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CHM is the commonest type of gestational trophoblastic disease.
Complete moles are characterised by the absence of a fetus or fetal parts (i.e. no embryonic tissues). There is a non-invasive, diffuse swelling of chorionic villi.
Approximately 90% of complete hydatidiform moles have a 46XX diploid chromosomal pattern with ~10% having a 46XY composition. All the chromosomes are derived from the sperm, suggesting fertilization of a single egg that has lost its chromosomes.
Serum beta HCG levels are markedly elevated, out of proportion to the pregnancy.
- may be seen as an intrauterine mass with cystic spaces without any associated fetal parts
- may be difficult to diagnose in the first trimester 6
- may appear similar to a normal pregnancy or as an empty gestational sac
- <50% are diagnosed in the first trimester
- bilateral theca lutein cysts may also be seen on ultrasound
MRI may demonstrate a heterogenous mass with cystic spaces distending the uterine cavity. Fetal parts are notably absent. Uterine zonal anatomy is often distorted although a hypoechoic irregular myometrial boundary may be seen 3.
- T1: there may be areas of high signal corresponding to foci of haemorrhage
- T2: there is heterogenous high signal from the cystic spaces
- T1 C+ (Gd): often demonstrates intense enhancement due to hypervascularity
MRI may also demonstrate bilateral theca lutein cysts.
Treatment and prognosis
Suction and curettage is used for evacuation.
- 1. Reuter K, Michlewitz H, Kahn PC. Early appearance of hydatidiform mole by ultrasound. AJR Am J Roentgenol. 1980;134 (3): 588-9. AJR Am J Roentgenol (citation) - Pubmed citation
- 2. Reece EA, Barbieri R. Obstetrics and Gynecology, The Essentials of Clinical Care. Thieme Medical Pub. (2009) ISBN:3131439513. Read it at Google Books - Find it at Amazon
- 3. Semelka RC. Abdominal-Pelvic MRI. Wiley-Blackwell. (2010) ISBN:0470487755. Read it at Google Books - Find it at Amazon
- 4. Fowler DJ, Lindsay I, Seckl MJ et-al. Routine pre-evacuation ultrasound diagnosis of hydatidiform mole: experience of more than 1000 cases from a regional referral center. Ultrasound Obstet Gynecol. 2006;27 (1): 56-60. doi:10.1002/uog.2592 - Pubmed citation
- 5. Benson CB, Genest DR, Bernstein MR et-al. Sonographic appearance of first trimester complete hydatidiform moles. Ultrasound Obstet Gynecol. 2000;16 (2): 188-91. doi:10.1046/j.1469-0705.2000.00201.x - Pubmed citation
- 6. Lazarus E, Hulka C, Siewert B et-al. Sonographic appearance of early complete molar pregnancies. J Ultrasound Med. 1999;18 (9): 589-94. Pubmed citation