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Evidence that antibiotic administration is effective in the treatment of a subset of patients with intra-amniotic infection/inflammation presenting with cervical insufficiency
Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Republic of KoreaDepartment of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seongnam-si, Republic of Korea
Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, MD, and Detroit, MIDepartment of Obstetrics and Gynecology, University of Michigan, Ann Arbor, MIDepartment of Epidemiology and Biostatistics, Michigan State University, East Lansing, MICenter for Molecular Medicine and Genetics, Wayne State University, Detroit, MI
Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Republic of KoreaDepartment of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seongnam-si, Republic of Korea
Department of Obstetrics and Gynecology, Institute of Women's Life Medical Science, Yonsei University College of Medicine, Yonsei University Health System, Seoul, Republic of Korea
Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, MD, and Detroit, MIDepartment of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, MI
Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Republic of KoreaDepartment of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seongnam-si, Republic of Korea
Cervical insufficiency is a risk factor for spontaneous midtrimester abortion or early preterm birth. Intra-amniotic infection has been reported in 8-52% of such patients and intra-amniotic inflammation in 81%. Some professional organizations have recommended perioperative antibiotic treatment when emergency cervical cerclage is performed. The use of prophylactic antibiotics is predicated largely on the basis that they reduce the rate of complications during the course of vaginal surgery. However, it is possible that antibiotic administration can also eradicate intra-amniotic infection/inflammation and improve pregnancy outcome.
Objective
To describe the outcome of antibiotic treatment in patients with cervical insufficiency and intra-amniotic infection/inflammation.
Study Design
The study population consisted of 22 women who met the following criteria: (1) singleton pregnancy; (2) painless cervical dilatation of >1 cm between 16.0 and 27.9 weeks of gestation; (3) intact membranes and absence of uterine contractions; (4) transabdominal amniocentesis performed for the evaluation of the microbiologic and inflammatory status of the amniotic cavity; (5) presence of intra-amniotic infection/inflammation; and (6) antibiotic treatment (regimen consisted of ceftriaxone, clarithromycin, and metronidazole). Amniotic fluid was cultured for aerobic and anaerobic bacteria and genital mycoplasmas, and polymerase chain reaction for Ureaplasma spp. was performed. Intra-amniotic infection was defined as a positive amniotic fluid culture for microorganisms or a positive polymerase chain reaction for Ureaplasma spp., and intra-amniotic inflammation was suspected when there was an elevated amniotic fluid white blood cell count (≥19 cells/mm3) or a positive rapid test for metalloproteinase-8 (sensitivity 10 ng/mL). For the purpose of this study, the “gold standard” for diagnosis of intra-amniotic inflammation was an elevated interleukin-6 concentration (>2.6 ng/mL) using an enzyme-linked immunosorbent assay. The results of amniotic fluid interleukin-6 were not available to managing clinicians. Follow-up amniocentesis was routinely offered to monitor the microbiologic and inflammatory status of the amniotic cavity and fetal lung maturity. Treatment success was defined as resolution of intra-amniotic infection/inflammation or delivery ≥34 weeks of gestation.
Results
Of 22 patients with cervical insufficiency and intra-amniotic infection/inflammation, 3 (14%) had microorganisms in the amniotic fluid. Of the 22 patients, 6 (27%) delivered within 1 week of amniocentesis and the remaining 16 (73%) delivered more than 1 week after the diagnostic procedure. Among these, 12 had a repeat amniocentesis to assess the microbial and inflammatory status of the amniotic cavity; in 75% (9/12), there was objective evidence of resolution of intra-amniotic inflammation or intra-amniotic infection demonstrated by analysis of amniotic fluid at the time of the repeat amniocentesis. Of the 4 patients who did not have a follow-up amniocentesis, all delivered ≥34 weeks, 2 of them at term; thus, treatment success occurred in 59% (13/22) of cases.
Conclusion
In patients with cervical insufficiency and intra-amniotic infection/inflammation, administration of antibiotics (ceftriaxone, clarithromycin, and metronidazole) was followed by resolution of the intra-amniotic inflammatory process or intra-amniotic infection in 75% of patients and was associated with treatment success in about 60% of cases.
The term “cervical insufficiency” refers to a condition in which patients present with a dilated cervix in the midtrimester of pregnancy, protruding membranes in the absence of uterine contractions, or vaginal bleeding.
Expectant management compared with physical examination-indicated cerclage (EM-PEC) in selected women with a dilated cervix at 14(0/7)-25(6/7) weeks: results from the EM-PEC international cohort study.
The best scientific evidence in support of this intervention derives from a randomized clinical trial that included patients with cervical insufficiency (ie, membranes at or below a dilated external cervical os <27 weeks) who were treated with bed rest and antibiotics and randomly assigned to emergency cerclage and indomethacin vs bed rest only.
Patients who received emergency cerclage, indomethacin, and antibiotics had a significantly lower rate of preterm delivery (<34 weeks) than those allocated to bed rest and antibiotics (53.8% [7/13] vs 100% [10/10], P = .02).
This study explored whether intra-amniotic infection/inflammation in patients with cervical insufficiency can be treated with antibiotics.
Key findings
Seventy-five percent of patients with intra-amniotic infection/inflammation had objective evidence of resolution of the intra-amniotic infectious/inflammatory process after treatment with antibiotics.
What does this add to what is known?
The conventional view is that cervical insufficiency complicated by intra-amniotic infection/inflammation leads to inevitable delivery. Herein we present the first objective evidence that intra-amniotic infection/inflammation can be eradicated with antibiotic treatment, as proven by serial amniotic fluid analysis before and after treatment. This has implications for optimizing patient care.
Intra-amniotic infection ascertained by amniocentesis has been reported in 8-52% of patients presenting with cervical insufficiency.
Infection and labor. VIII. Microbial invasion of the amniotic cavity in patients with suspected cervical incompetence: prevalence and clinical significance.
Amniocentesis prior to physical exam-indicated cerclage in women with midtrimester cervical dilation: results from the expectant management compared to Physical Exam-indicated Cerclage international cohort study.
The use of a cervical cerclage in such patients is associated with poor pregnancy outcome, given that pregnant women have developed clinical chorioamnionitis, rupture of the chorioamniotic membranes, or vaginal bleeding, requiring delivery.
