Interventional radiology for prevention and management of postpartum haemorrhage: a single centre retrospective cohort study.

PURPOSE: Postpartum haemorrhage (PPH) remains a leading cause of maternal death despite current medical management. Surgical interventions are still needed for refractory bleeding. Interventional radiology (IR) can be a successful intermediary that avoids the need for hysterectomy. Nevertheless, IR outcome data in a peripartum setting are limited. The objective of this study is to document the efficacy and safety of IR. METHODS: Retrospective study reviewed the records of consecutive patients who underwent peripartum IR from 01/01/2010 until 31/12/2020 in a tertiary academic centre. Patients were divided in a prophylactic and a therapeutic group. Information about interventions before and after IR, and IR specific complications was retrieved. Efficacy was defined by the number of transfusions and additional surgical interventions needed after IR, and safety was assessed by the incidence of IR related complications. RESULTS: Fifty-four patients, prophylactic group (n = 24) and therapeutic group (n = 30), were identified. In both groups, IR was successful with 1.5 ± 2.9 packed cells transfused post-IR (1.0 ± 2.1 prophylactic vs 1.9 ± 3.3 therapeutic; p = 0.261). Additional surgical interventions were required in n = 5 patients (9.2%), n = 1 (4.2%) in the prophylactic vs. n = 4 (13.3%) in the therapeutic group. Complications were reported in n = 12 patients (22.2%), n = 2 (8.3%) prophylactic vs. n = 10 (33.3%) in therapeutic group. Mostly minor complications, as puncture site hematoma or bleeding, were reported in n = 4 (7.4%). Severe complications as necrosis and metabolic complications were reported in n = 2 patients (3.9%). CONCLUSION: IR for prevention and treatment of PPH was highly successful and associated with minor complications.

Burden and outcomes of postpartum haemorrhage in Nigerian referral-level hospitals.

OBJECTIVE: To determine the prevalence of primary postpartum haemorrhage (PPH), risk factors, and maternal and neonatal outcomes in a multicentre study across Nigeria. DESIGN: A secondary data analysis using a cross-sectional design. SETTING: Referral-level hospitals (48 public and six private facilities). POPULATION: Women admitted for birth between 1 September 2019 and 31 August 2020. METHODS: Data collected over a 1-year period from the Maternal and Perinatal Database for Quality, Equity and Dignity programme in Nigeria were analysed, stratified by mode of delivery (vaginal or caesarean), using a mixed-effects logistic regression model. MAIN OUTCOME MEASURES: Prevalence of PPH and maternal and neonatal outcomes. RESULTS: Of 68 754 women, 2169 (3.2%, 95% CI 3.07%-3.30%) had PPH, with a prevalence of 2.7% (95% CI 2.55%-2.85%) and 4.0% (95% CI 3.75%-4.25%) for vaginal and caesarean deliveries, respectively. Factors associated with PPH following vaginal delivery were: no formal education (aOR 2.2, 95% CI 1.8-2.6, P < 0.001); multiple pregnancy (aOR 2.7, 95% CI 2.1-3.5, P < 0.001); and antepartum haemorrhage (aOR 11.7, 95% CI 9.4-14.7, P < 0.001). Factors associated with PPH in a caesarean delivery were: maternal age of >35 years (aOR 1.7, 95% CI 1.5-2.0, P < 0.001); referral from informal setting (aOR 2.4, 95% CI 1.4-4.0, P = 0.002); and antepartum haemorrhage (aOR 3.7, 95% CI 2.8-4.7, P < 0.001). Maternal mortality occurred in 4.8% (104/2169) of deliveries overall, and in 8.5% (101/1182) of intensive care unit admissions. One-quarter of all infants were stillborn (570/2307), representing 23.9% (429/1796) of neonatal intensive care unit admissions. CONCLUSIONS: A PPH prevalence of 3.2% can be reduced with improved access to skilled birth attendants.

Cost analysis of care and blood transfusions in patients with Major Obstetric Haemorrhage in Ireland.

