High-intensity focused ultrasound treatment of placenta accreta after vaginal delivery: a preliminary study

The Management of Placenta Accreta Spectrum Disorder

This chapter provides insight into current management strategies for the placenta accreta spectrum (PAS). PAS is one of the most morbid conditions of pregnancy, with significant maternal hemorrhage and surgical morbidity risks, and its increasing incidence. Here, we review the available data to help guide the clinical management of PAS, from time of diagnosis through delivery and postpartum care, while acknowledging the many areas of continued uncertainty. The evidence is strong for the importance of team-based, patient-centered, and multidisciplinary care for patients with PAS. However, much else remains uncertain and is predominantly guided by expert opinion. Ultimately, we aim to provide a current understanding of available literature and to emphasize that continued research is paramount to explore management and surgical approaches to move toward optimization of patient outcomes, including the patient experience.

High-Intensity Focused Ultrasound Ablation Combined With Hysteroscopy for the Treatment of Uterine Arteriovenous Fistula Associated With Retained Products of Conception: A Prospective Cohort Study

STUDY OBJECTIVE

To evaluate the efficacy of combining high-intensity focused ultrasound (HIFU) ablation with hysteroscopic removal of retained products of conception in the presence of a uterine arteriovenous fistula (UAVF).

DESIGN

Prospective cohort study SETTING: Tertiary hospital.

PATIENTS

Seventeen patients with UAVF and retained products of conception.

INTERVENTIONS

HIFU ablation combined with hysteroscopic removal of retained products of conception.

MEASUREMENTS AND MAIN RESULTS

All patients presented with irregular vaginal bleeding following pregnancy termination and were not responsive to medical treatment. Patients were confirmed to have a UAVF along with concurrent intrauterine residue using three-dimensional color Doppler ultrasonography, uterine angiography, or pelvic-enhanced magnetic resonance imaging; and demonstrated a poor response to medical treatment. Under real-time ultrasound guidance, HIFU was used to ablate the arteriovenous malformation region. Patients underwent hysteroscopic removal of retained products of conception; the removed tissue was subjected to pathological examination. All patients underwent monthly uterine color Doppler ultrasound examinations and menstrual status follow-up within 3 months postoperatively and showed normal menstrual recovery without signs of arteriovenous malformations on ultrasonography. Pathological examination of the tissues removed during hysteroscopic clearance revealed characteristics consistent with pregnancy, with abnormal blood vessels in some tissues. All patients experienced normal menstrual recovery postoperatively, without intrauterine adhesions.

CONCLUSION

Combining HIFU ablation with postoperative hysteroscopic surgery effectively treats pregnancy-related UAVF with minimal complications and preserves fertility, it offers an additional treatment option for patients wanting future fertility.

The effectiveness of single ultrasound-guided high-intensity focused ultrasound (USgHIFU) ablation in managing placenta accreta spectrum (PAS) disorder

OBJECTIVE

To evaluate the feasibility and effectiveness of single ultrasound-guided high-intensity focused ultrasound (USgHIFU) ablation in managing placenta accreta spectrum (PAS) disorder.

MATERIALS AND METHODS

We retrospectively analyzed 40 PAS patients between April 2017 and October 2021. All the patients received one session of HIFU treatment. Regular follow-up was done after HIFU treatment until normal menstruation returned and placental tissue disappeared. The patient's reproductive-related outcomes were obtained through telephone interviews.

RESULTS

The median follow-up time for the 40 patients was 30.50 (15.75-44.00) months and the mean placental tissue elimination time was 45.29 ± 33.32 days. The mean duration of bloody lochia was 13.43 ± 10.01 days, with no incidences of severe bleeding. Notably, Linear regression analysis showed that the residual placenta volume before HIFU was a factor affecting the duration of bloody lochia after HIFU (R2 = 0.284, B = 0.062, P = 0.000). The normal menstrual return time was 58.71 ± 31.14 days. One (2.50%) patient developed an infection. Two (5.00%) patients were subjected to ultrasound-guided suction curettage for persistent vaginal discharge for more than one month without infection. Notably, 7 of the 18 patients who expressed reproductive plans became pregnant during the 4 to 53 months of follow-up without placental abnormalities. The remaining 11 patients were on contraceptives.

