Placenta Accreta Spectrum (PAS)

Dr. Einerson is an assistant professor of OB/GYN in the division of Maternal Fetal Medicine (MFM) and Director of the Utah Placenta Accreta Program at the University of Utah, one of the busiest referral programs for PAS in the United States.

The doctors first discuss Dr. Einerson’s career path toward specialization in PAS. During his MFM fellowship in Utah, he encountered many difficult cases of PAS. He has had patients who have delivered 6-10 babies, and in Utah, family size is almost twice as large as the national average. PAS studies from overseas show that the median number of C-sections is 0 to 1 while Dr. Einerson's average accreta patient has had 2-3 prior C-sections. Given that there was not alot of research informing treatment for patients with PAS, Dr. Einerson was motivated to fill the void and embraced the diagnostic and surgical challenges associated with PAS.

Dr. Einerson goes on to give a definition for PAS, which is a rare obstetric complication where the placenta attaches abnormally into the uterus and doesn’t let go at the time of delivery. Consequently, there is an increased risk for significant hemorrhage. As its name suggests, PAS exists on a spectrum. There are milder cases where the placenta is just abnormally attached and may not even look different either sonographically or physically at the time of delivery. Then there are severe cases in which the placenta attaches into the prior scar, completely remodels the uterus, and distorts the normal pelvic anatomy by turning the pelvic vasculature into a kind of “superhighway of blood flow.”

Dr. Einerson then discusses the etiology and pathophysiology of PAS. An embryo or early placenta attaches into a very small area of C-section scar or other scar from prior surgery. In the most severe forms of PAS, the placenta is growing within a C-section scar, stretching, distorting, and ultimately remodeling that part of the uterus and possibly other surrounding anatomical structures. PAS is an attachment and remodeling problem.

The physicians go on to review the grading and classification of PAS. Although the traditional nomenclature uses accreta, increta, and percreta, pathologists and clinicians are noting that these descriptions of placenta accreta may not fully capture what the disease looks like in the hands of a surgeon. Now, there is increasing use of FIGO clinical grades 1, 2, and 3, which describes how PAS looks at the time of delivery. FIGO stage 1 involves attachment with no other changes, 2 describes vascular changes appearing on the outside of the uterus but no placental extension into the serosa, and stage 3 involves placenta that extends to the serosa with significant vascular changes.

Next, Dr. Einerson describes the logistics of setting up and operating an interdisciplinary PAS team. He suggests assembling a small, central team of people from the specialities involved who are interested in taking care of PAS cases and who can also form the core call team. A local champion is needed, and this person can be from general OB/GYN, gynecologic oncology, MIGS or MFM. At the Utah Placenta Accreta Program, the interdisciplinary team consists of a surgically inclined general OB/GYN, two MFMs who have received additional training in surgical care or PAS, and several interested gynecologic oncologists. Dr. Einerson recommends conducting a monthly interdisciplinary meeting, similar to tumor board, to discuss PAS cases. Other specialities to include in the meeting include anesthesia, radiology, pathology, NICU, gynecologic surgery, and others who may be involved such as urology, general surgery, trauma surgery, or interventional radiology.

Dr. Einerson goes on to discuss the difficulties of diagnosing PAS. Early PAS diagnosis starts with vigilant screening. Ultrasound is an important tool for screening, however even more critical is identifying patient risk factors such as prior C-sections and low-lying placenta. Caesarean scar pregnancy (CSP) and early placenta accreta spectrum are overlapping pathologies that have almost identical risk factors and very similar appearances. Dr. Einerson believes that most CSPs are early accretas. He advocates for high suspicion in patients with risk factors and a low threshold for referral to a specialty center for a second opinion.

Next, Dr. Einerson discusses what happens after PAS is diagnosed. His recommendation for black-and-white CSP deep within the scar at less than 10 weeks is pregnancy termination. The outcomes of early CSP treatment are much better than waiting for an ultrasound at 11 weeks, at which point the patient already has accreta and hysterectomy is almost unavoidable. Counseling patients with borderline PAS is much more difficult, according to Dr. Einerson. For these patients, overpreparation is key. This is likely to involve monthly ultrasounds as well as introducing the patients early on to the anesthesiology team, pelvic surgeons, and labor and delivery triage in case of a bleeding event. Unfortunately, patients may have to spend most of their pregnancy in the hospital.

Finally, the doctors end by discussing social determinants of health, access to care, as well as the psychological toll of a PAS diagnosis.