Ovarian torsion

Case contributed by Matt A. Morgan


Acute right lower quadrant / pelvic pain. Afebile. B-hCG negative.

Patient Data

Age: 30 years
Gender: Female

Initial pelvic ultrasound


In this set of TA and EV images, a number of findings were made

  • enlarged right ovary (6.7 x 6.7 x 4.7 cm), with moderately echoic central stroma and peripheral small follicles
  • left ovary is normal
  • uterus is normal
  • hypoechoic free fluid in the pelvis
  • spectral Doppler: flow detected in both ovaries

The patient was tender to the exam with both the TA transducer and the EV probe.

Follow up ED CT


There is an ill-defined heterogeneously enhancing mass in the posterior pelvis. The right ovary is not well seen. The left ovary is normal. There is no appendicitis or inflammatory disease elsewhere in the abdomen. Small amount of free fluid in the pelvis. No pleural effusion at the lung bases.

Follow-up MRI study


Multiple MRI sequences demonstrate findings compatible with torsion (1.5 T)

  • T2 and STIR: enlarged right ovary which is markedly T2 hyperintense, compatible with edematous change from torsion
  • T1 C+ (Gd)
    • only a tiny amount of streaky enhancement of the right ovary
    • the twisted right adnexal pedicle is well seen on the axial sequence
  • T1: right ovary is uniformly hypointense with a few small hyperintense foci, compatible with tiny hemorrhagic cysts

A hemorrhagic cyst / endometrioma in the left ovary is also noted.

Highlighted images

Annotated image

Collection of key images for the case:

  • spectral Doppler detects a small amount of blood flow in the right ovary
  • MR sequences to evaluate mass demonstrate a markedly asymmetrically enlarged right ovary, which has a twisted right adnexa (right open arrow), which demonstrates marked edema, and which has only a few small peripheral follicles

Case Discussion

It is a commonly held belief that if blood flow can be shown in an ovary that ovarian torsion can be excluded. This is not entirely correct. 

The most important factors for a diagnosis of ovarian torsion on ultrasound are the size and grayscale appearance and the clinical presentation. If the spectral Doppler exam is set with appropriate sensitivity and no blood flow is detected, then you can feel confident about diagnosing torsion (94% PPV in premenopausal women)... although this would be a late finding...

...however, if you detect blood flow in an ovary that otherwise looks torsed (as in this case), then torsion cannot be excluded. Blood flow in a torsed/torsing ovary may occur from intermittent torsion or from the ovary's dual blood supply.

In this situation, the original ultrasound was read as an "ovarian mass", because it demonstrated blood flow on spectral Doppler and presumably could not be torsed, thus prompting the CT and MRI studies which confirmed ovarian torsion. Of note, on the MRI, you can see a small amount of streaky contrast in the ovary, demonstrating that a tiny amount of blood is flowing into it... but the ovary is clearly twisted around its pedicle and is torsed. The patient went to the OR and the diagnosis was confirmed.

In summary: ovarian torsion can be a tricky diagnosis. It can occur with spectral Doppler flow, without spectral Doppler flow, with an enlarged ovary and even rarely with a normal-sized ovary. The grayscale appearance and the clinical presentation are the most important imaging factors.

[Case courtesy of Dr. Siva Raman]

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