Localization of appendix with MDCT and influence of findings on choice of appendectomy incision.

OBJECTIVE: The purpose of this study was to show the relation between McBurney's point and the appendix in patients undergoing 3D MDCT and to investigate the effect of this information on a surgeon's choice of appendectomy incision.

MATERIAL AND METHODS: Among 142 adults undergoing consecutive MDCT studies, 100 patients (35 women, 65 men; mean age, 52.1 years) with an identifiable appendix on abdominopelvic MDCT examinations were selected for the study group. The presence of intraabdominal mass or a history of abdominal surgery were the exclusion criteria. Three-dimensional reconstruction of the CT data was performed with a surface shaded display algorithm. The locations of the base of the appendix and McBurney's point were marked on a single 3D image that allowed display of the skin surface markings for each patient. The superoinferior and mediolateral distances from the level of the appendix to the level of McBurney's point were measured, and the radial distance was calculated from these measurements. A surgeon experienced in emergency abdominal surgery reviewed 3D CT images and one axial image showing the appendix, and his choice of incision for each patient based on the CT information was recorded. The influence of the superoinferior and mediolateral distances of the appendix from McBurney's point on the surgeon's decision was analyzed with a multivariate logistic regression model.

RESULTS: The appendix was exactly at McBurney's point in only 4% of the patients. In 36% of the cases, the appendix was within 3 cm, in 28% of cases it was 3-5 cm, and in 36% of the cases it was more than 5 cm away from McBurney's point. Mean +/- SD superoinferior, mediolateral, and radial distances between the appendix and McBurney's point were 33.0 +/- 24.1, 20.8 +/- 19.3, and 42.1 +/- 26.7 mm, respectively. After reviewing the images, the surgeon would have altered his incision site in 35% of the cases. The surgeon preferred a higher incision in 28% and a lower incision in 7% of the cases. Both positive and negative superoinferior displacement away from McBurney's point were significant factors regarding the surgeon's decision to alter the incision (p = 0.005), and the superoinferior distance was more than 3 cm in 94% of the cases in which the surgeon would have altered the incision.

CONCLUSION: The location of the appendix varies widely among individuals, and McBurney's point has limitations as an anatomic landmark. Three-dimensional MDCT findings can be useful to surgeons customizing appendectomy incisions. Additional information about the location of the appendix in the CT report (if possible, together with a 3D image showing the location of the appendix) may be beneficial for surgeons performing appendectomy.