Placentomegaly

Changed by Yuranga Weerakkody, 5 Mar 2016

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Placentomegaly is a term applied to an abnormally enlarged placenta.

Pathology

Associations

It can be associated with number of maternal and fetal disorders which include:

maternal
- maternal anaemia(s)
- maternal diabetes
- chronic intrauterine infections
- alpha-thalassemia
fetal
- umbilical vein obstruction
- fetal high output failure
- fetal malformation
  - Beckwith-Wiedemann syndrome ^1,5
  - sacrococcygeal teratoma
  - hydrops fetalis and causative underlying conditions
  - chromosomal anomalies
    - triploid: with extra set from paternal origin
- in utero infection ⁸
- Finnish type congenital nephrotic syndrome ⁶
fetomaternal ~~hemorrhage~~haemorrhage
placental abnormalities

Radiographic features

Antenatal ultrasound

May show an increase in placental thickness and/or placental extent. The increase in size may be homo or heterogeneous dependent on the cause. The maximum thickness considered normal at any stage in pregnancy is often taken at 4 cm.

Differential diagnosis

The differential for an apparent increased in placental size on ultrasound includes:

retroplacental haematoma: especially when it is isoechoic, e.g. from a placental abruption

~~-<li>alpha-thalassemia</li>~~
+<li><a title="alpha-thalassemia" href="/articles/alpha-thalassemia">alpha-thalassemia</a></li>
~~-<li><a title="Sacrococcygeal teratoma" href="/articles/sacrococcygeal-teratoma">sacrococcygeal teratoma</a></li>~~
+<li><a href="/articles/sacrococcygeal-teratoma">sacrococcygeal teratoma</a></li>
~~-<li>fetomaternal hemorrhage</li>~~
+<li><a title="fetomaternal haemorrhage" href="/articles/fetomaternal-haemorrhage">fetomaternal haemorrhage</a></li>
~~-<li>intraplacetnal hemorrhage </li>~~
+<li><a title="intraplacetnal haemorrhage " href="/articles/intraplacetnal-haemorrhage">intraplacetnal haemorrhage </a></li>