Value of pelvic embolization in the management of severe postpartum hemorrhage due to placenta accreta, increta or percreta

Embolization of the hypogastric artery after surgical ligation: A case series of two patients

INTRODUCTION

The increasing incidence of obstetric complications, such as post-partum hemorrhage in the case of placenta accreta spectrum, calls for innovative and adapted therapeutic approaches. This presentation highlights the effectiveness of arterial embolization of the hypogastric artery, properly known as the internal iliac artery, in managing obstetric bleeding, even after initial surgical ligation. An approach never described in the literature.

PRESENATION OF CASES

1st Case: A 38-year-old patient, in her fourth pregnancy with two previous caesarean sections, was admitted for moderate metrorrhagia at 19 weeks gestation. Ultrasound showed a monofetal pregnancy at 17 WG with a 6 cm placental abruption and an anterior placenta with accretion signs. An emergency subtotal hysterectomy with triple Tsirulsikov arterial ligation was performed after transfusion. Due to persistent bleeding, bilateral hypogastric artery ligation and abdominal packing were added, but without improvement. The patient was referred for embolization after hemodynamic stabilization. The procedure was carried out successfully and no complications were reported. 2nd Case: A 35-year-old patient with vaginal bleeding from placenta accreta at 25 WG required hemostasis hysterectomy. Despite the procedure, bleeding continued, leading to bilateral hypogastric artery ligation and pelvic packing. The patient was hemodynamically stabilized and transferred for hypogastric artery ligation, which was successfully performed without complication.

DISCUSSION

The role of interventional radiology in managing postpartum hemorrhage (PPH) is well established, with substantial literature supporting the benefits of uterine artery embolization as a lifesaving and often uterine-sparing procedure in PPH. While its indication for prevention is well-known, what about post-operatively? Our experience indicates that consulting a radiologist specializing in pelvic embolization can yield satisfactory outcomes despite technical difficulties.

CONCLUSION

Embolization of the hypogastric arteries as well as embolization followed by surgical ligation of these arteries have been well described in the literature, the originality in our case reports is the embolization performed after surgical ligation which has not been described before according to our knowledge and which despite its technical difficulty can be a satisfactory alternative for the control of post-partum hemorrhage.

Clinical outcomes and future fertility after uterine artery embolization for postpartum and post-abortion hemorrhage

BACKGROUND

Postpartum hemorrhage (PPH) and post-abortion hemorrhage (PAH) are life-threatening conditions.

PURPOSE

To evaluate the efficacy and safety of uterine arterial embolization (UAE) for PPH and PAH and to investigate future fertility after UAE.

MATERIAL AND METHODS

This study included 57 consecutive patients (mean age = 34 years) who underwent UAE for PPH (n = 46) and PAH (n = 11) at our institution between January 2011 and December 2022. Technical success, non-visualization of the peripheral portion of bilateral uterine arteries on angiography, and clinical success, complete hemostasis after UAE, were assessed. UAE-associated complications and factors related to clinical success were analyzed. Pregnancy outcomes after UAE and complications during subsequent pregnancy were investigated in 16 patients who desired fertility and were followed up for >1 year.

RESULTS

The technical and clinical success rates were 100% and 84.2%, respectively. Sepsis (n = 1) and uterine empyema (n = 1) were observed as severe complications. Placental disorder, bleeding within 24 h after delivery or abortion, ≥1.5 shock index, ≥6 units of transfusion erythrocytes, and ≥8 obstetrical disseminated intravascular coagulation score were significantly associated with unfavorable clinical outcomes. In total, 16 pregnancies were observed in 12 patients after UAE, three of which were miscarriages and 13 were successful live births. During pregnancy, uterine rupture (n = 1) and accreta (n = 1) were observed.

CONCLUSION

UAE is an effective treatment for PPH and PAH. Although UAE could preserve future fertility, careful attention should be paid to perinatal management for unusual complications.

Placenta accreta spectrum with severe morbidity: fibrosis associated with cervical-trigonal invasion

OBJECTIVE

Describe the clinical-surgical results of patients with PAS in the low-posterior cervical-trigonal space associated with fibrosis (PAS type 4) compared with PAS types in other locations (Types 1, upper bladder, 2 in upper parametrium) and in particular with PAS type 3, corresponding to dissectible cervical-trigonal invasion. The clinical-surgical results of using a standard hysterectomy were analyzed with a modified subtotal hysterectomy (MSTH) in patients with PAS type 4.

MATERIAL AND METHODS

A descriptive, retrospective, multicenter study included 337 patients of PAS; thirty-two corresponding to PAS type 4, from three PAS reference hospitals, CEMIC, Buenos Aires, Argentina, Fundación Valle de Lili, Cali, Colombia, and Dr. Soetomo General Hospital, Surabaya, Indonesia, between January 2015 and December 2020. PAS was diagnosed by abdominal and transvaginal ultrasound and topographically characterized by ultrafast T2 weighted MRI. In persistent macroscopic hematuria after MSTH, the surgeon performs an intentional cystotomy and uses a square compression suture to achieve the hemostasis inside the bladder wall.According to a PAS topographical classification, the patients with low-vesical cervical involvement compared with PAS located in relation with the upper blader (type1), upper parametrium (type 2 upper), and also with PAS situated in the lower vesical-trigon space (type 3). PAS 3 and 4 are located in identical area, but in type 3, group A, the vesicouterine space was dissectible, and in type 4, group B, significant fibrosis made surgical dissection extremely challenging. Furthermore, group B was divided into patients treated with total hysterectomy (HT) and those treated with a modified subtotal hysterectomy (MSTH). The surgical requirements to perform an MSHT included the availability of proximal vascular control at the aortic level (internal manual aortic compression, aortic endovascular balloon, aortic loop, or aortic cross-clamping). Then surgeon performed an upper segmental hysterotomy, avoiding the abnormal placenta invasion area; after that, the fetus was delivered, and the umbilical cord was ligated.After uterine exteriorization, the surgeon applies a continuous circular suture with number 2 polyglactin 910, taking some portions of the myometrium -to avoid unintentional slipping- around the lower uterine segment and a 3-4 cm proximal to the abnormal adhesion of the placenta. After tightening hard the circular suture, the uterine segment was circumferentially cut, three centimeters proximal to the circular hemostatic sutures. Next, the surgery follows the upper steps of conventional hysterectomy without changes. Additionally, the histological presence of fibrosis was examined in all samples.