Infection and labor. VIII. Microbial invasion of the amniotic cavity in patients with suspected cervical incompetence: prevalence and clinical significance.
Infection and labor. VIII. Microbial invasion of the amniotic cavity in patients with suspected cervical incompetence: prevalence and clinical significance.
Amniocentesis prior to physical exam-indicated cerclage in women with midtrimester cervical dilation: results from the expectant management compared to Physical Exam-indicated Cerclage international cohort study.
Inflammatory cytokine (interleukins 1, 6 and 8 and tumor necrosis factor-alpha) release from cultured human fetal membranes in response to endotoxic lipopolysaccharide mirrors amniotic fluid concentrations.
Am J Obstet Gynecol.1996; 174 (discussion 1861–2): 1855-1861
Interleukin (IL)-6 and IL-8 production by human amnion: regulation by cytokines, growth factors, glucocorticoids, phorbol esters, and bacterial lipopolysaccharide.
Amniotic fluid interleukin-6 levels correlate with histologic chorioamnionitis and amniotic fluid cultures in patients in premature labor with intact membranes.
A comparative study of the diagnostic performance of amniotic fluid glucose, white blood cell count, interleukin-6, and gram stain in the detection of microbial invasion in patients with preterm premature rupture of membranes.
The value of amniotic fluid interleukin-6 determination in patients with preterm labor and intact membranes in the detection of microbial invasion of the amniotic cavity.
Amniotic fluid interleukin-6: correlation with upper genital tract microbial colonization and gestational age in women delivered after spontaneous labor versus indicated delivery.
Interleukin-6 concentrations in cervical secretions identify microbial invasion of the amniotic cavity in patients with preterm labor and intact membranes.
Amniotic fluid concentrations of interleukin-1beta, interleukin-6 and TNF-alpha in chorioamnionitis before 32 weeks of gestation: histological associations and neonatal outcome.
The role of amniotic fluid interleukin-6, and cell adhesion molecules, intercellular adhesion molecule-1 and leukocyte adhesion molecule-1, in intra-amniotic infection.
Inflammatory markers in intrauterine and fetal blood and cerebrospinal fluid compartments are associated with adverse pulmonary and neurologic outcomes in preterm infants.
The relationship between the intensity of intra-amniotic inflammation and the presence and severity of acute histologic chorioamnionitis in preterm gestation.
Twenty-four percent of patients with clinical chorioamnionitis in preterm gestations have no evidence of either culture-proven intraamniotic infection or intraamniotic inflammation.
The combined exposure to intra-amniotic inflammation and neonatal respiratory distress syndrome increases the risk of intraventricular hemorrhage in preterm neonates.
Non-invasive prediction of intra-amniotic infection and/or inflammation in patients with cervical insufficiency or an asymptomatic short cervix (</=15 mm).
Non-invasive prediction of intra-amniotic infection and/or inflammation in patients with cervical insufficiency or an asymptomatic short cervix (</=15 mm).
A subset of patients with intra-amniotic inflammation had no demonstrable microorganisms and, therefore, represented cases of sterile intra-amniotic inflammation, caused by danger signals or alarmins,
Twenty-four percent of patients with clinical chorioamnionitis in preterm gestations have no evidence of either culture-proven intraamniotic infection or intraamniotic inflammation.
Evidence of the involvement of caspase-1 under physiologic and pathologic cellular stress during human pregnancy: a link between the inflammasome and parturition.
The traditional view has been that intra-amniotic infection in patients with cervical insufficiency cannot be successfully treated, and the same has been so for intra-amniotic inflammation. The objective of this report is to communicate a case series in which women with cervical insufficiency and intra-amniotic infection/inflammation were treated with antimicrobial agents, which resulted in eradication of intra-amniotic infection/inflammation in a subset of patients.
Materials and Methods
Study design
This was a retrospective case series study of patients admitted to Seoul National University Hospital between January 2004 and April 2014 who met the following criteria: (1) singleton gestation; (2) midtrimester painless cervical dilatation (>1 cm) with membranes visible through the cervical os and intact membranes confirmed by sterile speculum examination; (3) gestational age between 16 and 27.9 weeks; (4) absence of uterine contractility based on patient's self-report and a uterine tocodynamometer assessment; (5) transabdominal amniocentesis to evaluate the microbiologic and inflammatory status of the amniotic cavity; (6) presence of intra-amniotic infection/inflammation; and (7) administration of antibiotics (regimen consisted of ceftriaxone, clarithromycin, and metronidazole).
Intra-amniotic infection was defined as a positive amniotic fluid culture or positive polymerase chain reaction (PCR) assay for Ureaplasma spp., while intra-amniotic inflammation was defined as an elevated amniotic fluid IL-6 concentration (>2.6 ng/mL), as previously reported.
Midtrimester amniotic fluid concentrations of interleukin-6 and interferon-gamma-inducible protein-10: evidence for heterogeneity of intra-amniotic inflammation and associations with spontaneous early (<32 weeks) and late (>32 weeks) preterm delivery.
The diagnostic performance of the Mass Restricted (MR) score in the identification of microbial invasion of the amniotic cavity or intra-amniotic inflammation is not superior to amniotic fluid interleukin-6.
An elevated amniotic fluid prostaglandin F2alpha concentration is associated with intra-amniotic inflammation/infection, and clinical and histologic chorioamnionitis, as well as impending preterm delivery in patients with preterm labor and intact membranes.
Comparison of rapid MMP-8 and interleukin-6 point-of-care tests to identify intra-amniotic inflammation/infection and impending preterm delivery in patients with preterm labor and intact membranes.
Every effort was made to avoid digital examination to decrease the risk of ascending intra-amniotic infection.
Amniocentesis was routinely offered to all patients admitted with the diagnosis of cervical insufficiency to assess the microbiologic status of the amniotic cavity and the presence of intra-amniotic inflammation. This is based on previous studies that reported a 52% prevalence of microbial invasion of the amniotic cavity
Infection and labor. VIII. Microbial invasion of the amniotic cavity in patients with suspected cervical incompetence: prevalence and clinical significance.
Infection and labor. VIII. Microbial invasion of the amniotic cavity in patients with suspected cervical incompetence: prevalence and clinical significance.
