Right perinephric abscess: a rare presentation of ruptured retrocecal appendicitis.

Perinephric abscess commonly arises from rupture of an intrarenal abscess into the perinephric space. It rarely results from gastrointestinal pathology. We report two pediatric patients with retrocecal appendicitis that presented with perinephric abscess. A 3-year-old girl presented with high fever and right flank pain for more than 1 week. Ultrasonography showed a right perinephric fluid collection with normal renal parenchyma and collecting system. A perinephric abscess extending from a ruptured retrocecal appendix was diagnosed by abdominal computed tomographic (CT) scan. Her hospital course was complicated with empyema, peritonitis, and pericardial effusion. A 6-year-old girl had lower abdominal pain for 3 days and high fever on the day of admission. Ultrasonography showed a right perinephric abscess with a normal renal contour and a fecalith in the enlarged appendix in the right lower quadrant of the abdomen. Appendectomy and drainage of the perinephric abscess were performed in both cases. We suggest that a ruptured retrocecal appendix must be considered in cases of perinephric abscess, especially in patients with gas bubbles in the abscess and a normal urogenital appearance. Ultrasonography and abdominal CT scan are the preferred diagnostic tools. Prolonged antibiotics and drainage of the abscess are mandatory to decrease morbidity and mortality.