RESULTS

Modified subtotal hysterectomy in patients with PAS type 4 (cervical-trigonal fibrosis) resulted in a significant clínico-surgical improvement over total hysterectomy. The median operative time and intraoperative bleeding were 140 min (IQR 90--240) and 1895 mL (IQR 1300-2500) in patients undergoing modified subtotal hysterectomy, and 260 min (IQR 210-287) and 2900 mL (IQR 2150-5500) in patients treated with total hysterectomy, respectively. The complication rate was 20% for MSHT and 82.3% for patients with a total hysterectomy.

CONCLUSIONS

PAS in the cervical trigonal area associated with fibrosis implies a greater risk of complications due to uncontrollable bleeding and organ damage. MSTH is associated with lower morbidity and difficulties in PAS type 4. Prenatal or intrasurgical diagnosis is essential to plan surgical alternatives to improve the results.

Risk factors of MRI findings for predicting patient outcomes of placenta accreta spectrum and placenta previa after prophylactic balloon occlusion of the internal iliac artery

PURPOSE

Our study aimed to identify the risk factors of magnetic resonance imaging (MRI) findings for predicting patient outcomes of placenta accreta spectrum (PAS) and placenta previa after prophylactic balloon occlusion of the internal iliac artery (PBOIIA).

MATERIALS AND METHODS

This retrospective analysis was performed using the clinical records of 46 patients diagnosed with PAS and placenta previa who underwent PBOIIA during caesarean section (CS). The possible clinical risk factors for adverse maternal outcomes were evaluated by consulting patients' clinical records. The inclusion criteria for the massive bleeding group were as follows: estimated blood loss (EBL) > 2500 mL, packed red blood cell (pRBC) transfusion (>4 units), and need for hysterectomy or transcatheter arterial embolization after delivery. The MRI features were compared between the massive and non-massive bleeding groups.

RESULTS

Patients in the massive bleeding group (n = 22) had a significantly longer operation time (p < 0.001), more EBL (p < 0.001), more pRBC transfusions (p < 0.001), and a prolonged postoperative hospital stay (p < 0.05). MRI features showed a T2 dark bands, placenta bulge, and abnormal blood vessels in the placental bed more frequently in the massive bleeding group (p < 0.05). In the multiple logistic regression analysis, T2 dark bands (odds ratio 9.1, p = 0.048) and placental bulge (odds ratio 5.1, p = 0.014) remained statistically significant.

CONCLUSION

T2 dark bands and placental bulges observed on an MRI can predict adverse maternal outcomes in patients with PAS and placenta previa undergoing PBOIIA. If these findings are observed on a preoperative MRI, effective management strategies should be prepared for the possibility of massive hemorrhage during CS.

Angiographic features and transarterial embolization of retained placenta with abnormal vaginal bleeding

Objectives

To clarify characteristic angiographic features and clinical efficacy of selective transarterial embolization (TAE) of retained placenta with abnormal vaginal bleeding.

Methods

The study cohort comprised 22 patients (mean age, 33.5 years; range, 22–24 years) who underwent selective TAE for retained placenta with abnormal bleeding between January 2018 and December 2020 at our institution. Angiographic images were reviewed by two certified radiologists with consensus. Medical records were reviewed to evaluate the efficacy of TAE. Angiographic features of retained placenta, technical success (disappearance of abnormal findings on angiography), complications, clinical outcomes (hemostatic effects and recurrent bleeding) were evaluated.

Results

Pelvic angiography showed a dilated vascular channel mimicking arteriovenous fistulas or an aneurysm contiguous with dilated uterine arteries in the mid-arterial–capillary phase in 20 patients; it showed contrast brush in the remaining two patients. TAE technical success was achieved in all patients. No major complications were observed in any patients. Fifteen patients were followed up with expectant management after TAE; all but one patient showed no re-bleeding during the follow-up period (mean follow-up interval, 3.4 months; range, 1–17 months). One patient showed minor rebleeding, which resolved spontaneously. Seven patients underwent scheduled hysteroscopic resection within 1 week after TAE, and no excessive bleeding was observed during or after the surgical procedure in all seven patients.

Conclusions

The characteristic angiographic feature of retained placenta is “dilated vascular channel that mimic low flow AVM.” TAE is a safe and effective treatment to manage retained placenta with abnormal bleeding.

Uterine artery Embolization: Interventional Radiologist's Perspective in Management of Uncontrolled Obstetric Hemorrhage

Purpose

To study the efficacy and safety of uterine artery embolization in treatment of obstetric hemorrhage.

Methods

This ethically approved prospective study was conducted between November 2017 and October 2019, and written informed consent was obtained from all patients. Consecutive patients presenting with uncontrolled obstetric hemorrhage were evaluated. Fifty-three patients with uncontrolled bleeding underwent uterine artery embolization (UAE) and were followed up.

Results

Spectrum of patients encountered in this study was arteriovenous malformations (AVMs) (n = 25), retained products of conception (RPOC) (n = 16), RPOC with secondary AVMs (n = 5), ectopic pregnancy (n = 5) and iatrogenic trauma to cervix or vagina (n = 2). A total of 57 UAE procedures were performed in these 53 patients as repeat sessions were required in four patients. Most common embolic agent used was polyvinyl alcohol (PVA) particles with gelfoam followed by cyanoacrylate glue as second most common agent. Technical success was achieved in 57 (100%) of 57 UAE procedures. Primary clinical success was achieved in 49 (92%) of 53 patients and secondary clinical success in 52 (98%) patients. Clinical failure was observed in one patient who underwent hysterectomy.

Conclusion

Uterine artery embolization is a safe and effective procedure in the management of uncontrolled obstetric hemorrhage.

Endovascular uterine artery interventions

Percutaneous vascular embolization plays an important role in the management of various gynecologic and obstetric abnormalities. Transcatheter embolization is a minimally invasive alternative procedure to surgery with reduced morbidity and mortality, and preserves the patient's future fertility potential. The clinical indications for transcatheter embolization are much broader and include many benign gynecologic conditions, such as fibroid, adenomyosis, and arteriovenous malformations (AVMs), as well as intractable bleeding due to inoperable advanced-stage malignancies. The most well-known and well-studied indication is uterine fibroid embolization. Uterine artery embolization (UAE) may be performed to prevent or treat bleeding associated with various obstetric conditions, including postpartum hemorrhage (PPH), placental implantation abnormality, and ectopic pregnancy. Embolization of the uterine artery or the internal iliac artery also may be performed to control pelvic bleeding due to coagulopathy or iatrogenic injury. This article discusses these gynecologic and obstetric indications for transcatheter embolization and reviews procedural techniques and outcomes.

