Placenta Accreta Spectrum Among Patients Seeking Abortion

By Vinita Goyal, MD, MPH

Nearly one in every five U.S. residents seeking abortion in 2023 had to travel across states lines for care.¹ Many of these patients have complicated medical histories in which care could be optimized with preprocedural planning.² Placenta accreta spectrum (PAS), with its attendant risk of hemorrhage, is one such condition in which evaluation prior to abortion-related travel can improve patient outcomes and minimize delays in care.³

Definition and Incidence

PAS includes three variants of invasive placentation. Placenta accreta refers to the invasion of placental villi on the surface of the myometrium, increta involves invasion into the myometrium, and in percreta, villi penetrate through the myometrium to the uterine serosa.⁴

The incidence of PAS has increased since the 1970s, which likely is attributable to the increased rate of cesarean deliveries.⁵ An analysis of hospital discharges between 1998 and 2011 estimated 3.7 cases of placenta accreta per 1,000 deliveries.⁶ Despite case reports describing PAS among patients seeking abortion, its incidence in this population is unknown.^7-9

Risk Factors

Components of the patient’s medical history that may trigger evaluation for PAS include prior cesarean delivery, placenta previa, prior uterine curettage, Asherman syndrome, multiparity, and advanced maternal age.⁵ Although the complication rate associated with second trimester (14-27 weeks’ gestation) procedural abortions is approximately 1%, patients with a history of two or more cesarean deliveries have a seven-fold increased odds of major complications, including hemorrhage.¹⁰

Previa alone is not associated with postabortion hemorrhage, but previa in the setting of prior cesarean delivery is strongly associated with PAS.^5,11 Patients undergoing their first cesarean delivery who have placenta previa have a 3% risk of placenta accreta. The risk of placenta accreta diagnosed at the time of repeat cesarean delivery steadily increases as the number of cesarean deliveries increases (11% with the second, 40% with the third, 61% with the fourth, and 67% with the fifth or more cesarean deliveries in the setting of placenta previa).¹²

Sonographic Findings

Placenta previa in the context of prior cesarean delivery is the most important sonographic indicator of PAS, presenting in more than 80% of cases complicated by accreta in the second or third trimester. Other sonographic findings associated with PAS, which may be detected even in the first trimester, include numerous large and irregular lacunae within the placenta, loss of the normal hypoechoic zone between the placenta and myometrium, thinning of the myometrium overlying the placenta (less than 1 mm), interruption of the bladder wall, and extension of the placenta into myometrium, serosa, or bladder.^5,13-15 Use of color flow Doppler may be helpful in identifying other indicators of PAS, including turbulent lacunar blood flow, increased uterovesical or subplacental vascularity, gaps in myometrial blood flow, and bridging vessels from the placenta to uterine margin or bladder.^5,13,14

Ultrasonography is the primary diagnostic modality for evaluating PAS and is best performed by experienced healthcare professionals with expertise in sonography.⁵ Yet, no ultrasound features reliably predict the depth of placenta invasion or type of PAS. Additionally, the absence of suggestive ultrasound findings does not rule out PAS. Clinical risk factors remain as important as sonographic findings in the evaluation of and preparation for PAS.⁵

It is unclear if magnetic resonance imaging (MRI) improves PAS diagnosis beyond what is achieved by ultrasound. Currently, MRI is more expensive and less available, and there is limited expertise in interpretation for PAS compared to ultrasound.⁵

The American College of Obstetricians and Gynecologists recommends focused imaging to evaluate for PAS in a patient with placenta previa and prior cesarean delivery who is past 14 weeks’ gestation.¹⁶ Similarly, the Society of Family Planning recommends evaluation of placental location in all patients with a uterine scar presenting for second trimester abortion and detailed sonographic evaluation if complete previa is identified.¹¹

Although ultrasound is the best way to evaluate PAS, patients traveling for abortion may have difficulty accessing trustworthy care by an experienced clinician in their home state.¹⁷ Similarly, healthcare providers with expertise in evaluating patients with medically complicated pregnancies may feel constrained by state-based abortion restrictions, leading to limited shared decision-making, lack of coordinated multidisciplinary management, compromised patient care, and potentially greater risk for traveling patients.¹⁸

Management of Hemorrhage During Procedural Abortion Complicated by PAS

Patients with suspected or diagnosed PAS are considered high risk for abortion-related hemorrhage.¹¹ A case series of 42 patients undergoing postabortion uterine artery embolization attributed 17% of hemorrhage cases to abnormal placentation.¹⁹ Hemorrhage with first-trimester abortion from placenta accreta is rare; however, prolonged post-procedure bleeding may indicate undiagnosed placenta increta.¹¹ For second-trimester abortion procedures complicated by PAS, hemorrhage can occur at the time of placental detachment or removal.¹¹

