▶ Longitudinal transvesical ultrasound image of the right ovary (left) demonstrates that the ovary is enlarged and the follicles are distributed at the periphery (arrowheads).
▶ Comparison transverse image of the left ovary (right) shows normal size and diffuse distribution of the small follicles.
The differential of right lower quadrant pain in a child includes appendicitis, epiploic appendagitis, and pyelonephritis.
▶ Torsion of the ovary is usually due to the presence of a large cyst or mass within the ovary. Torsion of a normal ovary may occur in young girls (4–6 years of age).
▶ As with testicular torsion, prior history of similar painful episodes is frequently elicited.
▶ The demonstration of Doppler flow to the gonad is much less meaningful in girls than in boys and in women, because of the increased distance between the transducer and the ovary. In virginal girls, endovaginal ultrasound is not performed.
▶ Much more helpful in the evaluation of suspected ovarian torsion is the appearance of the ovary. The torsed ovary is enlarged compared to its mate, and tends to be located in the midline posterior to the uterus.
▶ In early torsion, the venous and lymphatic drainage is occluded while the arterial flow is initially maintained. This causes the enlargement as edematous fluid accumulates in the center of the ovary, pushing the follicles to the periphery. The edema increases the resistance to arterial inflow, so the spectral waveform changes from low resistance to higher resistance.
▶ If the torsion persists, arterial inflow will be compromised and no flow is detected. The ovary becomes hemorrhagic and infarcted and appears heterogeneously hypoechoic.
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