Optimal management of placenta accreta

Application of Color Doppler with 3- and 4-Dimensional Ultrasonography in the Prenatal Evaluation of Fetal Extracardiac and Placental Abnormalities

Using color Doppler flow imaging or high-definition flow imaging with three-dimensional volume or spatio-temporal image correlation (STIC) in the glass-body mode allows displaying both gray-scale and color information of the heart cycle-related flow events and vessel spatial relationship. Conventionally, STIC in the glass-body mode has been used to examine the fetal heart and assess heart defects. Recently, a novel application of STIC in the visualization of abdominal precordial veins and intraplacental vascularization in singleton pregnancies has been reported. The aim of this present review is to discuss the use of color Doppler with three- and four-dimensional ultrasonography in the evaluation of extracardiac, placental, umbilical cord and twin abnormalities with examples. The glass-body mode is complementary to conventional 2D ultrasonography. Further studies are required to investigate use of the glass-body mode in the assessment of intraplacental vascularization in singleton and twin pregnancies.

The value of a simple sonographic screening test for placenta accreta spectrum prediction: A case-control study

BACKGROUND

Placenta accreta spectrum (PAS) represents life-threatening conditions; however, early diagnosis reduces complications and mortality rates.

AIMS

To develop and evaluate the accuracy of a simple sonographic screening test for PAS prediction.

MATERIALS AND METHODS

A retrospective case-control study of 481 women with singleton pregnancies at 28 weeks or later, with a scarred uterus or placenta praevia, who underwent sonographic testing for PAS detection during 2010-2020. We compared demographic and sonographic features, and delivery outcomes between women who were and were not confirmed to have a PAS condition at delivery. We evaluated the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and predictive probability for the sonographic screening model.

RESULTS

Among all the women with at least one sonographic sign (large lacunae or loss of clear zone), the odds ratio (OR) of PAS was 21.7 (95% CI, 16.7-70.4), among those with placenta praevia (and at least one sonographic sign), the OR was 41.9 (95% CI, 15.8-111). For the screening model (the combinations of placental location (major or minor placenta praevia) with at least one sonographic sign (large lacunae or loss of clear zone)), sensitivity, specificity, PPV, NPV and predicted probability were 94.9% (85.8-98.9%), 91.5% (88.4-93.9%), 60.9% (50.1-70.9%), 99.2% (97.7-99.8%) and 92.3%, respectively.

CONCLUSIONS

A combination of simple ultrasound signs for PAS screening may be highly effective for prenatal assessment and prediction of placenta accreta. This screening test can be carried out as routine pregnancy follow-up for women with risk factors for PAS.

Antenatal diagnosis of placenta accreta spectrum (PAS) disorders

Antenatal diagnosis of placenta accreta spectrum (PAS) disorders allows planned management by a multidisciplinary team in a tertiary center, and thus can reduce hemorrhagic morbidity, compared with intrapartum diagnosis. Previous Cesarean section and placenta previa are the two most common risk factors. Prenatal ultrasound is a promising diagnostic tool for PAS in the second or third trimester. Recent evidence shows sonographic markers of PAS can be present in the first trimester. Prenatal ultrasound may help predict the depth and topography of placental invasion which are the major determinants of maternal morbidity. The presence of increased vascularity in the inferior part of the lower uterine segment and the parametrial region is associated with a more severe disorder according to a newly proposed staging system. In this chapter, we will discuss how to improve the prediction of PAS, the depth, and topography of placental invasion.

A comprehensive severity score for the morbidly adherent placenta: combining ultrasound and magnetic resonance imaging

BACKGROUND

Ultrasound (US) is the first-line imaging modality to assess the morbidly adherent placenta, but sensitivity and specificity are lacking.

OBJECTIVE

This investigation aims to improve diagnostic accuracy with a comprehensive score using clinical history, US, and magnetic resonance imaging (MRI).

MATERIALS AND METHODS

We conducted a retrospective cohort study of pregnant women who received both transvaginal US and MRI with suspicion for morbidly adherent placenta between 2009 and 2016. US was scored with the following metrics: (i) previa, (ii) hypervascularity, (iii) loss of retroplacental clear space and (iv) lacunae. MRI was evaluated for (i) intraparenchymal vessels, (ii) abnormally dilated vessels, (iii) fibrin deposition, (iv) placental bulge and (v) bladder dome irregularity. Bayesian analysis was used to estimate the probability of morbidly adherent placenta for a given score. Diagnostic testing parameters were calculated.

RESULTS

Among the 41 women with concerning imaging, histologically identified disease was confirmed in 16. The probability of morbidly adherent placenta increased with the score. At the highest US score, the probability of disease was 63.7%. With the highest MRI score, the probability of adherent placentation was 90.5%. Combining the US and MRI findings had a sensitivity of 56% and a specificity of 92%.

