Management of acute chorioamnionitis

Use of nonhuman primate models to investigate mechanisms of infection-associated preterm birth

Preterm birth is the most important direct cause of neonatal mortality and remains a major challenge for obstetrics and global health. Intrauterine infection causes approximately 50% of early preterm births. Animal models using pregnant mice, rabbits or sheep demonstrate the key link between infection and premature birth, but differ in the mechanisms of parturition and placental structure from humans. The nonhuman primate (NHP) is a powerful model which emulates many features of human placentation and parturition. The contributions of the NHP model to preterm birth research are reviewed, emphasising the role of infections and the potential development of preventative and therapeutic strategies.

Modern management of clinical chorioamnionitis

Clinical chorioamnionitis continues to contribute to fetal and maternal morbidity and mortality. Significant advances have been made in the last 20 years in understanding the pathophysiologic processes leading to chorioamnionitis. This review addresses the history, incidence, pathophysiology, host defenses, risk factors, diagnosis, and maternal and neonatal management of clinically evident chorioamnionitis. After a detailed review of the physiologic processes leading to clinical chorioamnionitis and sepsis, we present a modern management scheme designed to optimize perinatal outcome for both mother and fetus.

Amniotic fluid glucose concentration: a marker for infection in preterm labor and preterm premature rupture of membranes

Amniotic fluid Gram stain and culture have been utilized as laboratory tests of microbial invasion of the amniotic cavity. The Gram stain of amniotic fluid has a low sensitivity in the detection of clinical infection or microbial invasion of the amniotic cavity, and amniotic fluid culture results are not immediately available for management decisions. Glucose concentration is used to diagnose infection in other sites such as cerebrospinal fluid.

OBJECTIVE

The purpose of this study was to evaluate the usefulness of amniotic fluid glucose concentration in detecting microbial invasion of the amniotic cavity associated with preterm labor and preterm premature rupture of membranes.

METHODS

Amniocentesis was performed in 60 women with preterm labor and/or preterm premature rupture of membranes. Gram stain and culture for Mycoplasma hominis, Ureaplasma urealyticum, aerobic, and anaerobic bacteria were performed. Subjects were studied prospectively for the development of positive amniotic fluid cultures and the development of clinical chorioamnionitis.

RESULTS

The diagnosis of clinical chorioamnionitis was made in 25% (15/60) of women entered into the study. Low amniotic fluid glucose concentration Was considered < 15 mg/dl. The sensitivity, specificity, and positive predictive value of low amniotic, fluid glucose concentration to predict clinical chorioamnionitis were 73.3%, 88.1%, and 68.8% respectively, while positive amniotic fluid culture, hada sensitivity of 43.8%, specificity of 79.5%, and positive predictive value of 43.8%.

CONCLUSIONS

Amniotic fluid glucose concentration was more sensitive in predicting chorioamnionitis than either Gram stain or culture. Amniotic fluid glucose concentration was better in predicting clinical chorioamnionitis than predicting positive amniotic fluid culture results. Gestational age-dependent normal ranges and pathologic conditions that may alter amniotic fluid glucose concentrations should be considered when interpreting amniotic fluid glucose values to diagnose microbial invasion of the amniotic cavity.

Obstetric care in low-resource settings: what, who, and how to overcome challenges to scale up?

BACKGROUND

Each year, approximately 2 million babies die because of complications of childbirth, primarily in settings where effective care at birth, particularly prompt cesarean delivery, is unavailable.

OBJECTIVE

We reviewed the content, impact, risk-benefit, and feasibility of interventions for obstetric complications with high population attributable risk of intrapartum-related hypoxic injury, as well as human resource, skill development, and technological innovations to improve obstetric care quality and availability.

RESULTS

Despite ecological associations of obstetric care with improved perinatal outcomes, there is limited evidence that intrapartum interventions reduce intrapartum-related neonatal mortality or morbidity. No interventions had high-quality evidence of impact on intrapartum-related outcomes in low-resource settings. While data from high-resource settings support planned cesarean for breech presentation and post-term induction, these interventions may be unavailable or less safe in low-resource settings and require risk-benefit assessment. Promising interventions include use of the partograph, symphysiotomy, amnioinfusion, therapeutic maneuvers for shoulder dystocia, improved management of intra-amniotic infections, and continuous labor support. Obstetric drills, checklists, and innovative low-cost devices could improve care quality. Task-shifting to alternative cadres may increase coverage of care.

CONCLUSIONS

While intrapartum care aims to avert intrapartum-related hypoxic injury, rigorous evidence is lacking, especially in the settings where most deaths occur. Effective care at birth could save hundreds of thousands of lives a year, with investment in health infrastructure, personnel, and research--both for innovation and to improve implementation.

Neurological infections after neuraxial anesthesia

Infection is the commonest cause of serious neurologic sequelae of neuraxial anesthesia. The incidence depends on operator skill and patient population. Meningitis, a complication of dural puncture, is usually caused by viridans streptococci. The risk factors are dural puncture during labor, no mask and poor aseptic technique, vaginal infection and bacteremia. Epidural abscess is a complication of epidural catheterization, route of entry the catheter track and the organism usually the staphylococcus. Principal risk factors are prolonged catheterization, poor aseptic technique and traumatic insertion. Prevention includes wearing a mask, using a full sterile technique, avoiding prolonged catheterization and prescribing antibiotics in a high-risk situation.

Antibiotic administration to patients with preterm labor and intact membranes: is there a beneficial effect in patients with endocervical inflammation?

OBJECTIVE

To determine whether broad-spectrum antibiotic administration to patients with preterm labor and intact membranes is associated with an improvement in neonatal and maternal outcomes, particularly in patients with microbial invasion of the amniotic cavity (MIAC) or endocervical inflammation (ECI).

