Complete molar pregnancy vs Partial molar pregnancy
How to tell Complete molar pregnancy and Partial molar pregnancy apart when a board question makes them look alike.
Complete mole is no fetus with very high hCG and diploid paternal genome; partial mole has fetal parts and triploidy.
Side by side
Complete mole has diffuse villous swelling, no fetal tissue, very high hCG, theca lutein cysts, and higher risk of persistent trophoblastic disease.
Partial mole has abnormal fetal tissue or parts, triploidy, focal villous swelling, lower hCG, and lower malignant potential.
Complete mole usually results from an empty ovum fertilized by one sperm that duplicates or two sperm, producing androgenetic diploid tissue.
Partial mole usually results from dispermy fertilizing a normal ovum, producing triploid conceptus tissue.
Snowstorm uterus, markedly elevated hCG, absent fetus, and 46,XX or 46,XY paternal-only genetics support complete mole.
Triploidy such as 69,XXY, fetal parts, and focal placental abnormalities support partial mole.
The trap
Both are molar pregnancies with abnormal villi, but fetal tissue and ploidy separate them.
Watch it explained
Test it nowThe repair move
For molar pregnancy, ask whether fetal tissue is present and whether the genetics are diploid paternal-only or triploid.
Try a free question
CoreA 22-year-old G1 at supposed 10 weeks gestation has hyperemesis, vaginal bleeding, and uterine size larger than dates. Beta-hCG is 285,000 mIU/mL. Transvaginal ultrasound shows a snowstorm pattern with no identifiable fetus or fetal parts. Bilateral theca lutein cysts are present. Karyotype of evacuated tissue is 46,XX with all chromosomes paternal in origin. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Complete hydatidiform mole. Complete mole has no fetal tissue, very high hCG, theca lutein cysts, snowstorm uterine appearance, and 46,XX paternal-only karyotype from fertilization of an empty ovum.
Why the other choices are tempting
- B. Partial mole has identifiable fetal tissue or parts, lower hCG, and triploid karyotype (usually 69,XXY).
- C. Choriocarcinoma is a malignant gestational trophoblastic neoplasm; it can follow a mole but is not the initial molar diagnosis.
- D. Threatened abortion has a viable intrauterine pregnancy with cardiac activity, not a snowstorm pattern.
- E. Hyperemesis gravidarum is symptomatic only and does not explain the imaging or hCG findings.
Flashcards
Tap a card to flip it.
What fetal tissue clue supports complete mole?
Complete mole has no fetal tissue.
What ploidy supports partial mole?
Triploidy, often 69,XXY, supports partial mole.
Quick answers
What is the fastest way to tell Complete molar pregnancy from Partial molar pregnancy?
Complete mole is no fetus with very high hCG and diploid paternal genome; partial mole has fetal parts and triploidy.
What is the key clue for Complete molar pregnancy?
Complete mole has diffuse villous swelling, no fetal tissue, very high hCG, theca lutein cysts, and higher risk of persistent trophoblastic disease.
What is the key clue for Partial molar pregnancy?
Partial mole has abnormal fetal tissue or parts, triploidy, focal villous swelling, lower hCG, and lower malignant potential.
What is the common trap with Complete molar pregnancy vs Partial molar pregnancy?
Both are molar pregnancies with abnormal villi, but fetal tissue and ploidy separate them.