Accuracy of ultrasound and magnetic resonance imaging in predicting placenta accreta: A retrospective study

Premkumar Jaisankar; M Vasantha Kumar; R Rajesh Gowtham; T Vinoth

doi:10.4103/cmi.cmi_85_22

ORIGINAL ARTICLE

Year : 2023 | Volume : 21 | Issue : 2 | Page : 83-87

Accuracy of ultrasound and magnetic resonance imaging in predicting placenta accreta: A retrospective study

Premkumar Jaisankar¹, M Vasantha Kumar², R Rajesh Gowtham², T Vinoth²
¹ Department of Radiology, MGM Healthcare, Chennai, Tamil Nadu, India
² Department of Radiology, ACS Medical College and Hospital, Chennai, Tamil Nadu, India

Date of Submission	12-Aug-2022
Date of Decision	14-Oct-2022
Date of Acceptance	04-Nov-2022
Date of Web Publication	07-Apr-2023

Correspondence Address:
Dr. T Vinoth
No. 112, Canal Bank Road, CIT Nagar, Chennai - 600 035, Tamil Nadu
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/cmi.cmi_85_22

Abstract

Background: Placenta accreta can cause significant morbidity and mortality in pregnant women. Timely diagnosis is essential for management. This study aimed to evaluate the accuracy of ultrasound (USG) and magnetic resonance imaging (MRI) techniques in predicting placenta accreta. Methodology: A retrospective study was conducted at our institute from April 2014 to September 2017. Pregnant women with suspected placenta accrete were recruited for the study. Medical records of pregnant women who have undergone both USG and prenatal MRI were included. The accuracy of USG and MRI was compared. Results: Among the 56 cases evaluated in the study, the diagnosis was accurately obtained with ultrasonography in 75% of cases and with MRI in 68.51% of cases. Sensitivity for placenta accreta was 97.29% for USG and 78.37% for MRI. Specificities were 31.57% for USG and 47.05% for MRI. The positive predictive value was 73.46% for USG and 76.31% for MRI. Conclusion: Although a definite demarcation could not be obtained from the sensitivity, specificity, and positive predictive value of the placenta accrete with ultrasonography and MRI, the diagnostic accuracy may be taken as a definite pointer. Hence, ultrasonography remains the mainstay of diagnosis for placenta accrete; and MRI can be considered complementary in cases with few USG signs.

Keywords: Diagnosis, magnetic resonance imaging, placenta accreta, ultrasonography

How to cite this article:
Jaisankar P, Kumar M V, Gowtham R R, Vinoth T. Accuracy of ultrasound and magnetic resonance imaging in predicting placenta accreta: A retrospective study. Curr Med Issues 2023;21:83-7

How to cite this URL:
Jaisankar P, Kumar M V, Gowtham R R, Vinoth T. Accuracy of ultrasound and magnetic resonance imaging in predicting placenta accreta: A retrospective study. Curr Med Issues [serial online] 2023 [cited 2023 Jun 4];21:83-7. Available from: https://www.cmijournal.org/text.asp?2023/21/2/83/373760

Introduction

The term placenta accreta is used when there is pathological penetration of the placenta into the wall of the uterus. Currently, it is a major cause of morbidity and mortality among pregnant women. Placenta accreta has been classified based on the degree of penetration into superficial invasions (placenta accreta), middle-layer invasions (placenta increta), and deep invasions (placenta percreta). For the convenience of this study, all these types are considered placenta accreta.

Placenta accreta is closely associated with cesarean section.^[1],[2] Moreover, so, with a rise in the rate of cesarean section, the incidence of placenta accrete is also increasing. It has risen from 0.8/1000 deliveries in the 1980s to 3/1000 deliveries in the last decade.^{[3],[4],[5],[6],[7],[8]} Although the reasons for the increased incidence of placenta accrete are multifactorial, its association with the cesarean section is explained by the fact that the place placental penetration is mostly in the previous hysterotomy area.^[6],[8],[9] Various other risk factors include the age of the mother and high parity, previous surgeries on the uterus, previous uterine curettage, radiation exposure to the uterus, endometrial ablation procedures in past, and other anomalies of the uterus, hypertensive disorders of pregnancy, and smoking.^{[5],[6],[10],[11],[12],[13],[14],[15]} Studies have shown that placenta accreta is associated with poor neonatal outcomes including preterm birth, low birth weight, small for gestational age, and reduced APGAR score.^[11]