CONCLUSION

A combined scoring system using MRI and US may accurately identify patients at risk for morbidity associated with morbidly adherent placenta.

Ultrasound predictors of candidates for segmental resection in pregnants with placenta accreta

Objective: We aimed to assess the predictive values of individual sonographic findings of abnormal placentation to determine the candidates for segmental resectionStudy design: This was a retrospective review of 43 pregnancies with at least one prior cesarean delivery who received an ultrasound diagnosis of placenta previa or low-lying placenta with suspected abnormal placentation in the third trimester at our institution from 2015 through 2017. Sonographic images were reviewed by an investigator blinded to pregnancy outcome. Sonographic parameters were assessed including loss of retroplacental clear zone, irregularity and width of uterine-bladder interface, smallest myometrial thickness, presence of lacunar spaces, and bridging vessels. Diagnosis of placental invasion was based on histologic confirmation. Parameters were analyzed to predict candidates for conservative approach.Results: There were 27 cases with cesarean hysterectomy where as conservative approach was successful in 16 of the cases. Numbers of transfusions of packed red blood cells (2.6 vs. 1.7), fresh frozen plasma (2.3 vs. 0.9) and mean smallest retroplacental myometrial thickness (1.3 vs. 2.1 mm) were significantly different between the two groups (p < .05). Smallest retroplacental myometrial thickness was a significant predictor for the cases appropriate for successful conservative approach (Area Under Curve, AUC =0.911, p < .001), optimal cut off value was obtained at 1.6 mm with 94% sensitivity and 85% specificity.Conclusions: Our data showed that among some sonographic findings of abnormal placentation, smallest myometrial thickness was a significant predictor to determine candidates for conservative approach.

Prediction of morbidly adherent placenta using a scoring system

OBJECTIVE

To evaluate the accuracy of an ultrasound-based scoring system for diagnosing morbidly adherent placenta (MAP).

METHODS

This study included pregnant women referred to our ultrasound unit during 2013-2015 because of suspected MAP on a previous ultrasound examination or because they had at least one previous Cesarean delivery. All women were assessed using a scoring system based on the following: number and size of placental lacunae; obliteration of the demarcation between the uterus and placenta; placental location; color Doppler signals within placental lacunae; hypervascularity of the placenta-bladder and/or uteroplacental interface zone; and number of previous Cesarean deliveries. Each criterion was assigned 0, 1 or 2 points and the sum of points yielded the final score. Patients were classified into low, moderate or high probability for MAP based on the final score. The presence of MAP was determined by the surgeon at delivery and clinical descriptions were documented in the electronic patient file. Pathological diagnoses were available only in cases that underwent hysterectomy.

RESULTS

In total, 258 pregnant women were included in the study, of whom 23 (8.9%) were diagnosed with MAP. There was a statistically significant difference in the prevalence of MAP when women were grouped according to the scoring system, with 0.9%, 29.4% and 84.2% in the low, moderate and high probability groups, respectively (P < 0.0001). All sonographic criteria of the scoring system were significantly associated with MAP (P < 0.0001). Receiver-operating characteristics (ROC) curves for prediction of MAP using the number of placental lacunae and obliteration of the uteroplacental demarcation yielded an area under the ROC curve of 0.94 (95% CI, 0.86-1.00).

CONCLUSIONS

Our proposed scoring system is highly predictive of MAP in patients at risk. This allows an adequate multidisciplinary team approach for the planning and timing of delivery in such cases. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Abnormal placentation

Abnormal placentation poses a diagnostic and treatment challenge for all providers caring for pregnant women. As one of the leading causes of postpartum hemorrhage, abnormal placentation involves the attachment of placental villi directly to the myometrium with potentially deeper invasion into the uterine wall or surrounding organs. Surgical procedures that disrupt the integrity of uterus, including cesarean section, dilatation and curettage, and myomectomy, have been implicated as key risk factors for placenta accreta. The diagnosis is typically made by gray-scale ultrasound and confirmed with magnetic resonance imaging, which may better delineate the extent of placental invasion. It is critical to make the diagnosis before delivery because preoperative planning can significantly decrease blood loss and avoid substantial morbidity associated with placenta accreta. Aggressive management of hemorrhage through the use of uterotonics, fluid resuscitation, blood products, planned hysterectomy, and surgical hemostatic agents can be life-saving for these patients. Conservative management, including the use of uterine and placental preservation and subsequent methotrexate therapy or pelvic artery embolization, may be considered when a focal accreta is suspected; however, surgical management remains the current standard of care.