CONCLUSIONS

Single HIFU is an effective treatment option for managing PAS. However, future studies on further treatment strategies to reduce complications and promote patient recovery after HIFU ablation are desirable.

Non-invasive High-Intensity Focused Ultrasound Treatment of Liver Tissues in an In Vivo Porcine Model: Fast, Large and Safe Ablations Using a Toroidal Transducer

A toroidal high-intensity focused ultrasound (HIFU) transducer was used to non-invasively treat liver tissues in vivo in a pig model. The transducer was divided into 32 concentric rings with equal surface areas operating at 2.5 MHz. First, attenuation of skin, fat, muscle and liver tissues was measured in fresh animal samples to adjust the energy delivered to the focal zone. Then, 8 animals were included in the present protocol and placed in a dorsal decubitus proclive position at an angle of 15°. The device was held by hand, and sonications were performed during apnea. Two thermal HIFU lesions were created in 40 s in each animal. The average abdominal wall thickness was 14.8 ± 1.3 mm (12.5-17.6 mm). The longest and shortest axes of the HIFU ablations were 20.9 ± 6.3 mm (14.0-33.7 mm) and 14.2 ± 5.5 mm (7.0-22.0 mm), respectively. All HIFU lesions were visible on sonograms. The correlation between the dimensions of the HIFU lesions observed on sonograms and those obtained during gross examination was r = 0.84. Creating large and fast ablations with reliable ultrasound imaging guidance in the liver using this handheld device may represent a new therapeutic option for patients with liver tumors.

Treatment of Placenta Increta With High-Intensity Focused Ultrasound Ablation and Leaving the Placenta in situ: A Multicenter Comparative Study

Objective

To explore the feasibility of simple high-intensity focused ultrasound (HIFU) ablation for placenta increta.

Methods

Ninety-five patients after a vaginal delivery were enrolled in this retrospective cohort study, 53 patients were treated with simple HIFU ablation, and 42 patients were treated with HIFU followed by uterine curettage.

Results

All 95 patients were successfully treated with a single-session HIFU procedure, and in the control group, the necrotic placental tissue was removed with curettage. Vaginal hemorrhage did not occur in either group. The duration of bloody lochia was 25.9 ± 8.6 days in the sHIFU group and 24.2 ± 8.8 days in the control group (P > 0.05). The median serum human chorionic gonadotropin (HCG) level was 3,222 mIU/mL and 2,838 mIU/mL in the sHIFU and control groups, respectively, which decreased and returned to normal within 30 days, and the differences were not significantly on comparing the blood HCG level in the two groups at 7, 15, and 30 days after HIFU (all P > 0.05). Decreased menstrual volume occurred in 85.71% of patients in the control group, which was higher than that in the sHIFU group (23.08%) (χ² = 6.839, P < 0.001). During 2–8 years of follow-up, six pregnancies occurred in the sHIFU group without any recurrence of placenta increta, three pregnancies occurred in the control group, and one patient developed a repeat placenta increta.

Conclusion

Simple HIFU treatment is safe and effective for postpartum placenta increta and leaving the placenta in situ. It is a promising option for patients who wish to preserve their fertility and conceive.

