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Placenta Membranacea

Last updated Sept. 7, 2020

Reviewed by: Kashif M. Mohiuddin, MD

Approved by: Krish Tangella MD, MBA, FCAP

Placenta Membranacea (PM) is a very rare condition involving the placenta.


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

  • Placenta Diffusa
  • PM (Placenta Membranacea)

What is Placenta Membranacea? (Definition/Background Information)

  • Placenta Membranacea (PM) is a very rare condition involving the placenta. It may be observed in women of any age group and is typically associated with placenta accreta and placenta previa
  • The placenta is a thin membrane-like organ and covered with chorionic villi (tiny units of placenta) that connects the developing fetus to the uterine wall. It is a disc-shaped red-brown structure that connects the fetus to the mother through the umbilical cord
  • The normal function of placenta is to supply nutrients and oxygen to the fetus from the mother’s blood and remove wastes from the fetal body
  • Normally, during development of placenta, the chorionic villi in the decidua membranes (thick layer of modified uterus lining) get atrophied or wasted away. This does not take place in Placenta Membranacea as the chorionic villi remain without differentiation and cover almost the whole gestational sac (fetal membranes)
  • Placenta Membranacea can cause complications during delivery for the baby and mother. It can be managed effectively under the supervision of experienced clinicians, if diagnosed promptly during pregnancy. However, the prognosis can be highly variable and depends on the individual’s specific condition and associated complications

Who gets Placenta Membranacea? (Age and Incidence)

  • The incidence of Placenta Membranacea is about 1-2 in 40,000 pregnancies
  • Women of any age can be affected, although most cases in the literature are in women over 25 years of age
  • All races and ethnic groups can be affected, and no predilection is noted

What are the Risk Factors for Placenta Membranacea? (Predisposing Factors)

The risk factors for Placenta Membranacea include:

  • Previous surgical procedures involving the uterus resulting in uterine trauma
  • Repeated trauma to the endometrium due to endometritis, which is an inflammation of the endometrium (the innermost uterine wall lining)
  • Women with a history of Placenta Membranacea are at a higher risk in future pregnancies
  • The condition is also associated with other placental abnormalities such as vasa previa and placenta accreta (including placenta increta and placenta percreta)

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 Membranacea? (Etiology)

  • The exact cause of development of Placenta Membranacea is unknown
  • It is suggested that improper blood supply (poor or excessive blood supply) to the decidua or parts of the placental membrane, may cause persistence of the chorionic villi in the fetal membranes
  • The persistent chorionic villi may completely cover the gestational sac/fetal membranes leading to Placenta Membranacea

What are the Signs and Symptoms of Placenta Membranacea?

  • Generally, there are no significant signs and symptoms observed for Placenta Membranacea
  • Antenatal (painless) bleeding during mid-trimester occurs in some pregnant women with the condition; this is typically the only symptom that is noted. The bleeding may be during pregnancy or following delivery of the baby, antepartum hemorrhage (APH) or postpartum hemorrhage (PPH), respectively

How is Placenta Membranacea Diagnosed?

During pregnancy, Placenta Membranacea is diagnosed with the help of following methods:

  • Physical examination to evaluate for vaginal bleeding
  • Evaluation of medical history
  • Complete blood count (CBC) and other blood tests as necessary
  • Fetal monitoring to assess the fetal heart and for any lack of oxygen
  • Abdominal or vaginal ultrasound scan, wherein sound waves are used to create an image of the uterus and placenta on a monitor screen
  • MRI scans can be helpful in diagnosing placenta accreta associated with this condition, if present

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 Membranacea?

Placenta Membranacea can lead to complications both for the mother and the fetus.

Maternal complications may include:

  • Shock
  • Chorioamnionitis of placenta: Bacterial infection of the placenta and its membranes (the chorion and amnion)
  • Blood-clotting issues, such as disseminated intravascular coagulation (DIC)
  • Blood loss: Uncontrollable blood loss may necessitate a hysterectomy (a surgical procedure to remove the uterus)
  • Need for blood transfusion
  • Kidney failure; failure of other organs
  • Excess loss of blood may sometimes lead to fatalities

Complications involving the fetus:

  • Placenta Membranacea can lead to early labor
  • It can also lead to fetal growth restriction and intrauterine fetal demise

How is Placenta Membranacea Treated?

A treatment of Placenta Membranacea involves the following:

  • Fluid administration through the veins
  • Blood transfusion, if necessary
  • Close monitoring of the pregnancy until childbirth
  • Cesarean section (C-section) may be required, as opposed to a vaginal delivery
  • Uncontrollable blood loss may necessitate a hysterectomy (removal of the uterus)
  • In preterm pregnancies, medications may be given to assist the fetus in maturing

How can Placenta Membranacea be Prevented?

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

  • Seek early and appropriate treatment of endometriosis
  • It is important to seek out a healthcare provider towards prenatal care, in order to completely monitor the course of the pregnancy
  • If there is history of Placenta Membranacea, a discussion with the healthcare provider before conceiving again is recommended

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

The prognosis of Placenta Membranacea varies from one individual to another, and it depends on several factors including:

  • The severity of Placenta Membranacea and associated condition (if any), such as placenta previa or placenta accreta, and the amount of blood loss incurred
  • How soon timely medical attention was sought
  • Development of any complications

According to medical literature, almost 50% of the outcomes are poor for the fetus.

Additional and Relevant Useful Information for Placenta Membranacea:

Placenta Membranacea is seen usually in mammals, such as cetaceans (sea mammals), horses, and pigs. However, it is highly uncommon in humans.

What are some Useful Resources for Additional Information?


References and Information Sources used for the Article:


Helpful Peer-Reviewed Medical Articles:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Sept. 7, 2020
Last updated: Sept. 7, 2020