Is oligohydramnios a risk factor for infection in term premature rupture of membranes?

Clinical chorioamnionitis at term X: microbiology, clinical signs, placental pathology, and neonatal bacteremia - implications for clinical care

OBJECTIVES

Clinical chorioamnionitis at term is considered the most common infection-related diagnosis in labor and delivery units worldwide. The syndrome affects 5-12% of all term pregnancies and is a leading cause of maternal morbidity and mortality as well as neonatal death and sepsis. The objectives of this study were to determine the (1) amniotic fluid microbiology using cultivation and molecular microbiologic techniques; (2) diagnostic accuracy of the clinical criteria used to identify patients with intra-amniotic infection; (3) relationship between acute inflammatory lesions of the placenta (maternal and fetal inflammatory responses) and amniotic fluid microbiology and inflammatory markers; and (4) frequency of neonatal bacteremia.

METHODS

This retrospective cross-sectional study included 43 women with the diagnosis of clinical chorioamnionitis at term. The presence of microorganisms in the amniotic cavity was determined through the analysis of amniotic fluid samples by cultivation for aerobes, anaerobes, and genital mycoplasmas. A broad-range polymerase chain reaction coupled with electrospray ionization mass spectrometry was also used to detect bacteria, select viruses, and fungi. Intra-amniotic inflammation was defined as an elevated amniotic fluid interleukin-6 (IL-6) concentration ≥2.6 ng/mL.

RESULTS

(1) Intra-amniotic infection (defined as the combination of microorganisms detected in amniotic fluid and an elevated IL-6 concentration) was present in 63% (27/43) of cases; (2) the most common microorganisms found in the amniotic fluid samples were Ureaplasma species, followed by Gardnerella vaginalis; (3) sterile intra-amniotic inflammation (elevated IL-6 in amniotic fluid but without detectable microorganisms) was present in 5% (2/43) of cases; (4) 26% of patients with the diagnosis of clinical chorioamnionitis had no evidence of intra-amniotic infection or intra-amniotic inflammation; (5) intra-amniotic infection was more common when the membranes were ruptured than when they were intact (78% [21/27] vs. 38% [6/16]; p=0.01); (6) the traditional criteria for the diagnosis of clinical chorioamnionitis had poor diagnostic performance in identifying proven intra-amniotic infection (overall accuracy, 40-58%); (7) neonatal bacteremia was diagnosed in 4.9% (2/41) of cases; and (8) a fetal inflammatory response defined as the presence of severe acute funisitis was observed in 33% (9/27) of cases.

CONCLUSIONS

Clinical chorioamnionitis at term, a syndrome that can result from intra-amniotic infection, was diagnosed in approximately 63% of cases and sterile intra-amniotic inflammation in 5% of cases. However, a substantial number of patients had no evidence of intra-amniotic infection or intra-amniotic inflammation. Evidence of the fetal inflammatory response syndrome was frequently present, but microorganisms were detected in only 4.9% of cases based on cultures of aerobic and anaerobic bacteria in neonatal blood.

Detection of a microbial biofilm in intraamniotic infection

OBJECTIVE

Microbial biofilms are communities of sessile microorganisms formed by cells that are attached irreversibly to a substratum or interface or to each other and embedded in a hydrated matrix of extracellular polymeric substances. Microbial biofilms have been implicated in >80% of human infections such as periodontitis, urethritis, endocarditis, and device-associated infections. Thus far, intraamniotic infection has been attributed to planktonic (free-floating) bacteria. A case is presented in which "amniotic fluid sludge" was found to contain microbial biofilms. This represents the first report of a microbial biofilm in the amniotic cavity.

STUDY DESIGN

"Amniotic fluid sludge" was detected by transvaginal sonography and retrieved by transvaginal amniotomy. Bacteria were identified with scanning electron microscopy and fluorescence in situ hybridization for conserved regions of the microbial genome; the exopolymeric matrix was identified by histochemistry by the wheat germ agglutinin lectin method. The structure of the biofilm was imaged with confocal laser scanning microscopy.

