An analysis of antenatal tests to detect infection in preterm premature rupture of the membranes

Frequency of Maternal Anemia in Patients Presenting With Preterm Premature Rupture of Membranes

BACKGROUND

Preterm premature rupture of membranes (PPROM) is the rupture of fetal membranes before 38 weeks of gestation. The etiology is multifactorial. Maternal anemia is one of the factors leading to PPROM. This study aims to determine the frequency of maternal anemia in patients presenting with PPROM.

MATERIALS AND METHODS

This cross-sectional study was carried out at the Department of Obstetrics and Gynecology, Lady Reading Hospital, Peshawar. This study was conducted from July 1 to December 31, 2021. One hundred and twenty two patients with PPROM presenting to the Department of Obstetrics and Gynecology were included. The diagnosis of PPROM was made based on the history of the PV leak, followed by confirmation with the nitrazine litmus test, microscopic fern test, and ultrasonographic amniotic fluid index measurement. Anemia was determined by examination of hemoglobin levels in the maternal blood samples. Hb <11gm/dl was labeled as anemia. IBM Corp. Released 2011. IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM Corp. was used for statistical analysis.

RESULTS

 The age of the patients ranged from 20 to 40 years. The mean age was 29.14 ± 6.194 years. 63 patients (51.6%) were multiparous (parity 2 to 4). Maternal anemia was observed in 39 patients (32.0%). A significant association (p = 0.005) was observed between maternal anemia and grand multiparity (parity 2 to 4).

CONCLUSION

 Maternal anemia significantly contributes to PPROM, especially in multiple pregnancies. Meticulous family planning and consistent obstetrical monitoring throughout pregnancy are key to addressing this, potentially reducing both maternal anemia risk and PPROM complications.

Maternal inflammatory markers for chorioamnionitis in preterm prelabour rupture of membranes: a systematic review and meta-analysis of diagnostic test accuracy studies

BACKGROUND

There is no consensus on the role of inflammatory markers in identifying chorioamnionitis in preterm prelabour rupture of membranes (PPROM). We set out to evaluate the accuracy of maternal blood C-reactive protein (CRP), procalcitonin and interleukin 6 (IL6) in diagnosis of histological chorioamnionitis and/or funisitis (HCA/Funisitis) in PPROM.

METHODS

We searched MEDLINE, EMBASE and The Cochrane Library from inception to January 2020 for studies where maternal blood CRP, procalcitonin or IL6 was assessed against a reference standard of HCA/Funisitis in PPROM. The Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool was used to assess methodological quality. Hierarchical summary receiver operating characteristic (SROC) models were used to construct summary curves. Bivariate models were used to obtain summary estimates for studies with the same cut-off.

RESULTS

We included 23 studies reporting HCA/Funisitis in 902 of 1717 women, median prevalence 50% (inter-quartile range 38-57). Of these studies, 20 were prospective cohort design and 3 were retrospective cohort. Eleven studies reported the index test against a reference standard of HCA and/or funisitis, 10 reported HCA alone and 2 reported funisitis alone. Many studies had high risk of bias scores on the QUADAS-2 assessment but low concerns for applicability. Sensitivity and specificity for CRP ≥ 20 mg/L (5 studies, 252 participants) was 59% (95% CI 48-69) and 83% (95% CI 74-89) respectively. SROC curves are provided for each index test. At selected specificity of 80%, the sensitivities for CRP (all cut-offs, 17 studies, 1404 participants), PCT ( all cut-offs, 6 studies, 231 participants) and IL6 (all cut-offs, 5 studies, 299 participants) were 59%(95% CI 52-68), 56%(95% CI 50-69) and 52% (95% CI 50-86) respectively.

CONCLUSIONS

There is insufficient evidence to support use of CRP, procalcitonin or IL6 in maternal blood for diagnosis of HCA/Funisitis in PPROM. This review followed recommended methodology and data analytic methods that made the most of the data regardless of the different cut-offs used. However, the evidence is based on few studies with generally small sample sizes, poor-quality scores and substantial heterogeneity. There is a need for good-quality diagnostic accuracy studies to better assess the role of these biomarkers in PPROM.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number: CRD42015023899, registered on 8 October 2015.

