Key Takeaways
- Only 2 US-based trials are actively recruiting PAS patients as of early 2026
- The University of Utah has the only US-based randomized trial comparing conservative management to hysterectomy
- The majority of interventional PAS trials are based in Egypt, reflecting higher surgical volume there
- Conservative management (leaving the placenta in place to be reabsorbed) is the dominant research theme across active trials
US-Based Trials (Most Relevant)#
These are the trials most accessible to patients in the United States. Of the three listed, only two are currently recruiting participants.
NCT06512181 — U-PRESERVE
Status: RECRUITING
Site: Penn Medicine PAS Center of Excellence, Philadelphia, PA
Approach: Conservative/expectant management — the placenta is left in situ (in place) after delivery and monitored as it is reabsorbed by the body, with the goal of avoiding hysterectomy and preserving the uterus.
Size: 15 participants
Started: 2024
Eligibility:
- Age 18 or older
- 16–36 weeks pregnant
- Diagnosed with PAS
- Desire for uterine preservation
- Prior cesarean delivery
NCT05139498 — Conservative Management Pilot
Status: RECRUITING
Site: University of Utah, Salt Lake City, UT
Approach: The only US-based randomized trial comparing conservative management (leaving the placenta in situ) versus planned cesarean hysterectomy (surgical removal of the uterus at delivery). This is the gold-standard study design for comparing treatments.
PI: Brett Einerson, MD (brett.einerson@hsc.utah.edu)
Funding: NICHD K23HD106009
Eligibility:
- Prior cesarean delivery
- Placenta previa (placenta covering the cervix) or low-lying placenta
- Suspected PAS on imaging
- Planned delivery at 34–36 weeks
NCT04671680 — CNAP vs IABP
Status: ACTIVE, NOT RECRUITING
Site: Beth Israel Deaconess Medical Center, Boston, MA
Approach: Observational study comparing non-invasive blood pressure monitoring (CNAP) versus invasive arterial line monitoring (IABP) during PAS surgery. This is not a treatment trial, but its findings will inform anesthesia practice for PAS deliveries.
PI: John J. Kowalczyk, MD
Note: While not a treatment trial, understanding optimal monitoring during PAS surgery is important for improving surgical outcomes and patient safety.
International Conservative Management Trials#
Conservative management — leaving the placenta in situ after delivery rather than performing immediate hysterectomy — is the most actively studied approach worldwide. The majority of these trials are based in Egypt, where higher PAS surgical volume provides larger study populations.
Status: Recruiting
Location: Egypt
Description: Evaluates the safety and efficacy of conservative management in PAS patients, with outcomes including uterine preservation rates, blood loss, and complication rates.
Status: Recruiting
Location: Egypt
Description: Prospective study examining outcomes of expectant management in PAS, tracking time to placental resorption, complication rates, and need for secondary intervention.
Status: Active
Location: France
Description: Multicenter French study evaluating conservative treatment protocols for PAS, including methotrexate use and uterine artery embolization as adjunctive therapies to support placental resorption.
Status: Completed
Location: Egypt
Description: Study of conservative management outcomes in confirmed PAS cases, including uterine preservation success rates and maternal morbidity data.
Surgical Technique Trials#
These trials investigate specific surgical approaches designed to reduce blood loss and complications during cesarean hysterectomy or uterine-preserving surgery for PAS.
Status: Recruiting
Location: Egypt
Description: Evaluates the “N&H Sandwich” surgical technique, which combines compression sutures with intrauterine balloon tamponade to control hemorrhage during PAS surgery while potentially preserving the uterus.
Status: Completed
Location: Egypt
Description: Studied a double-incision surgical approach for cesarean delivery in PAS patients, where the uterine incision is placed away from the placental site to reduce blood loss during delivery.
Status: Recruiting
Location: Egypt
Description: Evaluates a modified version of the Triple-P procedure — Perioperative placental localization, Pelvic devascularization (reducing blood flow), and Placental non-separation with myometrial excision — as a uterine-preserving approach for PAS.
Diagnostic & Imaging Trials#
Improving how PAS is detected and classified before delivery is critical for surgical planning and outcomes. These trials focus on validating diagnostic tools.
Status: Active
Description: Prospective validation of the Placenta Accreta Index (PAI), a scoring system that uses ultrasound findings to predict the severity of placental invasion. A validated scoring system would help standardize PAS diagnosis and guide surgical planning.
Status: Active
Description: Further evaluation of the Placenta Accreta Index in clinical settings, assessing its predictive value for surgical outcomes and its utility in multidisciplinary team planning for PAS deliveries.
Fertility Outcomes#
For patients who wish to have more children after a PAS pregnancy, understanding fertility outcomes is essential. Research in this area remains limited.
Status: Active
Description: Longitudinal study tracking fertility outcomes in women who experienced PAS, including time to conception, pregnancy rates, recurrence of PAS in subsequent pregnancies, and obstetric outcomes. This study addresses a significant gap in the literature, as most PAS research focuses on the index pregnancy rather than long-term reproductive outcomes.