METHODS

A prospective clinical trial was conducted in which women in premature labor were alternately allocated to receive either antibiotics or placebo, and information about MIAC and ECI collected. Eighty-four pregnant women between 24 and 34 weeks of gestation with spontaneous preterm labor were enrolled. Exclusion criteria were cervical dilatation greater than 3 cm, clinical chorioamnionitis, abruption, rupture of membranes, vaginal bleeding, and several additional fetal and maternal conditions that may influence perinatal outcome. Amniocentesis was offered to all patients and the cervix and vagina were sampled for microbiological and cytological studies. Eligible patients were allocated to receive either clindamycin-gentamycin or placebo for 7 days. Corticosteroids and tocolysis with beta-adrenergic agents were used according to the standard management of our institution. MIAC was defined as the presence of a positive amniotic fluid culture obtained by trans-abdominal amniocentesis. ECI was diagnosed when a significant increase in the white blood cell count of the endocervical secretions was found. A composite neonatal morbidity/mortality outcome was created, including severe neonatal morbidity (respiratory distress syndrome, asphyxia, sepsis, pneumonia, intraventricular hemorrhage) and mortality.

RESULTS

Thirty-nine women received antibiotics and 40 received placebo. The prevalence of ECI and MIAC in both groups was comparable (antibiotic group ECI 61.5% (24/39) and MIAC 20.5% (8/39); placebo group ECI 62.5% (25/40) and MIAC 20% (8/40); p > 0.05). Overall, there were no significant differences in maternal infections and composite neonatal outcomes between antibiotic and placebo groups. Women who received antibiotics had a lower rate of subsequent rupture of membranes compared to patients who received placebo (2.6% (1/39) vs. 25% (10/40), respectively; p = 0.007). A sub-analysis showed that among patients with ECI, antibiotic administration was associated with a lower rate of composite neonatal morbidity/mortality outcome compared to those who received placebo (4.2% (1/24) vs. 28% (7/25), respectively; p < 0.05). This association was also present in patients with ECI without MIAC (0% (0/16) vs. 27.8% (5/18); p < 0.05), but not in patients with ECI and MIAC (antibiotic group 12.5% (1/8) vs. placebo group 28.6% (2/7); p > 0.05).

CONCLUSIONS

The combination of antibiotics used in this study did not improve maternal or perinatal outcome in patients with preterm labor and intact membranes. Further studies are required to determine if women with endocervicitis presenting with preterm labor and intact membranes may benefit from antibiotic administration.

The Maternal-Fetal Medicine Units cesarean registry: chorioamnionitis at term and its duration-relationship to outcomes

OBJECTIVE

The purpose of this study was to evaluate the relationship between chorioamnionitis and its duration to adverse maternal, fetal, and neonatal outcomes.

STUDY DESIGN

This was a 13-university center, prospective observational study. All women at term carrying a singleton gestation who underwent primary cesarean from January 1, 1999 to December 31, 2000 were eligible. Data abstraction was systematic and performed by trained research nurses. Selected adverse outcomes were compared between pregnancies with, and without, clinically diagnosed chorioamnionitis using relative risks (RRs) and 95% CIs. The duration of chorioamnionitis was stratified into 5 intervals (<or=3 h,>3-6 h,>6-9 h,>9-12 h, and>12 h), and respective outcomes compared by Mantel-Haenszel test for trend. Additionally, regression analysis was used to compute odds ratios (ORs) and 95% CIs for chorioamnionitis duration length as a continuous explanatory variable.

RESULTS

16,650 pregnancies were analyzed, 1965 (12%) with chorioamnionitis, which was associated with significantly increased risks of maternal blood transfusion, uterine atony, septic pelvic thrombophlebitis, and pelvic abscess (RR 2.3-3.7), as well as 5-minute Apgar <or=3, neonatal sepsis, and seizures (RR 2.1-2.8). By test of trend, only uterine atony (P <.01), maternal blood transfusion (P=.03), maternal admission to intensive care unit (P=.02), and 5-minute Apgar <or=3 (P <.01) were associated with duration of chorioamnionitis. By logistic analysis, only uterine atony (OR for each hour of chorioamnionitis 1.03, 95% CI 1.00-1.06), 5-minute Apgar <or=3 (OR 1.09, 95% CI 1.00-1.16), and neonatal mechanical ventilation within 24 hours of birth (OR 1.07, 95% CI 1.01-1.12) were significantly associated with chorioamnionitis duration.

CONCLUSION

Chorioamnionitis was associated with increased rates of morbidity after cesarean at term. The duration of chorioamnionitis, however, was not related to most measures of adverse maternal or fetal-neonatal outcome.

Complications associated with regional anesthesia in the obstetric patient

The majority of obstetric patients are concerned about labor pains but also have fears regarding regional anesthesia and its potential effects on themselves and their babies. Anesthesiologists and obstetricians alike must be familiar with potential complications of obstetric regional anesthesia and analgesia, and also be able to provide the information and reassurance each patient needs. If a problem occurs during labor and delivery, it must be dealt with expertly and immediately. This article discusses the diagnostic clues, laboratory tests, and management of neurologic complications related to obstetric delivery and regional anesthesia, as well as the topics of infections, obstetric- and anesthetic-related neurologic deficits, and special tips on neurologic examination. The most common neurologic complication of spinal and epidural anesthesia, postdural puncture headache, will not be discussed in detail here.

Antibiotic regimens for management of intraamniotic infection

BACKGROUND

Intraamniotic infection is associated with maternal morbidity and neonatal sepsis, pneumonia and death. Although antibiotic treatment is accepted as the standard of care, few studies have been conducted to examine the effectiveness of different antibiotic regimens for this infection and whether to administer antibiotics intrapartum or postpartum.

OBJECTIVES

To study the effects of different maternal antibiotic regimens for intraamniotic infection on maternal and perinatal morbidity and mortality.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register (May 2002) and the Cochrane Controlled Trials Register (The Cochrane Library, Issue 2, 2002).

SELECTION CRITERIA

Trials where there was a randomized comparison of different antibiotic regimens to treat women with a diagnosis of intraamniotic infection were included. The primary outcome was perinatal morbidity.

DATA COLLECTION AND ANALYSIS

Data were extracted from each publication independently by the authors.