[Management of preterm premature rupture of membranes (except for antibiotherapy): CNGOF preterm premature rupture of membranes guidelines]

OBJECTIVE

To review the different parts of therapeutic management of viable preterm premature rupture of membranes (PPROM), except the antibiotherapy and birth modalities.

METHODS

The Medline, Cochrane Library, and Google Scholar databases over a period from 1980 to September 2018 have been consulted.

RESULTS

When the diagnostic of viable PPROM is reached, the woman should be hospitalized and signs of intrauterine infection (IUI) should be sought (Professional consensus). If cervical assessment appears necessary, speculum, digital examination or cervical ultrasound may be performed (Professional consensus). It is recommended to limit cervical evaluation regardless of the method used (Professional consensus). Initial ultrasound is recommended to determine the fetal presentation, locate the placenta, estimate the fetal weight and the residual amniotic fluid volume (Professional consensus). Performing vaginal and urinary bacteriological sampling at admission is recommended before any antibiotic (Professional consensus). In the case of positive vaginal culture, an antibiogram is necessary since it can guide antibiotherapy in the case of IUI and early onset neonatal bacterial sepsis (Professional consensus). In absence of demonstrated neonatal benefit, there is insufficient evidence to recommend or to not recommend initial tocolysis in PPROM (Grade C). If tocolysis was administered, it is recommended not to prolong it for more than 48hours (Grade C). Antenatal corticosteroid administration is recommended before 34 weeks of gestation (WG) (Grade A) and magnesium sulfate administration is recommended for women at high risk of imminent preterm birth before 32 WG (Grade A). Vitamin supplementation (vitamins C and E) is not recommended (Professional consensus), and it is recommended not to impose strict bed rest in case of PPROM (Professional consensus). In case of clinical signs of IUI with cerclage, it is recommended to remove the cerclage immediately (Professional consensus). The home care management of clinically stable PPROM after 48hours of hospital observation can be considered (Professional consensus). During the monitoring of a PPROM, it is recommended to identify elements relating to the diagnosis of IUI (Professional consensus).

CONCLUSION

The level of evidence and scientific data in the literature concerning the management (except antibiotics) of PPROM are low. Initial management of viable PPROM requires hospitalization. The main objectives of the management are the detection and medical care of maternal and fetal complications.

Non-Invasive Prediction of Histologic Chorioamnionitis in Women with Preterm Premature Rupture of Membranes

PURPOSE

To develop a model based on non-invasive clinical and ultrasonographic parameters for predicting the likelihood of subsequent histologic chorioamnionitis in women with preterm premature rupture of membranes (PPROM) and to determine whether the inclusion of invasive test results improves the predictive value of the model.

MATERIALS AND METHODS

This retrospective cohort study included 146 consecutive women presenting with PPROM (20-33 weeks). Transvaginal ultrasonographic assessment of cervical length was performed. Maternal serum C-reactive protein (CRP) levels and white blood cell (WBC) counts were measured after amniocentesis. Amniotic fluid (AF) obtained by amniocentesis was cultured, and interleukin-6 (IL-6) levels and WBC counts were determined. The primary outcome measure was histologic chorioamnionitis.

RESULTS

Risk scores based on serum CRP concentrations and gestational age (model 1) were calculated for each patient. The model was shown to have adequate goodness of fit and an area under the receiver operating characteristic curve (AUC) of 0.742. When including AF test results (e.g., AF IL-6 levels) in model 1, serum CRP concentrations were found to be insignificant, and thus, were excluded from model 2, comprising AF IL-6 levels and gestational age. No significant difference in AUC was found between models 1 and 2.

CONCLUSION

For women with PPROM, the newly developed model incorporating non-invasive parameters (serum CRP and gestational age) was moderately predictive of histologic chorioamnionitis. The inclusion of invasive test results added no predictive information to the model in this setting.

Neonatal infections in Saudi Arabia: association with C-reactive protein, CRP -286 (C>T>A) gene polymorphism and IgG antibodies

Background

C-reactive protein (CRP) is a nonspecific, acute-phase protein that rises in response to infectious and non-infectious inflammatory processes. Infections are the single largest cause of neonatal deaths globally.

