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2001-03-30-10 Answer to the case of the week #47 © Comstock www.TheFetus.net

Answer to case #47

March 30-April 12,  2001

Submitted and discussed by Christine Comstock, MD

William Beaumont Hospital, Fetal Imaging, 3601 West 13 Mile Road, Royal Oak, MI 48073-6769 

These 4 fetuses have the same pathology. Part of this pathology is visible on the 4 following clips:

Quicktime Windows
31 weeks 0.3 MB 31 weeks 0.2 MB
20 weeks 1.6 MB 20 weeks 1.2 MB
26 weeks 0.3 MB 26 weeks 0.3 MB
20 weeks 1.7 MB 20 weeks 1.4 MB

The Quicktime and Windows clips demonstrate the same images. The finding is only visible on video-clips (hint, hint.. ) although the pathology responsible for the findings could be seen in conventional sections.

Findings:

These four fetuses have a hernia of the Foramen of Bochdalek.

The video shows "paradoxical" motion of the the diaphragm or descent of the diaghragm on the normal side with ascent of abdominal contents on the abnormal size. This produces a rocking motion. Normally both sides of the diaphragm descend upon inspiration. However, part of the diaphragm is missing in these fetuses and upon inspiration the abdominal pressure rises and forces its contents into the chest through the foramen of Bochdalek. Since the normal side descends at the same time we see a rocking motion.

This sign is only visible at the level of the hernia. More anteriorly you would see the intact diaphragm descend in a normal fashion. If you suspect a hernia of this foramen, position your transducer in the coronal plane of the descending aorta.  Wait for inspiratory motion or hiccoughs. Although many say that regular inspiratory motions do not develop until the early third trimester, we have not found this to be true. In our series we had no false positives using this sign, but we did have one false negative in a very small hernia. This fetus did extremely well and never experienced any significant distress. Note that this sign does not distinguish hernias from eventrations since the lack of muscle in the diaphragm in the latter causes paradoxical motion also.  

(See also Diaphragmatic hernia).

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