|Year : 2020 | Volume
| Issue : 2 | Page : 497-500
Role of uterine artery Doppler in the diagnosis of placenta accrete in patients with placenta previa
Mohammed Fahmy, Alaa Alhalabi, Haitham Hamza, Essam Abd El Zaher, Yara Abd El Fattah Khourshid, Mohammed El Sibai
Department of Obstetrics and Gynecology, Faculty of Medicine, Menoufia University, Menoufia, Egypt
|Date of Submission||20-Nov-2019|
|Date of Decision||16-Dec-2019|
|Date of Acceptance||21-Dec-2019|
|Date of Web Publication||27-Jun-2020|
Yara Abd El Fattah Khourshid
El Shohada, Menoufia
Source of Support: None, Conflict of Interest: None
To show the role of pulsatility index (PI) of uterine artery Doppler in the diagnosis of placenta accreta in patients with placenta previa.
Placenta accrete occurs in the complete or partial absence of the decidua basalis.
In clinical practice, nonseparation of the placenta at the time of delivery leads to massive blood transfusion, disseminated intravascular coagulability, injury to the bladder and intestine, and urgent need for hysterectomy.
Patients and methods
A diagnostic accuracy test study was done on 54 patients with placenta previa. Ultrasound examination (two-dimensional grayscale and color Doppler) via transabdominal and transvaginal approach and the PI of uterine artery Doppler was done to these patients. Data were collected and tabulated.
Significant changes in PI of uterine artery Doppler were detected. The accreta group had significantly lowered PI (0.62 ± 0.20) than the term group (0.89 ± 0.23) (P < 0.001).
From our study, we concluded that the accuracy of loss of normally presented retroplacental clear zone was the most important ultrasound criteria in the diagnosis of placenta accreta among patients who had a previous cesarean section with a placenta previa overlying previous uterine scar.
Keywords: doppler, placenta accrete, pulsatility index, uterine artery
|How to cite this article:|
Fahmy M, Alhalabi A, Hamza H, El Zaher EA, El Fattah Khourshid YA, El Sibai M. Role of uterine artery Doppler in the diagnosis of placenta accrete in patients with placenta previa. Menoufia Med J 2020;33:497-500
|How to cite this URL:|
Fahmy M, Alhalabi A, Hamza H, El Zaher EA, El Fattah Khourshid YA, El Sibai M. Role of uterine artery Doppler in the diagnosis of placenta accrete in patients with placenta previa. Menoufia Med J [serial online] 2020 [cited 2021 Mar 1];33:497-500. Available from: http://www.mmj.eg.net/text.asp?2020/33/2/497/287788
| Introduction|| |
Placenta accrete occurs in the complete or partial absence of the decidua basalis.
In clinical practice, nonseparation of the placenta at the time of delivery leads to massive blood transfusion, disseminated intravascular coagulability, injury to the bladder and intestine and the urgent need for hysterectomy.
Detection of placenta accreta is very important for the development of an effective treatment strategy and plan to minimize maternal morbidity and mortality. Placenta accrete is diagnosed with grayscale and color Doppler sonography. The sonographic signs suggestive of placenta accrete include the presence of placental vascular lacunas, loss of anechoic area, interruption of the bladder, uterine serosa, visualization of a focal protruding mass, and high-velocity pulsatile blood flow between the placenta and the bladder.
Placenta accreta originates from abnormal trophoblastic invasion. In addition, previous uterine artery Doppler studies have suggested that a high uterine artery pulsatility index (PI) might be an indirect sign of impaired placentation.
However, the relationship between placenta accreta and uterine artery Doppler velocimetric measurements have not been investigated previously.
The aim of our study was to show the role of PI of uterine artery Doppler in the diagnosis of placenta accreta in patients with placenta previa.
| Patients and Methods|| |
This was a diagnostic accuracy test study carried out on 54 pregnant women diagnosed with placenta previa by ultrasound and were candidates for either emergency or elective repeated cesarean section or hysterectomy (if diagnosis of placenta accreta is confirmed), recruited from the Obstetrics and Gynecology Department, Menoufia University Hospital, during the period from July 2018 to July 2019.