Related Hemorrhage Trials#
Massive hemorrhage (heavy bleeding) is the primary risk during PAS surgery. These trials investigate treatments to reduce blood loss, and while not PAS-specific, their findings directly impact PAS surgical management.
Status: Recruiting
Description: Investigates the use of tranexamic acid (TXA) — a medication that helps blood clot — specifically in PAS patients to reduce intraoperative blood loss during cesarean delivery. TXA is already widely used in postpartum hemorrhage, and this trial aims to establish its role in the PAS-specific surgical setting.
Status: Completed
Description: The only completed randomized controlled trial (RCT) to include PAS patients in a study of tranexamic acid. TAPPAS evaluated the efficacy of prophylactic TXA in reducing blood loss during cesarean delivery for patients with abnormally invasive placenta. Results from this trial provide the strongest existing evidence for TXA use in PAS.
Emerging Research (NICHD & Beyond)#
Beyond registered clinical trials, several research initiatives are shaping the future of PAS care.
The National Institute of Child Health and Human Development (NICHD) convened a workshop in June 2024 to define research priorities for PAS. Key findings emphasized the need for standardized diagnostic criteria, multicenter registries, and randomized trials comparing management strategies. The workshop proceedings have been published (PMID: 40311146).1
Active Research Initiatives
- Baylor College of Medicine: Developing new contrast agents for earlier and more accurate detection of PAS via imaging. Early detection remains a major factor in improving outcomes.
- University of Connecticut: Awarded a $2.5 million R01 grant to study the molecular mechanisms underlying abnormal placental invasion in PAS. Understanding why PAS occurs at the cellular level could lead to targeted therapies or prevention strategies.
- Cost-effectiveness of conservative management: A 2025 study published in BJOG analyzed the economic implications of conservative management versus immediate hysterectomy, providing data that may influence both clinical practice and insurance coverage decisions.2
How to Participate in a Clinical Trial#
- Talk to your MFM specialist (Maternal-Fetal Medicine doctor) about whether any active trials match your clinical situation and eligibility criteria.
- Visit ClinicalTrials.gov and search for “placenta accreta” to see the most current list of registered trials.
- Important: Most trials require delivery at the trial site. If a trial interests you, discuss the logistics of transferring care with both your current provider and the trial site.
- Clinical trial participation is always voluntary. You can withdraw at any time without affecting your standard care.
Research Gaps#
Despite growing interest in PAS, critical research gaps remain:
- No large-scale multicenter US randomized controlled trial (RCT) comparing conservative management to surgical management. The University of Utah pilot is a critical first step, but a definitive multicenter trial is needed.
- No trial addressing the psychological impact of PAS on patients and families. PAS diagnoses cause significant anxiety, grief, and trauma — yet no registered trial studies mental health outcomes or interventions.
- No randomized US trial for interventional radiology (IR) balloon occlusion — a widely used technique where balloons are placed in pelvic arteries to reduce blood loss during PAS surgery. Despite routine use at many centers, its efficacy has never been evaluated in a US randomized trial.
References#
- NICHD Placenta Accreta Spectrum Workshop Proceedings. 2024. PMID: 40311146
- Cost-effectiveness of conservative management versus hysterectomy for placenta accreta spectrum. BJOG. 2025. PubMed
- ClinicalTrials.gov. U-PRESERVE: Uterine Preservation in PAS. NCT06512181
- ClinicalTrials.gov. Conservative Management of Placenta Accreta Spectrum Pilot Trial. NCT05139498
- ClinicalTrials.gov. CNAP vs IABP in PAS Surgery. NCT04671680
- ClinicalTrials.gov. Conservative Management of PAS (Egypt). NCT05013749
- ClinicalTrials.gov. Expectant Management Outcomes in PAS. NCT05232981
- ClinicalTrials.gov. Conservative Treatment of PAS (France). NCT03273569
- ClinicalTrials.gov. Placenta Accreta Conservative Management. NCT03327818
- ClinicalTrials.gov. N&H Sandwich Technique for PAS. NCT03701386
- ClinicalTrials.gov. Double Incision Technique for PAS. NCT02702024
- ClinicalTrials.gov. Modified Triple-P Procedure for PAS. NCT04384510
- ClinicalTrials.gov. Placenta Accreta Index Validation. NCT04314791
- ClinicalTrials.gov. Placenta Accreta Index in Clinical Practice. NCT05513092
- ClinicalTrials.gov. Fertility Post Placenta Accreta. NCT02821702
- ClinicalTrials.gov. TRAPP — Tranexamic Acid in PAS. NCT05811676
- ClinicalTrials.gov. TAPPAS — TXA for Placenta Accreta Spectrum. NCT02806024
This page is for informational purposes only and does not constitute medical advice. Clinical trial information may change; always verify current status on ClinicalTrials.gov and consult with your healthcare team before making decisions about trial participation.