Obstetric Anesthesiology Research

Advancing Obstetric and Perinatal Anesthetic Care

Research Mission Statement

To advance knowledge in the field of obstetric anesthesiology and peripartum care through clinical, epidemiological, and outcomes-based research.

Research Vision Statement

To optimize and personalize maternal care provided by obstetric anesthesiologists.


Our Research Faculty

Our faculty are internationally recognized experts in obstetric anesthesiology. 

We aim to advance the health and well-being of mothers by:

  1. Ensuring each woman obtains high-quality pain relief during and after her delivery.
  2. Identifying approaches for preventing and treating postpartum hemorrhage.
  3. Expanding knowledge related to women’s recovery after delivery.

Featured Researchers

Brendan Carvalho, MD
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Pamela Flood, MD
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Alex Butwick, MD
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Pervez Sultan, MD
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How our research has changed practice

Research from our group has been instrumental in advancing maternal and peripartum care. Through our research, we have developed new protocols and approaches for preventing and managing postpartum hemorrhage, enhanced methods to manage mothers’ pain during labor and after cesarean delivery, improved knowledge of how drugs behave in the peripartum setting, and designed instruments to measure recovery after childbirth.

Research Recognition

Our faculty have gained recognition for their outstanding contributions to innovation and knowledge in peripartum care and obstetric anesthesiology. Our work has received funding support from the National Institute for Health, Stanford Maternal & Child Health Research Institute and industry partners. Our research has been recognized with the receipt of numerous scientific awards from several international medical societies.

At the Society of Obstetric Anesthesiology and Perinatology annual scientific meetings, the most prestigious obstetric anesthesia meeting in the world, we have won the Best Scientific Paper award on 3 occasions, and been a finalist for this award on 7 occasions. Our trainee-mentored research has been consistently recognized with an unprecedented 13 Resident/Fellow Research Presentation awards in the past 18 years. We have also received scientific meeting research awards from the American Society of Anesthesiology, Obstetric Anaesthetists’ Association of Great Britain, and the Canadian Anesthesiologists' Society.

Our work has been published in high-impact scientific journals on numerous occasions (see all publications). We have produced and contributed towards several national guidelines and consensus statements produced by the Society of Obstetric Anesthesiology and Perinatology, the American Heart Association and the World Health Organization.

Our obstetric anesthesia facility was the first in the nation to be designated as a Society for Obstetric Anesthesia and Perinatology Center of Excellence, and Brendan Carvalho was appointed as President of the Society for Obstetric Anesthesia and Perinatology between 2017 and 2018.

Recent Publications

Professor of Anesthesiology, Perioperative and Pain Medicine (Adult MSD)


  • Calcium chloride for the prevention of uterine atony during cesarean delivery: A pilot randomized controlled trial and pharmacokinetic study. Journal of clinical anesthesia Ansari, J. R., Kalariya, N., Carvalho, B., Flood, P., Guo, N., Riley, E. 2022; 80: 110796


    To assess the feasibility, patient tolerance, pharmacokinetics, and potential effectiveness of a randomized controlled trial protocol investigating intravenous calcium chloride for the prevention of uterine atony during cesarean delivery.Double-blind, randomized controlled pilot trial with nested population pharmacokinetic analysis.This study was performed at Lucile Packard Children's Hospital, from August 2018 to September 2019.Forty patients with at least two risk factors for uterine atony at the time of cesarean delivery.One gram of intravenous calcium chloride (n = 20 patients) or a saline placebo control (n = 20 patients), in addition to standard care with oxytocin, upon umbilical cord clamping.The primary efficacy-related outcome was the presence of uterine atony defined as the use of a second-line uterotonic medication, surgical interventions for atony, or hemorrhage with blood loss >1000 mL. Blood loss, uterine tone numerical rating scores, serial venous blood calcium levels, hemodynamics, and potential side effects were also assessed.The study protocol proved feasible. The incidence of atony was 20% in parturients who received calcium compared to 50% in the placebo group (relative risk 0.38, P = 0.07, 95% CI 0.15-1.07, NNT 3.3). Calcium recipients tolerated the drug infusion well, with no adverse events and an equal incidence of potential side effects in the calcium and placebo groups. Ionized calcium concentration rose significantly in all patients who received calcium infusion, from baseline 1.18 mmol/L to peak levels 1.50-1.60 mmol/L. One-compartment population pharmacokinetics established clearance of 0.93 (95% CI 0.63-1.52) L/min and volume of distribution 76 (95% CI 49-94) L.In this pilot study, investigators found that intravenous calcium chloride was well-tolerated by the 20 patients assigned to receive the study drug and may be effective in prevention of uterine atony. A 1-g dose was sufficient to substantially increase calcium levels without any critically elevated lab values or concern for adverse side effects. These encouraging findings warrant further investigation of calcium as a novel agent to prevent uterine atony with an adequately powered clinical trial. Clinical trial registry NCT03867383 https://clinicaltrials.gov/ct2/show/NCT03867383.

