Comparison between the role of transabdominal ultrasound versus transvaginal ultrasound in evaluation of placental invasion in cases of placenta previa anterior wall with previous uterine scar

INTRODUCTION

By enabling us to pick the ideal time and location of delivery, prenatal identification of Morbidly Adherent Placenta (MAP) and its variations may help decrease fetus/maternal sickness and death. Early diagnosis of placental disease allows for multidisciplinary surgical intervention, newborn critical care, preventive hypogastric artery balloon closure, embolization of the uterus, and an appropriate amount of blood units in the operation theatre.¹

The diagnosis of sonographic criteria for placenta accrete has been examined by many authors. Always evaluate the danger of undergoing a needless hysterectomy (false positive) or subsequent hemorrhage after attempted placental removal (false

negative). The use of diagnostic criteria cannot be justified merely on the basis of sensitivity and specificity; PPV and NPV must be assessed in order to plan appropriate patient treatment and information.²

A study of the literature from the previous decade suggests that placenta accreta is becoming more common, owing to more common CSs. A prior uterine scar is nearly often the location of aberrant placental invasion. Greater maternal age, myometrial injury after a myomectomy with endometrial entry, extensive curettage with subsequent Ashermandisorder, and submucosal myoma are all risk factors that are less significantly linked to MAP.¹

Women who have had a prior CS with a placenta previa atop the former uterine scars are at the biggest danger of an unusually invasive placenta.³

A variety of distinct ultrasonography criteria, some qualitative and others quantitative, are used to diagnose a morbidly adhered placenta. Several investigations have looked at the accuracy of several ultrasonography markers for placental attachment disorders (PAD). However, the efficacy of these markers varies a lot amongst investigations that use the same indicators. Limits on research population, retrospective methodology, and research requirements variation, as well as the eventual determination of AIP, have all been blamed for the differences.⁴

Moreover, like with other subjective diagnostic approaches, what defines a marker will influence whether or not each symptom is logged, according to the operator. This is especially crucial for practitioners who may not have much expertise with placental ultrasound or AIP diagnosis. Furthermore, there is no documented agreement on the characterization of the ultrasonography indicators that are typically used to diagnose AIP. Many indications have been recognized with several names, and in other instances, the same title has been used to many discoveries.⁵

The European Working Group on Unnaturally Invasive Placenta (EW-AIP) is a non-profit association with 29 members from 11 European countries, including obstetricians, gynecologists, pathologists, anesthesiologists, and basic science researchers. The group's mission is to enhance AIP diagnosis and treatment while also promoting research and understanding. The EW-AIP provides standardized definitions of the AIP imaging descriptors to enhance the comparability of future research, expand diagnostic capabilities, and promote international cooperation. All 23 papers in a recent systematic review of the prenatal sonographic detection of AIP were evaluated to establish these standardized criteria. ⁵

Six descriptions for 2D grayscale ultrasound, four for 2D color Doppler, and one for 3D power Doppler were created from the various wordings. The significance of describing each indication clearly was put on it, regardless of views about its predictive usefulness. ⁵

The aim of this research is to evaluate the influence of transabdominal versus transvaginal ultrasound in assessing placental invasion in situations of placenta previa anterior wall with a prior uterine scar using the unified ultrasonographic characteristics proposed by "EW-AIP," as well as to assess the sensitivity and accuracy of each characteristic by evaluating them to the pregnancy's end results..

PATIENTS AND METHODS

This was a prospective Observational Cohort research with 100 pregnant women with persisting placenta previa (beyond 28 weeks' pregnancy) who attended Al-Hussien Hospital between April 2021 and the conclusion of the research adhering to the below inclusion and exclusion criteria:

Inclusion Criteria:Pregnant women identified with persisting placenta previa anterior wall following 28 weeks of pregnancy, and a histories of prior cesarean deliveryand/or additional uterine procedures (age group 18-45 years).

Exclusion Criteria:Unscarred uterus and placenta previa posterior wall

All the patients were submitted to the following steps:

Complete history, including:Personal history (name, age, file number).Obstetric history (number of C.S., abortion, prior gestation placenta previa, ectopic gestation history, medical disorder with pregnancy and number of living children).Present history (complain, gestational age, medical disorder in present pregnancy and history of ante partum hemorrhage), and past history (postpartum sepsis, postpartum hemorrhage & chronic diseases).

