Role of ultrasound and MRI examination in predicting
placental abnormality and severe outcomes of pregnancies
All 747 pregnancies took ultrasound examination by which abnormal
placental adhesion were detected from 271 of them, while placenta
implantation was confirmed from 514 pregnancies by surgery, including
244 cases who had ultrasound-diagnosed abnormal placenta (Table 2). It
suggested that the predictive sensitivity and specificity by ultrasound
was 47.5% and 88.4%, respectively. In addition, misdiagnosis was
11.6% (27/233 cases) and missed diagnosis was 52.5% (270/514 cases).
Placenta implantation was predicted in 143 subjects taken MRI, and 141
of whom were confirmed later by surgery, showing 79.2% of sensitivity
and 97.8% of specificity for MRI-predicted placental implantation
(Table 2). The rate of misdiagnosis and missed diagnosis was 2.2% (2/90
cases) and 20.8% (37/178 cases), respectively (Table 2). Intriguingly,
56 patients had both predicted- (during gestation by both ultrasound and
MRI) and confirmed- (intra-operation) placenta implantation, indicating
100% of specificity. But, 122 surgery-confirmed placenta implantations
were not detected by both examinations with 68.5% of missed diagnosis.
In addition, 154 placenta implantations detected only by either of
examinations were confirmed later by surgery with a higher sensitivity
(86.5%). All these results revealed the essential role of ultrasound
and MRI in detecting placental abnormality during the gestation.
We also analyzed the relationship between ultrasound- and/or
MRI-predicted placenta implantation and other adverse outcomes in
patients. As shown in Table 3, bleeding volume during delivery, volume
of blood transfusion and hysterectomy were tightly associated with
placenta implantation no matter whether implantation was predicted by
ultrasound and/or MRI. The comparison between any two conditions
(α’=0.017) demonstrated that the amount of hemorrhage and blood
transfusion in the implantation-predicted groups were bigger than that
in the non-implanted group. The patients with placenta implantation
detected by both ultrasound and MRI, also had significant increase of
hemorrhage volume, blood transfusion and hysterectomy than those by
either of examinations.