Chorioamnionitis is a condition where the chorion and amnion, the membranes that surround the fetus, get a bacaterial infection along with the amniotic fluid where the fetus is floating. The infection occurs with organisms that normally inhabit the vagina such as E. coli, Group B Strep (GBS), and anaerobic bacteria. Chorioamnionitis occurs in 2-4% of term pregnancies.
Signs of chorioamnionitis include maternal fever, uterine tenderness, maternal tachycardia (fast heart rate), and maternal tachycardia. Sometimes, there will be a foul smelling vaginal discharge as well. There is also a subclinical chorioamnionitis which may not manifest any of the above signs. Chorioamnionitis can, in turn, cause inflammation of the umbilical cord connective tissue. This infection of the umbilical cord is known as funisitis.
Prolonged spontaneous rupture of membranes can place a patient at risk for chorioamnionitis. Usually, however, chorioamnionitis is associated with preterm rupture of membranes. On some occasions, chorioamnionitis may exist in the face of intact membranes. If there is a question of ruptured membranes, your provider may elect to perform a sterile speculum exam to assess cervical dilation and also whether there is amniotic fluid present in the vaginal vault. Your provider may also perform an ultrasound to evaluate the amniotic fluid volume. If there is still a suspicion of ruptured membranes, but the diagnosis has not been established, your provider may elect to introduce indigo carmen into the amniotic fluid via amniocentesis. The amniocentesis will also serve to obtain a specimen of amniotic fluid for bacterial culture, and gram stain. A tampon is placed in the vagina and then examined to see if dye is present on the tampon. An alternative dye to indigo carmen that can be used is methylene blue, but this is usually avoided as methylene blue can induce methemoglobinemia in some patients. Once a diagnosis of preterm rupture of membranes is made, your provider will start you on IV antibiotics to ward off infection or to treat an infection if one is present. The antibiotics may include a penicillin, an aminoglycoside, and/or cleocin.
Premature rupture of membranes is more common in multiple gestations (more than one infant in the uterus at the same time), in patients with a history of ruptured membranes in a previous pregnancy, and trauma. Often, the cause of premature rupture of membranes is unknown. Your provider will most likely attempt to prolong the pregnancy as long as possible before delivery takes place in order to have the fetus mature as much as possible. Regardless, labor is usually induced after 34 weeks gestation as there is less maternal morbidity at this gestational age without a corresponding increase in fetal morbidity. If there is a contraindication to induction, then a cesarean will be performed.
Other risk factors for chorioamnionitis, besides prolonged rupture of membranes and premature rupture of membranes, include multiple vaginal examinations, long labor, and lower socioeconomic status. The diagnosis of chorioamnionitis is usually made by a combination of clinical assessment and lab work. An elevated white blood cell count with an increased number of bands (a certain type of white blood cell) is suggestive of an infection. The white blood cell count for a pregnant woman is normally elevated due to physiology, but the white blood cell count increase in the infected patient is much higher.
Complications from the premature ruptured membranes include preterm labor, pelvic abscesses, sepsis (an overwhelming infection), septic pelvic thrombophlebitis (infected blood clots in the pelvic veins), disseminated intravascular coagulation (DIC) and maternal or fetal mortality. So it is important that the diagnosis of chorioamnionitis not be confused with benign conditions like round ligament pain, generalized musculoskeletal pain, nonspecific uterine discomfort, discomfort from an active fetus, or benign gynecologic conditions like a tender uterine fibroid.
The ultimate management of chorioamnionitis is treatment with antibiotics and delivery of the fetus. Chorioamnionitis does not necessarily mean a cesarean section. The fetus can still be delivered vaginally if the provider feels that the mother and infant are stable enough clinically to do so.
Wishing you a safe and uncomplicated delivery, Pablo.