Two skilled operators performed transabdominal and transvaginal imaging utilizing all diagnostic procedures (gray-scale, color Doppler), followed by an offline analysis of the collected pictures and volumes.

Intraoperative information, such as placental site, spontaneous separation, and placental invasion of the bladder and other organs. Administration during pregnancy. Injury to the bladder, ureter, or bowel. Blood transfusions and blood loss to prevent a hysterectomy and the requirement for critical care unit hospitalization, conservative treatment is used.

Histopathological examination in cases of hysterectomy.

Sample size justification:

According to Sedek et al.⁶, the overall accuracy of TVS identification was around 97.1 percent when using the EPI Info 7 software for sample size calculating. With a margin of error of 5% and a confidence level of 95 percent, a sample size of at least 100 women was required.

Statistical Analysis:

The statistical program for social sciences, version 23.0, was utilized to analyze the data (SPSS Inc., Chicago, Illinois, USA). The quantitative data was given in the form of a median, standard deviation, and range. The median and standard deviation were used to convey quantitative data (SD). Frequency and percentage were utilized to convey qualitative data. When comparing two averages, an independent-samples t-test of relevance was employed. To compare percentages between two qualitative factors, the Chi-square (X2) test of relevance was applied. For data correlation, Pearson's correlation coefficient (r) test was employed.Evaluation of Diagnostic Performance for histopathology and Transabdominal ultrasound & Transvaginal ultrasound. Sensitivity = (true +ve)/ [(true +ve) + (false –ve)]. Specificity = (true –ve) / [(true –ve) + (false +ve)]. PPV = (true +ve) / [(true +ve) + (false +ve)]. NPV = (true –ve)/ [(true –ve) + (false –ve)]. Accuracy = (TP+TN)/[TP+FP+TN+FN]. McNemar's test was used to examine the relationship between two (paired) qualitative variables. The tolerable margin of error was set at 5%, while the confidence interval was set at 95%.A P value of less than 0.05 was deemed substantial.

RESULTS

Table 1: Comparison between Histopathology Evaluation1 and TAS according abnormal lacunae.

Table 1 shows statistically substantial diagnostic performance of Abnormal lacunae TAS it was sensitivity 93%, specificity 85.7%, positive predictive value 14.3% and negative predictive value 7% and accuracy 92%.

Table 2: A comparison of TAS and TVS accuracyaccording to loss clear zone.

Table 2 reveal highly statistically substantialvariation between TAS and TVS according to loss clear zone, with p-value (<0.001).

Table 3: A comparison of TAS and TVS accuracyaccording to abnormal lacunae.

Table 3 shows no statistically substantial variation of TAS and TVS regarding abnormal lacunae, with p-value (>0.05 non-substantial).

Table 4: A comparison of TAS and TVS accuracyaccording to myometrial thining.

Table 4 shows no statistically substantial variation between TAS and TVS regarding myometrial thining, with p-value (>0.05 non-substantial).

Table 5: Comparison of the accuracy of TAS and TVS regarding uterovesical hypervascularity.

Table 5 shows no statistically substantial variation between TAS and TVS regarding uterovesical hypervascularity, with p-value (>0.05 non-substantial).

Table 6: Comparison of the accuracy of TAS and TVS according to subplacental hypervascularity.

Table 6 shows no statistically substantial variation between TAS and TVS regarding subplacental hypervascularity, with p-value (>0.05 non-substantial).

Table 7: Comparison of the accuracy of TAS and TVS regarding bridge vessels.

Table 7 shows no statistically substantial variation between TAS and TVS regarding bridge vessels, with p-value (>0.05 non-substantial).

Table 8: Comparison of the accuracy of TAS and TVS regarding placental lacunea feeder vessels.

Table 8 shows no statistically substantial variation of TAS and TVS regarding placental lacunae feeder vessels, with p-value (>0.05 non-substantial).

Table 9: Comparison of the accuracy of TAS and TVS according to overall finding.

Table 9 shows statistically significant diagnostic performance of overall, as for the transabdominal ultrasound it was sensitivity 94.2%, specificity 85%, positive predictive value 92% and negative predictive value 65.2% and accuracy 91.5%, while transvaginal ultrasound it was sensitivity 98.1%, specificity 93.8%, positive predictive value 97% and negative predictive value 89.1% and accuracy 97.5%, this indicates that the transvaginal ultrasound the most diagnosis for placental invasion.