Ovarian Torsion: Likelihood Ratios

Introduction: Torsion of the ovary blocks venous outflow (and less commonly arterial inflow), leading to swelling of the ovary and subsequent occlusion of arterial blood flow. In adults, 94% of ovarian torsions were from masses (half cysts and half neoplasms). However, >50% of torsions in children < 15 years of age occur in normal ovaries.

See UpToDate http://www.utdol.com/online/content/topic.do?topicKey=gyn_surg/5273

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The likelihood ratios of findings for Ovarian Torsion are listed below. See the left navigation bar to change the display.

Pre-Test Probability (Prevalence): %.	Post-Test Probability (Predictive Value): %.	Switch to display mode.
Note that calculating probabilities from more than one** finding is inherently inaccurate because findings are not independent. (For example, using two positive findings that share a common pathogenesis is likely to overestimate the true probability.)

Good Positive and Negative Likelihood Ratios
Finding	Result	+LR	-LR
[ + ] Doppler Ultrasound	+ 0 -	46.5	0.1
The findings may be decreased or absent venous and/or arterial flow - here the criterion is simply any abnormality. Study: J Ultrasound Med 2001 Oct;20(10):1083-9. PMID 11587015 Eur J Obstet Gynecol Reprod Biol 2002 Aug 5;104(1):64-6. PMID 12128265

Poorly Diagnostic Findings
Finding	Result	+LR	-LR
[ + ] Ovarian Mass by Ultrasound		Sensitivity = 100%
Only 15 patients. No specificity. Study: J Ultrasound Med 2001 Oct;20(10):1083-9. PMID 11587015
[ + ] Fluid in Cul-de-Sac		Sensitivity = 87%
(By ultrasound) Study: J Ultrasound Med 2001 Oct;20(10):1083-9. PMID 11587015