What is Intra-amniotic Infection?
Intra-amniotic infection is a bacterial infection that causes inflammation of the fetal membranes, amniotic fluid, placenta and the uterus. Chorion is the outer covering of the amniotic sac and supports the thinner membrane just underneath it. The amnion is in direct contact with the amniotic fluid that surrounds the fetus. Intra-amniotic infection, also called chorioamnionitis, breaks these barriers thus infecting the amniotic fluid too. It is one of the common complications of pregnancy. Other terms for this condition include amnionitis and intrapartum infection.
The bacteria enter from the vagina into the uterus and infect the tissues around the fetus. Under normal conditions, the placenta, mucus in cervix and the membranes around the fetus prevent the entry of the bacteria. But due to weakened defenses, bacteria enter and cause chaos in the amniotic fluid, thus resulting in preterm premature rupture of the membranes.
Intra-amniotic infection is a polymicrobial infection, caused by ascending genital microbes such as:
- Ureaplasma urealyticum and Mycoplasma hominis are the most common causes of neonatal complications.
- Gardnerella vaginalis, Group B Streptococcus and Escherichia coli are usually a part of the vaginal flora or intestinal flora. But if these bacteria ascend the placenta through the blood, they could cause intra-amniotic infection.
- Listeria monocytogenes cause the infection of the fetus, resulting in neonatal sepsis.
Various studies have reported several risk factors for intra-amniotic infections. Some of them are:
- Prolonged labor – a time gap of more than 6 hours between the breaking of the amniotic sac and induction of labor.
- Multiple vaginal examinations under unhygienic conditions
- Intrauterine pressure catheters
- Urogenital or cervical infections
- Sexually transmitted infections
- Smoking, drug abuse and alcohol use
- Epidural anesthesia
- Weakened immunity in mother like poor nutrition, emotional stress, etc.
- Presence of chronic illness or infection in the mother
- Presence of meconium (the first feces of the fetus, which is dark green in color) in the amniotic fluid
Symptoms of intra-amniotic infection may include the following:
- Fever more than 100.4°F
- Increased maternal heart rate (more than 100 beats per minute)
- Increased fetal heart rate (more than 160 beats per minute)
- Foul smelling discharge of amniotic fluid
- Abdominal pain
Complications of Intra-amniotic Infection
Intra-amniotic infection can be considered as a medical emergency as it can lead to serious complications in both the mother and the fetus. Some of the complications of intra-amniotic infection are:
- Preterm premature rupture of the amniotic fluid
- Increased risk of cesarean birth
- Bloodstream infection in the mother
- Bleeding after delivery due to hemorrhage
- Pus collection around the uterus (abscess)
- Blood clot in the legs in mother
- Decreased oxygen levels in blood during birth in the fetus
- Infections in the fetus such as pneumonia or meningitis
- Cerebral palsy
Diagnosis of intra-amniotic infection involves clinical presentation of symptoms. The physicians need to rule out upper respiratory infection and urinary tract infection, before concluding the diagnosis of intra-amniotic infection.
The following tests help in the diagnosis of intra-amniotic infection:
- Histologic examination of the fetal membranes
- Blood testing for leucocytes (more than 15,000 to 18,000 cells/mm3)
- Amniotic fluid culture and testing, obtained by amniocentesis. Pus cells may be found in amniotic fluid
Antibiotic therapy must be started immediately after a diagnosis is made based on clinical presentation. Broad-spectrum antibiotic therapy must be given to cover both aerobic and anaerobic bacteria.
Antibiotics used for treatment of intra-amniotic infection include:
- Combination of â-lactam like penicillin and an aminoglycoside like gentamicine is commonly recommended.
- The risk of postpartum endometritis in women undergoing cesarean section can be reduced by adding Clindamycin or Metronidazole.
- Vancomycin can replace penicillin in women with penicillin allergy.
- Antipyretic administration like acetaminophen is advised in the presence of maternal or fetal tachycardia.
- If fetal tachycardia persists after maternal tachycardia is alleviated, it indicates fetal acidemia.
Maintaining hygienic conditions and care during physical examinations goes a long way in preventing intra-amniotic infection. Antenatal education on the risks and signs and symptoms of intra-amniotic infection must be given to all pregnant women. The importance of reporting any vaginal discharge and symptoms of urinary infection must be emphasized.
If intra-amniotic infection is diagnosed in a preterm woman, antibiotic and antipyretic treatment must be initiated immediately. Appropriate management of labor and other measures to ensure the well being of the fetus must be taken.
- Maintain proper hygienic conditions during pregnancy and keep the pubic area clean and dry.
- Avoid physical contacts or sex with persons who are infected with any kind of bacteria.
- Avoid smoking, drugs and alcohol during and before pregnancy.
- Maintain good health with proper nutritional diet and regular exercise.
- Take medications for any existing infections to treat them properly.
- Report any signs of urogenital infections like discharge or itching in the genital area.
- Insist on using well-maintained equipment during physical examinations.
- Avoid multiple vaginal examinations when you are pregnant, since there could be an increased risk of intra-amniotic infection. Talk to your health care provider for proper guidance.
- Chorioamnionitis - (https://en.wikipedia.org/wiki/Chorioamnionitis)
- Diagnosis and Management of Clinical Chorioamnionitis - (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3008318/)
Latest Publications and Research on Intra-amniotic Infection
- Compartmentalized profiling of amniotic fluid cytokines in women with preterm labor. - Published by PubMed
- Microbial burden and inflammasome activation in amniotic fluid of patients with preterm prelabor rupture of membranes. - Published by PubMed
- Clinical chorioamnionitis criteria are not sufficient for predicting intra-amniotic infection. - Published by PubMed
- Prenatal inflammation suppresses blood Th1 polarization and gene clusters related to cellular energy metabolism in preterm newborns. - Published by PubMed
- Preterm labor is characterized by a high abundance of amniotic fluid prostaglandins in patients with intra-amniotic infection or sterile intra-amniotic inflammation. - Published by PubMed