The study had been approved by the local ethics committee in Menoufia Faculty of Medicine.
All of them were assorted according to certain inclusion and exclusion criteria as follows. Inclusion criteria included pregnant women with a gestational age of between 28 and 34 weeks, singleton pregnancy, and free of medically necessary indications.
Exclusion criteria included multiple pregnancies, hypertensive disorder, diabetes, renal disorder, and cardiovascular disorders.
All women were assessed by the physician on duty, including general, abdominal and local examination, and investigation. The study was explained to them and an informed consent was obtained before the ultrasound examination. The ultrasound assessment was performed by the same experienced operator.
Steps included that all patients had an ultrasound examination (two-dimensional grayscale and color Doppler) via transabdominal and transvaginal approach using an ultrasound machine IBE sonata plus 3–5 MHz: fetal biometry, confirming the presence of placenta previa, assessment of the possibility of concomitant placenta accrete in the form of loss of retroplacental zone, multiple vascular lacunae within placenta, blood vessels crossing uterine serosa, myometrial thickness of 1 mm, and bladder wall interruption.
Assessment of uterine artery Doppler in different cases of placenta previa transabdominally by identifying the right and left uterine arteries at the apparent crossover with external iliac arteries The sample gate was set at 2 mm, and measurements were taken 1 cm distal to the site of crossing with the smallest possible angle of insonation. After the arteries were identified by color Doppler, pulsed wave Doppler was used to obtain the waveforms. When at least three similar consecutive waveforms were obtained, PI was measured.
Histopathological examination of hysterectomy specimens for assessment of the degree of myometrial invasion was done.
Results were statistically analyzed by SPSS, version 22 (SPSS Inc., Chicago, Illinois, USA). Independent t test was used for parametric data. Mann–Whitney test was used for nonparametric data. χ2 and Fisher's exact tests were used for qualitative variables. P value less than 0.05 is considered significant. Receiver operating characteristic curve is a graphical plot of sensitivity versus false positive rate (one minus the specificity). Sensitivity or true positive rate = true +ve/(true +ve + false −ve). Specificity or true negative rate = true –ve/(true –ve + false +ve)=1–false +ve rate. Accuracy=(true +ve)+(true –ve)/(positive + negative). Positive predictive value (PPV): true +ve/(true +ve + false +ve). Negative predictive value (NPV): true −ve/(true −ve + false –ve).
| Results|| |
The demographic data of women included in the study showed that age and previous number of cesarean section were inversely related to the presence of accrete [Table 1].
There were significant differences in operative characteristics of the two groups, where lower uterine segment less than or equal to 1, lost retroplacental space, more than two lacunae, and hysterectomy management were significantly higher among the accrete group than the nonaccreta one [Table 2].
|Table 2: Management and ultrasonographic characteristics of the studied groups|
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The accreta group had significantly lower PI (0.62 ± 0.20) than the term group (0.89 ± 0.23) (P < 0.001) [Table 3].
The retroplacental space had the highest sensitivity of 94% followed by lacunae (88%), PI (78%), and lower uterine segment (66%), respectively, and their specificity are 91, 55, 91, and 95%, respectively [Table 4].
|Table 4: Validity of different parameters used for diagnosis of accreta among the studied patients|
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The receiver operating characteristic curve for PI is not significantly different from other parameters used in diagnosis of accrete [Figure 1].
|Figure 1: Receiver operating characteristic curve of the lower uterine segment (LUS), retroplacental space (RPS), and lacunae and pulsatility index (PI) among the studied groups.|
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| Discussion|| |
This study aimed to measure the ability of uterine artery Doppler to detect placenta accreta in patients with placenta previa. Regarding the presence of abnormal lacunas, this study showed a sensitivity of 88%, specificity of 55%, PPV of 74%, NPV of 75%, and accuracy of 74%. Our study agreed with Cali et al., who found that the presence of abnormal lacunae showed a sensitivity of 73.0% and specificity of 86.7%. Shih et al. reported a sensitivity rate of 74%. There was statistically significant difference related to the presence of four or more lacunae and risk of morbidly adherent placenta based on the pathological outcome findings with a P value of less than 0.001.
