Incomplete Ovarian torsion following ovulation induction.

Clinical History

A 28-year-old female presented in the emergency department, with acute onset pain in the left illiac fossa radiating to the groin . Pain was relieved intermittently by analgesics. She had been taking treatment for infertility and had undergone an intrauterine embryo transfer two days prior to presentation.

Imaging Findings

On Gray scale sonography, both ovaries were enlarged in volume and showed multiple large follicles consistent with ovarian hyper-stimulation (Figs. 1 and 2). There was a spherical mass with a ‘target appearance’ adjacent to the left ovary, indicating a twisted vascular pedicle. In the colour Doppler images (Figs. 3 and 4), arterial and venous blood supply to both the ovaries was well preserved, however the left vascular pedicle appeared coiled before entering into the left ovary (Whirlpool sign). Right ovarian vascular pedicle appeared normal. There was no free fluid in the pouch of Douglas. As vascularisation of both ovaries is preserved, this is a case of incomplete ovarian torsion in hyper-stimulated ovaries.

Discussion

Ovarian torsion is an infrequent but significant cause of acute lower abdominal pain. It is the fifth most common cause of gynaecological surgical emergencies [1]. Patients present with acute lower abdominal pain and concomitant nausea, vomiting. Torsion commonly occurs in women of reproductive age group, with a second peak in post menopausal women. Predisposing conditions include large cysts, cystic neoplasms and hyper-stimulated ovaries [2]. Endometriosis, pelvic inflammatory diseases and malignant lesions, which cause adhesion's are protective. The most consistent finding is ovarian enlargement, however in cases of hyper-stimulated ovaries it is difficult to interpret the increase in ovarian volume. A twisted hyper-stimulated ovary can be differentiated from its normal counterpart by the separation of its multiple cysts due to stromal edema caused by venous and lymphatic congestion in the torsed ovary [2]. Also, presence of significant ascites and pleural effusion infer ovarian hyper-stimulation syndrome rather than torsion. On gray scale images, a ellipsoid mass adjacent to the ovary with ‘target’ appearance or snail shell appearance is highly suggestive and specific of torsion. Free fluid in the cul-de-sac is often present. On colour Doppler study, there could be complete absence of arterial and venous flow, or the absence of either the arterial or the venous flow. Often the arterial and the venous flow to the ovaries is preserved, as was in this case, indicating incomplete ovarian torsion. Comparison of the gray scale and colour Doppler images of the affected side with that of the contra-lateral side can aid in reaching a conclusion. The most frequent finding is decreased venous flow, due to compliant venous walls [3]. Demonstration of a twisted vascular pedicle, the ‘whirlpool sign’, is quite specific for ovarian torsion. Importance of the Doppler findings lie in its ability to determine the preoperative viability of the ovary. Absence of central venous flow is suggestive of non-viability. To conclude, the diagnostic accuracy can be improved by incorporating various gray scale and colour doppler findings rather than relying on any single criteria. It should be kept in mind that a normal colour Doppler cannot exclude the diagnosis of ovarian torsion. Apart from a strong clinical suspicion, an Enlarged Ovary with peripherally situated cysts, Ellipsoid mass adjacent to the ovary, a twisted vascular pedicle with dampened or absent blood flow are all indications to perform a diagnostic/therapeutic laparoscopy. If diagnosed early, often the affected ovary can be salvaged, avoiding unnecessary oopherectomy [4].

Differential Diagnosis List

Final Diagnosis

Bilateral incomplete ovarian Torsion.

URL:	https://www.eurorad.org/case/9660
DOI:	10.1594/EURORAD/CASE.9660
ISSN:	1563-4086