Umbilical cord
Marked segmental thinning

Author: Paul J. Kowalski, M.D. (see Authors page)

Revised: 17 October 2017, last major update January 2017

Copyright: (c) 2002-2017,, Inc.

PubMed search: Marked segmental thinning

Cite this page: Kowalski, P.J. Marked segmental thinning. website. Accessed October 22nd, 2018.
Definition / general
  • Focal thinning of an umbilical vessel due to the (near) absence of tunica media layer
Essential features
  • Umbilical vein is usually affected in the majority (75%) of cases, with the umbilical arteries affected in the minority (25%) of cases
  • In affected vessels, the tunica media in at least one cord level is absent but usually less than 30% of the circumference of the affected level shows absent media
  • Similar changes can be seen in the placental stem vessels
  • Segmental thinning of an umbilical vessel should be distinguished from a thin umbilical cord, which is due to variable loss of supportive Wharton jelly in an affected segment of umbilical cord
  • Approximately 1.5% of term placentas are affected
  • Unknown
  • Unknown
Clinical features
  • Can be seen in association with fetal distress or congenital anomalies, such as cerebral palsy, anencephaly or urinary tract abnormalities
Gross description
  • No gross abnormality is usually seen
Microscopic (histologic) description
  • Affected vessel wall typically appears thin with (virtually) complete loss of the muscular tunica media layer
Microscopic (histologic) images

Images hosted on other servers:

Umbilical vein on right shows marked loss of tunica media in thinned region, affecting the
minority of the vein circumference (note: usually only one section through the umbilical
vein is present; this image may represent either loss or atrophy of the other umbilical vein or
a tortuous segment of umbilical vein that is present in a U shape in this 2 dimensional section)

Additional references