Subgroup analysis of accreta, increta and percreta cases using acoustic radiation force impulse elastography

Review of shear wave elastography in placental function evaluations

Background: Ultrasound is key to evaluating placental function. However, traditional ultrasound examinations cannot evaluate the changes in the biomechanical properties of the placenta in vivo. As a non-invasive technique, shear wave elastography (SWE) can be used analyze the physiological and biomechanical properties of the placenta. Moreover, it can evaluate the pathological changes in early placental insufficiency in a more direct and sensitive manner.Objective: This study aimed to systematically introduce SWE in placental function evaluations.Materials and methods: The terms 'placenta', 'ultrasound', and 'elastography' were searched on Pubmed, Embase, and CNKI databases (Apr 2023); this review was limited to results including placental sonoelastography.Results: Twenty-six studies satisfied the inclusion criteria and were included in this review. Herein, we introduce the basic principle of SWE, analyze the factors affecting placental measurements, and summarize the prospects of clinical applications of SWE in the field of obstetrical diseases.Conclusion: The SWE technology demonstrates excellent clinical application value and research prospects in obstetrics, particularly in placental function evaluation, owing to its objective and repeatable quantitative operation.

Modified Delphi study of ultrasound signs associated with placenta accreta spectrum

OBJECTIVE

To determine, by expert consensus through a modified Delphi process, the role of standardized and new ultrasound signs in the prenatal evaluation of patients at high risk of placenta accreta spectrum (PAS).

METHODS

A systematic review of articles providing information on ultrasound imaging signs or markers associated with PAS was performed before the development of questionnaires for the first round of the Delphi process. Only peer-reviewed original research studies in the English language describing one or more new ultrasound sign(s) for the prenatal evaluation of PAS were included. A three-round consensus-building Delphi method was then conducted under the guidance of a steering group, which included nine experts who invited an international panel of experts in obstetric ultrasound imaging in the evaluation of patients at high risk for PAS. Consensus was defined as agreement of ≥ 70% between participants.

RESULTS

The systematic review identified 15 articles describing eight new ultrasound signs for the prenatal evaluation of PAS. A total of 35 external experts were approached, of whom 31 agreed and participated in the first round. Thirty external experts (97%) and seven experts from the steering group completed all three Delphi rounds. A consensus was reached that a prior history of at least one Cesarean delivery, myomectomy or PAS should be an indication for detailed PAS ultrasound assessment. The panelists also reached a consensus that seven of the 11 conventional signs of PAS should be included in the examination of high-risk patients and the routine mid-gestation scan report: (1) loss of the 'clear zone', (2) myometrial thinning, (3) bladder-wall interruption, (4) placental bulge, (5) uterovesical hypervascularity, (6) placental lacunae and (7) bridging vessels. A consensus was not reached for any of the eight new signs identified by the systematic review. With respect to other ultrasound features that are not specific to PAS but increase the probability of PAS at birth, the panelists reached a consensus for the finding of anterior placenta previa or placenta previa with cervical involvement. The experts were also asked to determine which PAS signs should be quantified and consensus was reached only for the quantification of placental lacunae using an existing score. For predicting surgical outcome in patients with a high probability of PAS at delivery, a consensus was obtained for loss of the clear zone, bladder-wall interruption, presence of placental lacunae and presence of placenta previa involving the cervix.

CONCLUSIONS

We have confirmed the continued importance of seven established standardized ultrasound signs of PAS, highlighted the role of transvaginal ultrasound in evaluating the placental position and anatomy of the cervix, and identified new ultrasound signs that may become useful in the future prenatal evaluation and management of patients at high risk for PAS at birth. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Elevated serum YKL-40 levels as a diagnostic and prognostic marker in the placenta accreta spectrum

Objective:

Placenta accreta spectrum (PAS) is an important problem with increasing cesarean section (CS) rates recently. There is still no serum marker for the diagnosis. We determined whether serum YKL-40 levels can be used in the diagnosis and prognosis of PAS.

Materials and Methods:

The study was conducted with 50 patients with a PAS diagnosis, 27 individuals without PAS, and 33 normal pregnant women. The operations (CS + placental bed suture, CS + excision of the lower segment, CS-hysterectomy) and for individuals who had the excision of the lower segment /CS-hysterectomy, the histopathological diagnoses (accreta, increta, percreta) were recorded. Serum YKL-40 levels were analyzed.

Results:

The individuals with PAS possessed significantly greater serum YKL-40 grades (p=0.001). The surgical interventions included 4 CS + excision of the lower segment, 9 CS + placental bed sutures, and 37 CS-hysterectomy. The histopathological outcomes of the individuals who had the excision of the lower segment, CS-hysterectomy and diagnosed 6, 9, and 26 patients with accreta, increta, and percreta, respectively. The accreta, increta, and percreta groups showed statistically significant different serum YKL-40 grades (p=0.001). The receiver operating characteristic analysis was performed to discriminate the cut-off serum YKL-40 level as 32.81 ng/mL with a sensitivity of 66% and specificity of 70.37%. The positive and negative predictive values of YKL-40 in the indicator of PAS were 80.5% and 52.8%, respectively.