MAIN RESULTS

Two eligible trials (181 women) were included in this review. No trials were identified that compared antibiotic treatment with no treatment. Intrapartum treatment with antibiotics for intraamniotic infection was associated with a reduction in neonatal sepsis (relative risk (RR) 0.08; 95% confidence interval (CI) 0.00, 1.44) and pneumonia (RR 0.15; CI 0.01, 2.92) compared with treatment given immediately postpartum, but these results did not reach statistical significance (number of women studied = 45). There was no difference in the incidence of maternal bacteremia (RR 2.19; CI 0.25, 19.48). There was no difference in the outcomes of neonatal sepsis (RR 2.16; CI 0.20, 23.21) or neonatal death (RR 0.72; CI 0.12, 4.16) between a regimen with and without anaerobic activity (number of women studied = 133). There was a trend towards a decrease in the incidence of post-partum endometritis in women who received treatment with ampicillin, gentamicin and clindamycin compared with ampicillin and gentamicin alone, but this did not reach statistical significance (RR 0.54; CI 0.19, 1.49).

REVIEWER'S CONCLUSIONS

The conclusions that can be drawn from this meta-analysis are limited due to the small number of studies. For none of the outcomes was a statistically significant difference seen between the different interventions. Current consensus is for the intrapartum administration of antibiotics when the diagnosis of intraamniotic infection is made; however, the results of this review neither support nor refute this although there was a trend towards improved neonatal outcomes when antibiotics were administered intrapartum. No recommendations can be made on the most appropriate antimicrobial regimen to choose to treat intraamniotic infection.

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.

Neurological complications in obstetric regional anaesthesia

Neurological complications after obstetric central neural blocks are rare events. Although central neural blockade does cause neurological complications, there must be awareness that neurological deficits may either develop spontaneously (e.g. epidural abscess/haematoma) or as a result of the labour and delivery process (maternal obstetric palsies). We have attempted to review as completely as possible the published survey and case reports in the English literature on neurological complications of obstetric regional blockade obtained from Medline spanning the period 1966 to November 1998. We also performed cross-checking of our references to find important missing articles, e.g. papers published in journals not included in Index Medicus at the time of publication, such as the International Journal of Obstetric Anesthesia. We wish to provide some insight to the incidences, pathophysiology, clinical features, investigations, treatment and prognosis of these complications. Maternal obstetric palsies and case reports of spontaneous epidural abscess/haematoma are also discussed. It is often difficult, if not impossible, to determine the exact aetiology, but unfortunately for the anaesthetists, regional blockade is usually incriminated till proven otherwise. Although we cannot eliminate the occurrence of neurological complications completely, preventive measures can still be taken to decrease their incidence (e.g. aseptic technique). There must also be regular monitoring after neural blockade for the development of neurological complications. Early diagnosis and prompt appropriate treatment will usually lead to complete resolution of the neurological deficit even in cases of epidural haematoma/abscess.

Maternal intrapartum temperature elevation as a risk factor for cesarean delivery and assisted vaginal delivery

OBJECTIVES

This study investigated the association of intrapartum temperature elevation with cesarean delivery and assisted vaginal delivery.

METHODS

Participants were 1233 nulliparous women with singleton, term pregnancies in vertex presentations who had spontaneous labors and were afebrile (temperature: 99.5 degrees F [37.5 degrees C]) at admission for delivery. Rates of cesarean and assisted vaginal deliveries according to highest intrapartum temperature were examined by epidural status.

RESULTS

Women with maximum intrapartum temperatures higher than 99.5 degrees F were 3 times as likely to experience cesarean (25.2% vs 7.2%) or assisted vaginal delivery (25.2% vs 8.5%). The association was present in epidural users and nonusers and persisted after birthweight, epidural use, and labor length had been controlled. In adjusted analyses, temperature elevation was associated with a doubling in the risk of cesarean delivery (odds ratio [OR] = 2.3, 95% confidence interval [CI] = 1.5, 3.4) and assisted vaginal delivery (OR = 2.1, 95% CI = 1.4, 3.1).

CONCLUSIONS

Modest temperature elevation developing during labor was associated with higher rates of cesarean and assisted vaginal deliveries. More frequent temperature elevation among women with epidural analgesia may explain in part the higher rates of cesarean and assisted vaginal deliveries observed with epidural use.

Elevated amniotic fluid levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 in intra-amniotic infection

OBJECTIVE

The study's objective was to determine and correlate amniotic fluid levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 in patients with and without intra-amniotic infection.

STUDY DESIGN

Amniocentesis was performed on 41 pregnant women with preterm contractions, labor, or premature rupture of membranes. Intra-amniotic infection was defined as the presence of a positive amniotic fluid culture result. Amniotic fluid tests for Gram stain, glucose, leukocyte counts, creatinine level, pH, and specific gravity were performed. Amniotic fluid levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 were measured by an enzyme-linked immunoassay. Unlike in previous reports, cytokines were normalized by amniotic fluid creatinine levels.

RESULTS

Fifteen patients had intra-amniotic infection and 26 did not. Amniotic fluid median levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 were significantly higher in pregnant women with intra-amniotic infection than in those without intra-amniotic infection (leukemia inhibitory factor median 3912 pg/mg creatinine, range 0.0-199314, vs 56 pg/mg creatinine, range 0. 0-12148, P =.01; interleukin 6 median 2005 ng/mg creatinine, range 27-4071, vs 990 ng/mg creatinine, range 7.5-3409, P =.005; interleukin 8: median 4933 ng/mg creatinine, range 0.0-55058, vs 61 ng/mg creatinine, range 0.0-2399, P =.005). Amniotic fluid levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 were positively correlated.

CONCLUSIONS

The data indicate that leukemia inhibitory factor plays an important role in the pathogenesis of intra-amniotic infection. In addition, significant elevations of and correlations among amniotic fluid levels of leukemia inhibitory factor, interleukin 6, and interleukin 8 suggest that measurements of these cytokines in amniotic fluid may be of diagnostic and prognostic importance.

