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Molar Pregnancy (Hydatidiform mole)

Hydatiform mole is a tumour that grows, like a pregnancy, in the uterus. It can occur in 2 ways:

  • Complete mole - 1 sperm with an empty egg. This sperm then replicates to give a normal number of chromosomes. No foetal material will form; just a proliferation of swollen chorionic villi.

  • Partial mole - 2 sperm with a normal egg, so the new cell has 3 sets of chromosomes. Foetal material will form.

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It presents with:

  • Hyperemesis gravidarum as b-hCG is very high

  • PV bleeding

  • Uterus larger than expected for gestational age

  • Thyrotoxicosis as b-hCG can mimic TSH


Investigations:

  • B-hCG – Really high

  • TVUS – Snowstorm appearance

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“Hysterectomy specimen, fresh specimen, uncut.” © Ed Uthman CC BY 2.0 (https://creativecommons.org/licenses/by/2.0/) Transvaginal ultrasonography showing a molar pregnancy. The pattern is described as a bunch of grapes ("cluster of grapes" or "honeycombed uterus" or "snow-storm"). - Mikael Häggström © CC0 1.0 (https://en.wikipedia.org/wiki/File:Molar_pregnancy.jpg)

Managed with evacuation of the uterine contents.


Complications - Thyrotoxicosis, Choriocarcinoma (metastatic uterine cancer), Pre-eclampsia


N.B. After evacuation, the levels of b-hCG are expected to fall and pregnancy should be avoided for 1 year. However, if they fail to drop, you should suspect malignant choriocarcinoma.



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