Is B-Flow USG superior to Color Doppler USG for evaluating blood flow patterns in ovarian torsion?

Ovarian torsion is an uncommon gynecological emergency that most often affects women of reproductive age. Its signs and symptoms are similar to those of other abdominal conditions, which make its differential diagnosis challenging. Color Doppler (Doppler USG) and B-flow ultrasonography (B-flow USG) are used for the differential diagnosis of ovarian torsion, and in this study, we aimed to evaluate these two techniques, validate B-flow USG as the gold standard non invasive diagnostic tool in the early phase of an ovarian torsion, and show that the B-flow USG is superior to the color Doppler USG.

Sixteen rabbits of the same age and weight were separated into 2 subgroups of 8. In Group I (sham group), right ovaries were fixated, and in Group II (torsion group), right ovaries underwent 720° torsion in a counterclockwise direction. At 1h and 2h of ischemia, both ovaries were measured by the two techniques, and an additional measurement was taken at 24h to determine any changes in the left ovary due to the right ovary ischemia. Volume flow, peak systolic velocity (PSV), end diastolic velocity (EDV), resistive index (RI) and pulsatility index (PI) measurements were taken both with color Doppler USG (using a 12MHz linear probe, General Electric Medical Systems Logic 7, Milwaukee, USA) and with B-flow USG.

The right Doppler RI and PI values at 1h were significantly higher than the right B-flow values (p<0.05). The difference between the left B-flow RI and PI values and the left Doppler values at 1h was not significant (p>0.05), nor was the difference between the right B-flow RI value at 2h and the right Doppler RI value at 2h (p>0.05). The right B-flow PI value at 2h was statistically different from the right Doppler PI value at 2h (p<0.05), although the differences between the left B-flow RI and PI values at 1h and 2h and the left Doppler RI and PI values were not (p>0.05). However, there was a significant difference between the RI values at 24h (p<0.05).

In this study, the decrease in blood reperfusion at 1h measured by B-flow USG was apparently higher than that measured by Doppler USG. However, by the end of 2h, the measurements were equal (see Fig. 3 and 4). In conclusion, B-flow USG reveals the decrease in the blood flow more distinctly in the early phase. Moreover, B-flow Doppler USG is more reliable and advantageous than color Doppler USG because it provides a more accurate preoperative evaluation of the unilateral and contralateral preoperative adnexial structures, and allows for a better assessment of blood flow in the ovarian torsion.