Immunohistochemical localization of inducible nitric oxide synthase on human fetal amnion in intra-amniotic infection

OBJECTIVES

Amniotic fluid levels of nitric oxide metabolites are significantly elevated in intra-amniotic infection. We hypothesized that fetal amnion is a possible site for the production of nitric oxide. Because inducible nitric oxide synthase is the key enzyme responsible for the generation of nitric oxide in patients with intra-amniotic infection, we used immunohistochemistry to localize it on human fetal amnion.

STUDY DESIGN

Human fetal amnions were obtained from patients with and without intra-amniotic infection (n = 5, respectively). Intra-amniotic infection was diagnosed by positive amniotic fluid cultures and placental pathologic features. Human fetal amniotic membranes were processed into tissue blocks and embedded in paraffin. A rabbit polyclonal antibody against human inducible nitric oxide synthase was used as the primary antibody, followed by avidin-biotin immunoperoxidase localization. Normal rabbit serum was used as a negative control and ovarian carcinoma cells were used as the positive control.

RESULTS

Anti-inducible nitric oxide synthase labeling of human fetal amniotic membranes in patients with intra-amniotic infection showed positive immunostaining of epithelial cells, specifically in the cytoplasm of the perinuclear area. In contrast, no anti-inducible nitric oxide synthase immunostaining on human fetal amniotic membranes could be identified in patients without intra-amniotic infection.

CONCLUSIONS

Our data provide important evidence that inducible nitric oxide synthase can be induced on human fetal amnion in intra-amniotic infection. These findings strongly support our hypothesis that human fetal amnion may be a possible site for the synthesis of nitric oxide after inducible nitric oxide synthase is induced in response to infectious products in intra-amniotic infection.

Is amniotic fluid analysis the key to preterm labor? A model using interleukin-6 for predicting rapid delivery

OBJECTIVE

Our purpose was to create a model for predicting amnionitis and rapid delivery in preterm labor patients by use of amniotic fluid interleukin-6 and clinical parameters.

STUDY DESIGN

Amniotic fluid was cultured and analyzed, and a clinical score (incorporating gestational age, amniotic fluid Gram stain, glucose, leukocyte esterase, and maternal serum C-reactive protein) was determined in 111 patients diagnosed with preterm labor. Statistical analysis involved t tests, chi2, logarithmic regression, and multivariate regression analysis (P < or = .05).

RESULTS

The incidence of positive amniotic fluid cultures was 8.7% (9 of 103 patients). Patients with positive cultures of the amniotic fluid had a shorter delivery interval (4.8 +/- 7.5 vs 28.9 +/- 25.4 days, P < .001). Patients with elevated amniotic fluid interleukin-6 (> or = 7586 pg/ml) were more likely to have a positive amniotic fluid culture (relative risk = 8.8, 95% confidence interval = 1.6 to 47.4, P < .001) and to be delivered within 2 days (relative risk = 16.8, 95% confidence interval = 4.5 to 62.7, P < .001). Stepwise multivariate regression analysis yielded a model using interleukin-6, cervical dilatation, and gestational age (r2 = 0.63, P < .001) with a specificity of 100% for predicting delivery within 2 days of amniocentesis.

CONCLUSIONS

A mathematical model using maternal amniotic fluid interleukin-6 seems to be a useful clinical tool for quantifying the interval to preterm birth for patients in preterm labor.

The role of amniotic fluid L-selectin, GRO-alpha, and interleukin-8 in the pathogenesis of intraamniotic infection

OBJECTIVE

Our purpose was to compare and correlate amniotic fluid GRO-alpha, interleukin-8, and L-selectin in patients with and without intraamniotic infection.

STUDY DESIGN

Amniocentesis was performed on 45 pregnant women with preterm contractions, labor, or rupture of membranes. Fourteen patients had intraamniotic infection, and 31 did not. Intraamniotic infection was defined as the presence of a positive amniotic fluid culture. Amniotic fluid tests for Gram stain, glucose, neutrophil counts, creatinine, pH, and specific gravity were performed. Amniotic fluid levels of soluble L-selectin, interleukin-8, and GRO-alpha were measured by an enzyme-linked immunoassay and normalized by amniotic fluid creatinine levels. The Mann-Whitney Utest and Spearman's rank correlation test were used for statistical analyses.

RESULTS

Amniotic fluid median levels of soluble L-selectin, interleukin-8, and GRO-alpha were significantly higher in pregnant women with intraamniotic infection than in those without intraamniotic infection (soluble L-selectin: median 3334.6 ng/mg creatinine, range 408.4 to 15,956.8 vs 717.2 ng/mg creatinine, range 129.4 to 4601.9, p = 0.009; GRO-alpha: median 841.6 ng/mg creatinine, range 28.1 to 8591.7 vs 56.8 ng/mg creatinine, range 0.0 to 440.2, p < 0.0001; interleukin-8: median 4932.7 ng/mg creatinine, range 0.0 to 55,058.7 vs 28.3 ng/mg creatinine, range 0.0 to 1161.6, p = 0.0004). Patients with intraamniotic infection had significantly higher amniotic fluid leukocyte counts and leukocyte esterase activities and significantly lower amniotic fluid glucose concentrations compared with those without intraamniotic infection. Amniotic fluid GRO-alpha, interleukin-8, and soluble L-selectin were positively correlated, and each was positively correlated with amniotic fluid leukocytes and negatively correlated with amniotic fluid levels of glucose.

CONCLUSIONS

Our data indicate amniotic fluid GRO-alpha and interleukin-8 may be two potent leukocyte chemoattractants and activators, and L-selectin is rapidly shed from leukocytes in the amniotic fluid in patients with intraamniotic infection.

Elevated amniotic fluid nitric oxide metabolites and cyclic guanosine 3',5'-monophosphate in pregnant women with intraamniotic infection

OBJECTIVE

Our purpose was to compare amniotic fluid nitric oxide metabolites and cyclic guanosine 3',5'-monophosphate in pregnant women with and without intraamniotic infection.

