الفهرس 
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Abstract
S
UMMARY
lacenta previa is defined as placental implantation that takes place in the lower uterine segment, partially or completely covering the internal cervical os. The incidence of placenta previa is about 1 in 200 term pregnancies, and the rate appears to be rising as a consequence of the increasing rate of caesarean deliveries.
Symptomatic (bleeding) placenta previa is associated with increased maternal and neonatal morbidity and mortality. There is a threefold increase in neonatal mortality rate, in comparison with normally positioned placenta.
Ultrasound is the standard of care in the diagnosis of placenta previa, with transvaginal sonography being the gold standard for detecting placenta previa. It provides detailed and accurate information about the placental edge and can assess for changes in placental migration and implantation, in relation to endocervical os on follow-up exams. Placenta previa, especially with prior C-section, is a risk factor for placenta accreta spectrum (PAS) disorder and ultrasound also plays a vital role in detecting suspicious cases of PAS. While several imaging signs such as loss of the clear zone, thinning of the underlying myometrium, and vascular changes within the placenta, have been studied for the diagnosis of PAS, only a few studies have examined the relationship between placental thickness at lower uterine segment and PAS.
P
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In this study, we aimed to assess the clinical value of placental thickness assessment as marker for intra and postpartum bleeding in cases of placenta previa, thus, to provide reference for improving clinical outcome of pregnant women and newborns, and reducing the incidence of adverse pregnancy events.
This prospective study was conducted at tertiary care hospital at Ain Shams University hospitals from September 2022 till March 2023 and performed on seventy-five pregnant women with placenta previa.
As regards the demographic characteristics, the current study revealed that the mean age (years), gestational age (weeks), and Placental thickness (cm) was 31.5±5.5, 36.0±1.0 and 4.1±1.8 (range; 2.6-12.2) respectively. Median parity and previous cesarean section were 3.0 and 2.0 respectively. Placental thickness ≥10.0 mm was in 14.7% of the studied cases.
As regards the intraoperative complications, our study results revealed that hysterectomy and bladder injury occurred in 21.3% and 8.0% respectively while Ureteric injury and Intestinal injury did not occur in the studied cases.
As regards the hemoglobin changes and blood loss, our study results revealed that pre-operative hemoglobin level (gm/dL) and post-operative hemoglobin level (gm/dL) were
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11.4±0.9 and 9.8±1.1 respectively with Postoperative hemoglobin DROP (gm/dL) of 1.7±1.1 and the blood loss (ml) was 867.3±441.9. The Need to blood transfusion was in 54.7% of the studied cases. The number of transfused units of packed RBCs was one unit.
In correlation with placental thickness, our study results revealed that there was significant positive correlation between placental thickness and each of postoperative hemoglobin drop, blood loss and number of blood transfusion units, as well as significant negative correlation with postoperative hemoglobin level (p value= 0.044, 0.017, 0.024, 0.018) respectively, and cases with placental thickness ≥10.0 mm significantly had higher postoperative hemoglobin DROP and blood loss as well as more frequent bladder injury (p value= 0.013, 0.023, 0.028) respectively.
As regards prediction of hysterectomy, our study results revealed that the cases that needed hysterectomy significantly had older age, more frequent bladder injury and number to blood transfusion units, as well as lower Postoperative hemoglobin level with higher Postoperative hemoglobin drop, while Placental thickness was non-significantly lower in cases needed hysterectomy.
Consequently, placental thickness had non-significant diagnostic performance in predicting need to hysterectomy. It had high specificity and negative Predictive value, but poor
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other diagnostic characteristics. So, it could be used to exclude need to hysterectomy (<9.1 mm), but not to confirm it (≥9.1 cm).
As regards prediction of bladder injury, our study results revealed that cases that had bladder injury significantly had lower Preoperative and postoperative hemoglobin level, and more frequent placental thickness ≥10.0 mm, need to hysterectomy and blood transfusion, as well as higher number of blood transfusion units. Placental thickness was non-significantly lower in cases had bladder injury.
Consequently, Placental thickness had non-significant diagnostic performance in predicting bladder injury. It had high specificity and negative Predictive value, but poor other diagnostic characteristics. So, it could be used to exclude bladder injury (<11.1 mm), but not to confirm it (≥11.1 cm).
As regards prediction of blood transfusion, our study results revealed that the cases that needed blood transfusion significantly had lower Preoperative and postoperative hemoglobin level and higher blood loss, as well as more frequent Hysterectomy and Bladder injury. Placental thickness was non-significantly lower in cases that needed blood transfusion.
Consequently, Placental thickness had significant low diagnostic performance in predicting blood transfusion (p
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value= 0.033). It had high specificity and positive Predictive value, but poor other diagnostic characteristics. So, it could be used to confirm need to blood transfusion (≤7.7 mm), but not to exclude it (<7.7 cm).
We concluded that there was a significant increase in placental thickness at the lower uterine segment in patients with placenta previa and PAS (placental thickness ≥ 10.0 mm) compared to those with placenta previa but no morbid adherence. Measuring placental thickness is simple and easy to implement. So, it can be used as a screening test for patients with placenta previa, particularly those with a past history of cesarean section with significant low diagnostic performance in predicting blood loss and need for blood transfusion.
We recommend applying this simple and pragmatic sign of placental thickness which may be of clinical value in improving prenatal detection AIP in women with placental implantation in the lower uterine segment.