The clinical evaluation of preoperative abdominal aortic balloon occlusion for patients with placenta increta or percreta

OBJECTIVE

To evaluate the efficacy and safety of abdominal aortic balloon for pregnant women with placenta increta or percreta (PIP).

METHODS

Retrospective analysis of the parameters containing estimated blood loss, red cell suspension (RCS) transfusion volume, hysterectomy, surgery time, postoperative hospital days, neonatal status and complications between the two groups.

RESULTS

The patients with preoperative abdominal aortic balloon occlusion (AABO) had significant reduction in blood loss volume, red cell suspension transfusion volume and plasma transfusion volume compared to patients without balloon. Similarly, the surgery time and hysterectomy were obviously reduced in the AABO group. However, there were no difference in the Apgar scores and neonatal complications between the two groups, indicating that the abdominal aortic balloon has little adverse effect on the newborns.

CONCLUSION

AABO plays dramatic roles on reducing blood loss volume and blood transfusion volume and it is also a safe and effective technology providing new insight into the therapy of patient with PIP.

SYNOPSIS

Preoperative abdominal aortic balloon occlusion (AABO), as a new intravascular interventional therapy, is safe and effective in patients with placenta increta or percreta.

High-intensity focused ultrasound in management of placenta accreta spectrum: A systematic review

BACKGROUND

High-intensity focused ultrasound (HIFU) is a non-invasive procedure that has been studied in the management of placenta accreta spectrum (PAS).

OBJECTIVE

To appraise HIFU in the management of PAS and highlight the restrictions on converting uterus-preserving studies into evidence-based practice.

SEARCH STRATEGY

A search on Scopus, Cochrane, PubMed and Web of Science was conducted from date of inception to January 2020.

SELECTION CRITERIA

Studies on using HIFU in the management of PAS were eligible. Review articles, conference papers, and case reports were excluded.

DATA COLLECTION

A standardized sheet was used to abstract data from eligible studies. CON-PAS registry was used to include studies on other conservative modalities.

RESULTS

Four studies were eligible (399 patients). Average residual placental volume was 61.74 cm³ (6.01-339 cm³ ). Treatment was successful in all patients. Normal menstruation recovered after 48.8 days (15-150 days). No major complications were encountered. Sixty-one studies were retrieved from the CON-PAS registry; uterine artery embolization (23 studies), balloon placement (15 studies), compression sutures (10 studies), placenta in situ (7 studies), and uterine resection (6 studies) were successful in 83.7%, 92.9%, 87.9%, 85.2%, and 79.3% of cases, respectively.

CONCLUSIONS

HIFU may fit certain clinical situations in the management of PAS. A global research strategy is recommended to incorporate conservative approaches within a comprehensive management protocol.

Planned conservative management of placenta increta and percreta with prophylactic transcatheter arterial embolization and leaving placenta in situ for women who desire fertility preservation

INTRODUCTION

The objective of our study was to demonstrate planned conservative management of placenta increta and percreta in a single tertiary center.

METHODS

From April 2005 to July 2019, patients with placenta increta and percreta were managed conservatively at the Kaohsiung Chang Gung Memorial Hospital in Taiwan. The severity of placenta invasion was diagnosed by magnetic resonance imaging (MRI). After delivery of the neonate, prophylactic transcatheter arterial embolization (TAE) was performed immediately. The placenta was left in situ and prophylactic antibiotics were administered during hospitalization. The patient profiles, outcomes, and complications were retrospectively reviewed.

RESULTS

Based on the MRI findings, twenty-one patients with placenta increta or percreta were included. With prophylactic TAE, the mean surgical blood loss was 854.7 ± 478.2 mL. The mean natural resorption time of residual placenta was 4.69 ± 1.65 months. Regarding maternal complications, 4 patients (19%) had delayed postpartum hemorrhage (PPH), 12 patients (57.1%) developed postpartum infections, 3 patients (14.3%) progressed to sepsis, 4 patients (19%) underwent surgical evacuation, and 4 patients (19%) underwent hysterectomy. No maternal mortality was reported. Main neonatal complications were prematurity and respiratory distress. Regarding fertility, 16 (76.1%) patients had return of menstruation, and one (4.7%) had a subsequent pregnancy resulting in a live birth.

DISCUSSION

Planned conservative management with prophylactic TAE and leaving placenta in situ is feasible and safe for women with placenta increta or percreta who desire fertility preservation. Delayed PPH and postpartum infection are common complications after conservative treatment.

The role of interventional radiology in the management of abnormally invasive placenta: a systematic review of current evidences

Abnormally invasive placenta (AIP) is a potentially severe condition. To date, arterial embolization in women with postpartum hemorrhage due to AIP is the treatment option for which highest degrees of evidence are available. However, other techniques have been tested, including prophylactic catheter placement, balloon occlusion of the iliac arteries and abdominal aorta balloon occlusion. In this systematic review, we provide an overview of the currently reported interventional radiology procedures that are used for the treatment of postpartum hemorrhage due to AIP and suggest recommendations based on current evidences. Owing to a high rate of adverse events, prophylactic occlusion of internal iliac arteries should be used with caution and applied when the endpoint is hysterectomy. On the opposite, when a conservative management is considered to preserve future fertility, uterine artery embolization should be the preferred option as it is associated with a hysterectomy rate of 15.5% compared to 76.5% with prophylactic balloon occlusion of the internal iliac arteries and does not result in fetal irradiation. Limited data are available regarding the application of systematic prophylactic embolization and no comparative studies with arterial embolization are available.

Role of Interventional Procedures in Obstetrics and Gynecology

Radiological guided intervention techniques are discussed in obstetric and gynecologic patients. Fallopian tube recanalization, postpartum hemorrhage control, techniques of treating uterine leiomyomas, pelvic congestion treatment, and the use of percutaneous and transvaginal ultrasonography-guided aspirations and biopsy are covered. These techniques use basic radiological interventional skills and show how they are adapted for use in the female pelvis.

Long-term follow-up of abdominal aortic balloon occlusion for the treatment of pernicious placenta previa with placenta accreta

OBJECTIVE

To evaluate the efficacy and safety of balloon occlusion of the abdominal aorta for the treatment of pernicious placenta previa with placenta accreta.