STUDY DESIGN

Amniocentesis was performed on 72 pregnant women with preterm contractions, labor, or rupture of membranes. Fourteen patients had intraamniotic infection and 58 did not. Intraamniotic infection was defined as the presence of a positive amniotic fluid culture. Amniotic fluid Gram stain, glucose, leukocyte counts, leukocyte esterase activity, creatinine, pH, and specific gravity were performed. Endogenous nitrite was determined using Griess reagent. Amniotic fluid nitric oxide metabolites (nitrite and nitrate) were measured after reduction of nitrate to nitrite with Aspergillus nitrate reductase. Tests for amniotic fluid cyclic guanosine monophosphate levels were determined by enzyme immunoassay. Two-tailed t test, contingency table methods, linear regression, and correlation were used for statistical analyses.

RESULTS

Amniotic fluid levels of nitric oxide metabolites, endogenous nitrite, nitrate, and cyclic guanosine monophosphate were significantly higher in pregnant women with intraamniotic infection than in those without intraamniotic infection (2.66 +/- 0.49 vs 1.77 +/- 0.07 mumol/mg creatinine, p = 0.002; 0.69 +/- 0.15 vs 0.38 +/- 0.03 mumol/mg creatinine, p = 0.003; 1.99 +/- 0.41 vs 1.38 +/- 0.07 mumol/mg creatinine, p = 0.02; and 1.47 +/- 0.22 vs 0.90 +/- 0.08 nmol/mg creatinine, p = 0.004, respectively). Both amniotic fluid nitric oxide metabolites and cyclic guanosine monophosphate were positively correlated with amniotic fluid leukocyte counts and leukocyte esterase activity and negatively correlated with amniotic fluid glucose concentrations.

CONCLUSIONS

Our data indicate that amniotic fluid nitric oxide and cyclic guanosine monophosphate may play important roles in the pathogenesis of intraamniotic infection. Measurements of amniotic fluid nitric oxide metabolites and cyclic guanosine monophosphate may be part of a panel of tests that can be used to detect intraamniotic infection.

Chorioamnionitis and endometritis

Chorioamnionitis complicates 1% to 2% of all pregnancies and may affect 10% of women with certain risk factors. Intraamnionic infection may result in devastating morbidity for both the fetus and the mother. Also, chorioamnionitis is associated with higher cesarean section rates. As demonstrated earlier, endometritis is a common complication of cesarean delivery alone. Nevertheless, antibiotic prophylaxis has been shown to reduce postpartum morbidity. In the face of chorioamnionitis and a cesarean delivery, the risk of developing endometritis increases exponentially. However, if appropriate antibiotic therapy is instituted at the time of diagnosis, fetal and maternal outcomes improve dramatically. Similar to chorioamnionitis, endometritis is usually polymicrobial in nature. The preponderance of the organisms isolated are anaerobic. Established risk factors include operative delivery, prolonged ruptured fetal membranes, and prolonged labor. The diagnosis is based primarily on clinical examination with fever and the exclusion of other sources of extrapelvic infection. Once the diagnosis is established, appropriate empiric antibiotics are instituted. Antibiotic therapy should be continued until the patient is afebrile and asymptomatic for 24 to 36 hours. Over the past 20 years, the use of single-agent therapy in these serious infections has been shown to be safe as well as effective. Once successful therapy is completed, the patient is discharged home with no oral antibiotics.

Characterization and control of intraamniotic infection in an urban teaching hospital

OBJECTIVES

Our purpose was to determine (1) whether risk factors for intraamniotic infection were similar in women delivered of preterm infants versus term infants and (2) whether infection control techniques could decrease the incidence of intrapartum fever on a labor and delivery unit.

STUDY DESIGN

A total of 5409 consecutive patients (group 1) admitted to the Medical College of Virginia's labor and delivery unit were followed up prospectively to determine the development of intraamniotic infection. Demographic and intrapartum data were collected by use of a standard data form by infection control practitioners. An additional 2549 consecutive patients (group 2) were followed up after institution of infection-control measures.

RESULTS

Intraamniotic infection occurred in 416 of 5399 (7.7%) women (group 1) admitted to the labor and delivery suite. Odds ratios for term and preterm patients having intraamniotic infection with rupture of membranes > or = 12 hours compared with < 12 hours were 5.81 (95% confidence interval 512 to 6.59 and 2.49 (95% confidence interval 1.77 to 3.50), respectively. Odds ratios for term and preterm patients with internal monitors having intraamniotic infection compared with patients in whom internal monitors were not used were 2.01 (95% confidence interval 1.7 to 2.4) and 1.42 (95% confidence interval 0.99 to 2.04), respectively. Odds ratios for term and preterm patients having intraamniotic infection with more than four vaginal examinations compared with four or fewer vaginal examinations was 3.07 (95% confidence interval 2.53-3.73) and 1.59 (95% confidence interval 1.11-2.27), respectively. Intrapartum fever occurred in 475 (8.8%) women in group 1 and in 252 (9.8%) women in group 2 (not significant).

CONCLUSIONS

Risk factors (duration of ruptured membranes, use of internal monitoring, number of vaginal examinations) were similar in both term and preterm women with intraamniotic infection. Infection control measures failed to decrease the incidence of intrapartum fever in our patient population.

The effect of clinical chorioamnionitis on cord blood gas at term

OBJECTIVE

We sought to determine the effect of clinical chorioamnionitis on cord blood gas values in term pregnancies not complicated by any other disease.

STUDY DESIGN

2200 consecutive deliveries were studied. Following exclusion of twins, non-viable malformations and stillbirths, as well as mothers with high-risk pregnancy diseases--i.e. hypertension, diabetes, preterm labor, third-trimester bleeding, IUGR, postdates, oligohydramnios, i.v. drug abused, decreased fetal movement, maternal viral infection, UTI or pneumonia (n = 897)--two groups of patients remained: term pregnancies complicated only by clinical chorioamnionitis (n = 81) and uncomplicated term pregnancies (n = 1246).

