[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › [Female genital tract](https://durgical.com/en/general-pathology/areas/female-genital/) › Placental infections # Placental infections - Lesion Bacteria climbing from the vagina inflame the membranes and can start preterm labour; germs carried in the mother's blood inflame the villi instead. Updated Nov 12, 2026 ## Key points - Ascending route: group B streptococcus, Escherichia coli, mycoplasmas, Gardnerella and anaerobes; the commonest placental infection. - Maternal response: maternal neutrophils migrate from the decidua and intervillous space into the chorion and amnion (chorioamnionitis). - Fetal response: fetal neutrophils leave the umbilical and chorionic vessels (vasculitis, funisitis); strong responses are linked to cerebral palsy and neonatal sepsis. - Hematogenous: Listeria causes acute villitis with microabscesses; TORCH organisms cause chronic lymphohistiocytic villitis. - Candida gives small white-yellow plaques on the cord surface (peripheral funisitis). ## What it is Infection reaches the placenta by two routes. Ascending infection from the vagina and cervix is by far the most common; bacteria inflame the membranes (acute chorioamnionitis), often causing premature rupture of membranes and preterm birth, and the fetus responds with inflammation of its own cord and chorionic vessels. Hematogenous infection, from the mother's blood, inflames the villi: acute villitis with Listeria, and chronic villitis with the TORCH organisms such as cytomegalovirus, syphilis and toxoplasma. Chronic villitis can also be immune rather than infectious. ## Structure - Chorioamnionitis: cloudy, opaque membranes; neutrophils in the chorionic plate and membranes, then the amnion with necrosis. - Funisitis: neutrophils in the walls of the umbilical vessels and Wharton jelly. - Acute villitis (Listeria): villi destroyed by neutrophils, intervillous abscesses. - Chronic villitis: lymphocytes and histiocytes in villous stroma; cytomegalovirus inclusions and plasma cells; syphilis with large hypercellular villi and necrotizing funisitis. ## Step by step - Bacteria from the vaginal flora ascend through the cervix, more so after membranes rupture. - They infect the membranes and amniotic fluid; maternal neutrophils are recruited. - Inflammatory mediators and prostaglandins weaken the membranes and trigger contractions: preterm rupture and preterm labour. - The fetus inhales or swallows infected fluid and mounts its own inflammatory response, which can injure the brain and lungs. - In hematogenous infection, organisms in the maternal blood reach the intervillous space and infect the villi directly. ## Two routes of placental infection | Feature | Ascending | Hematogenous | | --- | --- | --- | | Frequency | Common | Less common | | Organisms | Vaginal bacteria (group B streptococcus, E. coli, mycoplasmas) | Listeria, cytomegalovirus, syphilis, toxoplasma, rubella, Zika | | [Main lesion](https://durgical.com/en/conditions/chorioamnionitis/) | Acute chorioamnionitis and funisitis | Villitis (acute or chronic) | | Clinical result | Preterm rupture, preterm labour, neonatal sepsis | Growth restriction, congenital infection, stillbirth | ## Clinical notes - Chorioamnionitis is a leading cause of spontaneous preterm birth and of early neonatal sepsis. - Pregnant women are advised to avoid foods that carry Listeria, such as unpasteurised dairy and ready-to-eat deli meats, because it crosses the placenta. - Congenital syphilis remains a public-health problem in Latin America and leaves characteristic placental changes. ## Memory aid From below, the membranes burn; from the blood, the villi do. ## Test yourself Think of the answer, then tap the question to see it. ## Which route of placental infection is most common, and what lesion does it cause? The ascending route from the vagina; it causes acute chorioamnionitis. ## How do you tell the fetal inflammatory response from the maternal one? Fetal neutrophils come from the umbilical and chorionic plate vessels (vasculitis, funisitis); maternal neutrophils come from the decidua and intervillous space into the membranes. ## Which bacterium causes acute villitis with microabscesses after maternal bacteraemia? Listeria monocytogenes. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/general-pathology/placental-infections/) [More Pathology questions →](https://durgical.com/en/practice/?f=pathology) ## Elsewhere in DurgiPedia - [Placenta](https://durgical.com/en/histology/placenta/) - [Fetal membranes: amnion, chorion, yolk sac and allantois](https://durgical.com/en/embryology/fetal-membranes-amnion-chorion-yolk-sac-and-allantois/) - [Neonatal immunity: maternal IgG and breast-milk IgA](https://durgical.com/en/immunology/neonatal-immunity-maternal-igg-and-breast-milk-iga/) ## Connections ## Related 6 - [The placenta in late pregnancy](https://durgical.com/en/general-pathology/the-placenta-in-late-pregnancy/) - [Spontaneous abortion](https://durgical.com/en/general-pathology/spontaneous-abortion/) - [Infections of the vulva, vagina and cervix](https://durgical.com/en/general-pathology/infections-of-the-vulva-vagina-and-cervix/) - [Patterns of acute inflammation: serous, fibrinous, purulent, abscess, ulcer](https://durgical.com/en/general-pathology/patterns-of-acute-inflammation-serous-fibrinous-purulent-abscess-ulcer/) - [Chronic inflammation: causes, cells and features](https://durgical.com/en/general-pathology/chronic-inflammation-causes-cells-and-features/) - [Prematurity and fetal growth restriction](https://durgical.com/en/general-pathology/prematurity-and-fetal-growth-restriction/) ## Related conditions 9 - [Chorioamnionitis (intra-amniotic infection)](https://durgical.com/en/conditions/chorioamnionitis/) - [Premature rupture of membranes (PROM and PPROM)](https://durgical.com/en/conditions/premature-rupture-of-membranes/) - [Preterm labour and birth](https://durgical.com/en/conditions/preterm-labour-and-birth/) - [Congenital (TORCH) infections: syphilis, toxoplasmosis, CMV and Zika](https://durgical.com/en/conditions/congenital-infections-syphilis-toxoplasmosis-cmv-and-zika/) - [Listeriosis](https://durgical.com/en/conditions/listeriosis/) - [Cerebral palsy](https://durgical.com/en/conditions/cerebral-palsy/) - [Neonatal sepsis](https://durgical.com/en/conditions/neonatal-sepsis/) - [Syphilis](https://durgical.com/en/conditions/syphilis/) - [Toxoplasmosis](https://durgical.com/en/conditions/toxoplasmosis/) ## Microorganisms 8 - [Streptococcus agalactiae](https://durgical.com/en/microbiology/streptococcus-agalactiae/) - [Listeria monocytogenes](https://durgical.com/en/microbiology/listeria-monocytogenes/) - [Cytomegalovirus](https://durgical.com/en/microbiology/cytomegalovirus/) - [Toxoplasma gondii](https://durgical.com/en/microbiology/toxoplasma-gondii/) - [Treponema pallidum](https://durgical.com/en/microbiology/treponema-pallidum/) - [Rubella virus](https://durgical.com/en/microbiology/rubella-virus/) - [Zika virus](https://durgical.com/en/microbiology/zika-virus/) - [Mycoplasma genitalium / Ureaplasma](https://durgical.com/en/microbiology/mycoplasma-genitalium-ureaplasma/) [← All of general pathology](https://durgical.com/en/general-pathology/) Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given. Sources: [About Group B Strep Disease | Group B Strep | CDC](https://www.cdc.gov/group-b-strep/about/index.html) (Centers for Disease Control and Prevention, 2026); [About Listeria Infection | Listeria Infection | CDC](https://www.cdc.gov/listeria/about/index.html) (Centers for Disease Control and Prevention, 2026). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/general-pathology/placental-infections/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/placental-infections/