BACKGROUND AND OBJECTIVES: Obstetric haemorrhage is the leading cause of maternal morbidity and mortality worldwide. We aimed to estimate the economic cost of Major Obstetric Haemorrhage (MOH) and the cost of therapeutic blood components used in the management of MOH in Ireland. MATERIALS AND METHODS: We performed a nationwide cross-sectional study utilising top-down and bottom-up costing methods on women who experienced MOH during the years 2011-2013. Women with MOH were allocated to Diagnostic Related Groups (DRGs) based on the approach to MOH management (MOH group). The total number of blood components used for MOH treatment and the corresponding costs were recorded. A control group representative of a MOH-free maternity population was designed with predicted costs. All costs were expressed in Euro (€) using 2022 prices and the incremental cost of MOH to maternity costs was calculated. Cost contributions are expressed as percentages from the estimated total cost. RESULTS: A total of 447 MOH cases were suitable for sorting into DRGs. The estimated total cost of managing women who experienced MOH is approximately €3.2 million. The incremental cost of MOH is estimated as €1.87 million. The estimated total cost of blood components used in MOH management was €1.08 million and was based on an estimated total of 3997 products transfused. Red blood cell transfusions accounted for the highest contribution (20.22%) to MOH total cost estimates compared to other blood components. CONCLUSIONS: The total cost of caring for women with MOH in Ireland was approximately €3.2 million with blood component transfusions accounting for between one third and one half of the cost.

Defining 'obstetric haemorrhage': Blood loss volume and severe morbidity.

AIMS AND OBJECTIVES: Our goal is to describe the association between total quantitative blood loss (QBL) and risk of obstetric haemorrhage-related morbidity (OBH-M) to assess the utility of the current definition of obstetric haemorrhage (OBH). METHODS: This was a retrospective cohort study completed of all patients who had a live delivery at the only urban safety-net hospital over a 2-year period from 2018 to 2019. We categorized deliveries into 10 equally sized deciles based on QBL and compared the proportion with OBH-M in each. Among the two deciles with the highest proportions of OBH-M, we stratified deliveries into seven groups of ascending intervals of 250cc QBL. Finally, we compared the positive predictive value (PPV) of the standard definition of OBH (QBL ≥ 1000cc) to a definition extrapolated from our stratified analysis. The primary outcome was proportion of deliveries within each QBL decile affected by OBH-M. The secondary outcome was PPV. RESULTS: We found a significant increase in OBH-M from decile 9 (895-1201cc QBL) to decile 10 (1205-8325cc QBL) (p < 0.001). In our stratified analysis, we found QBL of 1500cc to be an inflection point for an increased proportion of OBH-M. Our secondary analysis showed an increased PPV for OBH-M using QBL of 1500cc (20.5%) compared with that of QBL 1000cc (9.8%). CONCLUSIONS: Our findings suggest that a higher QBL threshold than the currently accepted definition of OBH is more predictive of OBH-M.

Concentration-effect relationship for tranexamic acid inhibition of tissue plasminogen activator-induced fibrinolysis in vitro using the viscoelastic ClotPro® TPA-test.

BACKGROUND: Tranexamic acid is an antifibrinolytic drug that is commonly administered for obstetric haemorrhage. Conventional viscoelastic tests are not sensitive to tranexamic acid, but the novel ClotPro® TPA-test can measure tranexamic acid-induced inhibition of fibrinolysis. We aimed to evaluate the TPA-test in pregnant and non-pregnant women. METHODS: We performed an in vitro study of whole blood samples spiked with tranexamic acid from pregnant women in the first, second, and third trimester (n=20 per group) and from non-pregnant women (n=20). We performed ClotPro TPA-tests of whole blood sample and ClotPro EX-tests, FIB-tests, and TPA-tests. RESULTS: Clot lysis was inhibited in a concentration-dependent manner up to a tranexamic acid concentration of 6.25 mg L-1. At tranexamic acid concentrations of 12.5 mg L-1 and above, clot lysis was completely inhibited. The concentration-effect relationship of tranexamic acid did not differ in a clinically important manner in blood from pregnant women across all three trimesters or from non-pregnant controls. A median maximum lysis cut-off value of at9 least 16% (25-75th percentiles 15-18), a median clot lysis time of 3600 s (25-75th percentiles 3600-3600), or both was associated with a tranexamic acid concentration of least 12.5 mg L-1. CONCLUSIONS: The ClotPro® TPA-test is sensitive in detecting inhibition of fibrinolysis by tranexamic acid in whole blood samples of pregnant and non-pregnant women. The concentration-effect relationship of tranexamic acid to inhibit fibrinolysis in whole blood did not differ for women in the first, second, and third trimester or for non-pregnant women.