    View details for DOI 10.1016/j.jclinane.2022.110796

    View details for PubMedID 35447502

  • Cardiac ultrasonography in obstetrics - a necessary skill for the present and future anesthesiologist. International journal of obstetric anesthesia Ortner, C. M., Padilla, C., Carvalho, B. 2022; 50: 103545

    View details for DOI 10.1016/j.ijoa.2022.103545

    View details for PubMedID 35381420

  • Accuracy of visual estimation of blood loss in obstetrics using clinical reconstructions: an observational simulation cohort study. International journal of obstetric anesthesia Athar, M. W., Abir, G., Seay, R. C., Guo, N., Butwick, A., Carvalho, B. 2022; 50: 103539


    INTRODUCTION: Postpartum hemorrhage is the leading cause of maternal mortality worldwide, and optimal management requires accurate blood loss estimations. The aim of this study was to assess whether differences exist between visually estimated blood loss versus actual blood loss based on delivery mode, blood volume or distribution/location and knowledge of patient's current cardiovascular status.METHODS: For this observational cohort study, photographs were taken of 18 blood loss scenarios for vaginal delivery and cesarean delivery, and six photographs were duplicated and annotated with maternal vital signs. Scenarios were categorized into 50% (500 mL), 100% (1000 mL) and 200% (2000 mL) of the defined blood loss volume for postpartum hemorrhage and the photographs were shown to participants to visually estimate blood loss volumes.RESULTS: The mean ± standard deviation estimates of actual 500 mL, 1000 mL and 2000 mL blood loss volumes were 1208 ± 438 mL, 1676 ± 630 mL and 2637 ± 1123 mL, respectively (P <0.001 among groups). The difference was significantly greater in vaginal delivery than cesarean delivery scenarios (1064 ± 849 mL vs. 284 ± 456 mL; P <0.001). Estimated blood loss volume was not influenced by blood loss distribution/location, or by provider group or experience. The cardiovascular status of the patient impacted estimations only if tachycardia and hypotension were present.CONCLUSIONS: Most providers significantly overestimated blood loss volumes (by nearly 700 mL). Provider and scenario factors that impact inaccuracies in visual estimated blood loss identified in this study can be used to guide education and training.

    View details for DOI 10.1016/j.ijoa.2022.103539

    View details for PubMedID 35397264

  • In-Hospital Opioid Consumption After the Previous Cesarean Delivery Weakly Predicts Opioid Consumption After Index Delivery: A Retrospective Cohort Study. Anesthesia and analgesia Komatsu, R., Nash, M., Mandalia, S., Dinges, E., Kamal, U., Singh, D., El-Omrani, H., Anwar, A., Delgado, C., Ziga, T. M., Carvalho, B. 2022


    BACKGROUND: To predict opioid consumption and pain intensity after the index cesarean delivery, we tested a hypothesis that opioid consumption after the previous cesarean delivery of the same patient can predict the opioid consumption after the index cesarean delivery. We further tested a secondary hypothesis that the pain scores after the previous cesarean delivery can predict the pain scores after the index cesarean delivery.METHODS: This is a retrospective cohort study of 470 women who underwent both previous and index cesarean deliveries at a single institution from January 2011 to June 2019. To predict the opioid consumption (primary outcome) and average pain scores (on 11-point numeric rating scale) after their index cesarean delivery, we used a linear regression model incorporating only the opioid consumption and average pain scores after the previous cesarean delivery, respectively (unadjusted models). Demographic and obstetric variables were then added as predictors (adjusted models). The bootstrap was used to compare these models with respect to proportion of variance of the outcome accounted for (R2).RESULTS: Unadjusted models were weakly predictive of opioid consumption (R2 = 0.268; 95% confidence interval [CI], 0.146-0.368) and average pain scores (R2 = 0.176; 95% CI, 0.057-0.250). An adjusted model for opioid consumption was weakly predictive (R2 = 0.363; 95% CI, 0.208-0.478), but an adjusted model for average pain scores was not predictive of the outcomes (R2 = 0.070; 95% CI, -0.143 to 0.219). Adjusted models failed to explain variances of opioid consumption and average pain scores significantly better than unadjusted models (P = .099 and P = .141, respectively).CONCLUSIONS: Opioid consumption and pain scores after women's previous cesarean delivery only explain 27% of variance of opioid consumption and 18% of variance of their pain after their index cesarean delivery. Therefore, previous cesarean delivery analgesic metrics are not robust enough to be used as clinically applicable predictors for index delivery.

    View details for DOI 10.1213/ANE.0000000000005918

    View details for PubMedID 35130195

  • World Health Organization Recommendation for Using Uterine Balloon Tamponade to Treat Postpartum Hemorrhage. Obstetrics and gynecology Weeks, A. D., Akinola, O. I., Amorim, M., Carvalho, B., Deneux-Tharaux, C., Liabsuetrakul, T., Meremikwu, M., Miller, S., Nabhan, A., Nagai, M., Wahabi, H., Walker, D. 1800


    The World Health Organization (WHO) recently published a new recommendation on the use of the uterine balloon tamponade for the treatment of postpartum hemorrhage. The recommendation that uterine balloon tamponade should be used only where there is already access to other postpartum hemorrhage treatments (including immediate recourse to surgery) has proved controversial. It is especially problematic for those working in low-level health care facilities in under-resourced settings, where there are already programs that have introduced low-cost uterine balloon tamponade devices for use, even in settings where recourse to surgical interventions is not possible. However, there are now two separate randomized trials that both unexpectedly show unfavorable outcomes in these settings when a condom catheter uterine balloon tamponade device was introduced. Considering the balance of potential benefits and these safety concerns, the WHO postpartum hemorrhage guideline panel therefore recommends that uterine balloon tamponade should be used only in contexts where other supportive postpartum hemorrhage interventions are available if needed.

    View details for DOI 10.1097/AOG.0000000000004674

    View details for PubMedID 35115478

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