METHODS

The clinical data of 623 patients with pernicious placenta previa combined with placenta accrete, who were admitted to our hospital from January 2013 to January 2019 were retrospectively analyzed. All patients underwent abdominal aortic balloon occlusion combined with cesarean section, and 78 patients underwent sequential bilateral uterine artery embolization. We analyzed the operation time, intraoperative blood loss, blood transfusion volume, intraoperative and postoperative complications, fetal radiation exposure time and dose, and the Apgar score of the newborns. We also performed other evaluations to ascertain the efficacy and safety of abdominal aortic balloon occlusion treatment for dangerous placenta previa with placenta accrete.

RESULTS

Of the 623 patients, 545 underwent only abdominal aortic balloon occlusion, and 78 underwent uterine artery embolization due to intraoperative or postoperative bleeding. The uterus was successfully preserved in all patients. Except for five cases of right lower extremity arterial thrombosis, the remaining patients did not have postoperative lower extremity arteriovenous thrombosis, renal insufficiency, late postpartum hemorrhage, ectopic embolism, spinal cord or peripheral nerve damage, pelvic infection, or other serious complications. The mean operative time was 65.3 (±14.5) min. The mean intraoperative blood loss was620 (±570) ml. Ninety-six patients (15.4%, 96/623) were treated with blood transfusion, and the average amount of blood transfused was 750 (±400) ml. The average number of hospitalization days was 6.8 (±3.4) days, the average time of fetal ray exposure was 5.2 (±1.6) s, and the average radiation dose was 4.1 (±2.7) mGy. The neonatal Apgar score, was 8.4 (±0.6) points at 1 ​min, and 9.6 (±0.4) points at 5 ​min. In the follow-up to May 31, 2019, 29 patients were lost to follow-up, 96 were lactating, and 498 were menstruating. Except for the cases lost to follow-up, the remaining 596 surviving newborns (including 2 twins) showed no abnormalities at the 42-day postnatal outpatient follow-up examination.

CONCLUSION

Balloon occlusion of the abdominal aorta is a safe and effective method for the treatment of pernicious placenta previa with placenta accreta.

Assessing the multidisciplinary team approaches to placenta accreta spectrum across five institutions within the University of California fetal Consortium (UCfC)

PURPOSE

To describe the multidisciplinary approaches to placenta accreta spectrum (PAS) across five tertiary care centers that comprise the University of California fetal Consortium (UCfC) and to identify potential best practices.

MATERIALS AND METHODS

Retrospective review of all cases of pathologically confirmed invasive placenta delivered from 2009 to 2014 at UCfC. Differences in intraoperative management and outcomes based on prenatal suspicion were compared. Interventions assessed included ureteral stent use, intravascular balloon use, anesthetic type, gynecologic oncology (Gyn Onc) involvement, and cell saver use. Intervention variation by institution was also assessed. Analyses were adjusted for final pathologic diagnosis. Chi-square, Fisher's exact, Student's t-test, and Mann-Whitney's U-test were used as appropriate. Binary logistic regression and multivariable linear regression were used to adjust for confounders.

RESULTS

One hundred and fifty-one cases of pathologically confirmed invasive placenta were identified, of which 82% (123) were suspected prenatally. There was no correlation between the degree of invasion on prenatal imaging and use of each intervention. Ureteral stents were placed in 33% (41) of cases and did not reduce GU injury. Intravascular balloons were placed in 29% (36) of cases and were associated with shorter OR time (161 versus 236 min, p < .01) and lower estimated blood loss (EBL) (1800 versus 2500 ml, p < .01). General endotracheal anesthesia (GETA) was used in 70% (86). EBL did not differ between GETA and regional anesthesia. Gyn Onc was involved in 58% (71) of cases and EBL adjusted for final pathology was reduced with their involvement (2200 versus 2250 ml, p = .02) while OR time and intraoperative complications did not differ. Cell saver was used in 20% (24) and was associated with longer OR time (296 versus 200 min, p < .01). Use of cell saver was not associated with a difference in EBL or number of units of packed red cells transfused. All analyses were adjusted for pathologic severity of invasion.

CONCLUSIONS

Intravascular interventions such as uterine artery balloons and the inclusion of Gynecologic Oncologists as part of a multidisciplinary approach to treating PAS reduce EBL. Additionally, the placement of intravascular balloons may reduce OR time. No significant differences were seen in outcomes when comparing the use of ureteral stents, general anesthesia, or institutions. A team of experienced operators with a standard approach may be more significant than specific practices.

Application of abdominal aortic balloon occlusion followed by uterine artery embolization for the treatment of pernicious placenta previa complicated with placenta accreta during cesarean section

OBJECTIVE

This study aimed to investigate the clinical effects of abdominal aortic balloon occlusion followed by uterine artery embolization for the treatment of pernicious placenta previa complicated with placenta accreta during cesarean section.

METHODS

We performed a retrospective analysis of the clinical data for 623 patients who experienced pernicious placenta previa complicated with placenta accreta and received treatment in our hospital from January 2013 to January 2019. All patients underwent abdominal aortic balloon occlusion before their cesarean section. Seventy-eight patients received bilateral uterine artery embolization, and among them, placenta accreta was found at the opening of the cervix in 13 patients. Due to suturing difficulty after the removal of the placenta, gauze packing was used to temporarily compress the hemorrhage. As soon as the uterus was sutured, emergent bilateral uterine artery embolization was performed. Active bleeding was noted in the remaining 65 patients when the lower part of the uterus was pressed after the placenta was removed and the uterus was sutured, therefor, bilateral uterine artery embolization was performed urgently.

RESULTS

Of the 623 patients, 545 patients underwent only abdominal aortic balloon occlusion and 78 patients underwent additional emergent bilateral uterine artery embolization due to hemorrhaging during or after their cesarean section. No hysterectomies were performed. In the 78 patients, the amount of bleeding was 800-3,200 ml with an average of 1,650 ml during the operation; the volume of blood transfused was 360-1,750 ml (average: 960 ml). The fetal fluoroscopy time was 3-8 s (average: 5 s). The dose of radiation exposure was (4.2 ± 2.9) mGy. Fetal appearance, pulse, grimace, activity, and respiration (Apgar) score were normal. No serious complications were observed during or after the operation in the follow-up visits. Conclusion: For patients with pernicious placenta previa complicated with placenta accreta who experience active bleeding after cesarean section and abdominal aortic balloon occlusion, bilateral uterine artery embolization can effectively reduce blood loss and requirement of blood transfusion during the operation, and lowers the risk of hysterectomy.