RESULTS

Evaluation of mean cord blood gas values revealed a significant difference in pH, PO2, PCO2 and BE values, with the infants of mothers with clinical chorioamnionitis having lower pH values (7.23 +/- 0.07 vs. 7.28 +/- 0.07). However, evaluating the independent effect of chorioamnionitis on arterial cord blood pH (using a logistic regression model) showed that clinical chorioamnionitis, by itself, did not contribute to this change in arterial cord blood pH.

CONCLUSION

Chorioamnionitis was neither the explanation nor the cause for differences in arterial cord blood pH found between the two groups in our study. In cases of chorioamnionitis, these differences were attributed to other factors, such as length of labor, mode of delivery, method of delivery and presence of meconium.

Previous pregnancy outcomes and subsequent risk of preterm rupture of amniotic sac membranes

OBJECTIVE

To test the hypothesis that previous unfavourable pregnancy outcomes increase the risk for premature birth, with (PP) or without (PTB) premature rupture of the amniotic sac (PROM) at the index pregnancy and that multiple undesirable outcomes increase risk.

DESIGN

Case control study.

SETTING

Two university hospitals.

SUBJECTS

Four hundred sixty-three women aged 15 to 45 years who were delivered preterm PROM, full term PROM and preterm without PROM matched with 463 women who delivered full term. All women included in the study had at least one previous pregnancy.

OUTCOME MEASURES

Odds ratio of previous adverse pregnancy outcome among index cases.

RESULTS

Compared with controls, PP cases had odds ratios of 95 for previous preterm birth, 186 for abortion and prematurity and 158 for fetal loss, abortion/prematurity after controlling for confounding variables. Compared with controls, PTB cases had an odds ratio of 96.5 for previous preterm delivery, 84 for abortion and prematurity, and 320 for fetal loss/abortion and prematurity after controlling for confounding variables.

CONCLUSIONS

Previous preterm delivery, abortion and prematurity and fetal loss/abortion and prematurity all increase risk for subsequent preterm birth with or without PROM.

Fetal mononuclear cells show a comparable capacity with maternal mononuclear cells to produce IL-8 in response to lipopolysaccharide in chorioamnionitis

IL-8 is a chemotactic and activating cytokine for neutrophils which eliminate invading bacteria by releasing bactericidal metabolites. Cord blood mononuclear cells (CBMCs) obtained from neonates born to mothers with chorioamnionitis actively produced a significantly higher amount of IL-8 than those of neonates without chorioamnionitis, suggesting that the mononuclear cells of fetuses with chorioamnionitis had been activated in utero. As lipopolysaccharide (LPS) can often be detected in the uteroplacental space in chorioamnionitis, the LPS-mediated activation mechanism of neonatal mononuclear cells was analyzed in vitro to produce IL-8. Neonatal mononuclear cells stimulated with LPS increased IL-8 production in a time- and dose-dependent manner. The ability of term or preterm neonatal mononuclear cells to produce IL-8 was comparable with that of adult (maternal) mononuclear cells, suggesting functional maturity of the neonatal or fetal mononuclear cells to produce IL-8. However, IL-8 production by neonatal CBMCs was down-regulated by dexamethasone, a glucocorticoid which is clinically administered to mothers to promote fetal lung maturity in preterm delivery. Our present study revealed a regulatory mechanism of fetal IL-8 production, suggesting that functionally mature fetal mononuclear cells produce IL-8 in response to LPS in chorioamnionitis and activate the fetal defense mechanism against infection.

Coitus late in pregnancy: risk of preterm rupture of amniotic sac membranes

OBJECTIVES

Coitus with or without orgasm in late pregnancy is inconsistently associated with preterm rupture of amniotic sac membranes. We tested the hypothesis that during late pregnancy sexual behaviors including sexual positioning relate to the occurrence of premature rupture of membranes.

STUDY DESIGN

Women aged 15 to 45 years having preterm premature rupture of membranes, term premature rupture of membranes, or preterm delivery without premature rupture of membranes were matched singly by age, race, and parity to control women delivered of term infants. Information about six sexual activities, obstetric history, cervical infections, smoking during pregnancy, and sociodemographic information was obtained by face-to-face interview.

RESULTS

Only the male superior position was significantly associated with preterm premature rupture of membranes (odds ratio 2.40, 95% confidence interval 1.16 to 4.97) and preterm delivery without premature rupture of membranes (odds ratio 1.82, confidence interval 1.02 to 3.25) after confounding variables were controlled for. No sexual positioning or sexual activities related significantly to term premature rupture of membranes.

CONCLUSION

Most sexual positions and activities during late pregnancy are not associated with adverse pregnancy outcomes.

Use of esterase inhibitors and zone electrophoresis to define bacterial esterases in amniotic fluid

OBJECTIVE

The purpose of our study was to define further the role of bacterial esterases in amniotic fluid obtained from women with chorioamnionitis.

STUDY DESIGN

Amniotic fluid samples from 39 patients with chorioamnionitis were submitted for bacterial cultures and in vitro assay. Esterase inhibitors diisopropyl fluorophosphate and iodoacetic acid were added and the degree of inhibition calculated. These results were compared with the amniotic fluid culture results. Chi square analysis was performed to compare the results of the esterase assay and the inhibition assay between the uninfected and infected amniotic fluid samples.

RESULTS

Thirty-one patients had positive bacterial cultures, with 21 being infected with gram-negative organisms. All samples showed significant inhibition (range 55% to 82%) with diisopropyl fluorophosphate. There was partial inhibition with iodoacetic acid (range 10% to 30%) in the gram-negative samples but no inhibition in the gram-positive and uninfected samples. Six infected and two uninfected samples were analyzed by using zone electrophoresis with human plasma as a control. Minimal esterase motility was noted in the amniotic fluid samples as compared with that in plasma.

CONCLUSION

The esterases in amniotic fluid appeared to be of bacterial, not human, origin. Furthermore, different groups of bacteria appeared to produce different esterases in infected amniotic fluid.

