The role of radiological imaging in the diagnosis of acute appendicitis: ULTRASONOGRAPHY Part 4
Many investigators have studied the diagnostic accuracy of ultrasonography for patients suspected of having appendicitis. Some of the largest and best designed of the prospective studies are summarized in Table 4. In most cases, graded compression technique was used, but the use of pelvic ultrasonography was usually not discussed specifically. Diagnostic accuracy seems to be similar in women and men, although most investigators have not reported their results separately according to sex. It is also accurate in pregnant women. Comparable performance characteristics are observed with adult and pediatric patients (Table 4), but it is less sensitive in patients with a body mass index of 25 or greater than in lean patients.
Prospective studies of sonography in the diagnosis of acute appendicitis
|Author, year (reference)||n||Acute appendicitis (%)||Sensitivity(%)||Specificity(%)||PPV(%)||NPV(%)||Accuracy(%)|
|Puylaert et al, 1987 (103)||60||47||89||100||89||91||95|
|Abu-Yousef et al, 1987 (99)||68||37||80||95||91||89||90|
|Jeffrey et al, 1988 (104)||250||36||90||96||93||94||94|
|Vignault et al, 1990 (207)*||70||47||94||89||89||94||91|
|Schwerk et al, 1990 (140)||857||23||90||98||94||97||96|
|Davies et al, 1991 (138)||152||27||96||94||96||94||95|
|Rioux, 1992 (208)||170||26||93||94||86||98||94|
|Sivit et al, 1992 (141)*||180||29||88||82||90||79||86|
|Chen et al, 1998 (209)||191||75||99||68||90||97||92|
|Hahn et al, 1998 (114)*||3859||13||90||97||82||98||96|
|Schulte et al, 1998 (210)*||1285||9||92||98||90||98||98|
|Sivit et al, 2000 (158)*||315||26||78||93||79||92||89|
|Douglas et al, 2000 (125)||129||46||95||89||88||95||91|
Studies comprised exclusively pediatric patients (other studies comprised mainly adults). NPV Negative predictive value; PPV Positive predictive value
Some investigators have stated that ultrasonography is more accurate than clinical assessment in diagnosing acute appendicitis, while others have found that it offers no advantage. It has been suggested that the use of ultrasonography would reduce the negative appendectomy rate to 7% or even lower, but the perforation rate is not decreased. Many studies may have been biased in favour of sonography. The radiological tests were performed after the initial clinical assessment with which they were compared, and thus after the illness had progressed. Not all patients underwent surgery, and it was not always clear that the ultrasound results did not influence the decision to operate. These factors introduce possible verification bias. The interactive nature of sonography could also have introduced additional biases, in that patients with localized pain and tenderness (ie, those with a high pretest probability of a surgical condition) would be more likely to have a definitive ultrasonography result than those without localizing symptoms or signs. You are always welcome to visit the best and most trusted pharmacy offering to buy Alesse online and giving you only most efficient medications with no rx required and fast delivery right to your doorstep.
Ultrasonography was generally performed and interpreted by experts in the field, whereas clinical assessments were often performed by junior surgeons, surgical residents or others using clinical scoring systems. Sonography is highly dependent on technical expertise and the nature of the equipment, however, and it is unlikely to perform as well in nonspecialized centres as in research centres.