Study design and setting
This was a retrospective observational study with a study period of 104 months from 1 April 2011 to 31 December 2019. The Trauma and Acute Critical Care Center of Osaka University Hospital, which is located in the northern part of Osaka Prefecture, Japan, annually treats about 1000 patients with conditions such as shock, cardiopulmonary arrest, severe trauma, and sepsis. The Center also treats critically ill patients with postpartum haemorrhage in cooperation with obstetricians and gynaecologists. This study included the patients who suffered haemorrhage in the postpartum period and were treated at this institution. On the basis of the diagnosis at hospital admission, we defined the patients with bleeding during the postpartum period as patients with postpartum haemorrhage. Patients experiencing bleeding due to miscarriage were excluded from the study, as were patients with eclampsia and HELLP (haemolysis, elevated liver enzymes, and low platelets) syndrome without postpartum haemorrhage. We also excluded patients who did not undergo CT scanning, were not admitted to the ICU, and were not initially treated by emergency physicians. This manuscript was written based on the STROBE statement to assess the reporting of cohort and cross-sectional studies . This study was approved by the institutional review board of Osaka University (approval no. 19509). Consent from individual patients was obtained comprehensively on admission.
Obstetric & Gynecologic Cooperative System in Osaka prefecture
In Japan, there are three levels of perinatal care depending on the risk of pregnancy and delivery . Low-risk pregnancies and deliveries are managed in small hospitals and clinics, whereas pregnancies and deliveries with moderate risk, such as emergency or abnormal deliveries and caesarean sections, are managed in regional perinatal medical centres (292 facilities in Japan) that can provide emergency deliveries, caesarean section, and intensive care management for the mothers and new-borns. High-risk pregnancies and deliveries and infants requiring neonatal intensive care are managed at general perinatal medical centres (104 facilities in Japan) that are equipped with maternal-foetal intensive care units and neonatal intensive care units and can provide intensive care for the mothers, foetuses, and new-borns. In Japan, there is a system for referral and transport to higher-level medical facilities according to changes in the risk of pregnancy and delivery throughout the course of the pregnancy. In addition, the Obstetric & Gynecologic Cooperative System (OGCS) for pregnant women and the Neonatal Mutual Cooperative System for new-borns have been established in Osaka prefecture . When emergency maternal events due to obstetric diseases such as massive bleeding and eclampsia, pulmonary embolism or complications related to obstetric anaesthesia occur, the OGCS allows obstetricians and gynaecologists to directly contact the obstetricians and gynaecologists at the higher-care facility for smooth transport. If serious complications such as placental abruption or severe postpartum haemorrhage occur in small hospitals and clinics, these patients can be transported to higher-level medical facilities through the OGCS for appropriate treatment. Osaka Prefecture has 17 regional perinatal medical centres and 6 general perinatal medical centres, and 34 facilities including 23 of these were registered in the OGCS. Because the most seriously ill pregnant women suffering a traffic accident, cerebral haemorrhage, or cardiopulmonary arrest cannot be adequately treated in normal medical facilities, they are transported to a hospital that has not only an emergency care centre but also a general or regional perinatal medical centre (7 facilities in Osaka Prefecture) for intensive care. Our hospital is designated as one of these institutions.
Management of postpartum haemorrhage at Osaka University Hospital
All critical obstetric patients transported to the Trauma and Acute Critical Care Centre are handled by emergency physicians, obstetricians, and gynaecologists who work together to treat them. The obstetricians and gynaecologists receive the request for patient transfer through the OGCS, and then they notify emergency physicians, anaesthesiologists, and radiologists about the critical obstetric patients being transferred to our hospital. When a woman is transported to our critical care centre, emergency physicians resuscitate her with treatments such as blood transfusion and circulation management. At the same time, the obstetricians and gynaecologists search for a cause by examination of the genital tract and ultrasonography; tone, tissue, trauma and thrombin and stop postpartum haemorrhage with manual compression of the uterus and balloon compressions. If the vital signs are stabilized and the active bleeding disappears after these procedures, CT scanning is not performed. When the vital signs are not stabilized, active bleeding is observed, or ultrasonography shows bleeding, CT scanning should be performed.
Our emergency room includes an emergency care room equipped with a computed tomography (CT) table as a treatment bed. Because patients are treated on the CT table, it is possible to perform the entire process from diagnosis to treatment, including resuscitation, without moving them . All examinations were performed using a single-source, 64-row helical scanner (SOMATOM Definition Flash, Siemens Healthineers®, Germany) with a slice thickness of 5 mm and a reconstruction interval of 5 mm during a single breath-hold. In the protocol for CE-CT scanning for postpartum haemorrhage, we use 95 mL of iohexol (Ioberin®) at an infusion rate of 4 mL/sec and the usual scanning time was 13–14 s. The area from the inferior margin of the sternum to the pelvic floor is examined in two phases of arterial and venous imaging. An Artis Q ceiling-mounted system (Siemens Healthineers®) was used for angiography.
The primary endpoint was the presence of arterial bleeding. We defined extravasation on angiography as arterial bleeding in this study. The secondary endpoint was discharge to death.
Continuous variables are indicated by medians (interquartile range [IQR]), and categorical variables are indicated by frequencies and percentages. The shock index (SI), serum lactate level, and blood loss within 24 h were used as indicators of the severity of the patients on hospital admission. The causes of postpartum haemorrhage were classified into four categories: Tone, Trauma, Tissue and Thrombin . We classified atonic postpartum haemorrhage as Tone; uterine rupture, uterine inversion, cervical and vaginal lacerations, retained placenta and perineal lacerations as Trauma; placenta accreta and placenta previa as Tissue; and disseminated intravascular coagulation and amniotic fluid embolism as Thrombin. We calculated the sensitivity, specificity and positive and negative predictive values of CE-CT scanning to detect arterial bleeding to determine the accuracy of CE-CT scanning to identify the source of arterial bleeding in patients with postpartum haemorrhage. The presence of arterial extravasation on CE-CT scanning was evaluated by two independent radiologists. In addition, we performed subgroup analysis according to the patients’ SI. The accuracy of CE-CT scanning to detect arterial bleeding was similarly calculated by dividing the patients into two groups: those with SI of less than 1 and those with SI of 1 or more. The Mann-Whitney U test was used to test the continuous variables, and the Fisher exact test was used to test the nominal variables. All analyses were performed using JMP 15 (SAS Institute Inc., Cary, NC, USA).