Multidisciplinary Approach to Placenta Accreta Spectrum

Educational Objectives

The goal of this program is to improve the management of placenta accreta spectrum (PAS) disorders. After hearing and assimilating this program, the clinician will be better able to:

1. Assess the key risk factors for PAS.
2. Detect markers of PAS disorders using appropriate imaging modalities.

Summary

Placenta accreta spectrum (PAS): refers to a condition in which the placenta abnormally attaches to the uterus; it includes a range of severities, ie, placenta accreta (mild; the placenta is embedded beyond the endometrium), increta (the placenta embeds into the uterine muscle), and percreta (rarest and most severe form; the placenta invades beyond the uterus; this abnormal attachment prevents the placenta from separating after delivery, leading to severe complications like hemorrhage and maternal morbidity or mortality); rates of placenta accreta have significantly increased over the decades, largely in parallel with rising rates of cesarean delivery (CD); in the 1950s, accreta was rare, but between 1982 and 2018, its prevalence grew to 1 in 588 births; this rise is associated with increasing CD rates, which have particularly affected certain racial and ethnic minority groups; non-Hispanic Black women have the highest rates of primary CD, followed by Hispanic and Asian women; these groups are also at greater risk for complications, eg, hemorrhage, shock, and urinary tract injury related to placenta accreta

Risks: it is a significant concern because it poses higher risks for severe maternal morbidity and mortality than many other high-risk pregnancy conditions, including preeclampsia and pulmonary hypertension; early detection is crucial for better outcomes, as predelivery diagnosis allows for careful planning; delivery at a specialized care facility (level 3 or 4) before labor or bleeding begins, along with a multidisciplinary team experienced in managing placenta accreta, is recommended for optimal outcomes; key risk factors for PAS — include a history of CD, particularly with placenta previa; risk for accreta increases dramatically with successive CDs and is higher when previa is present; other risk factors include previous myomectomy (especially hysteroscopic), Asherman syndrome, in vitro fertilization, endometrial ablation, twin gestations, and basal plate myometrial fibers on placental pathology reports; detecting accreta through imaging can be challenging, especially when previa is absent, requiring careful and thoughtful screening

Management: patients with PAS are typically referred to a multidisciplinary care team for delivery at 34 to 35 wk gestation, often involving a CD and sometimes a hysterectomy; at University of California, San Francisco (UCSF) — the accreta team consists of a wide range of specialists, including general OBGYNs trained in complex surgeries, gynecologic oncologists, maternal-fetal medicine experts, specialized pathologists, interventional radiologists, obstetric anesthesiologists, nurses across multiple departments, and staff from the neonatal intensive care unit (ICU); this team collaborates to develop individualized care plans for patients referred to the program

Evaluation: when a patient is referred to the multidisciplinary approach to placenta service, high-risk nurse coordinators conduct an intake over the phone and manage complex multidisciplinary organization; they provide continuity and support to patients throughout the antepartum, intrapartum, and postpartum periods; imaging — a critical part of the evaluation, with certain abnormal findings indicating the need for additional care; abnormal areas in the uterus (eg, an overly large placenta) may signal PAS and should prompt concern and potential referral for specialized management

Key markers of PAS: examine the placenta; consider transvaginal ultrasonography (USG), especially in patients with previous CD or placenta previa; markers for PAS can be seen as early as the first trimester; low implantation, CD scar ectopic pregnancy, and placental lacunae (dark blood collections that appear “moth-eaten”) are significant red flags; other markers include loss of the normal retroplacental hypoechoic zone, myometrial thinning, and hypervascularity, especially “bridging vessels”; an abnormal uterine contour (the lower uterine segment bulges out) should also raise concern for accreta

Magnetic resonance imaging (MRI): often used alongside USG for assessing placenta accreta, with both modalities providing complementary insights; MRI is especially helpful for surgical planning and for visualizing posterior placentas; at UCSF, patients undergoing accreta workup typically undergo USG and MRI on the same day; early diagnosis allows for outpatient consultations; if the diagnosis is made in the previable period, counseling on pregnancy termination is provided because of the high risks for maternal morbidity and mortality; counseling is based on imaging severity, gestational age, and symptoms

Management at UCSF: at UCSF, the care team holds a huddle, led by a high-risk nurse coordinator, to discuss the surgical plan, including the timing, location, diagnosis, personnel involved, anesthesia plan, and any necessary ancillary services; they also plan preoperative laboratory testing, pathology, and postoperative care; deliveries typically occur in a hybrid operating room with capability for surgery (eg, CD, hysterectomy) and interventional radiology (eg, uterine artery embolization [UAE]); anesthesia plans vary; patients typically receive combined spinal-epidural neuraxial anesthesia; many also undergo general anesthesia after birth; the team also uses cystoscopy with intraoperative ureteral stents to prevent urologic injuries; placental mapping is performed via direct USG on the uterus during surgery to guide a safe delivery; the rationale for UAE is to reduce blood flow to the uterus before hysterectomy to decrease blood loss during surgery; early assessment of the patient and planning are important because many patients have unscheduled deliveries; the protocol at UCSF has resulted in fewer intraoperative and postoperative complications, reduced maternal ICU admissions, and shorter hospital stays

Issues after discharge: patients often face significant long-term challenges post-discharge, including pain, depression, and anxiety that can persist for years; studies emphasize the need for better patient support, extended follow-up, and family-centered care; survivors report difficulties adapting to physical changes and accessing ongoing care; future research should explore alternatives to cesarean hysterectomy, the possibility of conservative management, and prevention strategies; early detection and specialized care are crucial for improving outcomes, but addressing long-term effects and developing preventive measures remain critical

Readings

Bloomfield V, Rogers S, Leyland N. Placenta accreta spectrum. CMAJ. 2020;192(34):E980. doi:10.1503/cmaj.200304; Donovan BM, Shainker SA. Placenta accreta spectrum. Neoreviews. 2021;22(11):e722-e733. doi:10.1542/neo.22-11-e722; Einerson BD, Gilner JB, Zuckerwise LC. Placenta accreta spectrum. Obstet Gynecol. 2023;142(1):31-50. doi:10.1097/AOG.0000000000005229; Horgan R, Abuhamad A. Placenta accreta spectrum: Prenatal diagnosis and management. Obstet Gynecol Clin North Am. 2022;49(3):423-438. doi:10.1016/j.ogc.2022.02.004; Jauniaux E, Jurkovic D, Hussein AM, et al. New insights into the etiopathology of placenta accreta spectrum. Am J Obstet Gynecol. 2022;227(3):384-391. doi:10.1016/j.ajog.2022.02.038; Liu X, Wang Y, Wu Y, et al. What we know about placenta accreta spectrum (PAS). Eur J Obstet Gynecol Reprod Biol. 2021;259:81-89. doi:10.1016/j.ejogrb.2021.02.001.

Disclosures

For this program, members of the faculty and planning committee reported nothing relevant to disclose.

Acknowledgements

Dr. Cassidy was recorded at the 47th Annual Antepartum and Intrapartum Management, held May 30 to June 1, 2024, in San Francisco, CA, and presented by University of California, San Francisco. For information about upcoming CME activities from this presenter, please visit Cme.ucsf.edu. Audio Digest thanks the speakers and presenters for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 1.00 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 1.00 CE contact hours.

Lecture ID:

OB711902

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.