The efficacy of pelvic arterial embolisation for the treatment in massive vaginal haemorrhage in obstetric and gynaecological emergencies: a single-centre experience

This study aimed to identify the role, efficacy and safety of pelvic arterial embolisation (PAE) in the management of massive vaginal haemorrhage occurring in 25 patients with obstetric and gynaecological emergencies where bleeding could not be controlled by conservative treatment methods. Nine of the cases had disseminated intravascular coagulation (DIC) and eight were haemodynamically unstable. PAE was successful in 23 of 25 patients without any major complication. Vascular blush was the most common (100%) angiographic finding. Active extravasation was observed in 9 of 25 of the cases. Permanent embolic agents including polyvinyl alcohol (PVA) particles or N-butyl-2-cyanoacrylate (NBCA) were used in all cases. Technical success in patients with disseminated intravascular coagulation (DIC), and in patients who were haemodynamically unstable were 9 of 11 and 6 of 8 cases, respectively. PAE was successful in all seven patients who had hysterectomy before PAE. PAE is a safe and effective alternative to surgical hysterectomy in obstetric and gynaecological emergencies when conservative management failed to control haemorrhage. It is an effective treatment option in cases of coagulation impairment and when bleeding cannot be controlled despite hysterectomy. Impact statement What is already known on this subject: Postpartum haemorrhage (PPH) is one of the most common causes of maternal morbidity and mortality worldwide. Most patients with PPH are treated conservatively but where this approach fails, hysterectomy is the standard option with loss of reproductive ability. During the past 20 years, pelvic arterial embolisation (PAE) has emerged as a safe, effective and preferred minimally invasive technique in most tertiary centres as an alternative to surgical treatments including hypogastric artery ligation and hysterectomy. The reported success rate of PAE using temporary and permanent embolic agents is 75-90% in cases of massive vaginal bleeding due to obstetric and gynaecological reasons. What the results of this study add? PAE showed high success rate in patients with coagulation disorders and in haemodynamically unstable patients. Permanent embolic agents such as polyvinyl alcohol particles (PVAs) or, N-butyl-2-cyanoacrylate (NBCA) should be used for embolisation in coagulation disorders or haemodynamic instability. The most important advantage of NBCA is that the embolisation effect occurs independently of the inherent coagulation cascade. What are the implications of these findings for clinical practice and/or further research? PAE is an effective and minimally invasive treatment option in cases of coagulopathy and in patients with bleeding that cannot be controlled despite hysterectomy. Our results suggest that haemodynamic instability and DIC should not be considered a contraindication for PAE. Embolic agent selection and the long-term effects of permanent embolic agents on fertilisation is an important issue requiring further investigation.

A proposal for standardized magnetic resonance imaging (MRI) descriptors of abnormally invasive placenta (AIP) - From the International Society for AIP

Abnormally invasive placenta (AIP) is used to describe a placenta that does not separate naturally after delivery and cannot be extirpated without causing abnormally high blood loss. Recently, the use of a standardized terminology for descriptors of AIP signs seen on ultrasound has been prosed but to date no such unified descriptors have been developed for magnetic resonance imaging (MRI). The purpose of this paper is to propose a unified terminology based on a consensus opinion from the members of the International Society for AIP (IS-AIP) that include obstetricians, gynecologists, radiologists, pathologists, anesthesiologists and basic science researchers. We assume that using these standardized MRI descriptors for AIP will be useful for clinical use, education, teaching and future research projects, thus assumably improving care of patients with this condition. In addition, using a uniform terminology for AIP should become the first step of a standardized MRI report.

Can the combination of internal iliac temporary occlusion and uterine artery embolization reduce bleeding and the need for intraoperative blood transfusion in cases of invasive placentation?

OBJECTIVES

Women with invasive placentation (IP) are at high risk of life-threatening hemorrhage. In the last two decades, less invasive surgical approaches combined with endovascular procedures have proven to be safe. Most case series describe the use of temporary balloon occlusion and embolization, either combined or not. Concerning hemorrhage rates, each separate interventional approach performs better than surgery alone does, yet it is not clear whether the combination of multiple interventional techniques can be beneficial and promote a lower incidence of intrapartum bleeding. We aim to evaluate whether combining temporary balloon occlusion of the internal iliac artery and uterine artery embolization promotes better hemorrhage control than do other individual interventional approaches reported in the scientific literature in the context of cesarean birth followed by hysterectomy in patients with IP.

METHODS

This is a retrospective analysis of patients with confirmed IP who underwent temporary balloon occlusion and embolization of the internal iliac arteries followed by puerperal hysterectomy. We compared patient results to data extracted from a recent systematic review and meta-analysis of the current literature that focused on interventional procedures in patients with IP.

RESULTS

A total of 35 patients underwent the procedure during the study period in our institution. The mean volume of packed red blood cells and the estimated blood loss were 487.9 mL and 1193 mL, respectively. Four patients experienced complications that were attributed to the endovascular procedure.

CONCLUSION

The combination of temporary balloon occlusion and uterine artery embolization does not seem to promote better hemorrhage control than each procedure performed individually does.

Prophylactic Transcatheter Arterial Embolization Helps Intraoperative Hemorrhagic Control for REMOVING Invasive Placenta

Objectives: The purpose of this article is to investigate the estimated blood loss in pregnant women undergoing cesarean section and placental extirpation to treat abnormal placentation and compare the outcomes of those who underwent prophylactic transcatheter arterial embolization (TAE) with those who did not. Methods: A retrospective study was conducted on 17 pregnant women diagnosed with abnormal placentation in 2001–2018 in a single tertiary center. The patients were diagnosed by surgical finding, ultrasound, or magnetic resonance imaging (MRI). These patients were divided into two groups: a prophylactic TAE group (11 patients) and a control group (6 patients). In the former group, prophylactic TAE of the bilateral uterine artery (UA) and/or internal iliac artery (IIA) was performed immediately after delivery of the infant. The placenta was removed in both groups. The primary outcomes were estimated blood loss (EBL), units of packed red blood cell (pRBC) transfusion, operative time, whether hysterectomy was performed, whether the patient was transferred to the intensive care unit (ICU), and hospitalization days. The secondary outcome was maternal complications. Results: Patients who received prophylactic TAE had significantly reduced intraoperative blood loss (990.9 ± 701.7 mL vs. 3448.3 ± 1767.4 mL, p = 0.018). Units of pRBC transfusion, operative time, hysterectomy, transfer to the ICU, and postoperative hospitalization days were not significantly different between the two groups. Thirteen patients (9 in the TAE group and 4 in the control group) received a blood transfusion during the operation. Three patients underwent a hysterectomy (1 in the TAE group and 2 in the control group). Five patients were transferred to the ICU (3 in the TAE group and 2 in the control group) for maternal complications or monitoring. In the prophylactic TAE group, 3 patients (27%) had a subsequent pregnancy within the next 5 years. Conclusions: Prophylactic TAE was safe and effective for reducing intraoperative hemorrhage from removing an invasive placenta in patients with abnormal placentation.

