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Placental inflammation   (Marta Ježová)

3  Atlas of fetal pathology

3.4  Placental inflammation

Marta Ježová

Introduction:

The placenta and fetal membranes may get infected in several ways:

3.4.1  Ascending infections

3.4.1.1  Placental inflammation, acute

Etiology, pathogenesis:

  • the infection ascends from the vagina and the cervix
  • inflammation of the fetal membranes (amnion, chorion), infectious agent penetrates the amniotic cavity
  • common flora of the urogenital tract is implicated:
    • Streptoccocus agalactiae (the most virulent agent)
    • Escherichia coli
    • anaerobic microorganisms: Fusobacterium, Bacteroides, Peptostreptococcus species

Clinical signs:

  • inflammation causes loss of membrane integrity, which is often the cause of premature rupture of fetal membranes (with effluence of the amniotic fluid) and premature delivery
  • is one of the most important causes of spontaneous abortion in 2nd trimester and premature birth before the 30th week of gravidity
  • mother is usually without other symptoms, sometimes there are subfebrilias and/or tenderness of the uterus

Macroscopic appearance:

  • fetal membranes and fetal surface of the placenta are are dim, yellowish or greenish, eventually fetid in severe inflammation
  • in twin gestation the infection attacks the presenting twin first (twin A)

Histology:

  • The inflammation begins in fetal membranes in the region of cervical os and spreads into the chorionic plate
  • fetal membranes are infiltrated with neutrophils
  • if the inflammation lasts longer acute funisitis develops: inflammation in the umbilical cord, neutrophils are first found in the walls of umbilical vessels, later in the Whartons jelly
  • at even longer persistence of the inflammation the fetus is also infected: it swallows the infected amniotic fluid, that gets into the lungs — adnate pneumonia, early sepsis of the newborn

3.4.2  Hematogenous infections

Introduction:

  • involve the placenta secondarily when the mother is infected the infectious agent is present in her blood
  • infections can be viral, protozoal or bacterial
  • the inflammation is located directly in the placenta — villitis (inflammation of the chorionic villi)
3.4.2.1  Fetomaternal listeriosis

Etiology, pathogenesis:

  • caused by bacterium Listeria monocytogenes which is especially dangerous for imunosuprimated individuals and pregnant women
  • the source of the infection is contaminated food (unpasteurized milk products etc.)
  • the placenta is infected by hematogenous and probably also ascendent way and the fetus subsequently swallow and breathe the amniotic fluid
  • in the fetus a serious diseminated infection with foci in many organs develops

Clinical signs:

  • subfebrilia (of the mother), elevation of the inflammatory markers with spontaneous recovery after the delivery
  • spontaneous abortion, premature birth of a dead or seriously infected newborn

Macroscopic appearance:

  • placenta: dim fetal membranes and fetal surface of the placenta; on the placenta cut there are whitish nodules similar to infarcts, but smaller
  • fetus: greyish-yellow focuses of a pin-head size in the liver, adrenals, lungs, purulent inflammation of the meninges, pus in the brain ventricles, pustular rash, small pustules on the mucosa of the GIT

Histology:

  • Placenta: besides the chorioamnionitis sometimes severe inflammation of the villous tissue with abscesses is found — acute villitis, intervilous abscesses, villous necrosis and increased deposits of intervillous fibrin
  • Fetus: in the early course of the disease there are necrotic foci and miliar abscesses in the liver, adrenals, leukocytic infiltration of the meninges, adnate pneumonia and later monocellular reaction and formation of small granulomas

Pictures

Purulent ventriculitis, listeriosis:
Listeriosis, ventriculitis, HE 40x (72131)

Placenta, purulent vilitis, listeriosis:
Listeriosis, chorioamnitis, HE 40x (72130)

Placenta, intervillous abscess and vilitis, listeriosis:
Listeriosis, placenta, intervillous abscess, HE 40x (72644)

Skin, small necroses:
Listeriosis (aborted fetus), HE 40x (5508)

