Re: Accuracy of first-trimester ultrasound in diagnosis of tubal ectopic pregnancy in the absence of an obvious extrauterine embryo: systematic review and meta-analysis
Year: 2016
Type: letter
Abstract: In this era of evidence-based medicine, when we read a meta-analysis, we expect to glean information that will be clinically useful. Indeed, before embarking on a meta-analysis, it is important for the researchers to understand the clinical importance of their topic and to include relevant articles in support of their research strategy. Thus, we were surprised by the description of the recent meta-analysis, ‘Accuracy of first-trimester ultrasound in diagnosis of tubal ectopic pregnancy in the absence of an obvious extrauterine embryo: systematic review and meta-analysis’1. The meta-analysis itself is well-described and follows guidelines appropriately; however, the authors never state why a review was needed, and what the current question is that needs to be answered. If a meta-analysis is to be helpful in changing care, the studies being assessed need to reflect the current standard of care. The vast majority of the articles reviewed were over 20 years old. One must consider that if there was clinical concern about the best method for imaging a diagnosis as common as ectopic pregnancy, there would be more recent accuracy studies. As the authors state, ‘The introduction of high-resolution transvaginal ultrasound has revolutionized the diagnosis of ectopic pregnancy’; why, then, did they include in their review some articles that used only the transabdominal technique? In the 1980s we did not have transvaginal scanning, and thus articles on sonographic diagnosis of ectopic pregnancy depended on transabdominal scanning alone. Even when transvaginal scanning became available, the frequency of the transducers was not as high as it is today. Indeed, one of the reasons for the increased incidence of ectopic pregnancy is felt to be the improvements in imaging technology. In the current era, pregnant women without visualization of an intrauterine pregnancy are scanned with transvaginal ultrasound. Transabdominal scanning alone is not standard of care, and has not been for decades. The authors did identify whether studies used transabdominal or transvaginal scanning during data extraction; it is somewhat disappointing that they did not take the extra step of performing subgroup analysis of those that used the transvaginal technique, since these would be the most indicative of present-day standard of care. Of similar concern is the analysis of criteria for diagnosis, such as the sole finding of free fluid or the sole finding of an empty uterus. These are not standard of care for diagnosis of ectopic pregnancy. While there is no doubt that the conclusions of the meta-analysis – that, based on sonographic findings, we can rule in ectopic pregnancy, but we cannot exclude it – are correct, one must wonder why old articles, using techniques no longer in use today, were needed in order to arrive at a conclusion that is already well-established in clinical care. D. Levine*† and M. McInnes‡ †Department of Radiology, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA; ‡Department of Radiology, University of Ottawa, The Ottawa Hospital Civic Campus, Ottawa, Ontario, Canada *Correspondence. (e-mail: [email protected])
DOI: 10.1002/uog.15877
Authors: D. Levine, M. McInnes
Language: English
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W2467071297