Amniocentesis prior to physical exam-indicated cerclage in women with midtrimester cervical dilation: results from the expectant management compared to Physical Exam-indicated Cerclage international cohort study.
All patients provided written informed consent. The Institutional Review Board of the Seoul National University Hospital approved the collection and use of these samples and clinical information for research purposes. The Seoul National University has a Federal Wide Assurance with the Office for Human Research Protections of the Department of Health and Human Services of the United States.
Amniotic fluid analysis
Amniotic fluid was cultured for aerobic and anaerobic bacteria as well as genital mycoplasmas (Ureaplasma spp. and Mycoplasma hominis). Samples were also assayed for Ureaplasma spp. using PCR with specific primers and examined in our clinical microbiology laboratory using methods previously described.
This test has been available in the clinical microbiology laboratory of the hospital since 2007. A PCR assay for Ureaplasma spp. was performed using stored amniotic fluid, which was obtained before 2007. An aliquot of amniotic fluid was examined in a hemocytometer chamber to determine the white blood cell (WBC) count.
Between March 2005 and December 2010, a rapid MMP-8 bedside test (MMP-8 PTD Check Test, SK Pharma Co, Ltd, Kyunggi-do, Republic of Korea), was performed and used in patient management. Details of the MMP-8 rapid test have been previously described.
About one-half of early spontaneous preterm deliveries can be identified by a rapid matrix metalloproteinase-8 (MMP-8) bedside test at the time of mid-trimester genetic amniocentesis.
In a subset of patients, MMP-8 concentration in amniotic fluid was measured in our laboratory using a commercially available enzyme-linked immunosorbent assay (Amersham Pharmacia Biotech, Inc, Bucks, UK) and the results were available to clinicians. Intra-amniotic inflammation was suspected when there was an elevated amniotic fluid WBC count (≥19 cells/mm3),
About one-half of early spontaneous preterm deliveries can be identified by a rapid matrix metalloproteinase-8 (MMP-8) bedside test at the time of mid-trimester genetic amniocentesis.
The relationship between the intensity of intra-amniotic inflammation and the presence and severity of acute histologic chorioamnionitis in preterm gestation.
Amniotic fluid not used for clinical diagnostic tests was centrifuged and stored in polypropylene tubes at −70°C. The stored amniotic fluid was analyzed for IL-6, which was measured using a commercially available enzyme-linked immunoassay (R&D Systems, Minneapolis, MN) in 2017 and 2018. The amniotic fluid IL-6 concentrations were measured for research purposes, and the results were not used in clinical decision management. The sensitivity of the assay was 0.7 pg/mL. The intra- and inter-assay coefficients of variation were <10%. For the purpose of this study, the final diagnosis of intra-amniotic inflammation was made when IL-6 concentration was >2.6 ng/mL
Intra-amniotic inflammation, isolation of microorganisms by amniotic fluid culture, or the detection of Ureaplasma nucleic acids was an indication for antibiotic administration. We used a combination of antimicrobial agents previously described by our group in the management of patients with preterm premature rupture of membranes (PROM),
A new anti-microbial combination prolongs the latency period, reduces acute histologic chorioamnionitis as well as funisitis, and improves neonatal outcomes in preterm PROM.
including ceftriaxone 1 g (intravenous) every 24 hours, clarithromycin 500 mg (oral) every 12 hours, and metronidazole (intravenous) 500 mg every 8 hours. Metronidazole was administered for a maximum of 4 weeks. A follow-up amniocentesis was offered to monitor the microbiologic and inflammatory status of the amniotic cavity and fetal lung maturity. The use and discontinuation of antibiotics, tocolytics, and progesterone; interval of follow-up amniocentesis; and the placement of a cervical cerclage were left to the discretion of treating clinicians because of the lack of uniformity among attending physicians. Tocolytics used were ritodrine, magnesium sulfate, or atosiban. Nonsteroidal anti-inflammatory agents were not used as tocolytic agents in this study.
Treatment success
Treatment success was defined as the resolution of intra-amniotic infection/inflammation (defined as a negative amniotic fluid culture or negative PCR assay for Ureaplasma spp., and as an IL-6 <2.6 ng/mL, respectively) or delivery at or after 34 weeks of gestation.
Diagnosis of chorioamnionitis and neonatal morbidity
Acute histologic chorioamnionitis was defined as the presence of acute inflammatory changes in the choriodecidua and amnion, respectively; acute funisitis was diagnosed by the presence of neutrophil infiltration into the umbilical vessel walls or Wharton’s jelly, using previously published criteria.
Amniotic fluid interleukin-6: a sensitive test for antenatal diagnosis of acute inflammatory lesions of preterm placenta and prediction of perinatal morbidity.
Clinical chorioamnionitis at term VI: acute chorioamnionitis and funisitis according to the presence or absence of microorganisms and inflammation in the amniotic cavity.
Clinical chorioamnionitis was diagnosed in the presence of a maternal temperature of ≥37.8°C and ≥2 of the following criteria: (1) uterine tenderness; (2) malodorous vaginal discharge; (3) maternal leukocytosis (WBC count of >15,000 cells/mm3); (4) maternal tachycardia (>100 beats/min); and (5) fetal tachycardia (>160 beats/min).
Significant neonatal morbidity was defined as the presence of any of the following conditions: respiratory distress syndrome, bronchopulmonary dysplasia, intraventricular hemorrhage (grade ≥II), proven congenital neonatal sepsis, and necrotizing enterocolitis. These conditions were diagnosed according to definitions previously described in detail.
Amniotic fluid interleukin-6: a sensitive test for antenatal diagnosis of acute inflammatory lesions of preterm placenta and prediction of perinatal morbidity.
Continuous variables were compared between 2 groups using the Mann-Whitney U test. Proportions were compared with a Fisher's exact test. A P value < .05 was considered statistically significant. Analysis was performed by SPSS, version 22 (SPSS Inc, Chicago, IL).