Yang et al. and his associates found that the presence of abnormal lacunae showed a sensitivity of 86.9%, specificity of 78.6%, PPV of 76.9, and an NPV of 88%. In a recent systematic review, the overall pooled sensitivity and specificity from 13 studies of lacunar spaces diagnosing mean arterial pressure was 77 and 95%, respectively, with an overall diagnostic accuracy of 88%. Hence it is sensitive but not specific whereas Maged et al. found that the presence of abnormal lacunae with a sensitivity of 93%, PPV of 80.82%, NPV of 85.19%, and accuracy of 82.00%. Pilloni et al. suggested the presence of abnormal lacunae with a specificity 94.6% and sensitivity of 48.6%. Tanimura et al. reported that grade 2 or high placental lacunae had a sensitivity of 73%, specificity of 86%, PPV of 64.7%, and NPV of 90.2% associated with high risk of morbidly adherent placenta with a P value of 0.01. Adding power and color Doppler increases the diagnostic value of the test.
Regarding loss of retroplacental clear zone, this study showed a sensitivity of 94%, specificity of 91%, PPV of 94%, NPV of 91%, and an accuracy of 93%. Maged et al. suggested the loss of retroplacental clear zone to have 87.3% sensitivity, 89.1% specificity, 93% PPV, 80% NPV, and 88% accuracy which agreed with our study. Pilloni et al. suggested 81% sensitivity and 97% specificity to the retroplacental zone disruption. In a recent systematic review, the overall pooled sensitivity and specificity from 13 studies of loss of retroplacental clear zone diagnosing mean arterial pressure was 66 and 95%, respectively. Wong et al. found absence of the clear space in 37 (65%) women without placenta accreta and in 100% of those women with it. The primary use of the clear space appears to be that its presence effectively excludes placenta accreta because it has a high NPV. On the contrary, Finberg and Williams stated that the loss of the retroplacental clear zone accounts for the majority of false positive results. Loss of retroplacental space has the highest accuracy among other criteria of ultrasound findings with high sensitivity and specificity. Regarding the presence myometrial thinning, this study showed a sensitivity of 66%, specificity of 95%, PPV of 95%, NPV of 66%, and accuracy of 78%. Our study agreed with Budorick et al. who suggested myometrial thinning in being a sensitive sign with 79% sensitivity and 77% specificity. Our study did not agree with Wong et al. who found a sensitivity of 22%, specificity of 100%, PPV of 100%, and NPV of 89%. These differences may be attributed to intraobserver variability. Regarding uterine artery Doppler value, our results showed that sensitivity, specificity, PPV, NPV, and accuracy were 78, 91, 93, 74, 83%, respectively. A study was held by Cho et al. who reported that the mean uterine artery PI was significantly lower in the placenta accreta group compared with the placenta previa group and this agreed with the present study as we observed significant association. Our study had some limitations as uterine artery Doppler velocimetry and placental morphology were performed by different operators during the whole study period. However, all operators were well-trained experts who understood the protocol before starting the examination, but a bias between operators may still have existed. A well-organized prospective study will be needed to address that issue. Yet what we conclude and address firmly is that planning which could be aided by such simple tools could easily decline morbidity and mortality both on maternal and fetal sides.
| Conclusion|| |
There was statistically significant values of uterine artery Doppler noticed during comparing those of accreta with nonaccreta like suggested by the mean uterine artery PI being significantly lower in the placenta accreta group compared with the previa alone (0.62 ± 0.20 vs. 0.89 ± 0.23; P < 0.001).
However, the uterine artery Doppler value alone might be insufficient for differentiating placenta accreta from placenta previa, but a combination with maternal characteristics will improve the diagnostic accuracy of placenta accrete.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]