The primary aim of this study is to examine the association between CRP gene polymorphism and serum levels of CRP in correlation with early onset sepsis (EOS) infection in newborns living in Taif city, Saudi Arabia. The second aim is to examine the relationship between specific IgG/IgG subclasses and early onset sepsis (EOS) infection among these newborns.

Methods

Staphylococcus aureus (S. aureus) is one of the most common organisms related to sepsis infection in the newborn at King Abdel Aziz Specialist Hospital (KAASH). This study was conducted in Taif city, at KAASH’s neonatal intensive care unit between March and August 2012. Neonates were consecutively enrolled onto the study having met our inclusion criteria (as per our research protocol).

The CRP concentration level was analysed using NycoCard® CRP Single Test. CRP -286 (C>T>A) A polymorphisms were analyzed using Pyrosequencing technology for CRP genotyping. IgG subclasses were analysed in the study population using ELISA.

Result

Logistic regression analyses showed that the AA and AC genotypes were negatively associated amongst EOS neonates compared to suspected neonates. The frequency of CC and CT were significantly associated with the EOS neonates compared to the suspected group. The levels of specific IgG1, IgG2 and IgG3 antibodies were significantly lower amongst EOS compared to the suspected group.

Conclusions

Taken together, the CRP-286 (C>T>A) A genotype polymorphism and specific IgG antibodies isotype levels can contribute to a reduced risk of EOS. Furthermore, CRP has a potential use in detecting EOS in neonates, which may mean earlier detection and management of EOS and subsequently better clinical outcome.

[Rupture of membranes: pathophysiology, diagnosis, consequences and management]

Rupture of membranes (ROM) depends on mechanical stretch, extracellular matrix components imbalance and increased apoptosis. It occurs in 2 to 3% of all pregnancies before 37 weeks' gestation (WG) and in up to 10% at term. Main consequences are labor induction and risk of maternal-fetal infection. ROM is associated with one third of preterm births and about 20% of perinatal mortality. This review deals with recent knowledge concerning ROM including diagnosis and management. In many cases, ROM is easily identified by clinical examination. In other cases, the use of vaginal pH appears to be less efficient than the use of immunochromatographic strips based on IGFBP-1 or PAMG-1 detection. Before 34WG, conservative management consists in in utero transfer, antibioprophylaxis and corticosteroids. After 37WG, delivery is the most appropriate option. Between 34 and 37WG, recent studies demonstrate that induction of labour does not improve pregnancy outcomes. Therefore, expectant management can be the first option between 34 and 37WG when no active infection is suspected especially in case of unfavourable cervix.

Prematurity, subclinical intraamniotic infection, and fetal biophysical parameters: is there a correlation?

Objective: This prospective study was undertaken to examine the effects of subclinical intraamniotic infection on fetal behavioral patterns.

Methods: Amniotic fluid was obtained from four groups of patients (n = 99): group 1, patients with preterm premature rupture of the fetal membranes (PPROM) without infection; group 2, patients with PPROM and infection; group 3, patients with preterm labor (PTL) and without infection; and group 4, patients with PTL and infection. Fetal biophysical profiles were obtained on admission to the labor suite. Amniotic fluid was analyzed for the presence of microorganisms and endotoxin to confirm intraamniotic infection; cytokines interleukin (IL)-1β, IL-6, and IL-8 were also assayed.

Results: We found no association between low scores for biophysical parameters and subclinical infection in patients with PPROM or PTL.

Conclusions: We could not demonstrate that upon a patient's admission to the labor hall absent fetal breathing and absent fetal movement, as well as reactivity, correlate with subclinical intraamniotic infection. Elevated cytokines, i.e. IL-1β, IL-6, and IL-8 were associated with subclinical chorioamnionitis.

Use of C-reactive protein as a predictor of chorioamnionitis in preterm prelabour rupture of membranes: a systematic review

BACKGROUND

Studies examining the use of C-reactive protein (CRP) as a predictor of chorioamnionitis in preterm prelabour rupture of membranes (PPROM) report highly conflicting results. Despite this, CRP is commonly used for the early diagnosis of chorioamnionitis.

OBJECTIVE

To determine the diagnostic accuracy of CRP in the detection of chorioamnionitis in women with PPROM.

DESIGN

Systematic review.