Antepartum identification of placenta accretes is commonly done in the second or third trimester using ultrasonography. The commonly observed ultrasonography findings are loss of normal hypoechoic retroplacental zone,^[11] multiple vascular lacunae (irregular vascular spaces) within the placenta, giving a “swiss cheese” appearance,^{[16],[17],[18]} blood vessels or placental tissue bridging uterine placental margin, myometrial–bladder interface, or crossing uterine serosa,^[19] and the retroplacental myometrial thickness of <1 mm.^[11] Numerous coherent vessels are visualized with three-dimensional power Doppler in basal view.^[20]

Studies comparing magnetic resonance imaging (MRI) with ultrasound (USG) for the identification of placenta accreta have shown conflicting results.^[16],[21]

Objectives

The objective of this study was to evaluate the accuracy of USG and MRI techniques in predicting placenta accreta.

Methodology

Study design and study setting

A descriptive retrospective analysis of all medical records of patients with suspicion of placenta accreta referred to the hospital from April 2014 to September 2017 was done.

Study population

The study population included pregnant women with both USG and prenatal MRI for suspicion of placenta accreta. The clinical data of the patient were recorded in a proforma.

Methods

The USG and MRI for these patients were performed by radiologists with experience of 5–10 years and specialized in fetal medicine. The equipment used was IU 22 system (Philips Medical Systems, Bothell, WA, USA) and the GE Voluson 730 or E8 (GE Medical Systems, Zipf, Austria) with 4–9 MHz or 5–9 MHz transabdominal transducers and 3–9 MHz and 4–8 MHz endovaginal transducers. MRI was performed with a 1.5 Tesla scanner (Siemens Magnetom-Avanto, Siemens Magnetom-vision [Siemens Medical Solutions], Philips Achieva). The MRI protocol included T1-weighted sequences in the sagittal and axial planes, single-shot fast spin echo T2-weighted magnetic resonance sequences (HASTE, single-shot TSE), and true fast imaging with steady-state precession (TrueFISP, FIESTA) in the axial, sagittal, and coronal planes. Seven MRI scans were done after intravenous injection of gadolinium, and six were MR diffusion-weighted imaging. No fetal sedation was used. For the purpose of the study, USG images and MRI were blindly reassessed external reviewers. Blinding was done regarding the diagnosis of the patient.

Operational definitions

In patients where pathologic examination was not possible, and the final diagnosis was done as per the clinical information provided at the time of delivery and surgery. The placenta was considered accreta when the delivery was impossible and as percreta when it was evident that the placenta had reached the uterine serosa or the adjacent organs.^[5]

Sample size calculation

The sample size was calculated assuming the sensitivity of USG and MRI in detecting placenta accreta as 100%–76.9%, respectively, as per a study by Riteau et al.^[22] By considering the 80% power and 2:1 positive-to-negative allocation ratio, the proposed sample size was 51. After consideration of 10% lost to follow-up, the final sample size considered in the study was 56.

Statistical analysis

The placenta accretes results as per USG and MRI results as count variables using frequency and percentages. The sensitivity, specificity, predictive values, and diagnostic accuracy of the USG and MRI in predicting placenta accreta, along with their 95% confidence interval have been presented. USG was used as a gold standard test. P < 0.05 was considered statistically significant. Data were analyzed using coGuide software, V.1.03 (BDSS, Bangalore, India).^[23]

Results

All the participants were between 21 and 32 years of age. Among them, 30 women were the second gravida and 26 women were the third gravida. USG scans and MRIs were performed in the third trimester for all pregnant women. All patients are delivered by lower-segment cesarean section.

