Group B Streptococcus Infection and Obstetric Hemorrhage Risk.

OBJECTIVE: To elucidate the association between GBS infection and maternal risk for obstetric hemorrhage (OBH) and OBH-related morbidities (OBH-M). METHODS: This was a retrospective cohort study of all deliveries with a documented GBS status at a single large academic medical center from 2018 to 2019. GBS status was determined by either urine culture or rectovaginal culture collected during the antepartum period. The primary outcomes were quantitative blood loss (QBL), OBH, and a composite of OBH-M. Secondary outcomes were individual components of the OBH-M composite and frequency of hemorrhage-related interventions utilized intrapartum and postpartum. A stratified analysis was conducted examining only patients who were diagnosed intrapartum with an intrapartum intraamniotic infection (III). RESULTS: Of 4679 pregnant individuals who delivered a live infant between January 1, 2018 and January 1,2019 with a documented GBS status, 1,487 were identified as GBS positive (+) and 3192 were identified as GBS negative (-). The GBS + group did not have significantly higher QBL (p = 0.29) or rate of OBH (p = 0.35). There were no significant differences by GBS status in OBH morbidity (p = 0.79) or its individual components or frequency of individual pharmacologic or non-pharmacologic OBHrelated interventions. There were also no significant differences by GBS status among patients with an III. CONCLUSIONS FOR PRACTICE: GBS infection at the time of delivery was not associated with increased risk for OBH or OBH-M. Further research is needed to further explore the relationship between peripartum infections and OBH risk.

Association between duration of intrapartum oxytocin exposure and obstetric hemorrhage.

PURPOSE: Prolonged duration of intrapartum oxytocin exposure is included as a risk factor within widely adopted obstetric hemorrhage risk stratification tools. However, the duration of exposure that confers increased risk is poorly understood. This study aimed to assess the association between duration of intrapartum oxytocin exposure and obstetric blood loss, as measured by quantitative blood loss, and hemorrhage-related maternal morbidity. METHODS: This was a retrospective cohort study of all deliveries from 2018 to 2019 at a single medical center. We included patients who had received any intrapartum oxytocin, and we categorized them into 1 of 5 groups: > 0-2, ≥ 2-4, ≥ 4-6, ≥ 6-12, and ≥ 12 h of intrapartum oxytocin exposure. The primary outcomes were mean quantitative blood loss, proportion with obstetric hemorrhage (defined as quantitative blood loss ≥ 1000 mL), and proportion with obstetric hemorrhage-related morbidity, a composite of hemorrhage-related morbidity outcomes. Secondary outcomes were hemorrhage-related pharmacologic and procedural interventions. A stratified analysis was also conducted to examine primary and secondary outcomes by delivery mode. RESULTS: Of 5332 deliveries between January 1, 2018 and December 31, 2019 at our institution, 2232 (41.9%) utilized oxytocin for induction or augmentation. 326 (14.6%) had exposure of > 0-2 h, 295 (13.2%) ≥ 2-4 h, 298 (13.4%) ≥ 4-6 h, 562 (25.2%) ≥ 6-12 h, and 751 (33.6%) ≥ 12 h. Across all deliveries, there was higher mean quantitative blood loss (p < 0.01) as well as increased odds of obstetric hemorrhage (adjusted odds ratio [aOR] 1.52, 95% confidence interval [CI] 1.21-1.91) for those with ≥ 12 h of oxytocin compared to all groups between > 0-12 h of exposure. In our stratified analysis, ≥ 12 h of oxytocin exposure was associated with higher mean quantitative blood loss (p = 0.04) and odds of obstetric hemorrhage in vaginal deliveries (aOR 1.47, 95% CI: 1.03-2.11), though not in cesarean deliveries (aOR 1.16, 95% CI 0.82-1.62). There were no differences in proportion with obstetric hemorrhage-related morbidity across all deliveries (p = 0.40) or in the stratified analysis. CONCLUSION: Intrapartum oxytocin exposure of ≥ 12 h was associated with increased quantitative blood loss and odds of obstetric hemorrhage in vaginal, but not cesarean, deliveries.

Intrapartum Risk Factors and Prediction of Obstetric Hemorrhage-Related Morbidity.

OBJECTIVE: The aim of this study was to assess whether inclusion of intrapartum risk factors improves our obstetric hemorrhage risk stratification tool in predicting obstetric hemorrhage, transfusion, and related severe morbidity. STUDY DESIGN: This is a retrospective cohort study using all live deliveries at a single institution over a 2-year period (n = 5,332). Obstetric hemorrhage risk factors, hemorrhage burden, and severe maternal morbidity index outcomes were assessed through chart abstraction. Hemorrhage risk was assessed at (1) "time of admission" through chart abstraction and (2) "predelivery" by calculation after inclusion of all abstracted intrapartum risk factors. Admission high risk was compared with predelivery high risk for sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio in predicting obstetric hemorrhage, obstetric hemorrhage requiring transfusion, and obstetric hemorrhage-related severe morbidity. Significance levels were calculated using descriptive statistical methods including chi-squared tests and McNemar's tests. RESULTS: The sensitivities of the risk assessment tool using admission risk classification for high-risk patients is 25% for obstetric hemorrhage, 37% for obstetric hemorrhage requiring transfusion, and 22% for obstetric hemorrhage-related severe morbidity. After intrapartum factor inclusion, the sensitivities increase to 55% for obstetric hemorrhage, 59% for obstetric hemorrhage requiring transfusion, and 47% for obstetric hemorrhage-related severe morbidity. This "predelivery" risk assessment is significantly more sensitive across all three end points (p < 0.001 for all three outcomes). While the positive likelihood ratios for obstetric hemorrhage are equal on admission and predelivery (2.10 on admission and predelivery), they increase after intrapartum factor inclusion for obstetric hemorrhage requiring transfusion and obstetric hemorrhage-related severe morbidity (on admission, 2.74 and 1.6, respectively, and predelivery: 4.57 and 3.58, respectively). CONCLUSION: Inclusion of intrapartum risk factors increases the accuracy of this obstetric hemorrhage risk stratification tool in predicting patients requiring hemorrhage management with transfusion and obstetric hemorrhage-related severe morbidity. KEY POINTS: · There are little data to validate intrapartum hemorrhage risk reassessment.. · Including intrapartum factors improves risk stratification for transfusion and related morbidity.. · Future research should clinically validate risk reassessment in the intrapartum period..

