Chorioamnionitis, also referred to as intraamniotic infection (IAI), is a common obstetric complication involving infection and inflammation of the fetal membranes, amniotic fluid, placenta, and/or the fetus itself. Chorioamnionitis is typically caused by a polymicrobial infection that ascends from the lower genitourinary tract. Primary risk factors include prolonged rupture of membranes and prolonged labor. Chorioamnionitis is diagnosed by clinical findings, including maternal fever, plus one or more additional specific findings. Chorioamnionitis is managed with antibiotics, and by ensuring continued labor progress (or initiating progress) toward delivery. Chorioamnionitis typically resolves soon after delivery. Significant maternal and fetal complications are possible (including arrest of labor, postpartum hemorrhage, and maternal and/or fetal sepsis), warranting prompt diagnosis and treatment.
Last updated: Feb 9, 2023
Also known as intraamniotic infection (IAI), chorioamnionitis is an infection, and resulting inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation, of any combination of the fetal membranes ( chorion Chorion The outermost extraembryonic membrane surrounding the developing embryo. In reptiles and birds, it adheres to the shell and allows exchange of gases between the egg and its environment. In mammals, the chorion evolves into the fetal contribution of the placenta. Placenta, Umbilical Cord, and Amniotic Cavity and amnion Amnion The innermost membranous sac that surrounds and protects the developing embryo which is bathed in the amniotic fluid. Amnion cells are secretory epithelial cells and contribute to the amniotic fluid. Placenta, Umbilical Cord, and Amniotic Cavity), amniotic fluid Amniotic fluid A clear, yellowish liquid that envelopes the fetus inside the sac of amnion. In the first trimester, it is likely a transudate of maternal or fetal plasma. In the second trimester, amniotic fluid derives primarily from fetal lung and kidney. Cells or substances in this fluid can be removed for prenatal diagnostic tests (amniocentesis). Placenta, Umbilical Cord, and Amniotic Cavity, placenta Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones). Placenta, Umbilical Cord, and Amniotic Cavity, umbilical cord Umbilical cord The flexible rope-like structure that connects a developing fetus to the placenta in mammals. The cord contains blood vessels which carry oxygen and nutrients from the mother to the fetus and waste products away from the fetus. Placenta, Umbilical Cord, and Amniotic Cavity (funisitis), and/or the fetus.
Chorioamnionitis is the most common cause of peripartum infection, with the following incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency rates:
Intraamniotic infection and inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation may be caused by the following mechanisms:
By far, the most common cause of chorioamnionitis is the ascending migration of cervicovaginal flora.
The vast majority of presenting women will either be in labor, have ruptured membranes, or both.
There are 3 categories of IAI:
Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, and at least 1 of the following:
Must meet criteria for “suspected IAI” and have at least 1 of the following:
The goal of management is to minimize the risks of maternal and fetal complications.
The earlier the gestational age Gestational age The age of the conceptus, beginning from the time of fertilization. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last menstruation which is about 2 weeks before ovulation and fertilization. Pregnancy: Diagnosis, Physiology, and Care at delivery, the higher the risk for neonatal complications.
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