There was no statistically significant difference between the two groups in USG outcome parameters such as intraplacental lacunae, thinning or disappearance of the myometrium, thinning or disruption of the hyperechogenic uterine serosa–bladder wall interface, increased vascularization at the uterine serosa–bladder wall interface, irregular bladder wall, and pseudotumoral appearance of placenta and uterine bulging (P > 0.05). There was a statistically significant difference between the two groups in USG outcome parameters such as loss of the normal retroplacental clear space, vascularization perpendicular to the uterine wall, and exophytic uterine masses [P < 0.05, [Table 1]].

Table 1: Ultrasound outcomes (n=56)

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There was no statistically significant difference between the two groups in MRI outcome parameters such as disruption of the interface between placenta and myometrium on T2-weighted images, the extension of the placenta on T2-weighted images, dark intraplacental bands, and thinning or disappearance of the myometrium, dark intraplacental bands, and disruption of the interface between placenta and myometrium and uterine bulging and dark intraplacental bands (P > 0.05). There was a statistically significant difference between the two groups in MRI outcome parameters such as uterine bulging, dark intraplacental bands on T2-weighted images, thinning or disappearance of the myometrium, and the presence of neovessels [P < 0.05, [Table 2]].

Table 2: Magnetic resonance imaging outcomes (n=56)

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The sensitivity for placenta accreta was 97.29% for USG and 78.37% for MRI. Specificities were 31.57% for USG and 47.05% for MRI. The positive-predictive value was 73.46% for USG and 76.31% for MRI. The diagnostic accuracy was 75% of cases with ultrasonography and in 68.51% with MRI [Table 3].

Table 3: Predictive validity of ultrasound and magnetic resonance imaging in predicting placenta accrete (n=56)

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Discussion

As per the existing literature, the sensitivity of Doppler USG in predicting placenta accreta arrays is from 33% to 100% and its specificity is from 50% to 96%.^{[20],[24],[25],[26],[27],[28],[29]} and the sensitivity of MRI varies from 38% to 100% and its specificity from 55% to 100%.^{[20],[25],[26],[27],[28],[29],[30]}

D'Antonio et al.^[30],[31] reported USG sensitivity of 90.7% and MRI sensitivity of 94.4% and a specificity of 96.9% for USG and 84% for MRI. While the sensitivity is similar to that of the present study, there is a wide difference in specificity; this difference can be attributed to the large sample size, the inclusion of multiple study findings, and the inclusion of the study population in which only one investigation was. The present study found a lower specificity of USG, perhaps because, as in Comstock et al.,^[18] placenta accrete was diagnosed even of one of the features was present. This can lead on to an increase in the number of false-positive diagnoses and a reduction in the overall specificity of the test.

The sensitivity observed for “loss of the normal retroplacental clear space” in the present study was higher than those found in the literature.^[18],[30] Cali et al.^[32] found the same results.

As in the literature,^{[31],[32],[33],[34],[35],[36],[37]} this study also found the statistical significance of MRI when dark intraplacental bands were associated with thinning and disappearance of the myometrium.

Ultrasonography is still considered the imaging modality with high sensitivity for the diagnosis of placenta accrete due to its accuracy, cost-effective nature, and being noninvasive and less time-consuming procedure. MRI can be considered a complement to ultrasonography, in cases where there are very few USG signs. MRI is very useful as it will reveal signs which may not be picked up by USG such as dark intraplacental bands, this feature can be used to confirm the diagnosis of placenta accreta.

As cesarean section rates are on the rise worldwide, the best strategy would be: to identify the early diagnosis and treatment strategy. There is a lack of randomized clinical trials and cohort studies done in cases of placenta accreta and not much evidence is available on the diagnosis and management. Such studies are needed to recommended in future to optimize care and to enable antepartum diagnosis of placenta accreta, thereby preventing morbidity and mortality caused.

Conclusion

Based on the diagnostic accuracy, it can be concluded that ultrasonography remains the backbone of diagnosis for placenta accrete; and MRI can be considered a complementary diagnostic modality to ultrasonography, especially when there are limited USG signs.

Limitations

Study is a hospital-based study performed at a single tertiary center. The generalizability of the study outcome is limited.

Acknowledgments

We acknowledge the technical support in manuscript editing by “Evidencian Research Associates.”

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Ethical statement

The Institutional Ethics Review Board approved the conduct of this study (Ref: CSP-MED/16/JUN/29/66).

