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Table 1 US, CT and MRI indications and findings

From: Radiological appearances of gynaecological emergencies

  US CT MRI
Simple ovarian cysts Indicated Not indicated Not indicated
Anechoic 3-6 cm cyst, with thin wall <3 mm and minimal thin septations Well-defined cystic adnexal mass of low attenuation and smooth well-defined wall Well-defined cystic adnexal mass of low T1 and high T2 signal intensity and smoothly enhancing wall
Haemorrhagic ovarian cyst Indicated Not indicated unless suspected cyst rupture with severe pain Not indicated unless a cyst is considered indeterminate on US
Isoechoic to ovarian stoma when acute. Develops fine, reticular “spider-web” or lace-like pattern. Vascular wall with avascular internal clot material. If ruptured, then free pelvic fluid with low-level echos is seen Hyperdense mass within the adnexa. Smooth enhancing cyst wall. If ruptured, then high-density free fluid is seen in pelvis and there may be contrast pooling in the pelvis on delayed images in cases of rupture Appearance depends on age of blood. Typically, high T1 material is seen within the cyst. Cyst rupture may demonstrate a combination of low and high T1 and T2 free fluid in pelvis
Endometriotic cysts Indicated Not indicated unless suspected acute rupture Not indicated unless a cyst is considered indeterminate on US
Ovarian cyst containing ground–glass appearance, with homogenous internal echogenicity. May be multiple Ruptured endometriotic cyst may be associated with loculated dense ascites often confined to the pelvic cavity due to adhesions Typically T1 hyperintense cysts with T2 shading; frequently bilateral. Chronic fibrotic changes in pouch of Douglas may be seen
Adnexal torsion Indicated although of low sensitivity May be undertaken due to acute pain with unclear diagnosis Not indicated unless the adnexal mass is considered indeterminate
Doppler whirlpool sign with corkscrew appearance of twisted vascular pedicle and an enlarged ovary with peripherally located follicles Twisted vascular pedicle Oedema of ovarian stroma. There may be absence of vascular supply and low level enhancement in the solid component of the ovarian mass
Wall thickening of torted adnexal mass. Poor contrast enhancement of internal solid components
Fibroid (complications) Indicated May be undertaken if patient has acute pain Not usually indicated. May be used to differentiate a degenerating fibroid from a complex adnexal mass
Degeneration gives a complex US appearance with areas of cystic change Degeneration gives cystic hypodense appearance of fibroid mass Cystic degeneration is seen as complex high T2 signal intensity within a fibroid
Doppler shows circumferential vascularity Can be difficult to distinguish from a complex ovarian cyst when large Red degeneration within a fibroid is seen as
Absence of flow if torted high T1 signal centrally due to blood with low T2 signal at periphery due to haemosiderin deposition
Submucosal pedunculated fibroid may extend into endocervix or vagina from a stalk and may tort
Pelvic inflammatory disease Indicated Not usually indicated but may be done if diagnosis is uncertain Not indicated unless the diagnosis is uncertain and US is indeterminate
Clinical signs are key to diagnosis. US may be normal. Thickened endometrium or pyosalpinx may be seen Tubo-ovarian abscesses appear as bilateral thick-walled complex enhancing masses with tubal configuration and surrounding inflammation Tubo-ovarian abcesses appear as complex thick-walled enhancing adnexal masses with surrounding inflammation