Wednesday, March 28, 2007

Molar pregnancies

Molar pregnancy aka Hydatidiform mole aka mola hydatidiforma is a common complication of pregnancy, occurring once in every 1000 pregnancies in the US, with much higher rates in Asia (e.g. up to one in 100 pregnancies in Indonesia).

It consists of a nonviable embryo which implants and proliferates within the uterus.

Clinical presentation

Molar pregnancies usually present with painless vaginal bleeding in the fourth to fifth month of preganancy.


  • Ultrasound makes the definitive Dx - the uterus may be larger than expected, or the ovaries may be enlarged.
  • There may also be hyperemesis (more vomiting than would be expected).
  • Sometimes there is an increase in BP along with proteinuria.
  • Blood tests will show very high levels of hCG.
  • Sometimes symptoms of hyperthyroidism are seen, due to the extremely high levels of hCG, which can mimick the normal TSH.


  • A mole is characterized by a conceptus of hyperplastic trophoblastic tissue attached to the placenta. The conceptus does not contain the inner cell mass (the mass of cells inside the primordial embryo that will eventually give rise to the fetus).
  • The hydatidiform mole can be of two types: a complete mole, in which the abnormal embryonic tissue is derived from the father only; and a partial mole, in which the abnormal tissue is derived from both parents.


  • Hydatidiform moles should be treated by evacuating the uterus by uterine suction or by surgical curettage as soon as possible after diagnosis.
  • Patients are followed up until their serum hCG titre has fallen to an undetectable level.
  • Invasive or metastatic moles often respond well to methotrexate. The response to treatment is nearly 100%.
  • Patients are advised not to conceive for one year after a molar pregnancy.
  • The chances of having another molar pregnancy are approximately 1%.


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