Results
Characteristics of the study population
During the study period, 44 patients with cervical insufficiency had 1 or more amniocentesis. Among these patients, stored amniotic fluid was available for IL-6 determination in 41 patients. Intra-amniotic infection/inflammation was identified in 68% (28/41). Among the 28 patients with intra-amniotic infection/inflammation, the antibiotic regimen (clarithromycin, ceftriaxone, and metronidazole) was administered in 22 cases. The antibiotic regimen was not given to the other 6 patients for the following reasons: 1) intra-amniotic infection/inflammation was not suspected because the patients had a low amniotic fluid WBC count when the MMP-8 rapid test was not available (before March 2005 and after January 2011) (n = 5); however, intra-amniotic inflammation was diagnosed by an elevated IL-6 concentration measured afterward; (2) in 1 patient who had a fever, the managing clinician preferred to use another antibiotic regimen.
Twenty-two patients with cervical insufficiency had intra-amniotic infection and/or intra-amniotic inflammation and were treated with the antimicrobial agent combination (ceftriaxone, clarithromycin, and metronidazole). Amniotic fluid culture was positive in 2 patients. Microorganisms identified by culture Candida albicans (n = 1) and Streptococcus anginosus (n = 1). Intra-amniotic inflammation was identified in 20 patients with a negative amniotic fluid culture for microorganisms. In one instance, nucleic acids for Ureaplasma spp. were detected using a specific PCR assay.
The Figure shows the distribution of patients. Among the 22 patients, 6 (27%) delivered within 1 week after amniocentesis and 16 (73%) remained undelivered for at least 1 week after amniocentesis. A repeat amniocentesis to evaluate the therapeutic response to antimicrobial agents was offered to patients and performed in 75% (12/16) of cases; in 75% (9/12) of those cases, there was objective evidence of resolution of intra-amniotic infection or intra-amniotic inflammation. Of the 4 patients who did not have a follow-up amniocentesis, all delivered ≥34 weeks, 2 of them at term (≥37 weeks). Thus, treatment success occurred in 59% (13/22) of patients with cervical insufficiency and intra-amniotic infection/inflammation who received the antibiotic regimen (Figure).
Table 1 compares the clinical characteristics and outcomes of the patients who delivered within 1 week of amniocentesis and those who remained undelivered for at least 1 week after administration of the antibiotic regimen. Patients who delivered within 1 week of amniocentesis had a significantly higher median amniotic fluid IL-6 concentration and a higher rate of history of preterm delivery than those who remained undelivered for at least 1 week after amniocentesis (P = .005 and P = .025, respectively). The median amniotic fluid WBC count and the rate of clinical chorioamnionitis were higher in patients who delivered within 7 days of amniocentesis than in those who were undelivered for at least 1 week after amniocentesis; however, the differences did not reach statistical significance (P > .05 for each, Table 1). Thus, patients with cervical insufficiency who delivered within 1 week of amniocentesis had a more intense intra-amniotic inflammatory response, as determined by the concentrations of a soluble component of the inflammatory response (ie, IL-6). Vaginal progesterone was administered to 2 patients who remained undelivered for at least 1 week.
Table 1Clinical characteristics and outcomes of patients with cervical insufficiency who received antimicrobial agents
Delivery before 1 week (N = 6)
Delivery after 1 week (N = 16)
P value
Maternal age (years)
35 (28–38)
32 (24–39)
.97
Nulliparity
16.7% (1/6)
43.8% (7/16)
.35
History of preterm delivery
66.7% (4/6)
12.5% (2/16)
.025
GA at amniocentesis (weeks)
22.2 (19.7–25.0)
23.2 (21.3–27.4)
.29
Positive amniotic fluid culture
16.7% (1/6)
6.3% (1/16)
.48
Positive amniotic fluid polymerase chain reaction for Ureaplasma spp.
0% (0/4)
7.1% (1/14)
1.00
Amniotic fluid white blood cell count (cells/mm3)
143 (0–430)
7 (0–2556)
.070
Amniotic fluid white blood cell count ≥19 cells/mm3
Among the 16 patients who remained undelivered for 1 week after amniocentesis, 12 underwent a follow-up amniocentesis. The median interval between amniocenteses was 8 days (interquartile range, 7-14 days). There were no significant differences in baseline characteristics, results of amniotic fluid analysis at the time of the initial amniocentesis, and median gestational age at delivery between patients who were undelivered for at least 1 week and underwent a follow-up amniocentesis and those who did not undergo another prenatal test.
Table 2 displays the clinical characteristics according to the results of amniotic fluid analysis obtained at the time of a repeat amniocentesis. Resolution of intra-amniotic infection/inflammation was observed in 75% (9/12) of patients. None of the neonates born to the 9 mothers with resolution of the intra-amniotic inflammatory response had significant complications. The median interval between the initial and follow-up amniocenteses that confirmed resolution of intra-amniotic infection/inflammation was 24 days (interquartile range, 14–30 days). Among the 9 patients, 8 delivered at or beyond 34 weeks of gestation, and 6 delivered at term. The median gestational age at amniocentesis and delivery of patients who delivered at or beyond 34 weeks was 23.4 weeks and 37.8 weeks, respectively. There were no significant differences in the median amniotic fluid WBC count and IL-6 concentration among the 3 groups of patients (P > .1).
Table 2Antenatal and postnatal characteristics of patients who were treated with antimicrobial agents and underwent follow-up amniocentesis after 1 week from initial amniocentesis
Resolution of intra-amniotic inflammation
Confirmed (n = 9)
Not confirmed (n = 3)
Delivery ≥34 weeks (n = 8)
Delivery <34 weeks (n = 1)
Delivery <34 weeks (n = 3)
Nulliparity
50% (4/8)
100% (1/1)
33.3% (1/3)
History of preterm delivery
12.5% (1/8)
0% (0/1)
0% (0/3)
Initial amniocentesis
Gestational age at amniocentesis
23.4 (21.0–26.7)
23.7
21.4 (21.3–27.4)
Positive amniotic fluid culture
0% (0/8)
0% (0/1)
33.3% (1/3)
Positive amniotic fluid polymerase chain reaction for Ureaplasma spp.
Changes in amniotic fluid culture, intra-amniotic inflammatory markers, and pregnancy and neonatal outcomes in patients with a follow-up amniocentesis
Table 3 shows the characteristics and outcomes of 12 patients who received antibiotics and underwent a follow-up amniocentesis. Nine patients (cases 1–9) had biochemical evidence of successful treatment of intra-amniotic inflammation. Bulging membranes (defined as the prolapse of membranes beyond the external os) were present in 10 of 12 patients (except cases 3 and 6). Three of 4 patients (cases 1, 2, and 4) who did not have cerclage placement had spontaneous reduction of membranes back into the uterine cavity while receiving antibiotic treatment. This was an unexpected observation made during the course of the study.
