What are Potential Problems with Placental Abnormalities?

Patient Presentation
A 2-week-old male came to clinic for his health supervision visit. He was a 36 week gestation infant born by planned cesarean section to a 32 year old, G2 now P2 mother. The pregnancy was complicated with placenta accreta along with a low-lying placenta that was identified on second trimester ultrasound examination. The father had no concerns and was very comfortable feeding and caring for the infant in the office. The baby had been delivered and the mother had undergone hysterectomy.

The pertinent physical exam showed a well appearing male whose weight was 48 grams past birthweight. He was 25% for all growth parameters. His examination was normal with a almost completely well-healing circumcision.

The diagnosis of a healthy male was made. The father said that they were a little overwhelmed, “We made the decision to have him and then she had a planned hysterectomy. My wife has done well but it’s really hard taking care of her, my other 2 year old and this one. Thank heavens that my in-laws are here and helping. That way we have one adult to help take care of each of them. I’m supposed to go back to work in a couple of days, but my work is really understanding and I have at least another week off and my mother-in-law is going to stay until my wife is better. She wanted to breastfeed this one like she did the first, but it’s too much right now. Formula is just fine. I’m just so thankful he is growing and that my wife is safe and healthy too.”

“The placenta is a unique organ that sits at the interface of, and facilitates nearly all interactions between, maternal and fetal physiology. It is the sole source of oxygen and nutrition for the fetus, and provides a protective barrier against external insults. The placenta is also a highly adaptable organ that is capable of showing a wide range of pathological changes in response to various maternal and fetal factors and stressors.” The placenta has 3 layers: the amnion (fetal side), the chorion, and decidua (maternal side). In addition to making observations about the maternal and fetal sides, cord variations (i.e. size, length, twists, number of vessels, insertion location) can be observed. Even with these these possible variations, most placentas are normal.

Learning Point
There are some important placental abnormalities which are clinically, and potentially critically important for maternal and fetal outcomes.

  • Location problems
    • Placenta previa is a placenta that overlies the cervical os to some extent. Those that are near but do not overlie are termed low-lying placentas.
      • Incidence 1:200
      • Diagnosis: found on routine ultrasound or painless vaginal bleeding usually in 3rd trimester
      • Treatment: cesarean section prior to labor, often before term
      • Maternal problems: hemorrhage which has its own risks such as blood transfusions, septicemia, thrombophlebitis, admission to intensive care unit, hysterectomy, maternal death
      • Neonatal problems: prematurity – up to ~45% delivered before 37 weeks gestation
    • Vasa previa are fetal blood vessels that are attached but unprotected which traverse the fetal membranes near or over the cervical os
      • Incidence 1:2500-5000
      • Diagnosis: found on ultrasound
      • Treatment: cesarean section prior to labor and before rupture of membranes
      • Maternal problems: emergency care and its attendant complications including surgical complications
      • Neonatal problems: severe fetal blood loss and ensuing mortality, compromised umbilical blood flow and its attendent risks, prematurity
    • Placenta accreta is the placenta attaching to the myometrium without decidua in between. If the placenta invades the myometrium it is termed placenta increta, and if it extends outside the uterus it is termed placental percreta. Placenta accreta is also used sometimes to refer to this entire spectrum.
      • Incidence 1:300-2500
      • Diagnosis: found on ultrasound and more common with subsequent births after cesarean section or any procedure where the endometrium would be instrumented
      • Treatment: various, but planned intervention before labor is important
      • Maternal problems: severe maternal hemorrhage and potential mortality, and risks from hemorrhage
      • Neonatal problems: prematurity
  • Vascular problems
    • Maternal vascular malperfusion
      • Vascular problems on the maternal side of the placenta. This can anffect the entire or part of the placenta and the placenta is small.
      • Maternal problems: preeclampia, antiphospholipid syndrome, autoimmune disease, pregestational diabetes
      • Neonatal problems: fetal growth restriction
    • Fetal vascular malperfusion
      • Vascular problems on the fetal side of the placenta.
      • Neonatal problems: fetal distress, fetal demise, intrauterine growth restriction, cardiac abnormalities and coagulopathies
  • Infection
    • Acute chorioamnionitis
      • Usually microorganisms invade via the ascending route from the vagina, breech the placenta into the amniotic fluid. There is a fetal and maternal inflammatory response. It is a clinical diagnosis but laboratory testing may be helpful.
      • Maternal problems: endometritis, sepsis
      • Neonatal problems: sepsis, respiratory problems, neurodisability, necrotizing enterocolitis
    • Chronic villitis also known as Villitis of Unknown Etiology
      • Affects the chorionic villi but there is no identifiable organism
      • Neonatal problems: intrauterine growth restriction
    • Villitis
      • Affects the chorionic villi with an identifiable organism
      • There are many, but common examples are:
        • TORCH infections – Toxoplasmosis, Other agents including Syphilis, Rubella, Cytomegalovirus, Herpes simplex
        • Listeria
        • Zika
      • Miscellaneous
        • COVID-19 intrauterine transmission has been documented but is considered rare. Most cases of neonatal COVID are from infected caregivers.
          For breastfeeding, “Replication- competent SARS-CoV-2 has not been detected in breastmilk, although breastmilk samples are occasionally polymerase chain reaction positive.” Given the current information available and weighting risks and benefits “Most guidelines support the rooming in of the newborn with an infected mother, particularly when the mother is afebrile and asymptomatic.”

Questions for Further Discussion
1. What other maternal complications can cause problems for the fetus and newborn?
2. What resources to you use to answer your question about maternal or fetal medicine?
3. What are indications for consultation with a neonatologist?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Silver RM. Abnormal Placentation: Placenta Previa, Vasa Previa, and Placenta Accreta. Obstet Gynecol. 2015;126(3):654-668. doi:10.1097/AOG.0000000000001005

Ravishankar S, Redline RW. What Obstetricians Need to Know About Placental Pathology. Obstet Gynecol Clin North Am. 2020;47(1):29-48. doi:10.1016/j.ogc.2019.10.007

Komine-Aizawa S, Takada K, Hayakawa S. Placental barrier against COVID-19. Placenta. 2020;99:45-49. doi:10.1016/j.placenta.2020.07.022

Jamieson DJ, Rasmussen SA. An update on COVID-19 and pregnancy. Am J Obstet Gynecol. 2022;226(2):177-186. doi:10.1016/j.ajog.2021.08.054

Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa