Calcium Carbonate as a Potential Intervention to Prevent Labor Dystocia: Narrative Review of the Literature

Anecdotally, there are attestations from clinicians of calcium carbonate being used successfully for laboring people experiencing labor dystocia. The goal of this narrative review was to provide a synopsis of pertinent literature on calcium use in obstetrics to explore the potential benefit of calcium carbonate as a simple and low-cost intervention for prevention or treatment of labor dystocia. To answer how calcium and carbonate physiologically contribute to myometrium contractility, we conducted a literature search of English-language peer-reviewed articles, with no year limitation, consisting of the keywords "calcium," "calcium carbonate," "calcium gluconate," "pregnancy," "hemorrhage," and variations of "smooth muscle contractility" and "uterine contractions." Though no overt evidence on calcium carbonate's ability to prevent labor dystocia was identified; relevant information was found regarding smooth muscle contractility, calcium's influence on uterine muscle contractility, and carbonate's potential impact on reducing amniotic fluid lactate levels to restore uterine contractility during labor. Studies reporting the potential effectiveness of calcium gluconate and sodium bicarbonate in preventing labor dystocia offer background, safety information, and rationale for a future randomized control trial to evaluate the ability of calcium carbonate to prevent labor dystocia and reduce rates of cesarean section.

A randomized controlled trial of an oral probiotic to reduce antepartum group B Streptococcus colonization and gastrointestinal symptoms

BACKGROUND

Probiotics have been suggested as a strategy to reduce antenatal group B Streptococcus colonization. Although probiotics are known to improve gastrointestinal symptoms, this has not been studied during pregnancy.

OBJECTIVE

This study aimed to evaluate the efficacy of a probiotic to reduce: (1) standard-of-care antenatal group B Streptococcus colonization and colony counts and (2) gastrointestinal symptoms of pregnancy.

STUDY DESIGN

In a double-blind fashion, 109 healthy adult pregnant people were randomized to Florajen3 probiotic or placebo capsules once daily from 28 weeks' gestation until labor onset. Baseline vaginal and rectal study swabs for group B Streptococcus colony-forming units and microbiome analysis were collected at 28 and 36 weeks' gestation. Standard-of-care vaginal to rectal group B Streptococcus swabs were collected from all participants at 36 weeks' gestation and determined the need for intrapartum antibiotic prophylaxis. Data collection included solicitation of adverse events, demographic information, Antepartum Gastrointestinal Symptom Assessment score, yogurt ingestion, sexual activity, and vaginal cleaning practices.

RESULTS

A total of 83 participants completed the study to 36 weeks' gestation with no adverse events. Standard-of-care group B Streptococcus colonization was 20.4% in the control group and 15.4% in probiotic group participants (-5%; P=.73). The relative risk for positive standard-of-care vaginal-rectal group B Streptococcus colonization was 1.33 (95% confidence interval, 0.5-3.40) times higher in the control group than in the probiotic group (P=.55). There were no differences in median vaginal (P=.16) or rectal (P=.20) group B streptococcus colony-forming units at baseline or at 36 weeks (vaginal P>.999; rectal P=.56). Antepartum Gastrointestinal Symptom Assessment scores were similar at baseline (P=.19), but significantly decreased in probiotic group participants at 36 weeks (P=.02). No covariates significantly altered group B Streptococcus colonization. Significantly more Florajen3 bacteria components were recovered from the vaginal-rectal samples of probiotic group participants (32%; P=.04) compared with controls.

CONCLUSION

The findings of this study provided insufficient evidence for the clinical application of the Florajen3 probiotic intervention to reduce standard-of-care vaginal-rectal group B Streptococcus colonization. The prevalence of group B Streptococcus was lower than expected in the study population, and intervention adherence was poor. Probiotic bacteria colonization of the genitourinary tract occurred more in intervention group participants than in controls and significantly reduced gastrointestinal symptoms of pregnancy.

Probiotic interventions to reduce antepartum Group B streptococcus colonization: A systematic review and meta-analysis

OBJECTIVE

To systematically review and meta-analyse studies of the efficacy of probiotics to reduce antenatal Group B Streptococcus (GBS) colonisation.

PARTICIPANTS

Antenatal participants with known positive GBS colonisation or unknown GBS status.

INTERVENTION

Probiotic interventions containing species of Lactobacillus or Streptococcus.

DESIGN

Systematic review and meta-analysis.

MEASUREMENTS AND FINDINGS

The systematic review included 10 studies. Five articles contained in vitro studies of probiotic interventions to determine antagonistic activity against GBS. Six clinical trials of probiotics to reduce antenatal GBS were systematically reviewed and meta-analysed. The meta-analysis revealed that the use of an antenatal probiotic increased the probability of a negative GBS result by 79% (OR = 0.56, 95% CI = 8.7%, 194.1%, p = 0.02) (n = 709). However, only one clinical trial of 6 had a low risk of bias.

