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2013-01-15-09 Case of the week #346 © Bronshtein 

Answer to the case of the week #346

June 06, 2013 - June 20, 2013 

Moshe Bronshtein, MD*; Inna Naroditsky, MD*; Yaniv Zohar, MD*; Frantisek Grochal; MD**.

*   Haifa, Israel;
** Femicare, s.r.o., Center of prenatal ultrasonographic diagnostics, Martin, Slovak republic.

Case report

This was a low risk pregnancy that we have seen at 15 and 19 weeks of pregnancy. Biochemical screening at 17 weeks found high levels of maternal serum alpha-fetoprotein (MS-AFP) - 2.5 MoM; and free beta-subunit of human chorionic gonadotropin (free beta-hCG) HCG - 23 MoM.

Our ultrasound examination at 15 weeks did not found any fetal anomaly, but the placenta was slightly enlarged and hyperechoic. At 19 weeks fetal biometry had lagged behind gestational age:

  • HC (Head Circumference) had correlated with 17 weeks of gestation;
  • AC (Abdominal Circumference) had correlated with 16 weeks of gestation;
  • FL (Femur Length) had correlated with 16 weeks of pregnancy;
  • Absent diastolic flow within the umbilical arteries was observed;
  • Placenta was thickened, hyperechoic with multiple small cystic lesions.
Beta-hCG levels reached 350000 mIU/ml and the placenta was thickened and hyperechoic. The findings had led us to the diagnosis of placental mesenchymal dysplasia. The parents opted for the termination of the pregnancy and the diagnosis was confirmed by histopathologist thereafter. Fetal umbilical cord was winded around the fetal neck and body (see images of the pathologic images of the fetus). 


Several entities leading to the placental mesenchymal dysplasia (PMD) were described in literature. Characteristic features of the PMD are:
  • enlarged, hydropic placenta having a "molar-like appearance";
  • fetal intrauterine growth restriction;
  • oligohydramnios;
  • high levels of HCG (beta-hCG).
We have encountered many other cases of placentomegaly in our practice that did not fulfill these criteria and where placental mesenchymal dysplasia was not found.
Reviewing the literature and considering our case, we found a connection of the anomaly with certain degree of long-standing umbilical cord compression or restriction. We do think that a chronic incomplete compression of the umbilical cord may be responsible for increasing of the difference between systolic arterial pressure (fetal cardiac output) and umbilical venous return (input). This leads to congestion of placental villi and "squeezing" of the chorionic gonadotropin (hCG) into maternal circulation. Consequent placental dysfunction is liable for all features of fetal hypoxia, intrauterine growth restriction and its symptoms (bowel dilatation, cardiomegaly, absent diastolic flow, etc.). Various aspects of hydropic placenta are obvious component of the findings.
Placental venous occlusion (restriction) which may be partial (affecting one of the venous branches) or complete in cases of sublethal chronic cord restriction (as it was in our case) may be etiologic factor of placental mesenchymal dysplasia. This possibility has not been described in the literature before. We think this possibility should be taken into consideration in cases of cystic placentomegaly, high levels of hCG and fetal intrauterine growth restriction.

The pathomechanism is similar to cases of pulmonary edema in which the systolic pulmonary arterial pressure is higher than the pulmonary venous pressure leading to congestion of the lungs.
Image 1: 15 weeks of pregnancy; the image shows prominent placenta, that was the only iregullar retrospective finding.

Images 2, 3, 4, 5, and videos 1, 2, 3: 19 weeks of pregnancy. The image shows prominent edematous placenta with several cystic areas.




Images 6, 7, 8: Postmortem fetus with enlarged placenta and umbilical cord winded around the fetal neck and body.


Images 9, 10: Histology of the placenta. Image 9 shows mildly congested villi (green arrow) and normal villi (black arrows). The image 10 shows hydropic villi of the placenta (green arrows).



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