References

1.	Martin JA, Hamilton BE, Sutton PD, Ventura SJ, Menacker F, Munson ML. Births: Final data for 2002. Natl Vital Stat Rep 2003;52:1-113.
2.	Kozak LJ, Weeks JD. U.S. Trends in obstetric procedures, 1990-2000. Birth 2002;29:157-61.
3.	Flood KM, Said S, Geary M, Robson M, Fitzpatrick C, Malone FD. Changing trends in peripartum hysterectomy over the last 4 decades. Am J Obstet Gynecol 2009;200:6.e1-6.
4.	Imudia AN, Awonuga AO, Dbouk T, Kumar S, Cordoba MI, Diamond MP, et al. Incidence, trends, risk factors, indications for, and complications associated with cesarean hysterectomy: A 17-year experience from a single institution. Arch Gynecol Obstet 2009;280:619-23.
5.	Wu S, Kocherginsky M, Hibbard JU. Abnormal placentation: Twenty-year analysis. Am J Obstet Gynecol 2005;192:1458-61.
6.	Clark SL, Koonings PP, Phelan JP. Placenta previa/accreta and prior cesarean section. Obstet Gynecol 1985;66:89-92.
7.	Read JA, Cotton DB, Miller FC. Placenta accreta: Changing clinical aspects and outcome. Obstet Gynecol 1980;56:31-4.
8.	Silver RM, Landon MB, Rouse DJ, Leveno KJ, Spong CY, Thom E. National Institute of child health and human development maternal-fetal medicine units network. Maternal morbidity associated with multiple repeat cesarean deliveries. Obs Gynecol 2006;107:1226-32.
9.	Usta IM, Hobeika EM, Musa AA, Gabriel GE, Nassar AH. Placenta previa-accreta: Risk factors and complications. Am J Obstet Gynecol 2005;193:1045-9.
10.	Miller DA, Chollet JA, Goodwin TM. Clinical risk factors for Placenta previa-Placenta accreta. Am J Obstet Gynecol 1997;177:210-4.
11.	Gielchinsky Y, Mankuta D, Rojansky N, Laufer N, Gielchinsky I, Ezra Y. Perinatal outcome of pregnancies complicated by Placenta accreta. Obstet Gynecol 2004;104:527-30.
12.	Norwitz ER, Stern HM, Grier H, Lee-Parritz A. Placenta percreta and uterine rupture associated with prior whole body radiation therapy. Obstet Gynecol 2001;98:929-31.
13.	Hoffman MK, Sciscione AC. Placenta accreta and intrauterine fetal death in a woman with prior endometrial ablation: A case report. J Reprod Med 2004;49:384-6.
14.	Shellhaas CS, Gilbert S, Landon MB, Varner MW, Leveno KJ, Hauth JC, et al. The frequency and complication rates of hysterectomy accompanying cesarean delivery. Obstet Gynecol 2009;114:224-9.
15.	Henriet E, Roman H, Zanati J, Lebreton B, Sabourin JC, Loic M. Pregnant noncommunicating rudimentary uterine horn with Placenta percreta. JSLS 2008;12:101-3.
16.	Levine D, Hulka CA, Ludmir J, Li W, Edelman RR. Placenta accreta: Evaluation with Color Doppler US, power Doppler US, and MR imaging. Radiology 1997;205:773-6.
17.	Hull AD, Salerno CC, Saenz CC, Pretorius DH. Three-dimensional ultrasonography and diagnosis of Placenta percreta with bladder involvement. J Ultrasound Med 1999;18:853-6.
18.	Comstock CH, Love JJ Jr., Bronsteen RA, Lee W, Vettraino IM, Huang RR, et al. Sonographic detection of Placenta accreta in the second and third trimesters of pregnancy. Am J Obstet Gynecol 2004;190:1135-40.
19.	Wong HS, Cheung YK, Zuccollo J, Tait J, Pringle KC. Evaluation of sonographic diagnostic criteria for Placenta accreta. J Clin Ultrasound 2008;36:551-9.
20.	Lam G, Kuller J, McMahon M. Use of magnetic resonance imaging and ultrasound in the antenatal diagnosis of Placenta accreta. J Soc Gynecol Investig 2002;9:37-40.
