Clinical History
11-year-old girl who reported acute abdominal pain focused on the right iliac fossa. No fever or other symptoms associated.
Imaging Findings
- US findings
1. Unilateral enlarged ovary (5 cm) in the right paravesical fossa. This enlarged mass could be the right ovary, but we should take into account that a heavy left ovary could tort and appear as a contralateral paravesical mass. (Fig.1a)
2. Multiple peripheral cysts (moderately sensitive and highly specific for torsion). (Fig.1) This appearance is probably caused by marked ovarian oedema which displaces follicles towards the peripheral zone.
3. Free pelvic fluid (Fig.1b; Fig.2b)
4. Absence of arterial or venous colour Doppler flow within the ovary (Fig.2)
Discussion
A- BACKGROUND [1, 4]
- Adnexal torsion is more accurate than ovarian torsion. Adnexal torsion includes ovarian torsion, fallopian tube torsion, or both (67% of cases).
- Twisting of the vascular pedicle (ovarian branches of uterine artery), fallopian tube, or both could result in ischaemia and haemorrhagic infarction. Remember: Ovaries have double arterial blood supply: 1. Ovarian branches of uterine artery (Mesosalpinx) 2. Ovarian artery of the suspensory ligament.
- Adnexal torsion is usually associated with large cysts and cystic neoplasms. Torsion without a predisposing lesion is more common in adolescents.
B- CLINICAL PERSPECTIVE [1]:
Symptoms of ovarian torsion are nonspecific, but classic presentation includes localized right or left lower abdominal pain with a palpable abdominal mass.
C- IMAGING PERSPECTIVE [1, 2, 3, 4]
- US findings
1. Unilateral enlarged ovary >4 cm is highly suggestive of torsion. However, between 9-26% of adnexal torsions occur in normal-sized ovaries and have normal appearances. (Fig.1) [2]
2. Multiple and peripheral ovarian cysts (highly specific for torsion). Fluid-filled cysts displaced peripherally by an oedematous ovarian stroma. (Fig.1b; Fig.2a)
3. Coexistent mass (if present, not in our case).
4. Twisted vascular pedicle (ovarian branches of uterine artery) in the suspensory ligament (whirlpool sign): Typically an echogenic round mass. If flow in the vascular pedicle is not detected, a necrotic or infarcted ovary is likely to be found. (Fig.3a)
5. Fallopian tube thickening (>10mm) (Fig.3a)
6. US Doppler: Presence of flow at colour Doppler imaging does not exclude torsion but suggests that the ovary may be viable. Initially, vascular pedicle torsion compromises venous and lymphatic outflow. Arterial inflow is sustained (by the ovarian artery or uterine artery) and this leads to ovarian oedema. Eventually, arterial thrombosis may occur and no colour Doppler flow is observed. (Fig.2a)
7. Free pelvic fluid (Fig.2b).
There are some mimics of ovarian torsion like haemorrhagic ovarian cysts, serous cystadenomas or ovarian hyperstimulation syndrome. We should bear in mind these cases while performing a sonography.
- CT Findings [2]
Nonspecific: adnexal mass toward the contralateral side of the pelvis, tubal thickening (subacute torsion), deviation of the uterus towards the affected side and ascites (may be haemorrhagic).
CECT: Lack of contrast enhancement could be observed.
- MR Findings [2, 3]
Nonspecific findings: Similar to those described on CT. Hyperintensity of ovarian stroma on T2-weighted sequences (oedematous stroma).
D- OUTCOME [1]
Conservative approach: untwisting the vascular pedicle (even if necrotic appearance of the ovary is found).
In postmenopausal women, the treatment of choice is bilateral oophorectomy.
Differential Diagnosis List
Left ovarian torsion in the right paravesical fossa.
Haemorrhagic corpus luteum
Ectopic pregnancy
Adnexal mass (serous cystadenoma)
Ovarian hyperstimulation syndrome
Final Diagnosis
Left ovarian torsion in the right paravesical fossa.
