In the July 2013 issue of Clinical Radiology, the authors from Harvard Medical School review 126 patient charts of non-pregnant women who had a negative abdominal/pelvic CT from 2005- 2010 who then had a pelvic ultrasound for pelvic pain. Despite the obvious question, which is “why did they get a CT and not an ultrasound in the first place?” which will not be discussed, their findings were surprising. Im not sure why, but I guess it goes to show how good multi-detector CT imaging is for these patients now. This raises the question whether a pelvic ultrasound is needed in these patients given the low yield. It would be nice if this was a multi-site study with thousands of patients to increase the power, but the numbers here cannot be ignored. Below is the abstract:
To determine the diagnostic value of pelvic ultrasound following negative abdominal/pelvic computed tomography (CT) in women presenting to the emergency room (ER) with abdominal/pelvic pain, and whether ultrasound altered clinical management in the acute-care setting.
MATERIALS AND METHODS:
Between January 2005 to October 2010, 126 consecutive, non-pregnant women with abdominal/pelvic pain underwent pelvic ultrasound within 24 h following negative abdominal/pelvic CT in the ER. Imaging findings/reports for the CT and ultrasound examinations, and clinical data/outcomes were recorded. The time interval between the CT and ultrasound examinations was calculated. Mean length of stay (LOS) was compared to that of age-matched controls who did not have subsequent ultrasound using the t-test.
Only 3% (four of 126 cases) of the pelvic ultrasound examinations showed positive findings, all of which were endometrial abnormalities. One patient was diagnosed with an endometrial polyp, whereas the others were lost to follow-up. In none of the four cases was the pelvic ultrasound finding relevant to the acute presentation or altered acute care. The average time between CT to ultrasound was 3 h and 4 min. Mean LOS was 22 h and 13 min for the cohort, and 16 h and 8 min for the age-matched controls, although this was not statistically significant (p = 0.29).
Immediate ultrasound re-imaging of the pelvis following negative CT in women with acute abdominal/pelvic pain yields no additional diagnostic information and does not alter acute care.
A similar study was done and published in 2011 out of NYU – abstract below: