Clinical History
Left iliac fossa pain, dysuria and pyrexia.
Imaging Findings
A premenarchal girl presented with severe intermittent left iliac fossa pain of 1 week duration. Clinical examination revealed tenderness in the left iliac fossa. She was treated for suspected
constipation with suppositories. After 2 days she developed further symptoms of dysuria and pyrexia. An ultrasound scan of abdomen was arranged. US identified an avascular complex mass lying
postero-superior to bladder. A debris laden collection of fluid was seen in the pouch of Douglas. A CT scan of the pelvis confirmed the US findings. IV contrast showed enhancement of only the rim of
the mass. The uterus and right ovary were seen to be normal. At laparoscopy, a diagnosis of a strangulated left ovary with torsion was made. A left salpingo-oophorectomy was performed and the right
ovary was pexed to the pelvic sidewall. Histopathology confirmed left-sided ovarian necrosis due to acute-on-chronic vascular insufficiency secondary to torsion.
Discussion
Ovarian torsion is a rare but serious cause of abdominal pain in female children. Its clinical presentation is frequently confused with other conditions, such as appendicitis, gastroenteritis, renal
colic, a complicated ovarian cyst, or pelvic inflamatory disease. It is seldom diagnosed pre-operatively. In ovarian torsion, the ovary (+/- fallopian tube) twist about their vascular pedicle,
occluding first the venous and lymphatic drainage, and later the arterial supply. This ultimately results in infarction of the involved organs. The condition is more commonly associated with ovarian
cysts or tumours, which act as a fulcrum for torsion. Normal adnexa are theorised to twist due to a long, mobile fallopian tube and mesosalpinx. In adolescents other theories include adnexal venous
congestion due to hormonal activity and abnormal tubal peristalsis. Left-sided adnexal torsion is less common presumably due to the presence of the sigmoid colon, which prevents excessive movement of
the left ovary and fallopian tube. Specific US findings of adnexal torsion consist of multiple enlarged peripheral follicles (8-12 mm in size) in a unilaterally enlarged ovary. This is due to
transudation of fluid into follicles as part of ovarian congestion and is seen in up to 75% of torsed normal adnexa. When grossly enlarged, the ovary often assumes a midline position, as in this
patient's case. The premenarchal uterus can be difficult to identify in these circumstances. Less specific US findings are of a solid, cystic or complex adnexal mass, with or without fluid in the
pouch of Douglas. Rarely, fallopian tube engorgement may be demonstrated. Doppler studies may confirm absent arterial or venous flow, but in general, the grey-scale US findings are more reliable than
those from Doppler interrogation. CT or MRI may be helpful in uncertain cases. Imaging appearances parallel the findings from US examination. Additional information on organ vascularity can be
determined by a dynamic scanning technique, following the administration of IV contrast. If adnexal torsion is detected early, the ovary can be salvaged preserving its hormonal and reproductive
function. Pre-operative US is excellent for evaluation in suspected cases. In proven torsion, pexing of the contra-lateral ovary and the torted ovary, if it is deemed viable, is routinely undertaken.
Differential Diagnosis List
