British Journal of Radiology 74 (2001),762-763 © 2001 The British Institute of Radiology
Torsion of a normal ovary in a post-pubertal female: unenhanced helical CT appearance
R Zissin, MD
Department of Diagnostic Imaging, Sapir Medical Center, Kfar Saba affiliated to the Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
Correspondence: Dr R Zissin, Department of Diagnostic Imaging, Sapir Medical Center, Meir General Hospital, Kfar Saba 44281, Israel
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Abstract
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This case report presents the CT features of torsion of normal adnexa in an adult woman. Unenhanced helical CT, initially performed for clinically suspected acute ureterolithiasis, established the diagnosis.
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Introduction
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Ovarian torsion is an infrequent but important clinical entity that may mimic other causes of acute abdomen. When clinically suspected, ultrasound is the imaging modality of choice for making the diagnosis [1, 2]. CT may be the initial imaging modality when the clinical presentation is unclear. We present a case of torsion of normal adnexa in which the correct diagnosis was established by unenhanced CT.
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Case report
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A 38-year-old woman with a history of laparoscopic detorsion of the right ovary 4 years previously presented with cramping right lower quadrant (RLQ) abdominal pain lasting 1week, with gradual worsening, radiating to theright flank and buttock. Physical examination elicited mild tenderness in the RLQ. Laboratory findings showed slight leucocytosis of 12 000 mm-3. An unenhanced helical CT was performed for a presumed diagnosis of acute right renal colic. No stone or secondary signs of urinary tract obstruction were found on CT. A 6 cm x 7 cm oval soft tissue mass was found in the midline behind the uterus. This mass showed relative hyperdensity compared with the normal left ovary and contained multiple peripheral small hypodense round lesions (Figure 1
). A small amount of free peritoneal fluid was also seen. A diagnosis of right ovarian torsion was made, which was further confirmed by ultrasound that demonstrated an 8 cm x 8 cm oedematous right ovary without visible intraovarian arterial flow. Adjacent to the ovary, a 6 cm x 2 cm echogenic lesion without visible flow was regarded as being a torted Fallopian tube, and a moderate amount of echogenic fluid in the pelvis was also seen. At laparoscopy, torsion of the right adnexa with an 8 cm x 8 cm congested, strangulated right ovary and haemorrhagic fluid were found. Laparoscopic right adnexectomy was performed. The final pathological diagnosis was haemorrhagic necrosis of the ovary and the Fallopian tube, consistent with torsion. The post-operative course was uneventful.
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Figure 1. (a) Unenhanced CT of the pelvis shows a non-homogeneous midline mass (arrowheads) behind the uterus (U), containing peripheral hypodense lesions. The mass generally has a higher density compared with the left ovary (arrow). Free peritoneal fluid surrounds the mass. (b) 15 mm caudally, the lower extension of the complex mass is seen (arrowhead), with multiple peripheral foci of low attenuation. Note also the free pelvic fluid (arrow).
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Discussion
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Tubo-ovarian torsion is a gynaecological emergency requiring prompt surgical intervention. Torsion may occur in normal ovaries but is more frequent in association with a pre-existing ovarian mass, and is most common in the first three decades of life [1–3]. When a high clinical suspicion of ovarian torsion exists, ultrasound with colour Doppler is the imaging modality of choice [1, 2]. The varied clinical presentations of ovarian torsion can mimic many non-gynaecological acute lower quadrant conditions and may not be clinically suspected. Helical abdominal CT may then be the initial diagnostic study. A wide range of acute abdominal clinical conditions are quickly and accurately diagnosed with CT [4]. Furthermore, unenhanced helical CT has become the premier imaging technique in evaluating patients with suspected "renal colic" [5]. Familiarity with this technique has led to expansion of the clinical indications for its use, with an increased detection rate of unsuspected extra-urinary pathological entities [6].
The multiple peripheral follicles in an enlarged ovary that were demonstrated on CT in our patient parallel the ultrasound features, which have been reported to be specific for torsion of apreviously normal ovary [7]. The relative hyperdensity of the torted ovary shown on CT was probably related to venous congestion within the ovary, while the free peritoneal fluid may have resulted from lymphatic and venous congestion or infarction with intraperitoneal haemorrhage. However, small amounts of pelvic fluid can be found in normal pre-menopausal females. Similar CT findings of a midline pelvic mass with multiple peripheral low attenuation foci have also been reported in four pre-pubertal girls in whom contrast enhanced CT was performed for an unclear clinical presentation. Ovarian torsion was confirmed by surgery in these patients [2, 8]. Although the CT findings of a twisted adnexal tumour have been reported in adults [3, 9], the CT appearance of torsion of an otherwise normal adult ovary has not been previously described.
Nowadays, CT is often used as the initial imaging modality for evaluating patients with acute abdominal and pelvic pain, and therefore the radiologist should be familiar with the specific although uncommon appearance of ovarian torsion, which may well be unsuspected clinically.
Received for publication January 3, 2001.
Revision received April 24, 2001.
Accepted for publication May 2, 2001.
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References
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M. Pansky, N. Smorgick, A. Herman, D. Schneider, and R. Halperin
Torsion of Normal Adnexa in Postmenarchal Women and Risk of Recurrence
Obstet. Gynecol.,
February 1, 2007;
109(2):
355 - 359.
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