Role of disruptions in O RhD negative donations in Colombia on increasing maternal mortality ratio from haemorrhage.

OBJECTIVE: The aim of this work was to evaluate the relationship of the maternal mortality ratio due to obstetric haemorrhage (MMROH) with the national blood donations, particularly O RhD negative (Oneg) before and during COVID-19 pandemic. BACKGROUND: The maternal mortality ratio is increasing in Colombia, yet little is known regarding the relationship between blood donations and maternal mortality due to obstetric haemorrhage. MATERIALS AND METHODS: A retrospective cross-sectional study between January 1, 2018, and December 31, 2021, was performed, to assess MMROH compared to the blood donations notified to the Colombian National Haemovigilance System, through non-parametric methods. Because a relationship between blood donations and MMROH was identified, the analysis was expanded from 2009 to 2017. RESULTS: In 2020, Colombia increased the MMROH by 32% compared to 2019 which coincided with the lockdown period to contain COVID-19. An inversed relationship (SumD2 = 631.0; rs = -0.7335; p 0.01) between blood donations, particularly Oneg (SumD2 = 652.0; rs = -0.7912; p 0.002) and MMROH was identified. For the years 2015-2019 and 2021, the annual mean MMROH was 8.5 ± 0.5 per 100 000 live births when the annual mean blood donations was 18.2 ± 0.4 donations per 1000 people and the Oneg was 1.0 ± 0.0 donations per 1000 people. In contrast, the years 2009-2014 and 2020 displayed an annual MMROH of 12.6 ± 0.8, when the annual collection of blood was 16.4 ± 0.8 donations and the Oneg was 0.9 ± 0.0, p < 0.001. CONCLUSION: There was an inverse relationship between blood donation, mainly Oneg, and maternal mortality from obstetric haemorrhage. However, we recognise these deaths could be related to other reasons, especially when they occurred in rural areas with limited access to medical services.

The impact of a blended multidisciplinary training for the management of obstetric haemorrhage in Mbeya, Tanzania.

Background: The Maternal Mortality Rate (MMR) in Tanzania is 78 times higher than that of the UK. Obstetric haemorrhage accounts for two-thirds of these deaths in Mbeya, Tanzania. A lack of healthcare providers' (HCPs') competencies has been the key attribute. This study measured the impact on HCP's competencies from a blended training programme on obstetric haemorrhage. Methods: A "before and after" cohort study was undertaken with HCPs in 4 hospitals in the Mbeya region of Tanzania between August 2021 and April 2022. A multidisciplinary cohort of 34 HCPs (doctors, nurses, midwives, anaesthetists and radiologists) were enrolled on a blended face-to-face and virtual training course. The training was delivered by a multidisciplinary team (MDT) from London, UK, assisted by local multidisciplinary trainers from Mbeya, Tanzania and covered anaesthetic, obstetrics, haematology and sonographic use. Results: There were 33 HCP in the cohort of trainees where 30/33 (90.9%) of HCPs improved their Anaesthesia skills with a mean score improvement of 26% i.e., 0.26 (-0.009 -0.50), 23 HCPs (69.7%) improved obstetric skills 18% i.e., 0.18 (-0.16 to 0.50), 19 (57.6%), (57.6%) improved competences in Haematology 15%.i.e., 0.15 (-0.33 to 0.87), 20 out of 29 HCPs with ultrasound access (68.8%) improved Sonographic skills 13%.i.e., 0.13 (-0.31 to 0.54). All 33 HCPs (100%) presented a combined change with the mean score improvement of difference of 25% i.e., 0.25 (0.05-0.66). The deaths attributed to obstetric haemorrhage, the mortality rate declined from 76/100,000 to 21/100,000 live births. Actual number of deaths due to obstetric haemorrhage declined from 8 before training to 3 after the completion of the training. Conclusion: This comprehensive blended training on anaesthetic surgical, haematological, and sonographic management of obstetric haemorrhage delivers a significant positive impact on the detection, management and outcomes of obstetric haemorrhage.

Use of super resolution reconstruction MRI for surgical planning in Placenta accreta spectrum disorder: Case series.