Table 3Characteristics and outcomes of 12 patients with administration of antimicrobial agents who underwent follow-up amniocentesis
Case no.
Gestational age (weeks)
Cervix dilatation (cm)
Bag bulging
Cerclage for cervical insufficiency
Analysis of amniotic fluid (initial amniocentesis)
Corticosteroid for fetal lung maturity
Interval between initial amniocentesis and resolution (days)
Of 9 patients in whom the resolution of intra-amniotic inflammation was confirmed by IL-6 determinations retrospectively, 7 underwent an additional amniocentesis after resolution. The number of amniocenteses after resolution was 1 for 6 patients and 2 for 1 patient. The procedures were performed due to the occurrence of labor or rupture of membranes (n = 3), a positive result of rapid MMP-8 test at the last amniocentesis (n = 1), acute elevation of maternal serum C-reactive protein and mild fever (n = 1), or reevaluation of intra-amniotic infection/inflammation at the discretion of the clinician caring for the patient (n = 2).
Intra-amniotic infection was eradicated in case 1: Ureaplasma spp. had been detected by PCR. This patient had an amniotic fluid IL-6 concentration of 4.8 ng/mL, a WBC count of 35 cells/mm3, and a positive rapid test for MMP-8 at initial amniocentesis (24.6 weeks). The antibiotics were administered after the first amniocentesis. One week later (25.6 weeks), membrane rupture occurred but follow-up amniocentesis revealed improvement of inflammatory markers (IL-6 concentration of 0.19 ng/mL, WBC count of 6 cells/mm3, and a weakly positive MMP-8 rapid kit test). The PCR test for Ureaplasma spp. was still positive. The fourth amniocentesis at 27.6 weeks showed no evidence of Ureaplasma spp. by cultivation or specific PCR assay, and all parameters of intra-amniotic inflammation improved (ie, IL-6 concentration of 0.17 ng/mL, WBC count of 6 cells/mm3, and a negative MMP-8 rapid kit test). At 34 weeks of gestation, the patient underwent labor induction secondary to preterm PROM. A neonate weighing 2000 g was delivered and did not develop any complications. There was no evidence of acute histologic chorioamnionitis or funisitis in placental pathologic examination.
Intra-amniotic infection with Candida albicans was identified in 1 patient (case 12). There was evidence of an intense amniotic fluid inflammatory response (ie, IL-6 concentration of 35.4 ng/mL and WBC count of 2556 cells/mm3), and the amniotic fluid culture was eventually positive for Candida albicans. A repeat amniocentesis showed a very high WBC count (1305 cells/mm3) and the managing physician and patient elected to proceed with labor induction given the concern for congenital candidiasis. The repeat amniotic fluid culture showed that Candida albicans was still present. After completion of corticosteroid administration for fetal lung maturation, the patient delivered at 28.7 weeks of gestation (10 days from initial amniocentesis) by oxytocin administration. The birthweight was 1100 g, and Apgar scores at 1 and 5 minutes were 7 and 8, respectively. The neonate survived without any significant morbidity, and placental examination showed acute histologic chorioamnionitis and funisitis.
Resolution of intra-amniotic inflammation was noted in 8 patients with a negative amniotic fluid culture and PCR (cases 2-9). Among these, 7 delivered at term (cases 3-8) or near term (case 2, delivered at 36.9 weeks by elective cesarean delivery). One patient (case 9) delivered at 29.9 weeks despite the resolution of intra-amniotic inflammation. The initial amniotic fluid inflammatory markers were as follows: IL-6 concentration, 3.8 ng/mL and WBC count, 4 cells/mm3. After 4 weeks of treatment with the antibiotic regimen, the amniotic fluid IL-6 concentration decreased to 1.0 ng/mL and the amniotic fluid WBC count was 2 cells/mm3. Antibiotics were discontinued, and the patient was discharged from the hospital. Ten days later, the patient was readmitted with spontaneous preterm labor, and the amniotic fluid IL-6 concentration had increased to 2.4 ng/mL. The patient progressed to spontaneous delivery at 29.9 weeks. The neonate weighed 1610 grams and survived without any significant morbidity. Acute histologic chorioamnionitis and funisitis were diagnosed upon placental examination.
Antibiotic treatment was not successful in 2 patients with intra-amniotic inflammation but without intra-amniotic infection (cases 10 and 11). Of these 2, microbial invasion of the amniotic cavity (by Candida tropicalis after 6 weeks from the initial amniocentesis in case 10, and by Enterococcus faecalis after 8 days from the initial amniocentesis in case 11) was identified in the follow-up amniocentesis. These 2 patients delivered at 27.4 weeks (1220 g) and 27 weeks (1220 g), respectively, because of spontaneous labor. The neonates survived but had respiratory distress syndrome (case 10), bronchopulmonary dysplasia (cases 10 and 11), and intraventricular hemorrhage (case 10).
Pregnancy and neonatal outcomes in patients who did not have a follow-up amniocentesis
Table 4 shows the clinical characteristics and outcomes of 4 patients who received antibiotics and remained undelivered for at least 1 week after amniocentesis, but did not have a follow-up amniocentesis. All 4 patients underwent an emergency cervical cerclage, and antibiotics were postoperatively administered for 4-5 days. Follow-up amniocentesis was not performed because there was no evidence of intra-amniotic infection/inflammation at initial amniocentesis (low amniotic fluid WBC count and negative culture; rapid MMP-8 test was not available at this time) in cases 14 and 16, or because of the decision made by the attending physician (cases 13 and 15). All patients in this group delivered after 34 weeks of gestation.
Table 4Characteristics and outcomes of 4 patients with administration of antimicrobial agents who delivered after 1 week of amniocentesis without follow-up amniocentesis
Gestational age (weeks)
Cervix dilatation (cm)
Bag bulging
Cerclage for cervical insufficiency
Analysis of amniotic fluid
Corticosteroid for fetal lung maturity
Acute histologic chorioamnionitis/funisitis
Neonatal outcome
Case no.
Amniocentesis
Delivery
Culture
Polymerase chain reaction for Ureaplasma spp.