Placenta Accreta Spectrum Outcomes Using Tourniquet and Forceps for Vascular Control

Objective: To evaluate the use of tourniquet and forceps to reduce bleeding during surgical treatment of severe placenta accreta spectrum (placenta increta and placenta percreta). Methods: A tourniquet was used in the lower part of the uterus during surgical treatment of severe placenta accreta spectrum. Severe placenta accreta spectrum was classified into two types according to the relative position of the placenta and tourniquet during surgery: upper-tourniquet type, in which the entire placenta was above the tourniquet, and lower-tourniquet type, in which part or all of the placenta was below the tourniquet. The surgical effects of the two types were retrospectively compared. We then added forceps to the lower-tourniquet group to achieve further bleeding reduction. Finally, the surgical effects of the two types were prospectively compared. Results: During the retrospective phase, patients in the lower-tourniquet group experienced more severe symptoms than did patients in the upper-tourniquet group, based on mean intraoperative blood loss (upper-tourniquet group 787.5 ml, lower-tourniquet group 1434.4 ml) intensive care unit admission rate (upper-tourniquet group 1.0%, lower-tourniquet group 33.3%), and length of hospital stay (upper-tourniquet group 10.2d, lower-tourniquet group 12.1d). During the prospective phase, after introduction of the revised surgical method involving forceps (in the lower-tourniquet group), the lower-tourniquet group exhibited improvements in the above indicators (intraoperative average blood loss 722.9 ml, intensive care unit admission rate 4.3%, hospital stays 9.0d). No increase in the rate of complications was observed. Conclusion: The relative positions of the placenta and tourniquet may influence the perioperative risk of severe placenta accreta spectrum. The method using a tourniquet (and forceps if necessary) can improve the surgical effect in cases of severe placenta accreta spectrum.

Early versus late hysteroscopic resection after high-intensity focused ultrasound for retained placenta accreta

Objective: To compare early and late hysteroscopic resection after high-intensity focused ultrasound (HIFU) for retained placenta accreta. Methods: This retrospective study included 63 women with retained placenta accreta who were treated with HIFU combined with hysteroscopic resection. They were divided into an early group (n = 40) and a late group (n = 23), depending on the time between the HIFU and the hysteroscopic resection. The number of sessions of hysteroscopy needed, adverse events, menstrual recovery, and reproductive outcomes were compared. Results: The mean largest diameter of the retained placenta accreta was 67.6 ± 14.0 mm and 71.6 ± 23.6 mm in each group (p = .47), respectively. In the early group, the first hysteroscopic procedure was done at a mean interval of 2.7 ± 1.4 days after HIFU ablation, while in the late group, the interval was 34.7 ± 15.0 days (p < .001). The rate of complete resection of placenta residue after one hysteroscopic procedure in the late group was 73.9% (17/23). This was significantly higher than in the early group, where the rate was 45% (p = .03). During the follow-up, there was no difference in menstrual recovery and pregnancy outcomes between the groups. Conclusion: This study was the first to compare the effects and safety of early and late hysteroscopic resection after HIFU for retained placenta accreta. Late hysteroscopic resection seems to increase the rate of complete resection of retained placenta accreta after one hysteroscopic procedure.

A comparison of results following the treatment of placenta accreta and placenta increta using high-intensity focused ultrasound followed by hysteroscopic resection

OBJECTIVE

To compare the safety and efficacy of high-intensity focused ultrasound (HIFU) followed by hysteroscopic resection for different placenta accreta spectrum disorders.

MATERIALS AND METHODS

Thirty-four patients with placenta accreta, placenta increta, or placenta percreta were treated with USgHIFU from January 2016 to December 2019 and were retrospectively reviewed. The patients were classified into three categories according to the relationship between the trophoblastic villi and the myometrium, based on magnetic resonance imaging (MRI). Fifteen patients were classified as placenta accreta, 17 patients were classified as placenta increta, and 2 were classified as placenta percreta. All patients completed follow-up. Treatment efficacy and safety were evaluated.

RESULTS

No significant differences in baseline characteristics and results of HIFU ablation were observed between the patients with placenta accreta and those with placenta increta. The return of HCG levels to normal was longer in patients with placenta accreta compared with patients with placenta increta, while no significant difference was observed in the amount of intraoperative blood loss, the return of normal menstruation and the length of hospital stay.

CONCLUSIONS

HIFU treatment followed by hysteroscopic resection is safe and effective in the treatment of patients with placenta accreta and placenta increta.