For patients undergoing procedural abortion in the outpatient setting in which PAS is unexpectedly recognized, temporizing measures may be used to reduce blood loss. Uterine massage and uterotonic therapy (methergine 0.2 mg intramuscularly [IM] and misoprostol 800 mcg to 1,000 mcg sublingually or buccally for the most rapid effect and highest concentration) are first-line.¹¹ Vasoconstriction with vasopressin placed intra- or paracervically may be helpful.¹¹

There is no evidence to guide the use of oxytocin in the treatment of post-abortion hemorrhage, but prophylactic administration of 10 units IM or 10 units to 40 units intravenously (IV) is associated with decreased blood loss during dilation and evacuation among patients at 18-24 weeks’ gestation who do not have PAS.^11,20

If bleeding is not controlled with first-line measures, secondary measures include placement of additional IV lines, fluid resuscitation, hemoglobin testing, and transfer to a higher acuity facility. Despite limited evidence in the setting of postabortion hemorrhage, the Society of Family Planning suggests tranexamic acid (TXA) is safe and effective for prophylaxis and treatment of hemorrhage at the time of abortion based on encouraging evidence in the treatment of postpartum hemorrhage.¹¹ TXA inhibits fibrinogen breakdown and can be administered in a 1,000-mg dose 30 minutes before the procedure over 10 minutes when used as prophylaxis or as an IV push when used as treatment.¹¹

Additional secondary measures that may be helpful include reaspiration if reaccumulation of intrauterine blood is noted on ultrasound. Intrauterine placement of a Foley catheter (inflated with 30 cc to 80 cc of normal saline) or Bakri balloon (maximum capacity 500 cc, but 120 cc to 250 cc may be sufficient) to tamponade the endometrium also may be effective. Intrauterine balloons can be left in place 12-24 hours for tamponade and patient stabilization. A shorter course of one to 12 hours may be sufficient if hemostasis is achieved rapidly and the patient is hemodynamically stable.¹¹

Tertiary treatments performed in a hospital setting include uterine artery embolization (UAE), laparoscopy, laparotomy, or hysterectomy if primary and secondary treatment measures are unsuccessful.¹¹ Pre-procedure UAE has been suggested to decrease blood loss when there is a high suspicion of placenta accreta, but this may not preclude the need for hysterectomy.¹¹ Management of postabortion hemorrhage with UAE may be more successful because bleeding vessels can be directly targeted.¹¹ Cesarean hysterectomy is the most generally accepted approach to PAS for patients delivering at or near term.⁵ Yet, there are no specific recommendations for planned gravid hysterectomy in patients seeking abortion.

Because PAS can lead to severe and sometimes life-threatening hemorrhage requiring blood transfusion or hysterectomy, patients with pre-operatively suspected or diagnosed PAS are recommended to receive care in higher-acuity facilities with continuously available interdisciplinary staff, including experienced obstetrician-gynecologists, maternal fetal medicine, pelvic surgeons, interventional radiologists, obstetric anesthesiologists, critical care experts, trauma surgeons, strong nursing leadership, and a blood bank accustomed to managing massive blood transfusions.^5,11,21

Pre-operative diagnosis of PAS may be associated with decreased blood loss at the time of second-trimester abortion as is true for term and near-term delivery.^5,11 Additionally, optimizing the patient’s hemoglobin level prior to abortion may lead to better outcomes.⁵

Conclusion

Abortion restrictions within the United States have placed all people, including those with complicated health histories, at risk for devastating psychological, financial, and medical outcomes.³ Patients at risk for PAS based on a history of cesarean delivery, especially in the setting of placenta previa, have a difficult time accessing ultrasound evaluation by experienced healthcare providers in their home states, leading to delays in obtaining care, challenges obtaining coordinated multidisciplinary and hospital-based care, if needed, and potentially worse outcomes.

From a human rights perspective, the World Health Organization advises that post-abortion care should be available on a confidential basis without the threat of criminal prosecution, regardless of whether abortion is legal.²² Likewise, no current U.S. state law prohibits pre-abortion evaluation for those traveling to obtain lawful abortion care.

The Society of Maternal-Fetal Medicine recommends evaluation and planned delivery at centers of excellence in placenta accreta for those who wish to continue their pregnancy.²³ In this era of state-based abortion restrictions requiring many patients to travel for care, relying on these centers of excellence for sonographic evaluation of PAS may lead to greater coordination of care between maternal-fetal medicine specialists practicing in restrictive states and abortion providers in states receiving traveling patients. This coordination can help minimize delays in care and may lead to better outcomes for patients with suspected PAS who are seeking abortion.

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Vinita Goyal, MD, MPH, is Clinician Researcher, Alamo Women’s Health Clinic of Albuquerque, Albuquerque, NM.