Ovarian torsion is like the MI of the pelvis. Sometimes all it takes is a good story to investigate.
When to worry, when to walk it off, and when to work it up:
What is the typical presentation of ovarian torsion?
There is none. The presentation varies so much, we need a rule to live by:
Unilateral pelvic pain in a girl is ovarian torsion until proven otherwise. This includes the cases in which you are concerned about appendicitis. They both can be fake-outs.
Often the pain is severe and abrupt, but trying to tease this out is often not fruitful.
Reported signs and symptoms associated with ovarian torsion:
Stabbing pain, 70%
Nausea and vomiting, 70%
Sudden, sharp pain in the lower abdomen, 59%
Pain radiating to the back, flank, or groin, 51%
Peritoneal signs, 3%
Fever, less than 2%
And of course…no pain on presentation…30%…intermittent torsion.
What is the mechanism of ovarian torsion?
- Structurally abnormal ovary (including cysts) that causes the ovary to flop over and twist on its vascular axis
- Hypermobile ovary with vigorous movement twists on its vascular pedicle and cuts off blood supply
What ultrasound findings suggest ovarian torsion?
- The enlarged hyper- or hypo-echoic ovary from generalized edema
- Peripherally displaced follicles with hyperechoic central stroma (string of pearls sign): stroma is edematous, leaving the follicles to stand out
- A midline ovary – if the ovary magically makes it to midline, something is up
- Free fluid in the pelvis – this is seen in the vast majority of cases
As far as Doppler flow goes, you may see one of several scenarios:
- Little or no venous flow – this is very common, as we talked about, because the low pressure venous system is the first to take a hit in torsion
- Totally absent arterial flow – this is not as common, but totally diagnostic
- No flow in diastole, or reversal in flow – the red and blue of dopple does not correspond to arterial and venous. Doppler is a vector. Red is fluid coming towards the probe, blue is programmed to present flow away from the probe. If you have just one or the other, then by definition there is a problem with the vascular circuit.
Other things you may see on ultrasound include focal tenderness with the probe, or the whirlpool sign – this is a twisted vascular pedicle.
In children, is there an ovarian size (volume) that rules out torsion?”
In the Journal of Pediatric Radiology, Servaes et al. catalogued the ultrasound findings in children with surgically confirmed torsion over a 12 year period. In this case series of 41 patients, the median age was 11. The age range was one month old to 21 years of age. They found that in torsed ovaries, the ovarian volume was 12 x that compared to the normal, non-torsed contralateral ovary.
That is to say, in this case series all torsed ovaries were larger than the normal contralateral ovary.
Sudden unilateral lower abdominal or pelvic pain in a female? Think torsion.
Have a low threshold for investigation.
Know the performance characteristics of ultrasound findings and involve a gynecologist early.
This post and podcast are dedicated to Stephanie Doniger, MD for her enthusiasm, spirit, and expertise in #MedEd #FOAMed #FOAMped #POCUS
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