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.

High-intensity focused ultrasound versus uterine artery embolization for patients with retained placenta accreta

OBJECTIVE

To compare the safety and clinical effectiveness of high-intensity focused ultrasound (HIFU) and uterine artery embolization (UAE) for retained placenta accreta.

STUDY DESIGN

A retrospective analysis was performed on women who underwent HIFU or UAE followed by hysteroscopic resection for retained placenta accreta from January 2015 to December 2019 at the Third Xiangya Hospital of Central South University.

RESULTS

A total of 63 and 31 patients who underwent HIFU and UAE followed by hysteroscopic resection, respectively, were analyzed. The baseline characteristics, including age, gravidity, parity, previous cesarean section rate, previous curettage rate, previous intrauterine adhesions rate, and delivery mode, were similar between the two groups. Vaginal bleeding was the major complaint in patients with retained placenta accreta. The number of hysteroscopy sessions, amount of intraoperative blood loss, and the length of hospital stays were also similar between the groups. No further hysterectomy was needed in either group.

CONCLUSION

Both HIFU and UAE combined with hysteroscopic resection seem to be safe and effective procedures in cases of retained placenta accreta.

Comparison between abdominal ultrasound and nuclear magnetic resonance imaging detection of placenta accreta in the second and third trimester of pregnancy

This study is to determine accuracy of abdominal ultrasound and nuclear magnetic resonance imaging (MRI) for placenta accreta in the second and third trimester of pregnancy and to define the most relevant features of abdominal ultrasound and MRI for placenta accreta prediction.Between September 2012 and September 2018, 245 high risk of placenta accreta in the second trimester of pregnancy were prenatal diagnosed by abdominal ultrasound and MRI and they were followed up until the end of pregnancy.Forty-six patients at the second trimester of pregnancy and 40 patients at the third trimester of pregnancy were confirmed as placenta accreta. For the second and third trimester of pregnancy, the sensitivity (Se), specificity (Sp), positive and negative predictive value (PPV and NPV) of abdominal ultrasound were 95.65% versus 97.50%, 91.78% versus 90.70%, 88% versus 83%, and 97% versus 99%, respectively, while the Se, Sp, PPV, and NPV of MRI were 89.13% versus 92.50%, 87.67% versus 8721%, 82% versus 77%, and 93% versus 96%, respectively. Five features having significant statistical differences between normal placentation women and placenta accreta patients in second or third trimester of pregnancy, including loss of the normal retroplacental clear space, thinning or disappearance of the myometrium, increased vascularization at the uterine serosa-bladder wall interface, and vascularization perpendicular to the uterine wall on abdominal ultrasound, and uterine bulging and dark intraplacental bands on MRI.Abdominal ultrasound and MRI for placenta accreta in the second and third trimester of pregnancy could provide meaningful imaging evidences.

Evidence-based guidelines for the management of abnormally invasive placenta: recommendations from the International Society for Abnormally Invasive Placenta

The worldwide incidence of abnormally invasive placenta is rapidly rising, following the trend of increasing cesarean delivery. It is a heterogeneous condition and has a high maternal morbidity and mortality rate, presenting specific intrapartum challenges. Its rarity makes developing individual expertise difficult for the majority of clinicians. The International Society for Abnormally Invasive Placenta aims to improve clinicians' understanding and skills in managing this difficult condition. By pooling knowledge, experience, and expertise gained within a variety of different healthcare systems, the Society seeks to improve the outcomes for women with abnormally invasive placenta globally. The recommendations presented herewith were reached using a modified Delphi technique and are based on the best available evidence. The evidence base for each is presented using a formal grading system. The topics chosen address the most pertinent questions regarding intrapartum management of abnormally invasive placenta with respect to clinically relevant outcomes, including the following: definition of a center of excellence; requirement for antenatal hospitalization; antenatal optimization of hemoglobin; gestational age for delivery; antenatal corticosteroid administration; use of preoperative cystoscopy, ureteric stents, and prophylactic pelvic arterial balloon catheters; maternal position for surgery; type of skin incision; position of the uterine incision; use of interoperative ultrasound; prophylactic administration of oxytocin; optimal method for intraoperative diagnosis; use of expectant management; adjuvant therapies for expectant management; use of local surgical resection; type of hysterectomy; use of delayed hysterectomy; intraoperative measures to treat life-threatening hemorrhage; and fertility after conservative management.