SEARCH STRATEGY

Studies were identified from MEDLINE (1966-2006), EMBASE (1974-2006), PubMed and the Cochrane Library (2005) and from reference lists from primary studies and reviews.

SELECTION CRITERIA

Only studies of good methodological quality that evaluated the diagnostic performance of CRP in chorioamnionitis in women with PPROM were selected.

DATA COLLECTION AND ANALYSIS

Positive and negative likelihood ratios (LR) and diagnostic odds ratios (DOR) were calculated. An attempt was made at pooling data for meta-analysis, but this was considered inappropriate due to the significant unexplained heterogeneity between studies.

MAIN RESULTS

There were eight primary studies comprising 610 cases which met the inclusion criteria. There was wide variation in the positive and negative LR and DOR between the studies, with significant lack of precision demonstrated by wide confidence intervals. Three of the studies concluded that CRP was a useful diagnostic tool for chorioamnionitis (DOR ranging from 4.2 to 191.6), although one of them suggested a higher CRP threshold. The other five studies concluded the opposite (DOR ranging from 1.4 to 17.7).

AUTHOR'S CONCLUSIONS

There is no clear evidence to support the use of CRP for the early diagnosis of chorioamnionitis. Further research is required to address the contradictory findings of diagnostic accuracy.

Maternal plasma interleukin-6, interleukin-1beta and C-reactive protein as indicators of tocolysis failure and neonatal outcome after preterm delivery

OBJECTIVE

To investigate whether maternal serum interleukin-6 (IL-6), interleukin-1beta (IL-1beta) and high sensitive C-reactive protein (CRP) could be used as markers of tocolysis failure and adverse neonatal outcome in pregnancies with preterm labor (PL).

METHODS

Forty-seven maternal blood samples taken because of PL at admission and delivery were analyzed. Control samples were taken from 20 gravidas with normal pregnancies. Differences in interleukins and CRP levels with or without chorioamnionitis, connatal infection or periventricular leukomalacia (PVL) were analyzed. Cut-off values were estimated for prediction of tocolysis failure and adverse neonatal outcome.

RESULTS

All three parameters were significantly higher in patients delivering prematurely than in patients delivering at term. All three parameters were significantly higher with than without histologic chorioamnionitis (p < 0.001), with than without connatal infection (p < 0.01), with than without PVL (p < 0.01 for IL-6 and IL-1beta, p < 0.05 for CRP), and in pregnancies with preterm premature rupture of membranes (PPROM) delivered within 48 hours compared to those more prolonged (p < 0.01). Choosing 50.9 pg/mL of IL-6 and a CRP of 19.7 as cut-offs in maternal blood admission concentrations for neonatal PVL, resulted in sensitivity of 81% and specificity of 91% and sensitivity of 91% and specificity of 81%, respectively. At respective maternal blood admission cut-off levels of 27.8 pg/mL of IL-6 and 8.9 of CRP, both parameters were effective predictors of connatal infection.

CONCLUSIONS

Maternal blood IL-6 and CRP could become useful in predicting tocolysis failure and intrauterine treat for the fetus.

Fetal thymus size as a predictor of chorioamnionitis in women with preterm premature rupture of membranes

OBJECTIVE

Emerging evidence indicates that chorioamnionitis is associated with a significant decrease in thymic size at birth in very low birth weight (VLBW) preterm infants. The aim of this study was to determine whether decreased fetal thymus size is associated with histological or clinical chorioamnionitis in patients with preterm premature rupture of membranes (PROM).

METHODS

Twenty-one patients between 24 and 35 weeks of gestation with preterm PROM were included. Serial ultrasound examinations were performed during the latency period, and measurements of the fetal thymus size were obtained. Small thymus was defined as a thymus perimeter < or = 5th percentile according to a fetal thymus nomogram, which was based on measurements of 403 fetuses. Diagnosis of chorioamnionitis was made using neonatal clinical parameters and histological examinations of the placentas.

RESULTS

In our study 13 patients presented with thymus size below the 5th percentile. Among the 13 patients with small thymus, nine (69%) had clinical or histological findings consistent with the diagnosis of chorioamnionitis. All eight women with a normal-sized thymus had no evidence of clinical or histological chorioamnionitis. Fetal thymus perimeter < or = 5th percentile yielded a sensitivity of 100%, specificity of 66.7%, a positive predictive value of 69% and a negative predictive value of 100% for identifying chorioamnionitis in patients with preterm PROM.

