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Findings in this case: 1) There is a large, complex pelvic-abdominal mass. 2) The mass is associated with peripheral areas of decreased attenuation with surrounding enhancement suggesting follicles.
Diagnosis: Ovarian torsion
File: 6A
Organ system: 6. Female Genital Tract
Organ: A period Ovaries.
Etiology and incidence: 1) Torsion refers to the rotation of organ or structure about its vascular pedicle with resulting ischemia and/or infarction. 2) Torsion involves the RIGHT ovary more frequently than the LEFT ovary. 3) The degree of ischemia as on the rotation and collateral vessels. The ovary, as more than one vascular supply to therefore torsion leads varying degrees of ischemia. 4) Less than 20% of ovarian torsion cases occur in pediatric population. 5) Approximately 20% of torsion cases occur during pregnancy. Patient’s with ovarian torsion during pregnancy are more likely to have a second episode of torsion. 6) In the adult population, most patient’s are younger than 30 years old. 7) When associated with a mass, greater than 50% of these masses will be dermoid/teratoma tumors. Malignant tumors are possible as a cause however this is much less common. 
Tubal ligation and other pelvic surgeries, e.g. cyst removal, have a higher incidence for torsion.
Diagnosis: 1) Clinical diagnosis: A) The most common symptom is not sent of pelvic pain. This is frequently accompanied by nausea and vomiting. B) The accurate diagnosis clinically and radiographically is difficult with torsion confirmed by surgery in less than half the patients undergoing exploration. C) Doppler ultrasound has a sensitivity and specificity of approximately 50% and 90% respectively for torsion. The positive/-negative predicted values are both at approximately 75%. D) Torsion is most commonly associated with an ovarian cyst or mass. E) 50 to 60% of cases involve benign or malignant ovarian tumors. Masses are typically greater than 4 to 6 centimeters. F) Torsion of a normal ovary more peripherally occurs children and may be associated with abnormalities of the fallopian tubes and/or mesosalpinx. G) Torsion during pregnancy most commonly occur secondary to a large corpus luteum cyst. H) Women undergoing fertility treatments are at increased risk secondary to the development of numerous follicles. I) Clinical differential diagnosis includes: Appendicitis, diverticulitis, bowel obstruction, UTI/renal stones, PID and endometriosis. 2) Radiographic diagnosis: Ultrasound is typically the examination of choice. A) Duplex/Doppler ultrasound findings: Due to the vascular supply of the ovary, torsion can occur in the presence of identifiable vascular flow. And, a finding of flow on Doppler ultrasound does not exclude torsion. Typically, torsion will affect the venous outflow early and the arterial inflow later untreated. Due to the venous outflow obstruction, the affected ovary typically enlarges and becomes edematous leading to greater resistance to arterial inflow. B) Identification of the twisted vascular pedicle is uncommon. C) Pelvic ultrasound: Solid, enlarged and/or complex mass views the most frequent specific finding. As benign and malignant masses are frequently associated with torsion, observation of a mass in the presence of appropriate clinical findings should suggest the diagnosis. Free fluid may be present. A) Solid mass with peripheral follicles is also a common feature depending upon age of patient and prior history i.e. fertility treatment, pediatric patients or tubal ligation etc. B) CT findings: Complex pelvic mass with peripheral follicles or associated complex mass (dermoid/teratoma or much less commonly malignant mass). Free fluid may be present. There may be thickening of the adnexal structures and/or fallopian tube. C)Thickening of the adnexa/fallopian tube should be evaluated.
Prognosis/Clinical: 1) Primary treatment is laparoscopic exploration and evaluation of the ovary. Laparoscopy can be used to detorse the ovary and perform oophoropexy to fix the ovary to the pelvic sidewall to resolve the current torsion and decrease the likelihood of further episodes of torsion. 2) Laparoscopic evaluation can also determine the specific cause of torsion if that has not already been determined by ultrasound or CT. Typically, the salvage rate for ovaries is less than 10% in adults due to the presence of masses or delay in diagnosis and treatment.
References:
Ovarian Torsion in Emergency Medicine. Erik D Schraga, MD; Chief Editor: Pamela L Dyne, MD. http://emedicine.medscape.com/article/795994-overview
Ovarian torsion. http://www.radswiki.net/main/index.php?title=Ovarian_torsion
CT and MR Imaging Features of Adnexal Torsion.
Sung E. Rha, Jae Y. Byun, Seung E. Jung, Jung I. Jung, Byung G. Choi, Bum S. Kim, Hyun Kim, and Jae M. Lee. RadioGraphics 2002 22: 283-294.
http://radiographics.rsna.org/content/22/2/283.abstract
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