Chorioamnionitis

Placenta
Infectious conditions
Chorioamnionitis

Editorial Board Member: Jennifer Bennett, M.D.

Topic Completed: 29 October 2019

Minor changes: 29 October 2019

Copyright: 2002-2019, PathologyOutlines.com, Inc.

PubMed Search: Placenta chorioamnionitis[TI] free full text[sb]

Page views in 2019: 12,560

Page views in 2020 to date: 6,340

Table of Contents

Cite this page: Özer E. Chorioamnionitis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/placentachorioamnionitis.html. Accessed June 1st, 2020.

Definition / general

Inflammation of the amniochorionic membranes of the placenta in response to microbial invasion
Diffuse maternal infiltration of the chorion or subchorionic fibrin by neutrophils originating in the intervillous space or decidual postcapillary venules (maternal inflammatory response)

Essential features

Due to maternal inflammatory response
Tissue evaluation is gold standard for the diagnosis of amniotic fluid infection
Often associated with maternal ascending infection, preterm premature rupture of membranes and spontaneous preterm birth
Higher risk of neonatal sepsis and fetal central nervous system injury
Sometimes associated with fetal inflammatory response, including chorionic vasculitis and funisitis

Terminology

Acute chorioamnionitis
Histologic chorioamnionitis
Chorionitis
Subchorionitis
Subacute chorioamnionitis

ICD coding

ICD-10: O41.1230 - chorioamnionitis, third trimester, not applicable or unspecified

Epidemiology

More common in younger women and those with amniotic fluid infection and preterm premature rupture of membranes (Placenta 2018;67:54)
Subacute chorioamnionitis associated with chronic lung disease (bronchopulmonary dysplasia) (Hum Pathol 2002;33:183)

Sites

Chorion or subchorion

Pathophysiology

Activation of inflammatory pathways by microbes
Neutrophil invasion into the placental membranes
Systemic effects of cytokines released by placental leukocytes (Am J Obstet Gynecol 2015;213:S29, Semin Perinatol 2015;39:2)

Etiology

2 or more microbes are common
Usually due to ascending bacterial infection caused by the genital mycoplasmas such as Ureaplasma urealyticum and Mycoplasma hominis, anaerobes such as Gardnerella vaginalis and Bacteriodes, aerobes such as group B Streptococcus and Escherichia coli and Fusobacterium nucleatum (PLoS One 2017;12:e0180167, Clin Perinatol 2010;37:339)
Subacute chorioamnionitis is due to longstanding infection by pathogens of low virulence
Chronic chorioamnionitis: etiology unknown, usually seen in late preterm birth, unusual to histologically diagnose (Placenta 2013;34:681)

Diagrams / tables

Contributed by Erdener Özer, M.D., Ph.D.

Histologic chorioamnionitis

Clinical features

Usually clinically silent
Maternal fever > 37.5 °C, uterine tenderness, abdominal pain, foul smelling vaginal discharge, maternal and fetal tachycardia (BJOG 2017;124:775)
Associated with fetal infection, neonatal sepsis, stillbirth, spontaneous preterm birth and fetal central nervous system injury (Semin Perinatol 2015;39:2)
Fetal inflammatory response associated with multiorgan injury, including chronic lung disease, periventricular leukomalacia and cerebral palsy (Clin Perinatol 2010;37:339)

Staging and grading

Amsterdam consensus criteria can be used to stage and grade the maternal and fetal inflammatory responses in ascending intrauterine infection (Arch Pathol Lab Med 2016;140:698)
Maternal inflammatory response
- Stage 1: acute subchorionitis or chorionitis
- Stage 2: acute chorioamnionitis (polymorphonuclear leukocytes extend into fibrous chorion or amnion)
- Stage 3: necrotizing chorioamnionitis (karyorrhexis of polymorphonuclear leukocytes, amniocyte necrosis or amnion basement membrane hypereosinophilia)
- Grade 1: not severe (as defined below)
- Grade 2: severe (confluent polymorphonuclear leukocytes or with subchorionic microabscesses)
Fetal inflammatory response
- Stage 1: chorionic vasculitis or umbilical phlebitis
- Stage 2: involvement of the umbilical vein and one or more umbilical arteries
- Stage 3: necrotizing funisitis
- Grade 1: not severe (as defined below)
- Grade 2: severe (near confluent intramural polymorphonuclear leukocytes with attenuation of vascular smooth muscle)

Diagnosis

Clinical signs and symptoms
Laboratory tests including white blood cell count, other blood tests and amniotic fluid testing (Clin Perinatol 2010;37:339)
Histologic evaluation of the placenta