CONCLUSIONS

Fetal thymus size is decreased in women with preterm PROM and chorioamnionitis. Measurement of the fetal thymus might allow an early diagnosis of chorioamnionitis in cases of preterm PROM. Normal thymus size might be used to rule out latent intrauterine infection.

Streptococcus porcinus as a cause of spontaneous preterm human stillbirth

We report, to our knowledge, on the first case of a woman suffering stillbirth due to Streptococcus porcinus on the basis of microbiologic and histologic data.

Intra-amniotic infection in patients with preterm prelabor rupture of membranes. Pathophysiology, detection, and management

The recent increase in knowledge about infection and preterm delivery has engendered many new questions and should make us rethink our long held beliefs and management strategies. Although this article focused primarily on infection as an important factor in the pathogenesis of PPROM, multiple other causes do exist. The various serologic and amniotic fluid assays that can identify activation of the host immune and inflammatory responses as a consequence of the microbial invasion of the amniotic cavity detailed in the preceding paragraphs are very promising but not yet available for clinical use. These tests identify the fetus in the early stages of an infectious process, before the full clinical manifestations of chorioamnionitis. Should such fetuses be treated with antibiotics in an effort to sterilize the amniotic cavity? Should patients with documented microbial invasion be delivered immediately or is there room for a more conservative management with aggressive antibiotic in utero treatment, altering the natural course of PPROM, avoiding extremely preterm deliveries? Certainly many questions remain unanswered. Continuing the search for information on the relationship between infection and PPROM can only add hope to one day finding an option for prevention, because many and probably most cases of PPROM are apparently caused by infection, and the opportunity for preventing this problem most probably lies here.

Management of premature rupture of membranes

The management of patients with PROM, regardless of gestational age, remains controversial. Generally, when patients are in labor, have infection, or there is irreversible fetal distress, there are few options other than delivery. For those not in labor, especially in premature gestational ages, the complexities of the many combinations of decisions to be made regarding the best methods for evaluating patients, prolonging gestation, reducing complications of prematurity, and choosing the timing and route of delivery make studying and solving the problem of the best option for management difficult at best. The administration of corticosteroids and broad-spectrum antibiotics of those patients in the very early premature gestational age groups has now been shown clearly to improve outcome. Beyond that, the remainder of these problems are somewhat unresolved and several reasonable options often exist and are likely to remain so for some time to come.

Serial Measurements of C-Reactive Protein and Interleukin-6 in the Immediate Postnatal Period: Reference Intervals and Analysis of Maternal and Perinatal Confounders

Background: There is a wide range of reported sensitivities and specificities for C-reactive protein (CRP) and interleukin-6 (IL-6) in the detection of early-onset neonatal infection. This prompted us to assess reference intervals for CRP and IL-6 during the 48-h period immediately after birth and to identify maternal and perinatal factors that may affect them.

Methods: CRP and IL-6 values were prospectively obtained for 148 healthy babies (113 term, 35 near-term) at birth and at 24 and 48 h of life, and from their mothers at delivery.

Results: Upper reference limits for CRP at each neonatal age were established. At birth, CRP was significantly lower than at 24 and 48 h of life. Rupture of membranes ≥18 h, perinatal distress, and gestational hypertension significantly affected the neonatal CRP dynamics, but at specific ages. There was no correlation between CRP concentrations in mothers and their offspring at birth. The IL-6 values observed in the delivering mothers and in their babies at all three neonatal ages were negatively associated with gestational age. In the immediate postnatal period, IL-6 dynamics for term babies were significantly different from those for near-term babies. Maternal IL-6 concentrations correlated with babies’ IL-6 concentrations only for term deliveries. Apgar score had a significant effect on babies’ IL-6 values at birth.

Conclusions: The patterns of CRP and IL-6 responses in the healthy neonate should be taken into account to optimize their use in the diagnosis of early-onset neonatal sepsis.