Infection and labor. VII. Microbial invasion of the amniotic cavity in spontaneous rupture of membranes at term

OBJECTIVE

The purpose of this study was to determine the frequency, microbiologic characteristics, and clinical significance of microbial invasion of the amniotic cavity in women with premature rupture of membranes at term.

STUDY DESIGN

Amniocentesis was performed in 32 women with term premature rupture of membranes and amniotic fluid cultured for aerobic and anaerobic bacteria and Mycoplasmas.

RESULTS

The prevalence of positive amniotic fluid cultures was 34.3% (11/32). The most common isolates were Ureaplasma urealyticum, Peptostreptococcus sp., Lactobacillus sp., Bacteroides fragilis, and Fusobacterium sp. Clinical chorioamnionitis occurred only in one patient with a positive amniotic fluid culture. Her neonate had ophthalmitis. Three patients (9.4%) had endometritis. Among women who were delivered vaginally, those with a positive amniotic fluid culture had a significantly higher rate of endometritis than those with a negative culture (33% [3/9] vs 0% [0/20], respectively, p = 0.023).

CONCLUSIONS

These data indicate that microbial invasion of the amniotic cavity occurs in approximately one third of patients with preterm premature rupture of membranes. Microbial invasion of the amniotic cavity is a risk factor for endometritis in women with term premature rupture of membranes.

Progress in pathogenesis and management of clinical intraamniotic infection

In the past decade, gratifying progress has been achieved in our understanding of clinical intraamniotic infection. With a usual incidence of 1% to 4%, clinical intraamniotic infection mainly develops as an ascending process after prolonged rupture of the membranes and labor, but other cases may be hematogenous in origin whereas still others complicate intrauterine procedures. The most common organisms isolated in amniotic fluid of cases of intraamniotic infections are anaerobes, genital mycoplasmas, group B streptococci, and Escherichia coli. The latter two are found most commonly in maternal or neonatal bacteremia complicating intraamniotic infection. Although the diagnosis remains largely a clinical one, laboratory tests have been suggested to confirm the diagnosis in women with symptoms. These include amniotic fluid Gram stain, gas-liquid chromatography, and leukocyte esterase measurement. Maternal treatment consists of antibiotic therapy and delivery. Studies to date have used a penicillin plus an aminoglycoside, with some authors advocating the addition of clindamycin after cesarean delivery. Other broad-spectrum regimens may be equally effective. Complications of clinical intraamniotic infections include an increase in cesarean section rate and in maternal and neonatal bacteremia. Poor neonatal outcomes in intraamniotic infection are more likely in the following cases: (1) when E. coli or group B streptococci are present in the amniotic fluid; (2) when the infant has a low birth weight; (3) when maternal antibiotic therapy is delayed until after delivery.

In vitro inhibition of esterase activity in amniotic fluid: comparison with bacterial cultures

Assessment of leukocyte esterase activity in amniotic fluid for the rapid and reliable diagnosis of chorioamnionitis has been demonstrated previously. We compared in vitro inhibition of esterase activity in amniotic fluid with bacterial cultures to identify the origins of the specific esterases released by the infecting organisms. One hundred forty-one samples were tested (90 uninfected, 51 infected). Each sample was evaluated for Gram stain, cultures, and an in vitro esterase assay followed by ebelactone inhibition. Forty-two patients had positive amniotic fluid cultures. Ebelactone produced varying degrees of inhibition of esterase activity (range, 20% to 60%) in the uninfected samples and in those infected with gram-negative organisms. There was no inhibition in the samples infected with gram-positive organisms. Thus different groups of bacteria may elicit the production of different and specific esterases in infected amniotic fluid, as shown by the differences in in vitro inhibition.

Preterm delivery: a risk factor for retained placenta

The purpose of this study was to determine whether preterm delivery, with and without intraamniotic infection, is a risk factor for retained placenta. This complication occurred more frequently in women with preterm vaginal delivery than in women with term vaginal delivery (9.1% [21/231] vs 1.1% [6/561]; p less than 0.00001; odds ratio = 9.25). There was no significant difference in the prevalence of retained placenta between women with preterm labor and intact membranes and those with preterm premature rupture of membranes (8% [10/125] vs 10.4% [11/106]; p greater than or equal to 0.05). A positive amniotic fluid culture or clinical chorioamnionitis was not associated with a higher incidence of retained placenta. This study indicates that preterm delivery is associated with an increased risk of complications of the third stage of labor.

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

The purpose of this study was to critically review published studies regarding sensitivity, specificity, and positive and negative predictive values of antenatal tests to diagnose chorioamnionitis or fetal-neonatal sepsis in preterm premature rupture of the membranes. A Medline Data-Base computer program search from 1980 to 1988 identified 39 studies, 23 of which were accepted after independent review with preset criteria. An ideal test to predict chorioamnionitis or neonatal sepsis was not found. The low success rate for amniocentesis and the need for repeat taps preclude the acceptance of tests on the basis of amniotic fluid. Single, small studies, the precision of which has never been tested, show good indices for repeatedly increased serum levels of C-reactive protein (greater than 20 mg/L), a high level of C-reactive protein greater than 40 mg/L, or a day-to-day coefficient of variation for C-reactive protein of greater than 30% in the prediction of histologic or clinical chorioamnionitis. Ultrasonographic observation of fetal activity, if published study results are confirmed, may be of value to predict amniotic fluid bacterial colonization.

Esterase activity in second- and third-trimester amniotic fluid: an indicator of chorioamnionitis

Accurate and rapid diagnosis of chorioamnionitis poses a major diagnostic dilemma. We previously reported that leukocyte esterase activity in amniotic fluid, as measured by dipstick assay, could be used as an aid in the diagnosis of chorioamnionitis. This study examines the effectiveness of an in vitro spectrophotometric assay of esterase activity in amniotic fluid. We define baseline levels of esterase activity in uninfected amniotic fluid and demonstrate a quantitative increase when infection is present. Fifty-seven amniotic fluid samples obtained at second- and third-trimester amniocenteses were divided into three parts, one for culture and two for a comparison of esterase activities by the dipstick and spectrophotometric methods. In this study, the spectrophotometric assay, because of its higher specificity and sensitivity in the determination of elevated esterase activity, was shown to be more reliable for predicting chorioamnionitis than either the dipstick or culture method.