21.	Shih JC, Palacios Jaraquemada JM, Su YN, Shyu MK, Lin CH, Lin SY, et al. Role of three-dimensional power Doppler in the antenatal diagnosis of Placenta accreta: comparison with gray-scale and color Doppler techniques. Ultrasound Obstet Gynecol 2009;33:193-203.
22.	Riteau AS, Tassin M, Chambon G, Le Vaillant C, de Laveaucoupet J, Quéré MP, et al. Accuracy of ultrasonography and magnetic resonance imaging in the diagnosis of Placenta accreta. PLoS One 2014;9:e94866.
23.	BDSS Corp. Released. Coguide Statistics Software, Version 1.0.3, India: BDSS corp; 2020. Available from: https://www.coguide.in. [Last accessed on 2022 Aug 09].
24.	Chou MM, Ho ES, Lee YH. Prenatal diagnosis of Placenta previa accreta by transabdominal color Doppler ultrasound. Ultrasound Obstet Gynecol 2000;15:28-35.
25.	Millischer-Bellaıche AE, Grange'G, Adamsbaum C. Imagerie des placentas accretas. Imag Femme 2009;19:84-8.
26.	Warshak CR, Eskander R, Hull AD, Scioscia AL, Mattrey RF, Benirschke K, et al. Accuracy of ultrasonography and magnetic resonance imaging in the diagnosis of Placenta accreta. Obstet Gynecol 2006;108:573-81.
27.	Dwyer BK, Belogolovkin V, Tran L, Rao A, Carroll I, Barth R, et al. Prenatal diagnosis of Placenta accreta: Sonography or magnetic resonance imaging? J Ultrasound Med 2008;27:1275-81.
28.	Masselli G, Brunelli R, Casciani E, Polettini E, Piccioni MG, Anceschi M, et al. Magnetic resonance imaging in the evaluation of placental adhesive disorders: Correlation with color Doppler ultrasound. Eur Radiol 2008;18:1292-9.
29.	Lim PS, Greenberg M, Edelson MI, Bell KA, Edmonds PR, Mackey AM. Utility of ultrasound and MRI in prenatal diagnosis of Placenta accreta: A pilot study. AJR Am J Roentgenol 2011;197:1506-13.
30.	D'Antonio F, Iacovella C, Bhide A. Prenatal identification of invasive placentation using ultrasound: Systematic review and meta-analysis. Ultrasound Obstet Gynecol 2013;42:509-17.
31.	D'Antonio F, Iacovella C, Palacios-Jaraquemada J, Bruno CH, Manzoli L, Bhide A. Prenatal identification of invasive placentation using magnetic resonance imaging: Systematic review and meta-analysis. Ultrasound Obstet Gynecol 2014;44:8-16.
32.	Calì G, Giambanco L, Puccio G, Forlani F. Morbidly adherent Placenta: Evaluation of ultrasound diagnostic criteria and differentiation of Placenta accreta from percreta. Ultrasound Obstet Gynecol 2013;41:406-12.
33.	Lax A, Prince MR, Mennitt KW, Schwebach JR, Budorick NE. The value of specific MRI features in the evaluation of suspected Placental invasion. Magn Reson Imaging 2007;25:87-93.
34.	Kayem G, Grangé G, Goffinet F. Management of placenta accreta. Gynecol Obstet Fertil 2007;35:186-92.
35.	Lerner JP, Deane S, Timor-Tritsch IE. Characterization of Placenta accreta using transvaginal sonography and color Doppler imaging. Ultrasound Obstet Gynecol 1995;5:198-201.
36.	Thorp JM Jr., Councell RB, Sandridge DA, Wiest HH. Antepartum diagnosis of Placenta previa percreta by magnetic resonance imaging. Obstet Gynecol 1992;80:506-8.
37.	Derman AY, Nikac V, Haberman S, Zelenko N, Opsha O, Flyer M. MRI of Placenta accreta: A new imaging perspective. AJR Am J Roentgenol 2011;197:1514-21.