Haematological effects of betamethasone treatment in late pregnancy

To assess the maternal haematological effects of betamethasone administered in late pregnancy, an automated full blood count was performed before and daily for 5 days after betamethasone in 25 women with a singleton pregnancy between 23 and 33 weeks' gestation. From a mean (+/- SD) baseline level of 11.0+/-2.2 x 10(9)/L, the total white cell count increased significantly to 13.2+/-2.9 x 10(9)/L and 13.5+/-3.1 x 10(9)/L on the first and second day after treatment respectively, returning to baseline on day 3 (p<0.0001, ANOVA). These changes represented a mean increase in the neutrophil count of 35% and a mean decrease in the lymphocyte count of 23%. While there was considerable intersubject variation in the extent of the changes, this study has quantified the leucocytosis induced by betamethasone in late pregnancy, information that may assist with the clinical evaluation of a woman at risk of preterm delivery.

Dexamethasone-induced leucocytosis in pregnancy

The effect of intramuscular dexamethasone administration in late pregnancy on the maternal peripheral white cell count was examined in 20 women. The mean total white cell count increased from a baseline of 11.3 x 10(9)/L (SD 2.3) to 16.2 x 10(9)/L (SD 4.6) on day 1, normalising thereafter. This 43% increase represented composite changes in the neutrophil and lymphocyte counts which, on average, increased by 62% and decreased by 22%, respectively. It is concluded that prenatal dexamethasone induces a significant neutrophilia on the first day following administration. This information may be helpful when monitoring for infection.

Maternal serum interleukin-6 concentrations in patients with preterm premature rupture of membranes and evidence of infection

OBJECTIVE

Our purpose was to determine whether maternal serum interleukin-6 concentrations are elevated in patients with preterm premature rupture of membranes and intrauterine infection.

STUDY DESIGN

By use of a sensitive enzyme-linked immunosorbent assay maternal serum interleukin-6 concentrations were measured in 110 samples from patients at 22 to 34 weeks gestation with the following conditions: nonlaboring, uninfected controls (n = 46), preterm premature rupture of membranes > 48 hours before delivery without infection (n = 27), preterm premature rupture of membranes 24 to 48 hours before delivery with subsequent clinical or histologic infection (n = 11), and preterm premature rupture of membranes < 24 hours before delivery with infection present by clinical or histologic criteria (n = 26). The Mann-Whitney U test was used for statistical analysis.

RESULTS

Compared with that of nonlaboring controls, serum interleukin-6 was significantly higher in patients with preterm premature rupture of membranes < 24 hours before delivery with evidence of infection (17.2 vs 1.6 pg/ml, p < 0.0001). Patients with preterm premature rupture of membranes 24 to 48 hours before delivery who had infection had significantly higher interleukin-6 concentrations than did nonlaboring controls (3.6 vs 1.6 pg/ml, p = 0.006). There was no significant difference in interleukin-6 concentrations in nonlaboring controls compared with patients with preterm premature rupture of membranes when serum was obtained > 48 hours before delivery (1.6 vs 1.6 pg/ml, p = 0.90). A serum interleukin-6 level > or = 8 pg/ml yielded a sensitivity of 81%, a specificity of 99%, a positive predictive value of 96%, and a negative predictive value of 95% for identifying intrauterine infection in patients with preterm premature rupture of membranes on the day of delivery.

CONCLUSIONS

Maternal serum interleukin-6 concentrations are elevated in patients with preterm premature rupture of membranes with clinical or histologic chorioamnionitis.

Bacterial 16S rDNA polymerase chain reaction in the detection of intra-amniotic infection

OBJECTIVE

Bacterial polymerase chain reaction (PCR) was used to detect early subclinical intraamhiotic infection. We used universal primers which amplify a DNA fragment of 16S ribosomal DNA (rDNA) from all known bacteria and sequenced the positive samples to identify the bacterial species.

DESIGN

Transabdominally obtained amniotic fluid samples from 20 pregnant women with prelabour rupture of the fetal membranes (PROM), showing no signs of clinical infection, and 16 control samples were analysed with universal bacterial PCR. In addition, routine bacterial culture and amniotic fluid glucose were studied.