INTRODUCTION: Comprehensive imaging using ultrasound and MRI of placenta accreta spectrum (PAS) aims to prevent catastrophic haemorrhage and maternal death. Standard MRI of the placenta is limited by between-slice motion which can be mitigated by super-resolution reconstruction (SRR) MRI. We applied SRR in suspected PAS cases to determine its ability to enhance anatomical placental assessment and predict adverse maternal outcome. METHODS: Suspected PAS patients (n = 22) underwent MRI at a gestational age (weeks + days) of (32+3±3+2, range (27+1-38+6)). SRR of the placental-myometrial-bladder interface involving rigid motion correction of acquired MRI slices combined with robust outlier detection to reconstruct an isotropic high-resolution volume, was achieved in twelve. 2D MRI or SRR images alone, and paired data were assessed by four radiologists in three review rounds. All radiologists were blinded to results of the ultrasound, original MR image reports, case outcomes, and PAS diagnosis. A Random Forest Classification model was used to highlight the most predictive pathological MRI markers for major obstetric haemorrhage (MOH), bladder adherence (BA), and placental attachment depth (PAD). RESULTS: At delivery, four patients had placenta praevia with no abnormal attachment, two were clinically diagnosed with PAS, and six had histopathological PAS confirmation. Pathological MRI markers (T2-dark intraplacental bands, and loss of retroplacental T2-hypointense line) predicting MOH were more visible using SRR imaging (accuracy 0.73), in comparison to 2D MRI or paired imaging. Bladder wall interruption, predicting BA, was only easily detected by paired imaging (accuracy 0.72). Better detection of certain pathological markers predicting PAD was found using 2D MRI (placental bulge and myometrial thinning (accuracy 0.81)), and SRR (loss of retroplacental T2-hypointense line (accuracy 0.82)). DISCUSSION: The addition of SRR to 2D MRI potentially improved anatomical assessment of certain pathological MRI markers of abnormal placentation that predict maternal morbidity which may benefit surgical planning.

Exploring the role of ex vivo metabolism on blood and plasma measurements of oxytocin among women in the third stage of labour: A post hoc study.

AIMS: To examine the role of ex vivo oxytocin metabolism in post-dose peptide measurements. METHODS: The stability of oxytocin (Study 1) and oxytocinase activity (Study 2) in late-stage pregnancy blood was quantified using liquid-chromatography tandem mass-spectrometry (LC-MS/MS) and a fluorogenic assay, respectively. Analyses were conducted using blood from pregnant women (>36 weeks gestation) evaluated in lithium heparin (LH), ethylenediaminetetraacetic acid (EDTA) and BD P100 blood collection tubes with or without protease inhibitors. In addition, plasma oxytocin concentrations following administration of oxytocin 240 IU inhaled, 5 IU intravenous or 10 IU intramuscular in women in third stage of labour (TSL) were analysed using enzyme-linked immunosorbent assay (ELISA) and LC-MS/MS to understand how quantified peptide concentrations differ between these analytical methods (Study 3). RESULTS: Study 1: Oxytocin was stable in blood collected into EDTA tubes with or without protease inhibitors but not in LH tubes. Study 2: Blood collected into all EDTA-containing collection tubes led to near-complete inhibition of oxytocinase (≤100 min). In plasma, a 35% reduction in oxytocinase activity was observed in LH tubes with EDTA added. In plasma from late-stage pregnancy compared to nonpregnant participants, the oxytocinase activity was approximately 11-fold higher. Study 3: Plasma oxytocin concentrations from nonpregnant or women in TSL following exogenous oxytocin administration were ≤33 times higher when analysed using ELISA vs. LC-MS/MS methods. CONCLUSIONS: Collection of blood from late-stage pregnant women into tubes containing EDTA inhibits oxytocinase effectively stabilizing oxytocin, suggesting low concentrations of oxytocin after dose administration reflect rapid in vivo metabolism.

Pharmacokinetics and safety of inhaled oxytocin compared with intramuscular oxytocin in women in the third stage of labour: A randomized open-label study.

