BACKGROUND: Crohn’s disease (CD) is an inflammatory bowel disease affecting approximately 1 in 3000 people in the United States. Since the inflammation of CD is transmural, patients are at risk for fistula and abscess formation. Retroperitoneal abscesses are one type of which physicians must be aware.

CASE REPORT: We present the case of a 29-year-old woman with CD who complained of right hip and flank pain that began when she was 6-months pregnant. After delivery, she continued to complain of severe right flank pain and was admitted to the hospital 1 month later. CT scan imaging revealed a complicated retroperitoneal and right flank abscess, possibly due to a colonic intramural fistula. She developed severe acute necrotizing soft-tissue infection requiring 13 days of intensive care. She required debridement of the necrotizing infection of the right flank, drainage of the abscess, and washout for intraperitoneal sepsis. The patient tolerated the procedures well and was discharged 1 month later.

CONCLUSIONS: Given that the clinical manifestation of retroperitoneal fistula with abscess is insidious and its formation is less common than intraperitoneal abscesses, we hope healthcare providers learn from this case to avoid morbidity and mortality. When presented with a pregnant CD patient complaining of nonspecific abdominal symptoms, providers should consider fistulization and/or abscess formation. The option to evaluate pregnant patients using noninvasive methods, such as ultrasound or low-dose CT scan, can decrease radiation exposure to the fetus and prevent delays in diagnosis and treatment.

Keywords: Abdominal Abscess, Crohn Disease, Fistula, Obstetrics, Pregnancy, Retroperitoneal Space