Gross features suggestive of cord compression:
(1) nuchal cord
(2) true knot
(3) other gross cord abnormality associated with cord compression
(4) thrombosis in or hemorrhage around the umbilical cord
(5) thrombosis in or hemorrhage around in the vessels of the chorionic plate
Histologic features suggestive of cord compression:
(1) vascular ectasia and/or thrombosis in the umbilical arteries and/or vein
(2) vascular ectasia and/or thrombosis in chorionic blood vessels
(3) vascular ectasia and/or thrombosis in blood vessels of the stem villi
(4) avascular villi ("downstream")
(5) stromal karyorrhexis in villi ("downstream")
Criteria of Parast and Boyd for cord accident - both of the following:
(1) clinical and/or gross finding suggestive of cord compression
(2) presence of one or both "downstream" findings (avascular villi and/or stromal karyorrhexis)
where:
• The criteria of Parast and Boyd do not specify histologic findings in the blood vessels of the cord, chorionic villi or stem villi. I will include them with the first category (clinical and/or gross findings).
Interpretation:
• The histologic criteria alone are relatively insensitive for identifying a cord accident but show a good specificity if present.
• The criteria of Parast and Boyd showed a better sensitivity (67%) and a reasonable specificity (up to 85%).
Performance:
• A false negative pathologic exam may occur if an inadequate examination of the cord, chorionic plate and blood vessels of the stem villi. Multiple sections (4 or more ideally) should be taken of the chorionic plate if a cord accident is suspected.
• A false negative pathologic exam may occur if the cord compression occurred acutely.
• A false positive can occur in a hypercoagulable state.