Fetomaternal listeriosis, liver:
Listeriosis, liver, HE 40x (72637)
Listeriosis, liver, HE 40x (72638)

Fetomaternal listeriosis, adrenals:
Listeriosis, suprarenal gland, HE 40x (72663)

Listeriosis, fetal membranes, HE and Gram:
Listeriosis, fetal membranes, HE 100x (72640)
Listeriosis, fetal membranes, Gram 100x (72639)

3.4.3  Pathology of the fetal membranes

3.4.3.1  Amniotic band syndrome

Etiology, pathogenesis:

From so far unknown reasons sometimes one membrane of the gestational sac (amnion) ruptures during the early gestation. Because amnion and chorion practically never fuse, the part of the amnion loosely floats in the uterine cavity, so called amniotic bands. The surface uncovered by the amnial epithelium is sticky and easily attaches to the surface of the developing embryo or fetus. By following traction, retraction and winding of the bands around the fetus body during its movments a serious malformations, mutilations of the face, head and body and limbs amputations occur.

Does not happen again in the next gravidity.

Macroscopic appearance:

  • atypical clefts of the lip, nose or orbita; extrusion of the abdominal and thoracic organs, brain prolapse (exencephalia), acrania (missing neurocranium)
  • entanglement of the moving limbs or fingers of the fetus into the amnial bands lead to their firm strangulation or amputation
  • constrictions of the umbilical cord by amniotic bands leads to intrauterine death of the fetus
  • ultrasound diagnosis is complicated, but the diagnosis is easily established autoptically and by histologic examination of the strangling bands (they histologically correspond to the normal amnium)
3.4.3.2  Meconium staining

Etiology, pathogenesis:

Sometimes in mature newborns the first stools (meconium) is released in the uterine cavity. The amniotic fluid is green and after some time the amniotic sac and tissues of the fetus are also stained. The meconium has strong vasoconstriction effects on the umbilical vessels and decreases blood flow into the tissues of the newborn. Amnial epithelium degenerates and gets necrotic in several hours. The newborn may breathe the amniotic fluid containing the meconium (the meconium aspiration syndrome), that damage the pulmonary tissue and clinically manifests as respiratory distress of the newborn.

Macroscopic appearance:

Fetal surface of the placenta is coloured to green or green-brown by the meconium.

Pictures

Placenta coloured by meconium, stillborn child:
Placenta, meconial discoloration, Macro, autopsy (72072)

Histology:

Degenerative changes in amnial epithelium, necrosis of the epithelium, macrophages with meconium pigment:

3.4.3.3  Candida infection of the placenta

Introduction:

Intrauterine Candida infection is quite rare in spite of of common occurrence of vaginal discharge in pregnant women. Most cases are associated with retained intrauterine device (IUD).

Etiology:

Intrauterine candida infection occurs as an ascending infection from the vagina. The most important risk factor is intrauterine foreign body — retained IUD, cervical cerclage.

It involves the fetal membranes producing chorionamnionitis. Involvement of the umbilical cord is common. Systemic fetal infection (pneumonitis, rash, meningitis, gastrointestinal) is uncommon, the cases are almost ofen associatied with maternal IUD.

Macroscopic appearance:

White or yellow tiny plaques may be seen on the fetal surface of the placenta or on the surface of the umbilical cord.

Histology:

Polymorphonuclear infiltration of the fetal membranes. Candida pseudohyphae are readily seen in hemotoxylin-eosin stains and special stains (Grocott, PAS ). Lesions of the umbilical cord are focal and subamnial.

Case study:

Intrauterine Candida infection
Marta Ježová

History:

25-year old woman with premature rupture of membranes in the 18 w.g. She became pregnant despite the intrauterine device in situ (confirmed by examination). The miscarriage was afebrile. Histological examination of the placenta and fetal tissues erevaled acute chorioamnionitis and congenital necrotizing pneumonia caused by Candida infection.


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