What are the other Names for this Condition? (Also known as/Synonyms)

• Mesenchymal Stem Villous Hyperplasia
• PMD (Placental Mesenchymal Dysplasia)
• Pseudo-Partial Mole

What is Placental Mesenchymal Dysplasia? (Definition/Background Information)

• Placental Mesenchymal Dysplasia (PMD) is a rare and benign condition of the placenta. Its characteristic features are the presence of grape-like vesicles with enlargement of the placenta (observed on imaging studies)
  • The placenta is an organ that connects the developing fetus to the uterine wall. It is a disc-shaped reddish-brown structure that connects the fetus to the mother through the umbilical cord
  • The normal function of the placenta is to supply nutrients and oxygen to the fetus from the mother’s blood and remove wastes from the fetal body
• There is a high rate of fetal demise and intrauterine growth restriction (IUGR) in Placental Mesenchymal Dysplasia associated pregnancies. PMD is also associated with a genetic disorder known as Beckwith-Wiedemann syndrome (BWS) that affects the baby
• Prenatal ultrasound scan findings are similar to what is observed in hydatidiform mole (or a molar pregnancy). Hence, it is important to differentiate between a Placental Mesenchymal Dysplasia and hydatidiform mole due to the high rates of IUGR and fetal death in PMD
• In most cases, in women with Placental Mesenchymal Dysplasia, a Cesarean section may be recommended for delivering the child. The severity of intrauterine growth retardation often determines the prognosis of the baby after birth, including its maintenance of health
• Pregnant women should have prenatal counselling, multiple prenatal check-ups and continuous monitoring with a healthcare provider, to periodically assess the baby’s growth and development until completion of the pregnancy

Who gets Placental Mesenchymal Dysplasia? (Age and Incidence)

• The incidence of Placental Mesenchymal Dysplasia is difficult to ascertain, but according to some estimates it is around 0.02% (or 1 in every 5,000 pregnancies)
• Women of advanced maternal age (defined as women over 35 years of age), are at a greater risk for PMD. However, it can occur in younger age groups too
• Both male and female fetuses are affected, although a high incidence is observed in female fetuses (female to male ratio of 7:2)
• All races and ethnic groups can be affected

What are the Risk Factors for Placental Mesenchymal Dysplasia? (Predisposing Factors)

• Fetuses with Beckwith-Wiedemann syndrome (BWS) are at increased risk for Placental Mesenchymal Dysplasia (PMD). It is reported that over 33% of the cases of PMD are associated with BWS

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Placenta Mesenchymal Dysplasia? (Etiology)

The exact cause of development of Placental Mesenchymal Dysplasia is presently unknown.

• The condition is observed in fetuses with Beckwith-Wiedemann syndrome (BWS)
• Beckwith-Wiedemann Syndrome (BWS) is an inherited genetic disorder characterized by an abnormal overgrowth of the body parts
• However, it is important to note that PMD occurs in fetuses without the syndrome too

What are the Signs and Symptoms of Placental Mesenchymal Dysplasia?

Most of the patients with Placental Mesenchymal Dysplasia do not show any symptoms. They are diagnosed incidentally on ultrasound scans on a routine check-up.

• Pregnant women may present with polyhydramnios (or an increase in the amount of amniotic fluid in the womb); specially, those who are affected with Beckwith-Wiedemann syndrome (BWS)
• A few cases may present with vaginal bleeding

Newborn children with underlying Beckwith-Wiedemann syndrome may exhibit specific symptoms of the disorder.

How is Placental Mesenchymal Dysplasia Diagnosed?

Placental Mesenchymal Dysplasia is diagnosed with the help of following exams and procedures:

• Physical examination to evaluate for vaginal bleeding
• Evaluation of medical history
• Complete blood count (CBC) and other blood tests as needed
• Alpha feto-protein (AFP) blood test in pregnancy, to determine the apparent risk for certain congenital abnormalities
• Abdominal or vaginal ultrasound scan, wherein sound waves are used to create an image of the uterus and placenta on a monitor screen. This helps in identifying the abnormal placenta and whether the fetal growth measurement is below average (for gestational age), in order to diagnose intrauterine growth retardation
• Ultrasonogram is also a helpful monitoring tool, to assess the fetal heart and for any lack of oxygen
• MRI scans may be required in some cases
• Examination of placental membranes under a microscope
• A differential diagnosis may be necessary to eliminate other conditions presenting similar signs and symptoms such as molar pregnancy or hydatidiform mole

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Placenta Mesenchymal Dysplasia?

The complications of Placental Mesenchymal Dysplasia may include:

• Maternal complications may include:
  • Swelling of the baby
  • Maternal diabetes
  • Preeclampsia; a condition in pregnant women characterized by high blood pressure, protein in urine, and edema (swelling due to the presence of fluid)
• Fetal complications may include:
  • Intrauterine growth restriction (IUGR); when a baby has less than the average growth in the womb during pregnancy
  • Premature birth
  • Intrauterine fetal demise

How is Placental Mesenchymal Dysplasia Treated/Managed?

A management of Placental Mesenchymal Dysplasia may involve the following measures:

• Fluid administration through the veins
• Blood transfusion, as needed
• Cesarean operation (C-section) may be required as opposed to a vaginal delivery
• Medication to reduce blood pressure in the mother: The various medications used to lower blood pressure include alpha blockers, angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), beta-blockers, calcium channel blockers, central alpha agonists, diuretics, and vasodilators, among others
• In preterm pregnancies, medications may be given to assist the fetus in maturing

How can Placental Mesenchymal Dysplasia be Prevented?

Currently, there are no definite measures available for preventing Placental Mesenchymal Dysplasia. However, the following may be observed to lower one’s risk for the same:

• Seek out prenatal care by a healthcare provider, in order to completely monitor the course of the pregnancy
• In cases where a history of Beckwith-Wiedemann syndrome is noted, a discussion with the healthcare provider about Placental Mesenchymal Dysplasia and related complications is recommended

In case of Beckwith-Wiedemann syndrome, then:

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child

What is the Prognosis of Placenta Mesenchymal Dysplasia? (Outcomes/Resolutions)

• The outcome of Placental Mesenchymal Dysplasia is reportedly variable; it may range from a completely normal fetus to the presence of intrauterine growth restriction or even fetal demise
• If the condition is associated with Beckwith-Wiedemann syndrome, then the overall outcomes depend on the severity of the condition, the complications that may develop, and treatment response

Additional and Relevant Useful Information for Placenta Mesenchymal Dysplasia:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/diseases-conditions/pregnancy-related-disorders/