RESULTS

Out of 20 PROM patients, five were positive in the PCR. PCR detected Ureaplasma urealyticum in two cases, Haemophilus influenzae in one case, Streptococcus oralis in one case and Fusobacterium sp. in one case. Only two of these were positive in a routine bacterial culture. Both were multibacterial infections, which caused discrepancies between the PCR and culture results. Two patients developed infectious complications: both were identified with the PCR assay. Amniotic fluid glucose was lower in PCR positive patients compared with PCR negative patients.

CONCLUSION

Bacterial 16S rDNA PCR, in properly controlled conditions, promises to be a fast and reliable test for early intra-amniotic infection especially concerning Ureaplasma urealyticum.

Randomized controlled trials and systematic reviews: a foundation for evidence-based perinatal medicine

The objective of this paper is to introduce the reader to clinical research methodologies and to illustrate how randomized controlled trials (RCTs) and systematic reviews provide a solid foundation for evidence-based perinatal practice. Relevant references were critically appraised for validity and usefulness. Random allocation is of utmost importance to avoid bias. There are thousands of reported perinatal RCTs. Systematic review techniques allow clinicians to assess the effectiveness of perinatal interventions. The application of the results of systematic reviews to perinatal practice is increasing. RCTs and systematic reviews provide the most valid results on which to build an evidence-based perinatal practice. A major challenge for perinatal researchers is the development of innovative means of communication. This assures that the evidence for an effective intervention is timely implemented. Consumers of care should be encouraged to actively participate in the design, execution and dissemination of perinatal research.

Augmentation of fetal granulopoiesis with chorioamnionitis during the second trimester of gestation

Chorioamnionitis is a major hazard to pregnancy in the second trimester. It affects the fetomaternal unit, causing febrile illness in the mother. The fetus eventually is expelled because uterine contractions can no longer be suppressed after a certain stage of the disease. To determine the effects of chorioamnionitis on the fetus we examined fetal hematopoiesis, which is, for the most part, located extramedullarily during the second trimester of gestation. The study was performed morphometrically on sections of fetal tissues; the results are given as an increase of cells per square millimeter. In chorioamnionitis the fetuses (n = 18) showed increased granulopoiesis in the parenchyma of the liver (x12), in the spleen (x 5), in the portal triads of the liver (x3), and in the bone marrow (x1.35). Erythropoiesis and total hematopoiesis were reduced in all compartments. Inflammatory disease in the mother other than chorioamnionitis did not alter fetal hematopoiesis (n = 13). Under normal conditions fetal liver granulopoiesis is at a very low level within the sinusoids, but an early and substantial increase can be seen most easily in this location during infection; chorioamnionitis can thus be diagnosed from the fetal liver alone. Alterations in fetal hematopoiesis might be caused by cytokines generated at the fetomaternal interface during chorioamnionitis.

Systematic reviews--theory and practice

The consumer of health care services experts that medical practice is based on scientific evidence with regard to efficacy and effectiveness. Randomized controlled trials provide the most valid basis for comparison of interventions in health care and offer the most reliable information to guide clinical practice. The need for well-designed and performed systematic reviews of the available information to address a specific clinical question should be obvious both to the practicing clinician and the consumer. A systematic review is defined as "the application of scientific strategies that limits bias to the systematic assembly, critical appraisal, and synthesis of all relevant studies on a specific topic". "Meta-analysis (quantitative overview) is a systematic review that employs statistical methods to combine and summarize the results of several trials". In a meta-analysis the individual studies are weighted according to the inverse of the variance; that is more weight is given to studies with more events. The pooling of data allows for an increase in power and thus a more precise estimate of the effect size. Systematic reviews that meet explicit criteria for validity offer the reader information that as a rule is less biased than the unstructured overview which has traditionally been performed by one or several experts in a specific content area. Recently statistical methods have been developed to summarize data from studies of diagnostic tests. Cumulative meta-analyses offer the caregiver and the health-care consumer with answers regarding the effectiveness of a certain intervention at the earliest possible date in time.