Conservative Management of Placenta Accreta Spectrum

The purpose of this review was to assist obstetricians and gynecologists in considering the most appropriate conservative treatment option to manage women with placenta accreta spectrum according to their individual need and local expertise of the heath care team. The issue is challenging, as the quality of evidence with regard to efficacy is poor, and is mainly based on retrospective studies with limited sample size.

High-intensity focused ultrasound combined procedures treatment of retained placenta accreta with marked vascularity after abortion or delivery

OBJECTIVE

To evaluate the safety and feasibility of combined procedures: HIFU combined with systemic MTX followed by ultrasound-guided curettage or hysteroscopic resection while treating placenta accreta (PA).

METHOD

This study included 21 patients diagnosed with retained PA with marked vascularity after abortion or delivery from July 2015 to December 2017. Patients with high serum β-hCG level (≥100 mIU/mL) received systemic MTX + HIFU treatment for 3 days and the ones with low β-hCG level (<100 mIU/mL) only received USgHIFU treatment for 3 days before ultrasound-guided curettage or hysteroscopic resection. All patients had completed follow-up data. The safety and feasibility of the treatment were evaluated retrospectively.

RESULT

Sixteen patients received systemic 100 mg MTX without myelosuppression. All patients received three days of HIFU ablation therapy; the median of HIFU treatment time was 60 minutes. Ultrasound-guided curettage and ovum forceps were used to extract planted placental tissue in 5 patients with one week after birth or after abortion. Sixteen patients received a hysteroscopic operation after the HIFU treatment. The median of intraoperative blood loss was 30 ml. Twenty patients had recovered normal menstruation on average 32 days (range 14-60) after the operation.

CONCLUSION

Based on the results of this study, with a relatively small number of patients, it seems that three-days' therapy of HIFU ± systemic MTX followed by ultrasound-guided curettage or hysteroscopic resection, is a safe and feasible treatment for retained PA with marked vascularity after abortion or delivery.

Comparison of ultrasound-guided high-intensity focused ultrasound ablation and surgery for abdominal wall endometriosis

BACKGROUND

Surgery constitutes the standard approach for abdominal wall endometriosis (AWE), but is invasive. High-intensity focused ultrasound (HIFU) ablation is effective and safe for the treatment of AWE, but no study has compared HIFU and surgery.

OBJECTIVE

To report our experience about the benefits and adverse events of surgery compared to HIFU for the treatment of AWE.

METHODS

This was a retrospective study of 54 consecutive Chinese women with AWE after cesarean section treated at the First Affiliated Hospital of Chongqing Medical University (China) between January 2012 and December 2014. The patients underwent surgery (n = 29) or HIFU (n = 25). The technical success rate, adverse events, and recurrence were assessed.

RESULTS

The technical success rate was 100% in both groups. The complete remission rate was 92.0% (23/25) in the HIFU group, and 100% (29/29) in the surgery group. Numeric rating scale (NRS) scores after HIFU were significantly improved from 6.9 to 0.3.During the median follow-up period of 32 months (range, 19-46 months), the durations of pain relief were 29.7 ± 12.6 months and 25.0 ± 13.5 months in the surgery and HIFU groups, respectively (p = .337). Three patients (10.7%) experienced pain recurrence in the surgery group, and two (8.0%) in the HIFU group. Major adverse events occurred in four (13.8%) and one (4.0%) patients in the surgery and HIFU groups, respectively (p > .05).

CONCLUSIONS

HIFU appears to be beneficial for the treatment of AWE, and may reduce adverse events. Compared with surgery, HIFU does not induce blood loss or tissue defects.

