Clinical course and imaging description

A previously healthy six-year-old boy presented with signs and symptoms of acute appendicitis. Ultrasound (Fig. 41.1a) and CT scan (Fig. 41.1b) were obtained to confirm the diagnosis. The patient had an appendectomy and five days of antibiotics, but due to continued fever and leukocytosis a repeat CT scan (Fig. 41.2) was obtained. This showed a multiloculated abscess that was well above the rectum, making it inaccessible to transrectal drainage, and surrounded by structures that made it seemingly inaccessible without passing through bladder, bowel, or bone. Regardless, the patient was referred to interventional radiology for drainage. Based on reports of successful drainage of such collections using a curved needle, the procedure was approved and the patient transported to the CT scanner, where a non-contrast scan was obtained in the prone position (Fig. 41.3a.) In order to delineate the abscess cavity and right ureter, however, intravenous contrast enhancement was required (Fig. 41.3b.) At this point, a 19-gauge, thin-walled Temno coaxial introducer needle (CareFusion, McGaw Park, IL) was bent to form a curve. Three methods were attempted. One way, without either the stylet or a guidewire through the needle (Fig. 41.4a, d), was unsuccessful because the needle bent at a sharp angle that precluded reinsertion of the stylet (Fig. 41.4b, d.) The second way, with the stylet inside the needle while bending it was stiff and resilient. Although the needle would bend and hold its new shape, the amount of curvature was less than hoped for. The third way was with the stiff segment of an Ultra Stiff Amplatz guidewire (Cook Inc., Bloomington, IN) passed through it (Fig. 41.4c, d). Although this became less curved when the stylet was reinserted, it still gave the most satisfactory result. The curved needle was then inserted through the upper right sacroiliac space aiming slightly laterally. Frequent mid course checks were performed with removal and repositioning required in order to avoid the right ureter. Figure 41.5 depicts the course of the needle from the skin surface to the abscess cavity. After aspirating a small amount of pus for cultures and smears, an Amplatz guidewire was inserted through the Temno needle, and the Temno needle was removed. However, a dilator could not be inserted over the guidewire into the abscess because it was too tight in the sacroiliac space.