Integration of Clinical Skills into Preclinical Medical Curriculum Via a Low-Cost Femoral Triangle Ultrasound Model.

We created a low-cost femoral triangle model that allows first year medical students to practice ultrasound-guided procedures while reinforcing their knowledge of femoral triangle anatomy. Use of this model also increased opportunities for informal near-peer teaching and student involvement in the creation of instructional materials.

Intrapartum magnesium sulfate exposure and obstetric hemorrhage risk.

BACKGROUND: The gold standard intrapartum treatment for preeclampsia with severe features is magnesium sulfate in order to provide prophylaxis against eclampsia. However, though magnesium sulfate is known to have a relaxant effect on uterine muscle, there have been variable reports in the literature in regard to the association between magnesium and obstetric hemorrhage (OBH). OBJECTIVE: We aim to compare OBH incidence in patients with hypertensive disease of pregnancy (HDP) with or without exposure to intrapartum magnesium sulfate. METHODS: We performed a retrospective cohort study of all deliveries at our institution associated with a diagnosis of hypertensive disease of pregnancy (HDP) (e.g. chronic and gestational hypertension, preeclampsia with or without severe features, eclampsia, or HELLP) from January 1, 2018 to December 31, 2019. The category of HDP diagnosis was determined by a detailed chart review by trained chart abstractors. The primary outcome was total quantitative blood loss (QBL) and the rate of obstetric hemorrhage. Secondary outcomes included a composite of obstetric hemorrhage-related maternal morbidity outcomes (OBH-M), the individual composite components and the incidence of additional hemorrhage-related interventions (e.g. uterotonics and surgical interventions). We also examined the same primary and secondary outcomes in a stratified analysis based on delivery mode (i.e. vaginal deliveries only and cesarean deliveries only). RESULTS: Of 791 patients with a diagnosis of HDP, 411 patients received magnesium sulfate for eclampsia prophylaxis and 380 patients did not receive magnesium sulfate. For all delivery modes, there was a significantly higher QBL (p < .01), increased rate of OBH (p = .04) and increased OBH-M (p < .01) in deliveries associated with intrapartum exposure to magnesium compared to those without. However, our stratified analysis by delivery mode demonstrated that magnesium-related hemorrhage risk only persisted for vaginal deliveries (QBL p < .01; OBH aOR 1.47, 95% CI: 0.75-2.85; OBH-M aOR 1.47, 95% CI 1.00-7.55) with no significant hemorrhage-related differences among cesareans with or without magnesium exposure (QBL p = .51; OBH aOR 1.45, 95% CI: 0.85-2.47; OBH-M 1.50 95% CI: 0.70-3.23). CONCLUSION: Intrapartum exposure to magnesium sulfate use was associated with an increase in QBL and risk of OBH-M in vaginal deliveries, but not associated with any hemorrhage-related outcome differences in cesarean deliveries. More research is needed to explore the effects of hypertensive disease, magnesium exposure, and delivery mode on obstetric hemorrhage risk.

The wiring diagram of a glomerular olfactory system.

The sense of smell enables animals to react to long-distance cues according to learned and innate valences. Here, we have mapped with electron microscopy the complete wiring diagram of the Drosophila larval antennal lobe, an olfactory neuropil similar to the vertebrate olfactory bulb. We found a canonical circuit with uniglomerular projection neurons (uPNs) relaying gain-controlled ORN activity to the mushroom body and the lateral horn. A second, parallel circuit with multiglomerular projection neurons (mPNs) and hierarchically connected local neurons (LNs) selectively integrates multiple ORN signals already at the first synapse. LN-LN synaptic connections putatively implement a bistable gain control mechanism that either computes odor saliency through panglomerular inhibition, or allows some glomeruli to respond to faint aversive odors in the presence of strong appetitive odors. This complete wiring diagram will support experimental and theoretical studies towards bridging the gap between circuits and behavior.

Reverse-correlation analysis of navigation dynamics in Drosophila larva using optogenetics.

Neural circuits for behavior transform sensory inputs into motor outputs in patterns with strategic value. Determining how neurons along a sensorimotor circuit contribute to this transformation is central to understanding behavior. To do this, a quantitative framework to describe behavioral dynamics is needed. In this study, we built a high-throughput optogenetic system for Drosophila larva to quantify the sensorimotor transformations underlying navigational behavior. We express CsChrimson, a red-shifted variant of channelrhodopsin, in specific chemosensory neurons and expose large numbers of freely moving animals to random optogenetic activation patterns. We quantify their behavioral responses and use reverse-correlation analysis to uncover the linear and static nonlinear components of navigation dynamics as functions of optogenetic activation patterns of specific sensory neurons. We find that linear-nonlinear models accurately predict navigational decision-making for different optogenetic activation waveforms. We use our method to establish the valence and dynamics of navigation driven by optogenetic activation of different combinations of bitter-sensing gustatory neurons. Our method captures the dynamics of optogenetically induced behavior in compact, quantitative transformations that can be used to characterize circuits for sensorimotor processing and their contribution to navigational decision making.