ABSTRACT
INTRODUCTION AND IMPORTANCE: Acute appendicitis is the most common abdominal surgical emergency in the world and often requires surgical intervention. One of the complications of appendicitis is abscess formation. In rare cases, a localised abscess can occur in the adjacent organs, such as the iliac and psoas muscles. Sacroiliitis occurring secondary to, or concomitant with, acute appendicitis is extremely rare. However, a missed diagnosis of either or both conditions can lead to serious complications, including mortality. CASE PRESENTATION: A 27-year-old male patient presented to the emergency department with a history of acute severe right hip pain that was aggravated by movement and associated with nausea and vomiting. CT suggested acute uncomplicated appendicitis with no localised contamination. He underwent an emergent laparoscopy which showed mild appendiceal inflammation and appendicectomy was performed. He became septic a few hours after the operation, resulting in admission to the high dependency care unit for close observation. On review the following day, he reported ongoing right hip pain and lower back pain with a new onset inability to weight-bear. An MRI scan was performed which showed features of infection around the right sacroiliac joint and Staphylococcus aureus grew in his blood culture. A diagnosis of acute pyogenic sacroiliitis was then made. The patient was treated with IV antibiotics for a total of four weeks, followed by two weeks of oral antibiotics. CLINICAL DISCUSSION: Acute pyogenic sacroiliitis is one of the rarer conditions seen that can mimic the acute abdomen, in this case acute appendicitis. MRI is the best diagnostic modality in sacroiliitis, in comparison to CT for appendicitis. In most cases of acute appendicitis, mixed bacteria including aerobes and anaerobes are seen in the blood culture while staphylococcus aureus is seen mostly in acute pyogenic sacroiliitis. Staphylococcus aureus-induced appendicitis is reported in less than 3.7 % of cases. An early diagnosis of either or both conditions can significantly reduce complications and, more importantly, expedite implementation of appropriate treatment. CONCLUSION: In our case we present a combination acute appendicitis, acute sacroiliitis and staphylococcus aureus septicaemia and provide proof that acute pyogenic sacroiliitis can be a rare complication of acute appendicitis. Thus, a high clinical index of suspicion should be considered in the appropriate clinical scenario.