Amniocentesis in the management of preterm premature rupture of the membranes

A retrospective analysis has been performed of perinatal outcome in 81 pregnancies in which preterm premature rupture of membranes (PPROM) was managed using amniocentesis to diagnose intrauterine infection and lung maturity. Ten patients (13%) had a positive Gram stain on microscopy whilst 29 (37%) had a positive culture. Forty-one patients (58%) had a mature lecithin:sphingomyelin ratio. There was evidence of sepsis in 13 neonates (16%), with a further 16 (20%) being colonized. Both Gram stain and amniotic fluid culture were relatively poor predictors of neonatal sepsis. For Gram stain the sensitivity was low at only 15%. Although the sensitivity for culture was higher (69%), the specificity (71%) was too low to be clinically useful. It is recommended that a randomized controlled trial of amniocentesis in PPROM is needed to define the role of this diagnostic test.

Preterm premature rupture of membranes: detection of infection

This prospective study was designed to determine the value of a daily modified biophysical profile in detecting infection in patients with preterm premature rupture of the membranes who were managed expectantly. Ninety-nine patients received daily nonstress tests and biophysical profile scores. Results of the last predelivery study were related to subsequent development of amnionitis or fetal sepsis. Infection was present in 16 patients. When the biophysical profile score was 0/8, infection was uniformly present. When fetal breathing was absent (biophysical profile score, less than or equal to 4/8) and nonstress test was nonreactive, infection was present in 75% of cases (sensitivity, 75%; specificity, 95%). Because a nonreactive nonstress test could be secondary to prematurity instead of infection, these results were analyzed over time. Those who initially had a reactive nonstress test that subsequently became nonreactive were more likely to be infected. We conclude that a daily biophysical profile score and nonstress test can detect infection and propose delivery of patients with a biophysical profile score of 0/8 and nonreactive nonstress test. Patients with absent fetal breathing and a nonstress test that changes from reactive to nonreactive also should be considered for delivery. Absent fetal breathing with a reactive nonstress test or a consistently nonreactive nonstress test should have further testing to rule out infection.

Correlation of amniotic fluid glucose concentration and intraamniotic infection in patients with preterm labor or premature rupture of membranes

Amniotic fluid glucose concentration has previously been suggested as a rapid and sensitive test for diagnosing intraamniotic infection. In this study, 204 patients less than or equal to 34 weeks estimated gestational age with preterm labor or premature rupture of membranes underwent amniocentesis to detect subclinical intraamniotic infection. Amniotic fluid was cultured for aerobic and anaerobic bacteria, as well as for Mycoplasma species. Amniotic fluid glucose levels were significantly lower in patients with positive amniotic fluid cultures than in patients with negative cultures (median, 10 mg/dl; range, 1 to 62 mg/dl vs median, 31 mg/dl; range, 2 to 126 mg/dl, respectively; p less than 0.001). In terms of predicting amniotic fluid culture results, an amniotic fluid glucose concentration of less than or equal to 16 mg/dl had a sensitivity of 79%, specificity of 94%, positive predictive value of 87%, and negative predictive value of 90%. The determination of amniotic fluid glucose concentration is useful in detecting subclinical intraamniotic infection in patients less than or equal to 34 weeks estimated gestational age with preterm labor or premature rupture of membranes.

Prediction of lethal pulmonary hypoplasia and chorioamnionitis by assessment of fetal breathing

Twenty-three pregnancies with fetuses at risk for pulmonary hypoplasia were studied weekly until delivery. The amount of time spent in fetal breathing activity was recorded under controlled conditions during 1 h using real-time ultrasound. An amniotic fluid index was determined. The clinicians and the pathologist were unaware of the ultrasound findings. Eight of 23 fetuses did not breathe at the last ultrasound examination. Three babies died of pulmonary hypoplasia and two of these showed fetal breathing before birth. The three deaths were associated with rupture of the membranes at less than or equal to 20 weeks gestation and of greater than or equal to 44 days duration. One infant developed bronchopulmonary dysplasia. The amniotic fluid index in these four pregnancies was low and the newborn infants had limb contractures. Chorioamnionitis/funisitis was noted in 13 placentas. Eight fetuses were assessed for fetal breathing within 2 days of birth. The lack of fetal breathing had sensitivity, specificity, positive and negative predictive values of 0.75 for chorioamnionitis/funisitis. In this pilot study the absence of fetal breathing was of no value in predicting lethal pulmonary hypoplasia, but was related to chorioamnionitis/funisitis. We recommend further studies of fetal breathing in relation to fetal/neonatal infections.