Interleukin-6 (ng/mL)
White blood cell count (cells/mm3)
Matrix metallo proteinase-8 rapid kit
13
21.6
39
3
Yes
Yes
Neg
Neg
8.3
1
Pos
No
N/A
Survival without morbidity
14
23
36.1
2
No
Yes
Neg
Neg
2.8
2
N/A
No
N/A
Survival without morbidity
15
23.4
39.4
2
Yes
Yes
Neg
N/A
3.0
1
Pos
No
N/A
Survival without morbidity
16
24.6
35.7
2
Yes
Yes
Neg
Neg
16.2
9
N/A
No
N/A
Survival without morbidity
N/A, not assessed; Neg, negative; Pos, positive.
Oh et al. Antibiotics in cervical insufficiency. Am J Obstet Gynecol 2019.
Table 5 summarizes the characteristics and outcomes of the 6 patients who delivered within 1 week of amniocentesis and received antibiotics. These patients had a significantly higher amniotic fluid IL-6 concentration than those who remained undelivered for at least 1 week after amniocentesis (P = .005, Table 1). The indication of delivery was clinical chorioamnionitis (cases 21 and 22), progression of spontaneous labor after preterm PROM (case 19) or with intact membranes (case 20), abruptio placentae (case 17), or the patient’s refusal to maintain pregnancy (case 18). Only 1 neonate survived with bronchopulmonary dysplasia (case 17) and the other 5 neonates died shortly after birth.
Table 5Characteristics and outcomes of 6 patients delivered within 1 week of amniocentesis who received antibiotics
Gestational age (weeks)
Cervix dilatation (cm)
Bag bulging
Cerclage for cervical insufficiency
Analysis of amniotic fluid
Corticosteroid for fetal lung maturity
Acute histologic chorioamnionitis/funisitis
Outcome (mother/newborn)
Case no.
Amniocentesis
Delivery
Culture
Polymerase chain reaction for Ureaplasma spp.
Interleukin-6 (ng/mL)
White blood cell count (cells/mm3)
Matrix metalloproteinase-8 rapid kit
17
24.1
24.9
2
Yes
Yes
Neg
N/A
47.7
430
Pos
Yes
+/-
Preterm labor and delivery due to placenta abruptio
Survival with bronchopulmonary dysplasia
18
23.6
24.4
3
Yes
No
Neg
Neg
5.7
0
Pos
No
N/A
Patient elected termination of pregnancy at other hospital
Neonatal death
19
20.7
21.6
4
Yes
Yes
Neg
N/A
26.9
123
Pos
No
+/+
Progress to spontaneous labor after rupture of membranes
Neonatal death
20
19.7
20
Full dilatation
Yes
No
Neg
Neg
48.7
360
N/A
No
+/-
Spontaneous preterm labor
Neonatal death
21
19.7
20.3
4
Yes
No
Streptococcus anginosus
Neg
47.7
81
N/A
No
N/A
Clinical chorioamnionitis
Patient elected termination of pregnancy
Neonatal death
22
25
25.7
3
Yes
No
Neg
Neg
49.3
162
Pos
Yes
-/-
Clinical chorioamnionitis after rupture of membranes
Neonatal death
N/A, not assessed; Neg, negative; Pos, positive.
Oh et al. Antibiotics in cervical insufficiency. Am J Obstet Gynecol 2019.
Principal findings were as follows: (1) eradication of intra-amniotic infection/inflammation was achieved in 75% (9/12) of patients with cervical insufficiency who were treated with antimicrobial agents; and (2) the overall treatment success (defined as resolution of intra-amniotic infection/inflammation or delivery ≥34 weeks) was 59% (13/22). These observations provide strong evidence that antibiotic administration can be effective in treating intra-amniotic infection/inflammation in patients with cervical insufficiency.
Recognition of cervical insufficiency as a clinical entity
The initial recognition of cervical insufficiency is attributed to Culpeper, Cole, and Rowland in their 1658 publication “Practice of Physick,”
Cerclage for sonographic short cervix in singleton gestations without prior spontaneous preterm birth: systematic review and meta-analysis of randomized controlled trials using individual patient-level data.
Vaginal progesterone is as effective as cervical cerclage to prevent preterm birth in women with a singleton gestation, previous spontaneous preterm birth, and a short cervix: updated indirect comparison meta-analysis.
Vaginal progesterone for preventing preterm birth and adverse perinatal outcomes in singleton gestations with a short cervix: a meta-analysis of individual patient data.
proposed a role for intra-amniotic infection and amniocentesis to study the microbial status of the amniotic cavity and decompression of the uterus by removing amniotic fluid prior to placement of a cerclage. Goodlin reported that 22.2% (2/9) of patients with cervical insufficiency had microorganisms in the amniotic cavity (1 had Escherichia coli and the other had group B Streptococcus).
He proposed treatment of intra-amniotic infection with the administration of ampicillin into the amniotic cavity at the time of amniocentesis. The patient with group B Streptococcus carried the pregnancy to term, suggesting a therapeutic value for antibiotic administration.
Infection and labor. VIII. Microbial invasion of the amniotic cavity in patients with suspected cervical incompetence: prevalence and clinical significance.
Amniocentesis prior to physical exam-indicated cerclage in women with midtrimester cervical dilation: results from the expectant management compared to Physical Exam-indicated Cerclage international cohort study.
Infection and labor. VIII. Microbial invasion of the amniotic cavity in patients with suspected cervical incompetence: prevalence and clinical significance.
Four of these patients had a cervical cerclage because the amniotic fluid Gram stain results were negative. All had complications, which consisted of rupture of membranes, clinical chorioamnionitis, or bleeding. When a cervical cerclage was not placed in patients with intra-amniotic infection, all (13/13) had a preterm delivery. On the other hand, patients without intra-amniotic infection had a favorable outcome, suggesting that the microbial status of the amniotic cavity is a major determinant of pregnancy outcome in patients with cervical insufficiency.
Intra-amniotic inflammation in cervical insufficiency
Microbial products (endotoxin or lipopolysaccharide, peptidoglycans, and glucans) and microorganisms can elicit an inflammatory response.
