration of the current and future pregnancies.

Management of echogenic bowel depends on the underlying cause. If it is an isolated finding, and cystic fibrosis and chromosomal conditions have been excluded, there is no need for postnatal follow-up or any further treatment.

If cystic fibrosis or a chromosomal condition (such as trisomy 21) are found to be the underlying cause, treatment would be as per the standard management for these conditions.

Quite often, there is no known or underlying cause, with no ongoing concerns.

For clinicians

• CPD by Window to the Womb: Echogenic bowel at 16 weeks (video, 55 seconds)
• Dr Jayesh Dabhi Ultrasound Training: Echogenic bowel (video, 2 minutes 14 seconds)
• Dr Joe’s Ultrasound Videos: Echogenic fetal bowel (video, six seconds)
• NHS England: National Genomic Test Directory

References:

• Chung K, Thayalan K and Kothari A. ‘Echogenic bowel in the second trimester – Where to from here?‘. Australasian Journal of Ultrasound in Medicine 2017: volume 21, issue 1, pages 49–54. DOI: 10.1002/ajum.12074
• D’Amico A, Buca D, Rizzo G and others. ‘Outcome of fetal echogenic bowel: A systematic review and meta-analysis‘. Prenatal Diagnosis 2021: volume 41, issue 4, pages 391–399. DOI: 10.1002/pd.5638

For patients

• Cystic Fibrosis Trust
• International Society of Ultrasound in Obstetrics and Gynaecology: Echogenic bowel
• University Hospital Southampton NHS Foundation Trust: Patient information factsheet: Echogenic bowel (PDF, four pages)