RESULTS

"Amniotic fluid sludge" was imaged with scanning electron microscopy, which allowed the identification of bacteria embedded in an amorphous material and inflammatory cells. Bacteria were demonstrated with fluorescent in situ hybridization using a eubacteria probe. Extracellular matrix was identified with the wheat germ agglutinin lectin stain. Confocal microscopy allowed 3-dimensional visualization of the microbial biofilm.

CONCLUSION

Microbial biofilms have been identified in a case of intraamniotic infection with "amniotic fluid sludge."

Intra- and early postpartum ultrasonography: a review. Part I

The objective of this article is to review current literature pertaining to intra- and early postpartum sonography. All the manuscripts published in the English language regarding this topic were selected from a MEDLINE search from 1966 through August 1997. Additional sources were identified through cross-referencing. Currently, intra- and early postpartum sonography may be performed for either maternal or fetal indications. Maternal indications include cervical assessment in preterm labor/rupture of membranes, assessment of the lower uterine segment, size and position of uterine fibroids, guided-placement of central venous or pulmonary artery catheters, detection of intraoperative venous air embolism, deep venous thrombosis, assist management of the third-stage of labor, postpartum hemorrhage or febrile morbidity. Fetal indications include an anatomical survey in patients presenting without prenatal care, verification of fetal presentation, estimated fetal weight, assessment of the breech-presenting fetus, external cephalic version, management of delivery of the second-twin, and internal podalic version. Doppler flow velocimetry is a useful tool in depicting both maternal and fetal intrapartum physiologic changes. We conclude that intra- and early postpartum sonography is an established versatile diagnostic and interventional-guiding modality for many obstetric conditions and should be readily available on labor and delivery suites.

Amniotic fluid index predicts the relief of variable decelerations after amnioinfusion bolus

OBJECTIVE

Our purpose was to determine whether intrapartum amniotic fluid index before amnioinfusion can be used to predict response to therapeutic amnioinfusion.

STUDY DESIGN

Intrapartum patients (n = 85) with repetitive variable decelerations in fetal heart rate that necessitated amnioinfusion (10 ml/min for 60 minutes) underwent determination of amniotic fluid index before and after bolus amnioinfusion. The fetal heart tracing was scored (scorer blinded to amniotic fluid index values) for number and characteristics of variable decelerations before and 1 hour after initiation of amnioinfusion. The amnioinfusion was considered successful if it resulted in a decrease of > or = 50% in total number of variable decelerations or a decrease of > or = 50% in the rate of atypical or severe variable decelerations after administration of the bolus. Spontaneous vaginal births before completion of administration of the bolus (n = 18) were excluded from analysis. The probability of success of amnioinfusion in relation to amniotic fluid index was analyzed with the chi(2) test for progressive sequence.

RESULTS

The mean amniotic fluid index before amnioinfusion was 6.2 +/- 3.3 cm. An amniotic fluid index of < or = 5 cm was present in 40% of patients (27/67), and an amniotic fluid index of < or = 8 cm was present in 72% of patients (48/67). The probability of success of amnioinfusion decreased with increasing amniotic fluid index before amnioinfusion (76% [16/21] when initial amniotic fluid index was 0 to 4 cm, 63% [17/27] when initial amniotic fluid index was 4 to 8 cm, 44% [7/16] when initial amniotic fluid index was 8 to 12 cm, and 33% [1/3] when initial amniotic fluid index was > 12 cm, p = 0.03). The incidence of nuchal cords or true umbilical cord knots increased in relation to amniotic fluid index before amnioinfusion.

CONCLUSIONS

Amniotic fluid index before amnioinfusion can be used to predict the success of amnioinfusion for relief of variable decelerations in fetal heart rate. Failure of amnioinfusion at a high amniotic fluid index before amnioinfusion may be explained by the increased prevalence of nuchal cords or true knots in the umbilical cord.