Premature membrane rupture in pregnancies of less than 34 weeks gestation

The outcome of pregnancies complicated by premature membrane rupture (PROM) at gestations of less than 34 weeks during a one-year period was reviewed. At presentation, infection was suspected in 12 of the 56 mothers, but confirmed in only three. All non-infected patients were then admitted to the ward and managed expectantly. Despite membrane rupture of up to 3-weeks duration, there were no episodes of proven maternal infection amongst the inpatients. Following delivery, seven babies had positive blood cultures; antenatal infection had been suspected, but not proven, in one case only. Four mothers developed postpartum infection which responded to antibiotic therapy. All mothers with infection, presenting either antenatally or postnatally, delivered within 48 h of membrane rupture and in all infected neonates the duration of membrane rupture was 72 h or less. The occurrence of sepsis was not related to the gestational age at onset of the membrane rupture. We conclude that patients with rupture of the membranes of 72 h duration or longer may be admitted for expectant management, even if presenting early in the second trimester, without an increased risk of infection.

Risk factors for intraamniotic infection: a prospective epidemiologic study

To determine the cumulative incidence of intraamniotic infection in our hospital and to identify potential risk factors for infection, 408 consecutive patients were followed up prospectively to determine development of intraamniotic infection. The clinical diagnosis of intraamniotic infection was made in 43 (10.5%) patients. Patients with intraamniotic infection were younger, of lower gravidity and parity, more likely to require oxytocin augmentation, and more likely to be monitored internally than were patients who were not infected. They also had longer durations of labor, ruptured membranes, and hospitalization before delivery, had significantly more vaginal examinations, and were more likely to be delivered of infants by cesarean section, as compared with patients without infection. Logistic regression analysis identified four variables independently associated with intraamniotic infection: the number of vaginal examinations, duration of ruptured membranes, use of internal monitors, and duration of total labor. Further study is necessary to clarify the role of these risk factors in the pathogenesis of intraamniotic infection so that infection control strategies can be developed.

Acute coagulopathy in pregnancy

Pregnancy alters both the fibrinolytic system and coagulation cascade. In addition, pregnancy presents unique triggering mechanisms for DIC. Management of DIC in pregnancy should include removal of the triggering mechanism, blood, and factor replacement. Inherited coagulation defects, while rarely resulting in bleeding diathesis in the pregnant patient, do require monitoring of maternal factor levels. Genetic counseling should be offered to all patients with inheritable coagulation disorders.

Intraamniotic infection and the onset of labor in preterm premature rupture of the membranes

The purpose of this study was to examine the relationship between intraamniotic infection and the onset of labor in patients with preterm premature rupture of the membranes. Two hundred and thirty consecutive patients were admitted with premature rupture of the membranes to Yale-New Haven Hospital from January 1985 to July 1987. Amniotic fluid was retrieved by amniocentesis from 96% (221/230). Sixty-one patients were in labor on admission (27.6%, 61/221) and 39% of them (24/61) had a positive amniotic fluid culture. Patients in labor on admission were more likely to have a positive amniotic fluid culture than those who were not in labor on admission (24/61 versus 41/160, p = 0.049). Of the 160-patients who were not in labor on admission, 81 subsequently went into spontaneous labor; microbiologic information at the time of labor was known in 48 of these patients (59.2%). Seventy-five percent (36/48) of these patients had a positive amniotic fluid culture. The incidence of intraamniotic infection in quiescent women who subsequently went into labor was higher than that of patients admitted in active labor (75% versus 39%, p = 0.0004). These results provide a basis for the clinical impression that the onset of labor in women with preterm premature rupture of the membranes is associated with a subclinical intraamniotic infection. The mechanisms responsible for the onset of labor in women without an intraamniotic infection may be associated with an extraamniotic infection (e.g., deciduitis) or a noninfectious process.

Intrapartum treatment of acute chorioamnionitis: impact on neonatal sepsis

In a study of 312 women with acute chorioamnionitis, 152 women received antibiotics before delivery, 90 received antibiotics after cord clamping, and 70 did not receive antibiotics. Antibiotics were administered during labor rather than after cord clamping if delivery was not imminent. Although endometritis developed more frequently in the patients receiving antibiotics after cord clamping, the difference was not statistically significant (5.6% versus 3.9%, difference not significant). There were two cases of verified sepsis in the group of infants (35 weeks) born to mothers receiving intrapartum antibiotics and there were eight cases in the no antibiotics group (p = 0.06). More importantly, in neonates greater than or equal to 35 weeks' gestational age, there was a significant difference in the frequency of positive blood cultures for group B streptococci (0/133 versus 8/140, p less than 0.05). We conclude that administration of antibiotics to the mother during labor may result in a decreased incidence of neonatal sepsis.

Short-course antibiotic therapy for the treatment of chorioamnionitis and postpartum endomyometritis

The development of chorioamnionitis and endomyometritis has traditionally required treatment with broad-spectrum antibiotic therapy and extended hospitalization. In the past, once parenteral antibiotic therapy was instituted, it was continued for 5 to 7 days and until the patient remained afebrile for 48 hours. To shorten the length of hospital stay, the length of parenteral antibiotic administration was reduced and an oral antibiotic was added, to complete a 7- to 10-day course of therapy. We evaluated the effectiveness of an even shorter course of parenteral antibiotics without the addition of oral antibiotics. Forty-two patients with chorioamnionitis and 64 with endomyometritis were enrolled in the study. Antibiotic therapy was continued until the patient's temperature was less than 99.5 degrees F for 12 to 24 hours. Of the 106 patients, only two were readmitted, both as a result of superficial wound separation. No patient had an infectious complication. A shorter course of parenteral antibiotics without the addition of an oral antibiotic gives results comparable to the standard extended treatment regimens, but is advantageous with respect to cost, patient compliance, and hospital stay.