 Introduction/Background The differential diagnosis for left lower quadrant pain includes gastrointestinal, gynecologic, urologic, and body wall pathology. These conditions range from the benign and self-limited to life-threatening surgical emergencies. Along with patient history, physical examination, and laboratory tests, imaging is often critical to limit the differential diagnosis and identify life-threatening abnormalities [1]. Appropriate imaging triage for patients with left lower quadrant pain should address the diagnostic possibilities and consider which imaging modality can best add clinically relevant information to help guide management. In older patients, early diagnosis is important because this population has a higher rate of comorbid disease-related complications [2-6]. Furthermore, symptoms and clinical findings may be nonspecific in this population, with atypical presentation of common diseases. Acute colonic diverticulitis is the most common explanation for left lower quadrant pain, and the prevalence is rising. There was a 50% increase in diverticulitis events between 2000 and 2007 [6,7]. Colonic diverticulitis, which results from inflammation of colonic diverticula, is common in Western populations, likely due to inadequate dietary fiber. Approximately 10% of the Western population has diverticulosis at 40 years of age; this increases to 70% or more in older patients. It has been estimated that between 5% and 25% of patients with diverticulosis will develop diverticulitis [3,8]. Although the most common cause of adult left lower quadrant pain is acute diverticulitis of the sigmoid or descending colon, other common causes of left lower quadrant pain include colitis, inflammatory bowel disease, epiploic appendagitis, bowel obstruction, hernia, ovarian and fallopian tube pathology, pyelonephritis, and urolithiasis [6,9]. Many of these conditions can present with symptoms that overlap with the acute presentation of diverticulitis.
Left Lower Quadrant Pain.  Introduction/Background The differential diagnosis for left lower quadrant pain includes gastrointestinal, gynecologic, urologic, and body wall pathology. These conditions range from the benign and self-limited to life-threatening surgical emergencies. Along with patient history, physical examination, and laboratory tests, imaging is often critical to limit the differential diagnosis and identify life-threatening abnormalities [1]. Appropriate imaging triage for patients with left lower quadrant pain should address the diagnostic possibilities and consider which imaging modality can best add clinically relevant information to help guide management. In older patients, early diagnosis is important because this population has a higher rate of comorbid disease-related complications [2-6]. Furthermore, symptoms and clinical findings may be nonspecific in this population, with atypical presentation of common diseases. Acute colonic diverticulitis is the most common explanation for left lower quadrant pain, and the prevalence is rising. There was a 50% increase in diverticulitis events between 2000 and 2007 [6,7]. Colonic diverticulitis, which results from inflammation of colonic diverticula, is common in Western populations, likely due to inadequate dietary fiber. Approximately 10% of the Western population has diverticulosis at 40 years of age; this increases to 70% or more in older patients. It has been estimated that between 5% and 25% of patients with diverticulosis will develop diverticulitis [3,8]. Although the most common cause of adult left lower quadrant pain is acute diverticulitis of the sigmoid or descending colon, other common causes of left lower quadrant pain include colitis, inflammatory bowel disease, epiploic appendagitis, bowel obstruction, hernia, ovarian and fallopian tube pathology, pyelonephritis, and urolithiasis [6,9]. Many of these conditions can present with symptoms that overlap with the acute presentation of diverticulitis.