In-Depth Notes on Placental Pathology and Pregnancy

Pathology of the Placenta and Pregnancy

Introduction

Dr. Tibor Mezei, Pathology Department, UMFST, "GE Palade" Târgu Mureş
This topic encompasses the various pathologies associated with the placenta and pregnancy, referencing essential literature and guidelines to aid in understanding these complexities.

Key Literature

  • Robbins Basic Pathology, 10th Edition by Kumar, Abbas, Aster.

  • Amsterdam Placental Workshop Group Consensus Statement: Addresses the importance of standardization in placental examination and diagnostic protocols.

Sampling and Definitions of Placental Lesions

Context

The examination of placentas plays a critical role in understanding adverse pregnancy outcomes. This consensus aims to standardize sampling and diagnostic criteria across different hospitals.

Recommendations

  • Establish uniform sampling and reporting criteria for placental lesions.

  • Agreed terminologies include descriptions for:

    • Maternal vascular malperfusion

    • Fetal vascular malperfusion

    • Delayed villous maturation

    • Intrauterine infections

    • Villitis of unknown etiology

Import

The guidance will improve international comparability and assist in refining the clinical significance of placental lesions.

Normal Placental Anatomy and Functions

  • Diameter: ~22 cm

  • Weight: ~450 g

Functions

  • Delivers oxygen and nutrients to the fetus.

  • Removes waste products like carbon dioxide.

  • Provides immunological protection to the embryo/fetus.

Placental Anatomical Structures

  • Chorion laeve: Smooth chorion.

  • Chorion frondosum: Villi-bearing chorion.

  • Amnion: Surrounds the amniotic cavity.

  • Yolk sac: Early nutrient source before placental function.

  • Decidua: Maternal tissue involved in implantation.

Fetal Circulation in the Placenta

  • Umbilical Vein: Single vessel bringing oxygenated blood from the placenta to the fetus.

  • Umbilical Arteries: Two vessels carrying deoxygenated blood from the fetus to the placenta.

Placental Development Stages

  1. Fertilization (Day 1): Formation of zygote.

  2. Cleavage (Days 2-4): Development from 2-cell stage to morula.

  3. Blastocyst formation (Days 5-9): Implantation stage; critical for successful pregnancy initiation.

Placental Pathologies

Overview

  1. Intrauterine infections and inflammations

  2. Ectopic pregnancy

  3. Gestational trophoblast disease

  4. Preeclampsia/eclampsia

  5. Abnormal placentation

  6. Other placental pathologies

Intrauterine Infections

  • Routes: Ascending and hematogenous.

  • Pathogens: Bacterial, viral, parasitic infections; can lead to serious consequences such as chorioamnionitis.

    • Ascending infection: Most common, primarily bacterial (e.g., Mycoplasma).

    • Hematogenous infection: Less frequent, associated with pathogens like syphilis and CMV.

Ectopic Pregnancy

  • Occurs in 1% of pregnancies, predominantly in the fallopian tubes.

  • Morphological changes can include intratubal hematoma and signs of placentation.

Gestational Trophoblast Disease

  1. Hydatidiform mole: Benign tumor, can be partial or complete.

  2. Choriocarcinoma: Malignant, associated with gestational trophoblast cells.

    • Clinical features include high hCG levels and potential metastasis without marked uterine enlargement.

Preeclampsia/Eclampsia

  • Defined by hypertension, proteinuria, and edema.

  • Associated with maternal vascular malperfusion and may lead to severe complications like HELLP syndrome.

Abnormal Placentation

  • Includes conditions such as placenta accreta, increta, and percreta.

  • Placenta previa characterized by improper location can lead to significant complications.

Twin-Twin Transfusion Syndrome

  • Complication in monochorionic twins, leads to serious risk of morbidity and mortality.

  • Diagnosis is performed via ultrasound imaging.

Sequelae of Infections

  • Potential outcomes include congenital anomalies, growth restrictions, stillbirth, and developmental delays.

Conclusion

Understanding the pathologies associated with the placenta is essential in managing pregnancies effectively and anticipating complications. Current guidelines and advances in research contribute to improved outcomes for mothers and infants alike.