Why has computed tomography won and ultrasound lost the market share of imaging for acute pelvic conditions in the female patient?

n the late 1970s when I was a radiology resident, there was an ultrasound machine in the emergency radiology suite but no computed tomographic (CT) scanner. There was only 1 CT scanner in our hospital (Massachusetts General Hospital, 1977–1980), and all of the CT scans ordered by the emergency room were for head trauma. Nowadays, not only is there a CT scanner in the emergency room, but it is working around the clock and has become the first-line evaluation for many patients presenting with abdominal or pelvic conditions. Somehow over the years, ultrasound has inexplicably lost the market share for evaluating women with pelvic or lower abdominal pain. This practice is evident daily in my ultrasound unit when patients are referred to me for pelvic ultrasound because of a finding on their recent CT scan that was equivocal or inconclusive. Don’t these ordering physicians remember that ultrasound is far better for evaluating the female pelvis than CT and ultrasound has no ionizing radiation? How have we evolved to ordering the most expensive imaging technique first for these patients, only to be followed frequently by a far less costly ultrasound examination to clarify the CT findings? Ultrasound is the established modality of choice to evaluate the female pelvis, so why do patients with pelvic masses or pain get a CT scan? In my opinion, doing a CT scan first for female patients with lower abdominal pain is dangerous and wasteful, a drain of much-needed health care dollars. Several articles in the literature, mostly pictorial essays, describe the CT appearance of some of the common acute female pelvic conditions, such as ovarian cysts, hemorrhagic cysts, hydrosalpinx, pedunculated fibroids, and tubo-ovarian abscesses.1,2 While all of these articles claim that ultrasound is well known to be the imaging modality of choice for evaluation of the female pelvis, they show the appearance of these conditions on CT images because of the rampant use of CT in these patients who present to the emergency room.1,2 Rather than trying to teach the appearance of these gynecologic diseases on CT, why not simply order an ultrasound examination first and make the diagnosis more easily and without radiation or high costs? The effect of exposure to low-dose radiation from the multitude of CT scans merits further discussion. A recent study in the New England Journal of Medicine reported that among 952,420 adults aged 18 to 64 years seen between January 1, 2005, and December 31, 2007, 68.8% underwent at least 1 imaging procedure that involved radiation exposure.3 We must keep in mind that radiation exposure is cumulative, and each exposure