What type of ultrasound should I order when evaluating a patient for possible ovarian cysts?

Ultrasound Imaging for Suspected Ovarian Cysts

Order transvaginal ultrasound as the primary imaging modality, supplemented with transabdominal ultrasound when needed for complete evaluation. 1

Primary Imaging Approach

• Transvaginal ultrasound is the gold standard for evaluating ovarian cysts and should be the first-line imaging modality ordered. 1, 2

• Transabdominal ultrasound should be performed in addition to transvaginal imaging, not instead of it, particularly when:

  • Large masses extend beyond the transvaginal field of view 1
  • You need an overview of the entire pelvis 1
  • The patient cannot tolerate transvaginal examination 1

• The optimal sequence is to perform transabdominal imaging first, then proceed to transvaginal examination, as this allows assessment of bladder fullness, uterine position, and anatomic variations before the more detailed transvaginal study. 1

Essential Technical Components

• Color or power Doppler must be included in the ultrasound examination to differentiate true solid components from debris and to assess vascularity of any solid areas. 1

• The examination should systematically scan organs in real time through all tissue planes in at least two orthogonal directions (short and long axis). 1

• Both ovaries should be completely visualized in two planes to identify masses adjacent to the ovary and cysts on the periphery. 1

Why Transvaginal Ultrasound is Superior

• Transvaginal sonography has demonstrated considerable advantage over conventional transabdominal sonography alone for characterizing ovarian pathology. 3

• It provides superior accuracy for diagnosing serous cysts, ovarian carcinoma, and endometriomas compared to CT imaging, even when CT is combined with clinical parameters and CA-125 levels. 2

• Morphologic assessment with transvaginal ultrasound achieves sensitivity of 80% and specificity of 93% for distinguishing benign from malignant masses. 3

Common Pitfalls to Avoid

• Do not order CT scan for further characterization of indeterminate adnexal masses—if ultrasound is inconclusive, MRI with IV contrast is the preferred next step, not CT. 1, 4

• Do not perform ultrasound with a full bladder for transvaginal examination; the best imaging is achieved with an empty bladder for the transvaginal component. 1

• Do not rely on spectral Doppler parameters (resistive index, pulsatility index) alone, as they do not provide significant improvement over morphologic assessment—use color/power Doppler primarily to detect flow in solid areas. 1

• Avoid ordering PET/CT, as it cannot reliably differentiate between benign and malignant adnexal lesions. 4

When to Add MRI

• If the ultrasound findings are indeterminate (uncertain organ of origin or unclear benign vs. malignant features), order MRI pelvis with IV contrast as the problem-solving modality. 1, 4

• MRI without contrast can still achieve 85% sensitivity and 96% specificity for detecting malignancy when IV contrast is contraindicated. 4