Inflammatory cytokine (interleukins 1, 6 and 8 and tumor necrosis factor-alpha) release from cultured human fetal membranes in response to endotoxic lipopolysaccharide mirrors amniotic fluid concentrations.
Am J Obstet Gynecol.1996; 174 (discussion 1861–2): 1855-1861
Interleukin (IL)-6 and IL-8 production by human amnion: regulation by cytokines, growth factors, glucocorticoids, phorbol esters, and bacterial lipopolysaccharide.
In practice, it is easier and faster to diagnose intra-amniotic inflammation than intra-amniotic infection because an elevated amniotic fluid WBC count or inflammatory molecules (such as IL-6 or MMP-8) can be rapidly detected in clinical practice, whereas the results of amniotic fluid culture or molecular microbiologic techniques will take longer than a bedside test.
An elevated amniotic fluid prostaglandin F2alpha concentration is associated with intra-amniotic inflammation/infection, and clinical and histologic chorioamnionitis, as well as impending preterm delivery in patients with preterm labor and intact membranes.
Comparison of rapid MMP-8 and interleukin-6 point-of-care tests to identify intra-amniotic inflammation/infection and impending preterm delivery in patients with preterm labor and intact membranes.
About one-half of early spontaneous preterm deliveries can be identified by a rapid matrix metalloproteinase-8 (MMP-8) bedside test at the time of mid-trimester genetic amniocentesis.
It is now recognized that some cases of intra-amniotic inflammation occur in the absence of demonstrable microorganisms detected with cultivation or molecular methods (“sterile intra-amniotic inflammation”),
reported that 81% (42/52) of patients with cervical insufficiency had evidence of intra-amniotic inflammation, defined as an amniotic fluid concentration of MMP-8 >23 ng/mL. Only 4 patients in that study had evidence of intra-amniotic infection using cultivation methods. Therefore, most cases of intra-amniotic inflammation were not attributed to bacteria. The prevalence of intra-amniotic inflammation in other studies has ranged from 22.2% (16/72) to 64.5% (20/31) using different cutoffs of IL-6 concentrations for the definition of intra-amniotic inflammation.
Non-invasive prediction of intra-amniotic infection and/or inflammation in patients with cervical insufficiency or an asymptomatic short cervix (</=15 mm).
The prognosis of patients with cervical insufficiency and intra-amniotic inflammation is poor, with 50% delivering within 7 days; in 84% of cases, patients had a preterm delivery <34 weeks.
Importantly, Lee et al reported that there were no differences in the amniocentesis-to-delivery interval or the rate of adverse pregnancy outcome between patients with intra-amniotic inflammation and a negative amniotic fluid culture and patients with proven intra-amniotic infection.
Collectively, these data suggest that intra-amniotic inflammation is a poor prognostic factor in cervical insufficiency.
Antimicrobial agents to treat cervical insufficiency
In this study, clinicians elected to use a combination of ceftriaxone, clarithromycin, and metronidazole based on previous studies of the pharmacokinetics of antibiotics during pregnancy.
A new anti-microbial combination prolongs the latency period, reduces acute histologic chorioamnionitis as well as funisitis, and improves neonatal outcomes in preterm PROM.
In brief, erythromycin or azithromycin were frequently inadequate in eradicating intra-amniotic infection with Ureaplasma spp., the most common microorganism identified in the amniotic fluid of patients at risk for preterm delivery, perhaps due to limited transplacental passage, which results in inadequate antimicrobial activity in amniotic fluid (only 3% of erythromycin and 2.6% of azithromycin cross the placenta).
Clarithromycin, on the other hand, has a much higher rate of transplacental passage, and is effective for the treatment of intra-amniotic infection with Ureaplasma spp.
Comparison of gram stain, leukocyte esterase activity, and amniotic fluid glucose concentration in predicting amniotic fluid culture results in preterm premature rupture of membranes.
Prevalence and diversity of microbes in the amniotic fluid, the fetal inflammatory response, and pregnancy outcome in women with preterm pre-labor rupture of membranes.
In a previous study, we demonstrated successful eradication of intra-amniotic infection and/or inflammation in at least 33% of patients with preterm PROM after the administration of this antibiotic regimen.
reported the successful treatment of intra-amniotic infection in 1 case after the administration of a single dose of 1 gram of ampicillin into the amniotic cavity. However, since that report in 1979, there is a paucity of investigation about the treatment of intra-amniotic infection and inflammation. Antibiotics have been successful in eradicating amniotic fluid infection in animal models.
reported that antibiotic administration within 12 hours of transcervical inoculations of Escherichia coli, but not after 18 hours, increased the duration of pregnancy (by reducing the rate of preterm delivery) and neonatal survival in rabbits. More recently, Grigsby et al
showed that maternal azithromycin can eradicate Ureaplasma spp. from the amniotic fluid and key fetal organs in a nonhuman primate model. Gravett et al
reported that the combination of immunomodulators (dexamethasone and indomethacin) and antibiotics was able to eradicate intra-amniotic infection, suppress intra-amniotic and placental inflammation, and prolong gestation in a nonhuman primate model.
The results reported herein show that antibiotic administration can eradicate intra-amniotic infection, as demonstrated by repeat amniotic fluid analyses of 1 patient who had Ureaplasma spp. detected by PCR at 24.6 weeks of gestation. This patient delivered at 34 weeks and the neonate had no significant morbidity. In contrast, 1 patient was admitted at 27.4 weeks and received antibiotics, and the amniotic fluid culture eventually became positive for Candida albicans. A repeat amniocentesis showed a very high WBC count (1305 cells/mm3) and the managing physician and patient elected to proceed with labor induction given the concern of congenital candidiasis. The repeat amniotic fluid culture showed that Candida albicans was still present. Such observation underscores the importance of identifying the specific microorganism involved and selecting antibiotics that are effective against the pathogen. Previous reports have shown that fluconazole may be effective in cases of intra-amniotic infection with Candida albicans.
Antibiotics can eradicate intra-amniotic inflammation in cervical insufficiency
An observation made during the course of this case series is that antibiotic administration in patients with intra-amniotic inflammation was effective in treating intra-amniotic inflammation, even when microorganisms were not detectable. We have reported similar results in patients with preterm PROM.
A new anti-microbial combination prolongs the latency period, reduces acute histologic chorioamnionitis as well as funisitis, and improves neonatal outcomes in preterm PROM.