AIMS: To compare pharmacokinetics (PK) and safety of heat-stable inhaled (IH) oxytocin with intramuscular (IM) oxytocin in women in third stage of labour (TSL), the primary endpoint being PK profiles of oxytocin IH and secondary endpoint of safety. METHODS: A phase 1, randomized, cross-over study was undertaken in 2 UK and 1 Australian centres. Subjects were recruited into 2 groups: Group 1, women in TSL; Group 2, nonpregnant women of childbearing potential (Cohort A, combined oral contraception; Cohort B, nonhormonal contraception). Participants were randomized 1:1 to: Group 1, oxytocin 10 IU (17 µg) IM or oxytocin 240 IU (400 µg) IH immediately after delivery; Group 2, oxytocin 5 IU (8.5 µg) intravenously and oxytocin 240 IU (400 µg) IH at 2 separate dosing sessions. RESULTS: Participants were recruited between 23 November 2016 to 4 March 2019. In Group 1, 17 participants were randomized; received either IH (n = 9) or IM (n = 8) oxytocin. After IH and IM administration, most plasma oxytocin concentrations were below quantification limits (2 pg/mL). In Group 2 (n = 14), oxytocin IH concentrations remained quantifiable ≤3 h postdose. Adverse events were reported in both groups, with no deaths reported: Group 1, IH n = 3 (33%) and IM n = 2 (25%); Group 2, n = 14 (100%). CONCLUSION: Safety profiles of oxytocin IH and IM were similar. However, PK profiles could not be established for oxytocin IH or IM in women in TSL, despite using a highly sensitive and specific assay.

Changes in practice and management of placenta accreta spectrum disorder: A 20-year retrospective cohort study.

BACKGROUND: Placenta accreta spectrum disorder is an increasingly prevalent cause of maternal morbidity in developed countries. AIMS: This study aimed to review the management and outcomes of cases of placenta accreta spectrum, and compare blood loss and blood transfusion rates, over time after an institutional change in planned primary surgeon from gynaecological oncologists to experienced obstetricians. METHODS: This retrospective cohort study included all cases of suspected or confirmed placenta accreta spectrum disorder (PASD) between 1999 and 2021 at Monash Health. Data were collected by reviewing medical records to obtain baseline characteristics, details of surgical planning and management and major maternal morbidity outcomes over a 20-year period. The primary surgical lead was recorded as either gynaecological oncologist or experienced obstetricians. The primary outcomes were estimated maternal blood loss and number of units of blood transfused. RESULTS: A total of 88 patients were identified: 43 between 1999 and 2015 where gynaecological oncologists were the primary surgeon in 79% of cases and 45 between 2016 and 2021 where experienced obstetricians were the primary surgeon in 73.3% of cases. There was no statistically significant difference in the estimated blood loss between the two time periods (median: 2000 vs 2500 mL, P = 0.669). Hysterectomy rates were significantly reduced in the second time period, from 100 to 73.3%, P < 0.001. CONCLUSION: Management of cases of PASDs has improved over time with changes in antenatal diagnosis and perioperative management, and management by experienced obstetricians has similar maternal outcomes compared to those whose management includes the presence of gynaecological oncologists.

Incidence and risk factors for severe postpartum haemorrhage in women with anterior low-lying or praevia placenta and prior caesarean: Prospective population-based study.

OBJECTIVE: To assess the incidence and risk factors for severe postpartum haemorrhage (PPH) in women with an anterior low-lying or praevia placenta, prior caesarean and no prenatal suspicion of placenta accreta spectrum (PAS). DESIGN: Population-based study in 176 maternity units in France. POPULATION: All women with anterior low-lying (0-19 mm from the cervical internal os) or praevia placenta, diagnosed prospectively before birth, prior caesarean and no prenatal suspicion of PAS. METHODS: Multivariable logistic regression to identify risk factors for severe PPH in the main population and after exclusion of women with PAS diagnosed only at birth. MAIN OUTCOME MEASURES: Severe PPH defined by a composite criterion either estimated blood loss of ≥1500 ml, transfusion of ≥4 or more units of packed red blood cells, embolisation or surgical treatment. RESULTS: Of the 520 114 women constituting the source population, 230 (0.44/1000 women; 95% confidence interval [CI] 0.38-0.50) met the inclusion criteria. Severe PPH rate was 24.8% (95% CI 19.2-30.4) overall, 27.5% (95% CI 21.8-33.3) in women with placenta praevia and 15.4% (95% CI 10.7-20.0) in women with low-lying placenta. PAS was diagnosed at birth in 22 women (9.9%; 95% CI 5.8-13.4), although previously unsuspected. After their exclusion, severe PPH incidence was 17.3% (95% CI 12.4-22.2). In multivariate analysis, the only factor associated with a higher severe PPH risk was placenta previa (aOR, 3.65; 95%CI, 1.20-15.8). CONCLUSION: Severe PPH is frequent among women with anterior low-lying or praevia placenta and prior caesarean, even after exclusion of women with PAS. The risk of severe PPH for those with praevia is nearly twice that with low-lying placenta.