Conclusion:

Elevated serum YKL-40 grades were correlated with the diagnosis and severity of PAS. If our findings are corroborated and elaborated by larger patient series, the YKL-40 levels should be used along with ultrasonography to construct a model identical to that used in aneuploidy screening.

Shear wave velocity by quantitative acoustic radiation force impulse in the placenta of normal and high-risk pregnancy

Background

Traditionally, the placental functional integrity is suggested by indirect ultrasound measurements like fetal growth, amniotic fluid index, and uterine and umbilical artery Doppler indices. Only recently the elasticity of the placenta is studied as a measure of placental consistency and biomechanical prosperities and may reflect the placental function. Shear wave velocity is the quantitative parameter of the shear wave elastography. A high-risk pregnancy is a situation which puts the mother, the fetus, or both at greater risk than a normal pregnancy.

Results

The shear wave velocity (SWV) showed no significant difference between the placenta of normal pregnancies in the second and third trimesters (0.85 ± 0.43 m/s and 0.89 ± 0.57 m/s, respectively). The placenta of patients with preeclampsia/eclampsia had high SWV in the second and third trimesters (2.13 ± 1.48 m/s and 2.23 ± 1.48 m/s) with a highly significant difference from the normal placenta (P < 0.001). The placentas with abnormal location (placenta previa) and penetration (placenta accreta) had higher SWV than the placenta of normal pregnancies. The mean SWV for placenta previa was 1.1 ± 0.74 m/s and 1.3 ± 0.81 m/s in the second and third trimesters, respectively, with a mildly significant difference with the normal placenta. The placenta accreta shows high mean SWV in the second and third trimesters (1.6 ± 0.65 m/s and 1.961.6 ± 0.65, respectively) which differed significantly (P < 0.001) from SWV in the normal placenta in the second and third trimesters.

Conclusion

Shear wave velocity measurement as the quantitative parameter of acoustic radiation force impulse (ARFI) elastography reflects the placental elasticity in normal and high-risk pregnancies. The SWV increases in conditions like hypertension, preeclampsia, maternal renal disease, and diabetes and reflects the structural and biomechanical abnormalities in such diseases. High shear wave velocity correlates with the incidence of growth restriction and abnormal Doppler parameters especially in the hypertensive disease. The virtual touch quantification (VTQ) can be used as a complementary diagnostic and prognostic tool in high-risk pregnancy.

Can placental elasticity predict the time of delivery in cases of threatened preterm labor?

AIM

We aimed to evaluate placental elasticity for the short-time prediction of delivery in cases of threatened preterm labor (TPL).

METHODS

We performed a prospective study with consented pregnant women diagnosed with TPL (24th to 34th gestational week). According to the birth time, the patients were grouped into two groups, whether the delivery happened in the following first week or not. We compared the placental strain ratio (PSR) values between these two groups.

RESULTS

A total of 108 pregnant women divided into two groups according to the delivery time were enrolled in our study. The pregnant women who had a delivery in 1 week after hospitalization have increased PSR values when compared to those who have not delivered within 1 week (P < 0.001). Multivariate logistic regression analysis showed that cervical length and PSR were significantly associated with delivery in 1 week after hospitalization. When the cervical length was entered as a covariate (control) variable, PSR was significantly associated with delivery time (B = 0.504, odds ratio: 1.655, 95% confidence interval: 1.339-2.045, P < 0.001). A PSR value of 4.04 had a sensitivity of 77.78% and a specificity of 87.04% in terms of short-time prediction of the delivery time, in the receiver-operator curves analysis to determine the cut-off point PSR value.

CONCLUSION

Elastography may contribute to predict the delivery time in high-risk pregnants with TPL.

Obstetric ultrasound: where are we and where are we going?

Diagnostic ultrasound (DUS) is, arguably, the most common technique used in obstetrical practice. From A mode, first described by Ian Donald for gynecology in the late 1950s, to B mode in the 1970s, real-time and gray-scale in the early 1980s, Doppler a little later, sophisticated color Doppler in the 1990s and three dimensional/four-dimensional ultrasound in the 2000s, DUS has not ceased to be closely associated with the practice of obstetrics. The latest innovation is the use of artificial intelligence which will, undoubtedly, take an increasing role in all aspects of our lives, including medicine and, specifically, obstetric ultrasound. In addition, in the future, new visualization methods may be developed, training methods expanded, and workflow and ergonomics improved.