Intermittent aortic balloon occlusion combined with cesarean section for the treatment of patients with placenta previa complicated by placenta accreta: A retrospective study

AIM

To compare the efficacy of cesarean section (CS) combined with intermittent aortic balloon occlusion with that of CS alone for treating patients with placenta previa complicated by placenta accreta.

METHODS

Forty-five patients with placenta previa complicated by placenta accreta who underwent CS were retrospectively studied. Twenty-two patients had undergone CS combined with intermittent aortic balloon occlusion (combination group) and 23 patients received conventional hemostatic support only (control group). The postpartum hemorrhage, transfusion requirements, operation time and recovery time, and the ability to preserve the uterus and fertility were analyzed.

RESULTS

Intermittent aortic balloon occlusion significantly decreased the volume of blood loss in the combination group relative to the control group (597 ± 359 mL vs 2687 ± 575 mL; P < 0.001), and transfusion requirements were also reduced (498 ±195 mL vs 2390 ±789 mL; P <0.001). We observed shorter operation time in the combination group relative to the control group (63.8 ± 12.3 min vs 118.8 ± 22.4 min; P < 0.001), and fewer patients required uterine cavity stuffing followed by uterine artery embolization (n = 2 vs n = 10; P <0.05), uterine artery ligation (n = 1 vs n = 9; P < 0.05), and hysterectomy (n = 0 vs n =7; P < 0.05).

CONCLUSION

Intermittent aortic balloon occlusion may control postpartum hemorrhage in pregnancies complicated by placenta accreta, and improve the postoperative conditions.

Recent Update of Embolization of Postpartum Hemorrhage

Postpartum hemorrhage (PPH) is a life-threatening condition and remains a leading cause of maternal mortality. Transcatheter arterial embolization (TAE) is an effective therapeutic strategy for PPH with the advantages of fast speed, repeatability, and the possibility of fertility preservation. We reviewed the vascular anatomy relevant to PPH, the practical details of TAE emphasizing the timing of embolization, and various clinical conditions of PPH according to a recent literature review.

A Case of Placenta Percreta Managed with Sequential Embolisation Procedures

Background

The incidence of morbidly adherent placenta, including placenta percreta, has increased significantly over recent years due to rising caesarean section rates. Historically, abnormally invasive placenta has been managed with caesarean hysterectomy; however nonsurgical interventions such as uterine artery embolisation (UAE) are emerging as safe alternative management techniques. UAE can be utilised to decrease placental perfusion and encourage placental resorption, thereby reducing the risk of haemorrhage and other morbidities.

Case

We describe one of the very few reported cases of placenta percreta which was successfully treated primarily with sequential artery embolisation. Our patient underwent four embolisation procedures over a period of 248 days, with no major morbidity or complications.

Conclusion

Repeat UAE may be a beneficial primary management modality in cases of placenta percreta with bladder involvement.

Conventional MRI features for predicting the clinical outcome of patients with invasive placenta

PURPOSE

We aimed to evaluate whether morphologic magnetic resonance imaging (MRI) features could help to predict the maternal outcome after uterine artery embolization (UAE)-assisted cesarean section (CS) in patients with invasive placenta previa.

METHODS

We retrospectively reviewed the MRI data of 40 pregnant women who have undergone UAE-assisted cesarean section due to suspected high risk of massive hemorrhage caused by invasive placenta previa. Patients were divided into two groups based on the maternal outcome (good-outcome group: minor hemorrhage and uterus preserved; poor-outcome group: significant hemorrhage or emergency hysterectomy). Morphologic MRI features were compared between the two groups. Multivariate logistic regression analysis was used to identify the most valuable variables, and predictive value of the identified risk factor was determined.

RESULTS

Low signal intensity bands on T2-weighted imaging (P < 0.001), placenta percreta (P = 0.011), and placental cervical protrusion sign (P = 0.002) were more frequently observed in patients with poor outcome. Low signal intensity bands on T2-weighted imaging was the only significant predictor of poor maternal outcome in multivariate analysis (P = 0.020; odds ratio, 14.79), with 81.3% sensitivity and 84.3% specificity.

CONCLUSION

Low signal intensity bands on T2-weighted imaging might be a predictor of poor maternal outcome after UAE-assisted cesarean section in patients with invasive placenta previa.

Prophylactic temporary abdominal aorta balloon occlusion in women with placenta previa accretism during late gestation

BACKGROUND

To evaluate the clinical efficacy of prophylactic temporary balloon occlusion of the abdominal aorta in patients with placenta previa accretism during cesarean section.

METHODS

Twenty-three consecutive patients, prenatally confirmed with placenta previa accretism were retrospectively analyzed in our center from August 2012 to October 2014. All 23 subjects underwent cesarean section with prophylactic balloon occlusion of the abdominal aorta.

RESULTS

All of the 23 subjects experienced singleton pregnancies leading to the birth of live infants. Of these subjects, the following problems were diagnosed: placenta accrete (n = 10), placenta increte (n = 10), and placenta precrete (n = 3). Mean intraoperative hemorrhage was 1170.0 mL. Fifteen patients received red blood cell transfusion with a mean transfusion volume of 2.3 units. The incidence of hysterectomy was 21.74% (5/23) with blood loss ranging from 2000 to 5000 mL (mean 3360.0 mL). One complication encountered in this retrospective study was lower extremity arterial thrombosis. Eighteen patients were followed-up by telephone to 14 months following discharge, all babies were noted to be healthy.

