Ultrasound sensitive for appendicitis, improves outcomes [Classics Series]

1. Among patients with signs and symptoms consistent with acute appendicitis (AA), ultrasound demonstrated a sensitivity and specificity of 80% and 100%, respectively.

2. The use of ultrasound led to an appropriate change in patient management in 26.1% of cases.

Original Date of Publication: September 1987

This study summary is an excerpt from the book 2 Minute Medicine’s The Classics in Medicine: Summaries of the Landmark Trials, 2e (The Classics Series).

Study Rundown: AA is a common cause of abdominal pain in both children and adults, and can be challenging to diagnose by physical examination alone. By the mid-1980s a number of small, retrospective studies had been performed suggesting a diagnostic role for graded-compression ultrasound (GCUS), a technique that involves the application of pressure to abdominal wall with the ultrasound probe to minimize obscuring bowel gas. However, the results were felt to be equivocal, and GCUS was not widely adopted. In the present trial, the question of GCUS as a diagnostic tool in the evaluation of patients with suspected AA was addressed prospectively in a large cohort of patients at a single academic medical center. All enrolled patients were imaged after initial assessment by a surgeon, and changes in planned patient management were recorded alongside the diagnostic performance of GCUS. Results showed a high sensitivity and specificity for AA as well as a favorable trend toward improved patient care, with changes in management made for over one-quarter of patients. Notably, GCUS was not able to visualize the appendix in a significant minority of cases, in part reflecting limitations in ultrasound technology at the time of the study’s publication.

Please click to read study in NEJM

In-Depth [prospective cohort]: A total of 111 consecutive patients (mean age 29 years, range 8-86 years) with a clinical presentation concerning for AA were prospectively enrolled at a single academic medical center over a 5 month period. All enrolled patients were first clinically evaluated by a member of the surgical staff using a combination of physical examination, laboratory studies, and plain x-ray images. Immediately following this, patients then received comprehensive abdominal ultrasound using graded compression for optimization of bowel visualization. All ultrasound studies were performed by radiologists and evaluated on several parameters, including appendiceal visualization, certainty of appendiceal visualization, and the presence imaging findings consistent with complications such as appendiceal perforation. After a maximum period of 6 hours of patient observation and prior to being informed of ultrasound findings, the evaluating surgeon was then asked to provide recommendations for operative or non-operative management. Imaging findings were then provided alongside an opportunity to alter management plans. The final diagnosis was determined using surgical pathology, intraoperative findings, or clinical diagnosis in combination with radiology and other supporting data.

An unequivocal ultrasound diagnosis was rendered in 83 (74.8%) patients. Among these patients, the overall sensitivity and specificity for the diagnosis of AA were 80% and 100%, respectively. When considering only those patients with non-perforated AA, the sensitivity remained essentially unchanged at 80.5% but decreased to 28.5% for patients with perforated AA. This was felt to be related to obscuration of the bowel wall by free intra-abdominal fluid and difficult patient examination secondary to peritonitis. In 29 (26.1%) patients, GCUS led to an appropriate change in management, including 16 (14.4%) patients originally triaged to conservative management who instead underwent surgical intervention. Among 4 of the 28 (14.3%) patients without a definitive final diagnosis, the appendix was unequivocally visualized but the patients did not undergo surgery because of symptom resolution.

Puylaert JBCM, Rutgers PH, Lalisang RI, de Vries BC, van der Werf SDJ, Dörr JPJ, et al. A Prospective Study of Ultrasonography in the Diagnosis of Appendicitis. New England Journal of Medicine. 1987 Sep 10;317(11):666–9.

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