Chorioamnionitis is an infectious inflammation of the fetal membranes and amniotic fluid caused by polymicrobial associations. It is manifested by hyperthermia, pain in the uterus, purulent or succulent discharge from the vagina. A subclinical course of the disease with minimal symptoms is possible. It is diagnosed with the help of gynecological examination, CTG of the fetus, laboratory tests, ultrasound of the pelvis. The tactics of managing a pregnant woman involves urgent delivery through the natural birth canal or by caesarean section with simultaneous appointment of intensive antibacterial, anti-inflammatory, infusion therapy.
O41.1 Infection of the amniotic cavity and fetal membranes
Chorioamnionitis (intraamniotic infection, amniotic infectious syndrome) occurs more often in the second trimester and, according to various authors, is detected in 0.9-10.5% of pregnant women. The development of the disease in the third trimester is usually associated with a long anhydrous period after premature outpouring of water. Pathology is more often found in women suffering from chronic genital and extragenital infections. The urgency of timely diagnosis and treatment of antenatal infection is due to the fact that chorioamnionitis is one of the most common causes of premature termination of pregnancy, increases the likelihood of life-threatening complications for the fetus and the woman.
Inflammation of the membranes surrounding the fetus is a polymicrobial infectious disease caused by an association of two or more pathogenic or conditionally pathogenic microorganisms. The direct causative agents of chorioamnionitis can be group B streptococci, peptostreptococci, staphylococci, E. coli, mycoplasmas, ureaplasmas, enterococci, chlamydia, trichomonas, gonococci, Gardnerella, candida, bacteroids, herpes simplex virus, cytomegalovirus, etc. To start the inflammatory process, as a rule, a combination of several predisposing conditions is required, the main of which are:
- The presence of an infectious focus. Infection of the amniotic membranes usually occurs in an ascending way. The risk of developing chorioamnionitis increases in the presence of bacterial vaginosis, vulvovaginitis, colpitis, endocervicitis, endometritis. Descending infection is possible with salpingitis, oophoritis, adnexitis. Hematogenic introduction of microorganisms from existing extragenital foci of chronic infection is not excluded.
- Access to the uterus and fetal bladder. In 98% of cases of physiological pregnancy, the amniotic fluid is sterile. It is protected from infection by the fetal membranes and mucus that closes the cervical canal. The effect of these protective mechanisms is weakened by cervical insufficiency, leakage of amniotic fluid, rupture of the fetal bladder. The probability of inflammation increases especially in childbirth with an anhydrous interval of more than 24 hours.
- Invasive diagnostic and therapeutic manipulations. In some cases, with a complicated course of pregnancy, suspected developmental abnormalities or fetal diseases, studies are performed with penetration into the uterine cavity and fetal bladder. The most dangerous in terms of the development of chorioamnionitis are amnioscopy, amniocentesis, cordocentesis, placentocentesis. Infection is also possible during amnioinfusion and intrauterine blood transfusion.
- Decreased immunity. More active reproduction of opportunistic and pathogenic microorganisms occurs when the body’s defenses weaken. The provoking factors of immune insufficiency are colds, exacerbations of extragenital pathology, prolonged or intense physical and mental stress, taking medications with direct or secondary immunosuppressive effect.
The risk of chorioamnionitis also increases with the onset of natural childbirth, especially if during their course finger vaginal examinations are repeatedly performed after opening the fetal membranes or internal cardiotocography of the fetus is performed to obtain objective data on its condition and characteristics of contractile activity of the uterus.
During the normal course of pregnancy, the development of inflammatory changes in the chorion and other fetal membranes is hindered by natural placental defense mechanisms represented by several types of Toll-like receptors that detect the presence of microbial ligands and initiate a protective reaction in response to epithelial damage. Isolation of defensins, secretory leukocyte proteinase inhibitors, and elafins promotes bacterial lysis and inactivation of their damaging factors. Massive ascending, descending or hematogenic intake of infectious agents provokes a breakdown of local immunity, and the proteases produced by them destroy the collagen fibers that are part of the fetal membranes, have a direct damaging effect on the placenta.
Mediated effects contributing to the development of the inflammatory process in chorioamnionitis are associated with the release of cytotoxic cytokines and matrix metalloproteases, apoptosis. The increased concentration of microbial phospholipases in the amniotic fluid promotes enhanced synthesis of prostaglandins from tissue phospholipids, which is accompanied by premature onset of labor. Swallowing infected amniotic fluid, the fetus becomes infected in utero. In more than 80% of cases of the disease, the fetoplacental complex suffers – inflammation spreads to the interstitial space, the vessels of the basal decidual membrane are thrombosed.
When systematizing clinical forms of chorioamnionitis, the course of the pathological process is taken into account — the speed of its development and the severity of clinical manifestations. Morphological changes occurring in the tissues of the amniotic membranes and the likelihood of complications are directly related to the severity of inflammation. Specialists in the field of obstetrics and gynecology distinguish two types of chorioamnionitis:
- Sharp. The most common form of the disease. Inflammation develops rapidly, manifests itself with pronounced symptoms. Leukocyte infiltrates form in the membranes surrounding the fetus, the placenta, chorion, amnion, and umbilical cord are usually involved in the process. Vascular lesion in the form of chorionic vasculitis, funiculitis is characteristic.
- Chronic. It is extremely rare, mainly in patients with herpes, syphilis, toxoplasmosis. It is combined with arterial hypertension, diabetes mellitus, Rh conflict. It is determined by the presence of complications. Morphologically, lymphocytic infiltration of extra-placental membranes and chronic villitis are detected.