Postpartum haemorrhage in high-resource settings: Variations in clinical management and future research directions based on a comparative study of national guidelines.

OBJECTIVE: To compare guidelines from eight high-income countries on prevention and management of postpartum haemorrhage (PPH), with a particular focus on severe PPH. DESIGN: Comparative study. SETTING: High-resource countries. POPULATION: Women with PPH. METHODS: Systematic comparison of guidance on PPH from eight high-income countries. MAIN OUTCOME MEASURES: Definition of PPH, prophylactic management, measurement of blood loss, initial PPH-management, second-line uterotonics, non-pharmacological management, resuscitation/transfusion management, organisation of care, quality/methodological rigour. CONCLUSIONS: Our study highlights areas where strong evidence is lacking. There is need for a universal definition of (severe) PPH. Consensus is required on how and when to quantify blood loss to identify PPH promptly. Future research may focus on timing and sequence of second-line uterotonics and non-pharmacological interventions and how these impact maternal outcome. Until more data are available, different transfusion strategies will be applied. The use of clear transfusion-protocols are nonetheless recommended to reduce delays in initiation. There is a need for a collaborative effort to develop standardised, evidence-based PPH guidelines. RESULTS: Definitions of (severe) PPH varied as to the applied cut-off of blood loss and incorporation of clinical parameters. Dose and mode of administration of prophylactic uterotonics and methods of blood loss measurement were heterogeneous. Recommendations on second-line uterotonics differed as to type and dose. Obstetric management diverged particularly regarding procedures for uterine atony. Recommendations on transfusion approaches varied with different thresholds for blood transfusion and supplementation of haemostatic agents. Quality of guidelines varied considerably.

Severe maternal morbidity trends over 20 years in a tertiary referral stand-alone maternity unit.

OBJECTIVE: Severe maternal morbidity (SMM) is a better indicator of quality of care than maternal mortality, which is a rare event. Risk factors such as advanced maternal age, caesarean section (CS) and obesity are increasing. The aim of this study was to examine the rate and trends in SMM at our hospital over a 20-year period. STUDY DESIGN: Retrospective review was performed of cases of SMM from January 1st 2000 to December 31st 2019. Yearly rates for SMM and Major Obstetric Haemorrhage (MOH) were calculated (per 1000 maternities) and linear regression analysis was used to model the trends over time. Average SMM and MOH rates were also calculated for the periods 2000-2009 and 2010-2019 and compared using a chi-square test. The patient demographics of the SMM group were compared to the background population delivered at our hospital using a chi-square test. RESULTS: 702 women with SMM were identified out of 162,462 maternities over the study period yielding an incidence of 4.3 per 1000 maternities. When the two time periods (2000-2009 and 2010-2019) are compared, the rate of SMM increased 2.4 vs 6.2 (p < 0.001), largely due to an increase in MOH 1.72 vs 3.86 (p < 0.001) and pulmonary embolus (PE) also increased 0.2 vs 0.5 (p = 0.012). Intensive-care unit (ICU) transfer rates more than doubled 0.19 vs 0.44 (p = 0.006). Eclampsia rates decreased 0.3 vs 0.1 (p = 0.047) but the rate of peripartum hysterectomy 0.39 vs 0.38 (p = 0.495), uterine rupture 0.16 vs 0.14 (p = 0.867), cardiac arrest (0.04 vs 0.04) and cerebrovascular accidents (CVA) (0.04 vs 0.04) remained unchanged. Maternal age > 40 years 9.7% vs 5% (p = 0.005), previous CS 25.7% vs 14.4%; p < 0.001 and multiple pregnancy 8 vs 3.6% (p = 0.002) were more prevalent in the SMM cohort compared to the hospital population. CONCLUSIONS: Overall, rates of SMM have increased threefold and transfer for ICU care has doubled over 20 years in our unit. The main driver is MOH. The rate of eclampsia has decreased and peripartum hysterectomy, uterine rupture, CVA and cardiac arrest remain unchanged. Advanced maternal age, previous caesarean delivery and multiple pregnancy were more prevalent in the SMM cohort compared to the background population.