The mechanisms whereby antibiotics can treat intra-amniotic inflammation are not clear. One possibility is that these agents are effective against microorganisms that were not detected using cultivation techniques
Prevalence and diversity of microbes in the amniotic fluid, the fetal inflammatory response, and pregnancy outcome in women with preterm pre-labor rupture of membranes.
It is also possible that macrolides (ie, clarithromycin) suppress intra-amniotic inflammation caused by danger signals by down-regulating the expression of proinflammatory transcription factors, such as nuclear factor κB and activator protein-1, which can induce the production of proinflammatory cytokines. Such observations have been made in other organ systems.
Clarithromycin delays progression of bronchial epithelial cells from G1 phase to S phase and delays cell growth via extracellular signal-regulated protein kinase suppression.
It is unlikely that antibiotics were effective in reducing decidual infection because careful studies to locate microorganisms in the chorioamniotic membranes and decidua have shown that organisms first invade the amniotic cavity and are only a secondary presence in the decidua. Thus, the initial view that organisms would be present in the decidua and, from there, would invade the amniotic cavity is contradicted by empirical evidence using morphologic and molecular microbiologic techniques.
A relevant question is the relative contribution of antibiotics and cervical cerclage to the outcomes in this study. There are no data to support that cervical cerclage alone can eradicate intra-amniotic inflammation. A cervical cer-clage was placed in 64% of patients, and it may have had a beneficial effect in improving pregnancy outcome. However, it can be postulated that some patients with intra-amniotic infection/inflammation benefited from the administration of the combination of antimicrobial agents, which eradicated bacteria from the amniotic cavity or down-regulated the inflammatory response.
For those patients in whom infection or inflammation was successfully treated, a cervical cerclage may have contributed to the prevention of preterm labor or pregnancy loss by closing the cervix and preventing further exposure of the chorioamniotic membranes to microorganisms present in the vagina. Therefore, the improved clinical outcomes observed in this study may have been attributable to the combination of antibiotic administration, with a direct effect on microbial invasion of the amniotic cavity and intra-amniotic inflammation, and cerclage, which prevented reinfection or recurrence of the inflammatory process. Cerclage placement may also have had a protective role by supporting the cervix, as cervical disorders may be a cause of preterm labor and midtrimester pregnancy loss.
Strengths and limitations
This is an observational study in which women with intra-amniotic infection/inflammation were treated with antibiotics and monitored with follow-up amniocenteses. It represents an objective demonstration that a case of intra-amniotic infection was successfully treated, and that intra-amniotic inflammation could also be down-regulated and followed by a favorable pregnancy outcome.
reported the first case of eradication of intra-amniotic infection in cervical insufficiency, the current study reports the successful treatment of intra-amniotic inflammation in the absence of detectable microorganisms. This was possible because of the availability of rapid tests for detection of intra-amniotic inflammation, such as amniotic fluid WBC count and a rapid amniotic fluid test for MMP-8. It is unlikely that the eradication of intra-amniotic inflammation can be attributed to the administration of corticosteroids, because these agents were not administered in 69.2% (9/13) of patients in whom treatment was successful.
A limitation of this study is that it is not a randomized clinical trial, but rather a case series, and therefore, further studies to confirm these observations are desirable. Another limitation is that we combined patients with intra-amniotic infection and those with intra-amniotic inflammation but without proven intra-amniotic infection. Lee et al
previously demonstrated that these 2 conditions have similar pregnancy outcomes. Additional research is required to examine whether there is a differential effect of antibiotics in patients with intra-amniotic infection vs those with “sterile” intra-amniotic inflammation. The main claim of this paper is that antimicrobial agents can be useful in eradicating intra-amniotic inflammation and, in some cases, intra-amniotic infection. While our data suggest that the frequency of complications in the neonatal period is lower, other studies will need to examine long-term follow-up.
This study included patients with cervical insufficiency diagnosed by physical examination, and therefore it does not address the entity of an asymptomatic short cervix diagnosed by ultrasound. We previously demonstrated that microbial invasion of the amniotic cavity in asymptomatic patients with a short cervix can be treated with antibiotics, as demonstrated by repeat amniocentesis in which amniotic fluid cultures became negative, and patients delivered close to term.
The choice of antimicrobial agents used in this study, route of administration, and duration of treatment represent the choice of clinicians practicing in a university hospital that has studied intra-amniotic infection/inflammation, the microbiology of infection, and the short- and long-term consequences of these conditions. It is possible that similar success could be achieved with other antibiotic regimens that provide adequate coverage for the most frequent microorganisms found in the amniotic cavity (genital mycoplasmas) and administered in a different manner.
Medicine is evolving toward the individualized treatment of patients, and we believe that, with the application of modern molecular microbiologic techniques, it may be possible to tailor treatment for a specific patient based on the results of amniotic fluid analysis.
Conclusion
Antibiotic administration to women with cervical insufficiency and intra-amniotic infection/inflammation can eradicate these pathologic processes in a subset of patients.
References
American College of Obstetricians and Gynecologists
ACOG Practice Bulletin No.142: Cerclage for the management of cervical insufficiency.
Expectant management compared with physical examination-indicated cerclage (EM-PEC) in selected women with a dilated cervix at 14(0/7)-25(6/7) weeks: results from the EM-PEC international cohort study.
Infection and labor. VIII. Microbial invasion of the amniotic cavity in patients with suspected cervical incompetence: prevalence and clinical significance.
Amniocentesis prior to physical exam-indicated cerclage in women with midtrimester cervical dilation: results from the expectant management compared to Physical Exam-indicated Cerclage international cohort study.
Inflammatory cytokine (interleukins 1, 6 and 8 and tumor necrosis factor-alpha) release from cultured human fetal membranes in response to endotoxic lipopolysaccharide mirrors amniotic fluid concentrations.
Am J Obstet Gynecol.1996; 174 (discussion 1861–2): 1855-1861
Interleukin (IL)-6 and IL-8 production by human amnion: regulation by cytokines, growth factors, glucocorticoids, phorbol esters, and bacterial lipopolysaccharide.
Amniotic fluid interleukin-6 levels correlate with histologic chorioamnionitis and amniotic fluid cultures in patients in premature labor with intact membranes.
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