Symptoms of chorioamnionitis
In the acute course of the disease, a pregnant woman has pains of varying intensity in the lower abdomen. It can radiate into the inguinal region, the sacrum, and increase when probing the uterus through the anterior abdominal wall. The body temperature is often elevated to 38 ° C and above, the patient has a pronounced chill, the pulse increases to 100 contractions per minute and above. The general well-being of the woman worsens, she experiences weakness, fatigue. There may be pathological vaginal discharge with an unpleasant odor — gray-green (purulent) or with an admixture of blood. In some cases, chorioamnionitis is asymptomatic and is diagnosed after a sudden termination of pregnancy or by the presence of characteristic complications of the postpartum period.
The most serious complications of chorioamnionitis are fetoplacental insufficiency, premature rupture of the fetal membranes, detachment of the normally located placenta, early delivery in 2-3 trimesters. Such pregnant women are more likely to have bacteremia, weakness of labor, atonic postpartum bleeding, thromboembolism, postpartum endometritis, obstetric peritonitis, pelvic abscesses, infectious complications of traumatic wounds received in childbirth. Coagulopathy, septic shock, respiratory distress syndrome are possible.
Violation of the normal functioning of the fetoplacental complex in chorioamnionitis can provoke a delay in fetal development. Newborns have an increased risk of injury during childbirth, the development of congenital neonatal infections (pneumonia, sepsis, meningitis), cerebral palsy and death.
Since chorioamnionitis poses a serious threat to the further course of pregnancy, if the development of the disease is suspected, all examinations are performed urgently. The diagnostic search is aimed at identifying signs of local inflammation of the amniotic membranes, assessing the condition of the fetus and determining possible pathogens. The most informative for diagnosis:
- Examination on the chair. Bimanual vaginal examination allows you to detect the tenderness of the uterine wall, the expansion of the cervical canal. Due to tissue edema, the size of the pregnant uterus may be greater than the gestational age. When viewed in mirrors, characteristic secretions are noticeable.
- Fetal cardiotocography. Compensatory tachycardia is considered a sign of a malfunction of the fetoplacental complex and possible intrauterine infection of a child with chorioamnionitis. The fetal heart rate during inflammation of the membranes exceeds 160 beats per minute.
- Laboratory tests. Typical laboratory signs of the disorder are leukocytosis over 15 × 109 / l and acceleration of ESR in the general blood test. The general inflammatory changes are also indicated by the shift of the leukocyte formula to the left. The level of C-reactive protein exceeds 5.0 mg/l.
- Ultrasound of the uterus and fetus. Ultrasound criteria for chorioamnionitis include thickening of the placental tissue, expansion of the interstitial and subchorial spaces. The chorial plate is usually hypoechoic. Signs of premature maturation of the placenta are revealed, the quantity and quality of amniotic fluid is changed.
- Bacteriological studies. Microscopy and bacterial culture of a vaginal smear make it possible to identify possible pathogens of the infectious and inflammatory process. According to indications, microbiological analyses are supplemented with special methods for detecting infections (RIF, ELISA, PCR).
Additional signs of inflammatory lesions of the fetal membranes are a drop in the level of estriol, an increase in the content of chorionic gonadotropin, increased thromboagregation in combination with violations of the plasma link of hemostasis. After childbirth, the presence of inflammation is detected by histological examination of the fetal membranes. Differential diagnosis is performed with endometritis, other inflammatory diseases of the reproductive organs, acute surgical pathology of the abdominal cavity. If necessary, prescribe consultations of a surgeon, an infectious disease specialist, a urologist, a neonatologist.
Treatment of chorioamnionitis
Inflammation of the membranes of the fetus is an indication for emergency hospitalization of a pregnant woman and her transfer to bed rest. The tactics of the patient’s management involves the fastest possible delivery (stimulated delivery or cesarean section) with the appointment of massive antibacterial and symptomatic therapy, which continue in the postpartum period. The choice of delivery method depends on the severity of inflammatory changes, the duration of the anhydrous period (with premature discharge of amniotic fluid), the condition of the woman and fetus. The scheme of drug treatment is aimed at solving such therapeutic tasks as:
- Fight against infectious agents. Usually, with chorioamnionitis, even before receiving the results of an antibioticogram, broad-spectrum antibiotics are used, including those affecting chlamydia and mycoplasmas. In the future, it is possible to correct the appointments depending on the sensitivity of the flora.
- Prevention of complications of antibiotic therapy. Taking into account the pharmacotherapeutic and pharmacodynamic characteristics of antibacterial agents, antihistamines and anti-candidiasis drugs may be recommended to the patient. Eubiotics are used to restore normal microflora.
- Infusion therapy. With severe hemodynamic disorders, signs of general intoxication, detoxification, colloidal and saline solutions are prescribed. According to the indications, drip administration of drugs that improve cardiac activity, peripheral microcirculation, hemostasis indicators is possible.
- Effects on inflammatory processes. The use of nonsteroidal anti-inflammatory drugs can reduce the secretion of inflammatory mediators, reduce body temperature with significant hyperthermia. NSAIDs are also able to relieve pain by increasing the threshold of pain sensitivity of the receptors.
The appointment of vitamin and mineral complexes, immunostimulating agents to patients with chorioamnionitis accelerates the recovery process and reduces the likelihood of complications. During the recovery period, physiotherapeutic treatment using UHF therapy, infrared laser therapy, and electric pulse therapy is indicated.
Prognosis and prevention
With timely diagnosis, the prognosis of chorioamnionitis for a pregnant woman is favorable. The probability of a positive outcome for the fetus increases as the gestational age at which the disease occurred increases. Preventive measures involve early registration in a women’s clinic for the detection and treatment of genital infections, extragenital pathology. A reasonable approach to the appointment of invasive prenatal diagnostics, emergency hospitalization and the choice of optimal tactics for pregnancy and childbirth with premature discharge of amniotic fluid are recommended.