Testing equivalence of two doses of intravenous iron to treat iron deficiency in pregnancy: A randomised controlled trial.

OBJECTIVE: To test the equivalence of two doses of intravenous iron (ferric carboxymaltose) in pregnancy. DESIGN: Parallel, two-arm equivalence randomised controlled trial with an equivalence margin of 5%. SETTING: Single centre in Australia. POPULATION: 278 pregnant women with iron deficiency. METHODS: Participants received either 500 mg (n = 152) or 1000 mg (n = 126) of intravenous ferric carboxymaltose in the second or third trimester. MAIN OUTCOME MEASURES: The proportion of participants requiring additional intravenous iron (500 mg) to achieve and maintain ferritin >30 microg/L (diagnostic threshold for iron deficiency) at 4 weeks post-infusion, and at 6 weeks, and 3-, 6- and 12-months postpartum. Secondary endpoints included repeat infusion rate, iron status, birth and safety outcomes. RESULTS: The two doses were not equivalent within a 5% margin at any time point. At 4 weeks post infusion, 26/73 (36%) participants required a repeat infusion in the 500-mg group compared with 5/67 (8%) in the 1000-mg group: difference in proportions, 0.283 (95% confidence interval [CI] 0.177-0.389). Overall, participants in the 500-mg arm received twice the repeat infusion rate (0.81 [SD = 0.824] versus 0.40 [SD = 0.69], rate ratio 2.05, 95% CI 1.45-2.91). CONCLUSIONS: Administration of 1000 mg ferric carboxymaltose in pregnancy maintains iron stores and reduces the need for repeat infusions. A 500- mg dose requires ongoing monitoring to ensure adequate iron stores are reached and sustained.

Maternal body weight and estimated circulating blood volume: a review and practical nonlinear approach.

Postpartum haemorrhage continues to be a leading cause of morbidity and mortality in the obstetric population worldwide, especially in patients at extremes of body weight. Quantification of blood loss has been considered extensively in the literature. However, these volumes must be contextualised to appreciate the consequences of blood loss for individual parturients. Knowledge of a patient's peripartum circulating blood volume is essential to allow accurate interpretation of the significance of haemorrhage and appropriate resuscitation. Greater body weight in obesity can lead to overestimation of blood volume, resulting in inappropriately high thresholds for blood product transfusion and delays in treatment. The most recent Mothers and Babies: Reducing Risk through Audits and Confidential Enquiries across the UK (MBRRACE-UK) surveillance report demonstrated the risk to this population, with more than half of all maternal mortality recorded in parturients who were either overweight or obese. Current linear calculations used to estimate circulating blood volumes based on patients' weights could be contributing to this phenomenon, as blood volume increases at a disproportional rate to body composition. In this review, we summarise the relevant physiology and explore the existing literature on the estimation of circulating blood volume, both during pregnancy and in obesity. Building on key works and principal findings, we present a practical, nonlinear approach to the adjustment of estimated blood volume with increasing body mass. This clinical tool aims to reduce the clinical bias influencing the management of obstetric haemorrhage in a population already at increased risk of morbidity and mortality. Discussion of the limitations of this approach and the call for further research within this field completes this review.

Emergencies in obstetric anaesthesia: a narrative review.

We conducted a narrative review in six areas of obstetric emergencies: category-1 caesarean section; difficult and failed airway; massive obstetric haemorrhage; hypertensive crisis; emergencies related to neuraxial anaesthesia; and maternal cardiac arrest. These areas represent significant research published within the last five years, with emphasis on large multicentre randomised trials, national or international practice guidelines and recommendations from major professional societies. Key topics discussed: prevention and management of failed neuraxial technique; role of high-flow nasal oxygenation and choice of neuromuscular drug in obstetric patients; prevention of accidental awareness during general anaesthesia; management of the difficult and failed obstetric airway; current perspectives on the use of tranexamic acid, fibrinogen concentrate and cell salvage; guidance on neuraxial placement in a thrombocytopenic obstetric patient; management of neuraxial drug errors, local anaesthetic systemic toxicity and unusually prolonged neuraxial block regression; and extracorporeal membrane oxygenation use in maternal cardiac arrest.