Adnexal torsion in pregnancy - a gynaecological emergency!

A 33-year-old G2 P1 L1 lady at 25 weeks 4 days period of gestation presented to the ER with complaints of sudden onset of left pelvic pain. She gave a past history of laparoscopic right salpingo-oophorectomy for cyst with torsion, and a hystero-laparoscopic surgery for infertility workup .

Ultrasound of the pelvis (Fig. 1), revealed a left adnexal hypoecechoic lesion measuring 10 x 5.6 cm, with no significant vascularity on colour Doppler. Left ovary was not seen separately. Right ovary was not seen (post-operative status). MRI of the pelvis revealed a T2 (Fig. 2a, b) and T2-SPAIR (Fig. 2c, d) hypointense left adnexal lesion which was ovoid in shape with tiny hyperintense cysts located in the periphery. A twisted pedicle (black arrow) was visualised on T2-FSE sequence (Fig. 3a-c). No intravoxel fat signals were seen in the torsioned left ovary on in and out-of-phase Images (Fig. 4). An overview of the abdomen and pelvis can be appreciated on MR coronal T2-SPAIR (Fig. 5) and Balanced Turbo Field Echo (bTFE) sequences (Fig. 6).

Adnexal torsion is the fifth most common gynaecological emergency. It is defined as a partial or complete rotation of the ovarian pedicle on its long axis, usually affecting both the ovary and fallopian tube, and hence the term “adnexal torsion” is often preferred over “ovarian torsion”. Initially, following torsion, the venous flow is compromised leading to congestion and oedema of the affected ovary, which is further complicated by a reduced arterial flow leading to ischaemia and finally necrosis, that can even be fatal [1, 2]. Pregnancy in patients with a history of ovarian cysts is a recognised risk factor for adnexal torsion [2]. Adnexal torsion affects one in every 5000 pregnancies and has its highest incidence during the 1st and early 2nd trimester [3]. Clinical symptoms are non-specific and include abdominal pain, vomiting, fever and leucocytosis [4].

Ultrasound (USG) is the initial modality of choice for evaluation. However, it is highly operator-dependant and the findings may be nonspecific. Findings of adnexal torsion include a solid/cystic/complex mass with/without pelvic fluid, thickening of the wall and cystic haemorrhage. As the ovary has a dual blood supply (ovarian artery from aorta and ovarian branches from uterine artery), it is not uncommon to find normal adnexal arterial waveforms during an adnexal torsion. Identifying the twisted vascular pedicle which can produce a “whirlpool sign” on colour Doppler may be a useful sign indicating preserved arterial and venous flow in the vascular pedicle [5]. The most common finding on USG is an enlarged ovary. Presence of multiple small follicles placed peripherally within the ovary is an additional sign [1]. Similar findings can also be seen on CT/MRI. Twisting of the ovarian pedicle is pathognomic for adnexal torsion, however, it is seen in < 30% of cases. Multi-planar reformations and acquisitions are required for visualising this feature. Additional features better depicted on CT/MRI include ovarian haematoma, abnormal or absent ovarian enhancement, uterine deviation to the side of the torsed ovary, engorged vessels on the twisted side and fallopian tube thickening. The enlarged ovary with peripherally located follicles are best appreciated on post-contrast images or on T2-FSE sequences without fat saturation [6]. Our patient underwent diagnostic laparsoscopy and salpingo-oophorectomy. The left ovary and tube were oedematous and twisted 3 times around the infundibulo-pelvic ligament. Post-operative period was uneventful.

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