Trans-abdominal in vivo placental vessel occlusion using High Intensity Focused Ultrasound

Pre-clinically, High Intensity Focused Ultrasound (HIFU) has been shown to safely and effectively occlude placental blood vessels in the acute setting, when applied through the uterus. However, further development of the technique to overcome the technical challenges of targeting and occluding blood vessels through intact skin remains essential to translation into human studies. So too does the assessment of fetal wellbeing following this procedure, and demonstration of the persistence of vascular occlusion. At 115 ± 10 d gestational age (term~147 days) 12 pregnant sheep were exposed to HIFU (n = 6), or to a sham (n = 6) therapy through intact abdominal skin (1.66 MHz, 5 s duration, in situ ISPTA 1.3-4.4 kW.cm-2). Treatment success was defined as undetectable colour Doppler signal in the target placental vessel following HIFU exposures. Pregnancies were monitored for 21 days using diagnostic ultrasound from one day before HIFU exposure until term, when post-mortem examination was performed. Placental vessels were examined histologically for evidence of persistent vascular occlusion. HIFU occluded 31/34 (91%) of placental vessels targeted, with persistent vascular occlusion evident on histological examination 20 days after treatment. The mean diameter of occluded vessels was 1.4 mm (range 0.3-3.3 mm). All pregnancies survived until post mortem without evidence of significant maternal or fetal iatrogenic harm, preterm labour, maternal or fetal haemorrhage or infection. Three of six ewes exposed to HIFU experienced abdominal skin burns, which healed without intervention within 21 days. Mean fetal weight, fetal growth velocity and other measures of fetal biometry were not affected by exposure to HIFU. Fetal Doppler studies indicated a transient increase in the umbilical artery pulsatility index (PI) and a decrease in middle cerebral artery PI as a result of general anaesthesia, which was not different between sham and treatment groups. We report the first successful application of fully non-invasive HIFU for occlusion of placental blood flow in a pregnant sheep model, with a low risk of significant complications. This proof of concept study demonstrates the potential of this technique for clinical translation.

Non-invasive high-intensity focused ultrasound treatment of the placenta: a preliminary in-vivo study using a simian model

OBJECTIVE

To demonstrate the feasibility and efficacy of high-intensity focused ultrasound (HIFU) for the non-invasive creation of placental lesions in a simian model.

METHODS

Eight pregnant monkeys were exposed to HIFU treatment after anesthesia, using a toroidal HIFU 2.5-MHz transducer with an integrated ultrasound imaging probe. Lesions on the placental tissue were created non-invasively by placing the HIFU probe on the skin surface. Fetal and maternal parameters, such as maternal heart rate, fetal heart rate and subcutaneous and intra-amniotic fluid temperature, were recorded during HIFU exposure. Cesarean section was performed immediately after the procedure to extract the placenta and examine the fetus and the maternal abdominal cavity. Placental HIFU lesions were assessed by ultrasound, gross pathology and histology.

RESULTS

The mean gestational age of the monkeys was 72 ± 4 days. In total, 13 HIFU procedures were performed. The acoustic power and exposure time were increased progressively. This gradual increase in total energy delivered was used to determine a set of parameters to create reproducible lesions in the placenta without complications. Five placental lesions were observed with average diameters of 6.4 ± 0.5 mm and 7.8 ± 0.7 mm and an average depth of 3.8 ± 1.5 mm. Ultrasound examination of the placentae revealed hyperechoic regions that correlated well with macroscopic analysis of the HIFU lesions. Necrosis of placental tissue exposed to HIFU was confirmed with macroscopic and microscopic analysis. There was no significant variation in maternal and fetal parameters during HIFU exposure.

CONCLUSIONS

This study demonstrates the feasibility of HIFU applied non-invasively to the placental unit in an in-vivo pregnant monkey model. The technique is safe in the immediate short term and is potentially translatable to human pregnancy. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.