Laboratory

Elevated white blood cell count (> 15,000 cells/mm³) (BJOG 2017;124:775)
Microbial growth in amniotic fluid culture (Clin Perinatol 2010;37:339)

Prognostic factors

Unfavorable factor: necrotizing chorioamnionitis (Clin Perinatol 2010;37:339)
Favorable factor: acute subchorionitis (Am J Obstet Gynecol 2015;213:S29)

Case reports

20 year old woman with intrauterine tuberculosis associated with acute chorioamnionitis (Pediatr Dev Pathol 2015;18:335)
21 year old woman with acute chorioamnionitis caused by Fusobacterium (Hawaii J Med Public Health 2012;71:280)
23 year old woman with Staphylococcus aureus chorioamnionitis (J Obstet Gynaecol 2018;38:285)
25 and 34 year old women with chorioamnionitis with placental listeriosis (Obstet Gynecol Sci 2018;61:688)
33 year old woman with Candida glabrata sepsis associated with acute chorioamnionitis (J Obstet Gynaecol Res 2015;41:962)
47 year old primipara woman with Candida chorioamnionitis (J Obstet Gynaecol 2016;36:843)

Treatment

Maternal and neonatal antibiotic therapy

Gross description

Dull, opaque membranes with yellow-green discoloration and cloudy amniotic fluid, possibly with purulent exudate
Seldom grossly normal
Acute marginal hemorrhage in preterm deliveries (ISRN Obstet Gynecol 2012;2012:856971)
Multifocal abscesses in C. albicans infections (APMIS 2018;126:570)

Gross images

Contributed by Erdener Özer, M.D., Ph.D.

Chorioamnionitis in term placenta

Chorioamnionitis in twin placenta

C. albicans associated chorioamnionitis

Microscopic (histologic) description

Neutrophilic infiltrate of membranes and those overlying the chorionic plate
Variable fetal inflammatory response including chorionic plate vasculitis, umbilical phlebitis, umbilical arteritis and umbilical concentric perivasculitis
Subacute chorioamnionitis
- Mixed cell infiltrate of mononuclear cells (usually macrophages) and neutrophils, primarily in the amnion and upper chorion, and polarization of mononuclear cells towards the amnion
- Amniotic necrosis (stage 3)
Sometimes accompanied by acute intervillositis (often due to Listeria monocytogenes), peripheral funisitis (often due to Candida) and acute deciduitis in preterm deliveries
Chronic chorioamnionitis
- Primarily lymphocytic infiltration of chorioamnion

Microscopic (histologic) images

Contributed by Erdener Özer, M.D., Ph.D.

Acute subchorionitis (stage 1)

Acute chorioamnionitis (stage 2)

Necrotizing chorioamnionitis (stage 3)

Acute chorioamnionitis (mild)

Acute subchorionitis (severe)

Subacute chorioamnionitis

Chronic chorioamnionitis

Chorionic plate vasculitis

Umbilical concentric perivasculitis

C. albicans chorioamnionitis

Positive stains

PAS and GMS for demonstrating blastospore and hyphal forms of Candida species

Negative stains

Gram (usually)

Sample pathology report

Placenta, delivery:
- Acute chorioamnionitis

Board review style question #1

A 25 year old pregnant woman presented with uterine tenderness, abdominal pain and foul smelling vaginal discharge. The pathological examination of the placental membranes revealed multifocal abscess and severe acute inflammation. GMS stained section is below. Which of the following pathogens is most likely to cause chorioamnionitis?

Actinomyces
Aspergillus
Candida albicans
Cryptococcus
Histoplasma

Board review answer #1

C. Candida albicans. Fungal infections rarely cause chorioamnionitis. C. albicans is the most common yeast isolated from the vagina in both symptomatic and asymptomatic patients. Multifocal abscesses are common. GMS staining demonstrates hyphal forms.

Reference: Placenta - Chorioamnionitis

Comment here

Board review style question #2

Which of the following is related to the maternal inflammatory response in chorioamnionitis?

Acute subchorionitis
Deciduitis
Chorionic vasculitis
Intervillitis
Umblical phlebitis

Board review answer #2

A. Acute subchorionitis. Maternal inflammatory response in chorioamnionitis include acute subchorionitis or chorionitis, acute chorioamnionitis and necrotizing chorioamnionitis, in contrast to chorionic vasculitis, umbilical phlebitis and necrotizing funisitis, which are the findings of fetal inflammatory response.

Reference: Placenta - Chorioamnionitis

Comment here