CONCLUSION

Prophylactic abdominal aorta balloon occlusion (ABO) was relatively safe in the treatment of patients with placenta previa accretism. This approach could represent a key aspect in a multidisciplinary algorithm in reducing hemorrhage in abnormal placentation.

Retrospective cohort study of prophylactic intraoperative uterine artery embolization for abnormally invasive placenta

OBJECTIVE

To evaluate the safety and efficacy of prophylactic intraoperative uterine artery embolization (UAE) during cesarean delivery as conservative treatment for patients with abnormally invasive placenta.

METHODS

A retrospective cohort study enrolled patients surgically diagnosed with abnormally invasive placenta who underwent cesarean delivery at the First Affiliated Hospital of Nanjing Medical University, Nanjing, China, between February 1, 2012, and February 28, 2015. Postpartum estimated blood loss, blood transfusions, hysterectomy, and adverse events were compared between patients who underwent cesarean delivery only (control group) and those who underwent concurrent prophylactic intraoperative UAE (UAE group).

RESULTS

There were 45 patients included in the study; 26 and 19 in the UAE and control groups, respectively. Among patients who did not undergo hysterectomy owing to placenta accreta, the mean estimated blood loss was lower among patients in the UAE group (P=0.005); however, among patients who did undergo hysterectomy for placenta increta or percreta, no difference in mean estimated blood loss was observed (P=0.973). There were no differences in the hysterectomy rate (P=0.639) or incidence of requiring massive blood transfusion (P=0.050) between the groups. Only one patient in the UAE group experienced uterine necrosis.

CONCLUSION

Prophylactic intraoperative UAE was relatively safe and effective for reducing postpartum hemorrhage among patients with placenta accreta. The potential benefits could be lower among patients with placenta increta or percreta.

Use of uterine artery embolization to prevent peripartum hemorrhage of placental abruption with fetal demise & severe DIC

Uterine artery embolization (UAE) is typically not indicated in the pre-operative management of pregnancies with a live fetus, because risk of fetal death from reduced uteroplacental blood flow. However, pre-operative UAE in pregnancies with a fetal demise poses no fetal risk, and may offer maternal benefits. Patients with placental abruption resulting in fetal demise are at high-risk for developing disseminated intravascular coagulation (DIC), which could have devastating complications such as peri-operative hemorrhage and death. This case report describes the first successful execution of a pre-operative UAE that effectively prevented antepartum and postpartum hemorrhage in a patient with DIC secondary to a placental abruption and recent fetal demise.

Outcome of Pregnancies After Balloon Occlusion of the Infrarenal Abdominal Aorta During Caesarean in 230 Patients With Placenta Praevia Accreta

Purpose

To explore the efficacy and safety of prophylactic temporary balloon occlusion of the infrarenal abdominal aorta during caesarean for the management of patients with placenta praevia accreta.

Methods

Two hundred and sixty-eight cases of placenta praevia accreta from January 2012 to June 2015 were retrospectively reviewed. Group A included two hundred and thirty patients who underwent prophylactic temporary balloon occlusion of infrarenal abdominal aorta followed by caesarean section. Group B included thirty-eight patients who underwent caesarean without endovascular intervention. The parameters including operating room time, estimated blood loss, blood transfusion volume, PT (prothrombin time) during operation, days in the intensive care unit, and total hospital days were compared between the two groups.

Results

The operating room time, estimated blood loss, PT, the incidence of hysterectomy, blood transfusion volume, postpartum haemorrhage, and days in intensive care unit were lower in group A than in group B, with statistical significance (P < 0.05). There was no significant difference in the Apgar scores of the neonates and the incidences of thrombosis in lower limbs between the two groups (P > 0.05). No patient in the group with prophylactic temporary balloon occlusion of the infrarenal abdominal aorta was performed hysterectomy, while three patients in group B were performed hysterectomy because of uncontrollable haemorrhage.

Conclusions

The results indicate that prophylactic temporary balloon occlusion of infrarenal abdominal aorta followed by caesarean section is safe and effective to control intraoperative blood loss and greatly decreases the risk of hysterectomy in patients with placenta praevia accreta.

Management of two placenta percreta cases

Placental invasion anomalies are divided into three according to invasion of uterine wall as placenta accreta, increta and percreta. In placenta percreta, the most severe but the least common form, the placenta invades the full thickness of the uterine wall and also it can attach to adjacent organs in the abdomen like the bladder and rectum. It is a potentially life treating condition. There is no recommended management strategy for placenta percreta. We herein report two cases managed differently and discuss the management options in the light of the literature.

Emergency hysterectomy for life-threatening postpartum haemorrhage: Risk factors and psychological impact

BACKGROUND

Emergency postpartum hysterectomy (EPH) is usually considered the final resort for the management of postpartum hemorrhage (PPH). The aim of this observational study was to identify the risk factors for EPH, to evaluate the ability of EPH to stop bleeding and, finally, to estimate its psychological impact.

METHODS

This was a retrospective analysis of postpartum hysterectomy in all patients with PPH admitted between 2004 and 2011 to Lariboisière Hospital. We compared women for whom EPH was successful and those who required an advanced interventional procedure (AIP) to stop the bleeding despite hysterectomy. We also evaluated the severe PPH (SPPH) score in this particular setting. The psychological impact of emergency hysterectomy was also assessed.

RESULTS

A total of 44 hysterectomies were performed among 869 cases of PPH. Twenty were successful, while an additional AIP was required in 22 others (50%). Prothrombin time<50% and a shorter interval between the onset of PPH and hysterectomy were independently associated with the need for an additional AIP. The area under the ROC curve of the SPPH score to predict the need for another AIP was 0.738 (95% confidence interval 0.548-0.748). Furthermore, 64% of the hysterectomized patients suffered from post-traumatic stress disorder.

CONCLUSION

Failure of postpartum hysterectomy to control bleeding was frequent, and it was associated with persistence of coagulopathy. Hysterectomy in this context had important psychological impacts.

Preliminary findings of arterial embolization with balloon-occluded and flow-dependent histoacryl glue embolization in a swine model

PURPOSE

To evaluate the potential usefulness of the balloon-occluded histoacryl glue embolization (B-glue) technique.

MATERIALS AND METHODS

Both flow-dependent (no balloon occlusion) and B-glue techniques were used for 24 intercostal arteries of two female swine. N-butyl 2-cyanoacrylate (NBCA) was diluted with lipiodol to a 50 % solution, which was infused after occluding the arteries with microballoon catheters. The embolization range, fragmentation, reflux, adhesion, and glue particle attachment were compared between flow-dependent and B-glue techniques.

