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Am J Perinatol 2023; 40(13): 1398-1405
DOI: 10.1055/a-2099-4542
SMFM Fellowship Series Article

Factors Limiting Magnetic Resonance Imaging Diagnosis of Placenta Accreta Spectrum

CeCe Cheng 
1   Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Texas Health Science Center at San Antonio, Texas
,
Patrick S. Ramsey
1   Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Texas Health Science Center at San Antonio, Texas
,
John J. Byrne
1   Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Texas Health Science Center at San Antonio, Texas
,
Venkata S. Katabathina
2   Department of Radiology, University of Texas Health Science Center at San Antonio, Texas
,
Kayla E. Ireland
3   Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Methodist Hospital San Antonio, Texas
,
Jessian L. Munoz 
4   Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, Texas
› Author Affiliations
Funding None.
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Abstract

Objective Placenta accreta spectrum (PAS) disorders are characterized by an abnormal adherence of the placenta to the uterine myometrium. Magnetic resonance imaging (MRI) is an important adjunct in antenatal diagnosis. We sought to determine if there are patient and MRI characteristics that limit the accuracy of PAS diagnosis and degree of invasion.

Study Design We conducted a retrospective cohort analysis of patients who were evaluated for PAS by MRI from January 2007 to December 2020. Patient characteristics evaluated included number of prior cesarean deliveries, history of dilation and curettage (D&C) or dilation and evacuation (D&E), short interval pregnancy less than 18 months, and delivery body mass index (BMI). All patients were followed until delivery and MRI diagnosis was compared with final histopathology.

Results Of the 353 patients with suspected PAS, 152 (43%) underwent MRI evaluation and were included in the final analysis. In patients who underwent MRI evaluation, 105 (69%) had confirmed PAS on pathology. Patient characteristics were similar between groups and not associated with accuracy of MRI diagnosis. MRI was accurate in diagnosing PAS and the associated degree of invasion in 83 (55%) patients. Accuracy was associated with lacunae (8 vs. 0%, p = 0.02), abnormal bladder interface (25 vs. 6%, p = 0.002), and T1 hyperintensity (13 vs. 1%, p = 0.002). Of the 69 (45%) patients in whom MRI was inaccurate, overdiagnosis was seen in 44 (64%) patients and underdiagnosis in 25 (36%) patients. Overdiagnosis was significantly associated with dark T2 bands (45 vs. 22%, p = 0.005). Underdiagnosis was associated with earlier gestational age at MRI (28 vs. 30 weeks, p = 0.049) and lateral placentation (16 vs. 2.4%, p = 0.025).

Conclusion Patient factors did not change MRI accuracy of PAS diagnosis. MRI is associated with a significant overdiagnosis of PAS when dark T2 bands are present, and underdiagnose PAS when performed earlier in gestation or when lateral placentation is present.

Key Points

  • Patient factors are not associated with MRI accuracy of PAS diagnosis.

  • MRI overdiagnoses PAS invasion when there are dark T2 bands.

  • MRI underdiagnoses PAS invasion when performed earlier in gestation.

  • Underdiagnosis of PAS is associated with lateral placentation.

Keywords

magnetic resonance imaging - placenta accreta spectrum - abnormally invasive placenta - ultrasonography - diagnosis - accuracy - limitations

Note

These findings of this study were presented at the Society for Maternal-Fetal Medicine's 42nd Annual Pregnancy Meeting, Virtual, January 31–February 5, 2022.




Publication History

Received: 02 November 2022

Accepted: 22 May 2023

Accepted Manuscript online:
24 May 2023

Article published online:
26 June 2023

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