KEY CONCLUSIONS

The probiotic interventions subjected to in vitro testing showed antagonistic activity against GBS through the mechanisms of acidification, immune modulation, and adhesion. The findings of the meta-analysis of the clinical trials revealed that probiotics are a moderately effective intervention to reduce antenatal GBS colonisation. More well-controlled trials with diverse participants and with better elucidation of variables influencing GBS colonisation rates are needed.

IMPLICATIONS FOR PRACTICE

Probiotic interventions appear to be a safe and effective primary prevention strategy for antenatal GBS colonisation. Application of this low-risk intervention needs more study but may reduce the need for intrapartum antibiotic prophylaxis in countries or regions where antenatal GBS screening is used. Midwives can be instrumental in conducting and supporting larger well-controlled clinical trials.

Dancing During Labor: Are Women Down to Boogie?

Recent social media trends have demonstrated increased interest in dancing during the final weeks of pregnancy and labor. However, there is limited evidence about dancing during labor and its impact on labor pain and duration as well as patient satisfaction. Before conducting a prospective study, given that enrollment is often challenging, our feasibility study aimed to assess the willingness of pregnant women to participate in a future study evaluating low-impact dance during labor. We anonymously surveyed a convenience sample of English-speaking/reading pregnant women who presented for prenatal care at 1 of 3 clinics from June 2019 to July 2019. Questions related to women's interest in dancing during labor and limited demographic information were collected and analyzed. Overall, 88.6% of pregnant women who completed the survey expressed interest in participating in a future study on low-impact dance during labor, with Caucasian patients and those ≥35 years of age being less interested in future participation (P<0.05 for both). Interest in participating was not influenced by any other demographic characteristic, pregnancy history, or current activity level. Given sufficient interest among pregnant women in participating in a study aimed at evaluating the potential benefits of low-impact dance during labor, enrollment numbers may be easier to achieve than previously expected.

Baseline imaging after therapy for unprovoked venous thromboembolism: a randomized controlled comparison of baseline imaging for diagnosis of suspected recurrence

BACKGROUND

After a first unprovoked venous thromboembolism (VTE), many patients have residual pulmonary and/or lower limb vascular obstruction following completion of short-term anticoagulation. Residual vascular obstruction may complicate the diagnosis of recurrent VTE. Whether baseline imaging, conducted after completion of anticoagulation, helps in interpreting diagnostic testing in patients who subsequently have suspected recurrent VTE is unknown.

STUDY DESIGN

The REVERSE study is a cohort study whose primary aim was to derive a clinical decision rule to guide the duration of anticoagulation after a first unprovoked VTE. All patients underwent baseline imaging after completing 5-7 months of anticoagulant therapy. We performed a post hoc randomized controlled comparison among 121 patients investigated for a suspected recurrent VTE during follow-up: the decision on recurrent VTE with or without baseline imaging was made available to two independent adjudicators.

RESULTS

The proportion of patients not classifiable for recurrent VTE was statistically significantly higher in the group with no baseline imaging than in the group with baseline imaging: one in five as compared with one in 25. The interobserver agreement between the two adjudicators was better in the group with baseline imaging than in the group with no baseline imaging: κ-values were 0.78 and 0.54, respectively.

CONCLUSIONS

In patients with a first unprovoked VTE, baseline imaging at completion of anticoagulant therapy helps in interpreting diagnostic tests performed in cases of suspected recurrent VTE.

Excluding pulmonary embolism at the bedside without diagnostic imaging: management of patients with suspected pulmonary embolism presenting to the emergency department by using a simple clinical model and d-dimer

BACKGROUND

The limitations of the current diagnostic standard, ventilation-perfusion lung scanning, complicate the management of patients with suspected pulmonary embolism. We previously demonstrated that determining the pretest probability can assist with management and that the high negative predictive value of certain D -dimer assays may simplify the diagnostic process.

OBJECTIVE

To determine the safety of using a simple clinical model combined with D -dimer assay to manage patients presenting to the emergency department with suspected pulmonary embolism.

DESIGN

Prospective cohort study.

SETTING

Emergency departments at four tertiary care hospitals in Canada.

PATIENTS

930 consecutive patients with suspected pulmonary embolism.

INTERVENTIONS

Physicians first used a clinical model to determine patients' pretest probability of pulmonary embolism and then performed a D -dimer test. Patients with low pretest probability and a negative D -dimer result had no further tests and were considered to have a diagnosis of pulmonary embolism excluded. All other patients underwent ventilation-perfusion lung scanning. If the scan was nondiagnostic, bilateral deep venous ultrasonography was done. Whether further testing (by serial ultrasonography or angiography) was done depended on the patients' pretest probability and the lung scanning results.