RESULTS

The B-glue technique was performed in a controlled fashion resulting in successful arterial occlusion without fragmented migration of the injected glue cast. Reflux occurred less frequently with the B-glue technique and was significantly different (p = 0.039) [Corrected] from that for the flow-dependent technique. Catheters were safely removed from the arterial walls, although in one instance (8.3 %), large glue particles were found to be attached to the catheter tip on removal. Conversely, the flow-dependent technique was more difficult to control and resulted in several instances of higher rates of fragmentation.

CONCLUSION

The B-glue technique can efficiently control NBCA delivery with lower rates of reflux.

Pelvic Artery Embolization in the Management of Obstetrical Hemorrhage: Predictive Factors for Clinical Outcomes

PURPOSE

To evaluate clinical outcomes of pelvic artery embolization (PAE) for treatment of obstetric hemorrhage, and determine the predictive factors associated with failure.

MATERIALS AND METHODS

This retrospective study included all consecutive patients who underwent PAE for obstetric hemorrhage (not only in the post-partum setting), between January 2003 and January 2013 at three tertiary care centers. Medical records and imaging were reviewed to identify the study population and collect data on patient characteristics, PAE characteristics, and outcomes. Multiple parameters were compared between the failed and successful PAE groups, and univariate analysis was performed to determine the predictive factors for PAE failure.

RESULTS

A total of 74 PAE procedures were performed in 68 patients. Primary clinical success rate was 78%. On univariate analysis, three factors were associated with PAE failure: hemodynamic instability (p < 0.022), hemoglobin level <95 g/dL (p < 0.024), and disseminated intravascular coagulation (DIC) (p < 0.046). Other factors, including maternal characteristics, antecedent history, angiographic finding, embolic agent, operator experience, procedure done after hours, and unilateral versus bilateral embolization, did not show any statistically significant association with PAE failure. Only one major complication was encountered, which was fetal demise in a pregnant patient with a uterine arteriovenous malformations. Out of the 68 patients, there were 61 total pregnancies at follow-up.

CONCLUSION

PAE is an effective treatment for obstetric hemorrhage, with a low complication rate, and preserves fertility. Factors significantly associated with PAE failure include hemodynamic instability, hemoglobin level <95 g/dL, and DIC.

Failed pelvic arterial embolization for postpartum hemorrhage: clinical outcomes and predictive factors

PURPOSE

To evaluate clinical outcomes of failed pelvic arterial embolization (PAE) and determine predictive factors associated with this failure in the treatment of postpartum hemorrhage (PPH).

MATERIALS AND METHODS

This retrospective study included all consecutive patients who underwent PAE for life-threatening PPH between March 2004 and January 2011 at a tertiary-care center. Medical records and imaging studies were reviewed to identify cases of failed PAE and their clinical outcomes. Multiple parameters were compared between the failed and successful PAE groups, and multivariate analysis was performed to determine the predictive factors associated with failed PAE.

RESULTS

PAE was performed in 257 patients (mean age, 32 y; range, 20-40 y). A total of 24 cases of PAE involved a failure to achieve hemostasis (9.3%). Patients in the failed PAE group experienced more major complications than those in the successful PAE group (37.5% [nine of 24] vs 9.4% [22 of 233]). Factors more frequently found in failed PAE included hemodynamic instability, hemoglobin level lower than 8g/dL, disseminated intravascular coagulation (DIC), and extravasation detected on angiography. After multivariate analysis, DIC emerged as the only significant predictive factor (odds ratio, 6.569; 95% confidence interval, 1.602-26.932; P = .009).

CONCLUSIONS

PAE is an effective treatment for medically intractable PPH. However, PAE failed in a high percentage of patients and was commonly associated with major complications. DIC was the only significant predictor of failed PAE.

Beyond hemostasis: spectrum of gynecologic and obstetric indications for transcatheter embolization

Percutaneous vascular embolization is a useful therapeutic option for a wide range of gynecologic and obstetric abnormalities. Transcatheter embolization procedures performed with the use of radiologic imaging for guidance are minimally invasive and may obviate surgery, thereby decreasing morbidity and mortality and safeguarding the patient's future fertility potential. To integrate this treatment method optimally into patient care, knowledge is needed about the clinical indications for therapeutic embolization, the relevant vascular anatomy, technical considerations of the procedure, and the potential risks and benefits of embolization. The most well-known and well-studied transcatheter embolization technique for treating a gynecologic-obstetric condition is uterine fibroid embolization. However, the clinical indications for transcatheter embolization are much broader and include many benign gynecologic conditions, such as adenomyosis and arteriovenous malformations, as well as intractable bleeding due to inoperable advanced-stage malignancies. Uterine artery embolization may be performed to prevent or treat bleeding associated with various obstetric conditions, including postpartum hemorrhage, placental implantation abnormality, and ectopic pregnancy. Embolization of the uterine artery or the internal iliac artery also may be performed to control pelvic bleeding due to coagulopathy or iatrogenic injury, and ovarian vein embolization has been shown to be effective for the management of pelvic congestion syndrome. The article discusses these and other gynecologic and obstetric indications for transcatheter embolization, provides detailed descriptions of imaging findings before and after embolization, and reviews procedural techniques and outcomes.

[Placenta accreta: screening, management and complications]

Abnormal placental invasion can result in major obstetric haemorrhage during delivery. The most important risk factors are the following: previous caesarean delivery, placenta praevia maternal age over 35, smoking, previous myomectomy, dilatation and curettage. When placenta accreta is suspected on ultrasound, an RMI can complete the diagnostic. Therefore, patients must be managed, as far as possible, in a reference centre, by a trained medical team. Birth must be planned in order to decrease complications rate. Treatment can consist in radical management (caesarean-hysterectomy) or conservative management (preservation of both uterus and placenta). Conservative management allows patients to keep fertility but can also decrease blood loss during delivery. Side effects of this therapy are secondary haemorrhage, sepsis, long-term follow-up and vaginal loss. There are few studies describing fertility after conservative management, but it seems to be a secure treatment for future pregnancies. Embolization can be a very useful, already demonstrated, help when massive haemorrhage occurs. Management of placenta accreta is multidisciplinary and patients must be informed of all options. Treatment is decided regarding history of the patients, operative findings and peri-partum blood loss.