MEASUREMENTS

Patients received a diagnosis of pulmonary embolism if they had a high-probability ventilation-perfusion scan, an abnormal result on ultrasonography or pulmonary angiography, or a venous thromboembolic event during follow-up. Patients for whom the diagnosis was considered excluded were followed up for 3 months for the development of thromboembolic events.

RESULTS

The pretest probability of pulmonary embolism was low, moderate, and high in 527, 339, and 64 patients (1.3%, 16.2%, and 37.5% had pulmonary embolism), respectively. Of 849 patients in whom a diagnosis of pulmonary-embolism had initially been excluded, 5 (0.6% [95% CI, 0.2% to 1.4%]) developed pulmonary embolism or deep venous thrombosis during follow-up. However, 4 of these patients had not undergone the proper diagnostic testing protocol. In 7 of the patients who received a diagnosis of pulmonary embolism, the physician had performed more diagnostic tests than were called for by the algorithm. In 759 of the 849 patients in whom pulmonary embolism was not found on initial evaluation, the diagnostic protocol was followed correctly. Only 1 (0.1% [CI, 0.0% to 0.7%]) of these 759 patients developed thromboembolic events during follow-up. Of the 437 patients with a negative D -dimer result and low clinical probability, only 1 developed pulmonary embolism during follow-up; thus, the negative predictive value for the combined strategy of using the clinical model with D -dimer testing in these patients was 99.5% (CI, 99.1% to 100%).

CONCLUSION

Managing patients for suspected pulmonary embolism on the basis of pretest probability and D -dimer result is safe and decreases the need for diagnostic imaging.

Excluding pulmonary embolism at the bedside without diagnostic imaging: management of patients with suspected pulmonary embolism presenting to the emergency department by using a simple clinical model and d-dimer

BACKGROUND

The limitations of the current diagnostic standard, ventilation-perfusion lung scanning, complicate the management of patients with suspected pulmonary embolism. We previously demonstrated that determining the pretest probability can assist with management and that the high negative predictive value of certain D -dimer assays may simplify the diagnostic process.

OBJECTIVE

To determine the safety of using a simple clinical model combined with D -dimer assay to manage patients presenting to the emergency department with suspected pulmonary embolism.

DESIGN

Prospective cohort study.

SETTING

Emergency departments at four tertiary care hospitals in Canada.

PATIENTS

930 consecutive patients with suspected pulmonary embolism.

INTERVENTIONS

Physicians first used a clinical model to determine patients' pretest probability of pulmonary embolism and then performed a D -dimer test. Patients with low pretest probability and a negative D -dimer result had no further tests and were considered to have a diagnosis of pulmonary embolism excluded. All other patients underwent ventilation-perfusion lung scanning. If the scan was nondiagnostic, bilateral deep venous ultrasonography was done. Whether further testing (by serial ultrasonography or angiography) was done depended on the patients' pretest probability and the lung scanning results.

MEASUREMENTS

Patients received a diagnosis of pulmonary embolism if they had a high-probability ventilation-perfusion scan, an abnormal result on ultrasonography or pulmonary angiography, or a venous thromboembolic event during follow-up. Patients for whom the diagnosis was considered excluded were followed up for 3 months for the development of thromboembolic events.

RESULTS

The pretest probability of pulmonary embolism was low, moderate, and high in 527, 339, and 64 patients (1.3%, 16.2%, and 37.5% had pulmonary embolism), respectively. Of 849 patients in whom a diagnosis of pulmonary-embolism had initially been excluded, 5 (0.6% [95% CI, 0.2% to 1.4%]) developed pulmonary embolism or deep venous thrombosis during follow-up. However, 4 of these patients had not undergone the proper diagnostic testing protocol. In 7 of the patients who received a diagnosis of pulmonary embolism, the physician had performed more diagnostic tests than were called for by the algorithm. In 759 of the 849 patients in whom pulmonary embolism was not found on initial evaluation, the diagnostic protocol was followed correctly. Only 1 (0.1% [CI, 0.0% to 0.7%]) of these 759 patients developed thromboembolic events during follow-up. Of the 437 patients with a negative D -dimer result and low clinical probability, only 1 developed pulmonary embolism during follow-up; thus, the negative predictive value for the combined strategy of using the clinical model with D -dimer testing in these patients was 99.5% (CI, 99.1% to 100%).

CONCLUSION

Managing patients for suspected pulmonary embolism on the basis of pretest probability and D -dimer result is safe and decreases the need for diagnostic imaging.

Age, experience and the changing brain

In this review, various aspects of how environmental experience effects the structure of the cortex at different times in the age of the animal are summarized. The interactions of brain injury and sex on the age-dependent plastic changes in the cortex are also considered. Finally, we have attempted to reach some general conclusions that describe the effects of age, experience, sex, and injury on the cortex.