Differential Diagnosis for Right-Sided Abdominal Pain

Most Common Etiologies by Frequency

The American College of Radiology suggests that appendicitis is the most common surgical pathology in the United States, representing the primary diagnosis requiring operative management 1, 2
Right colonic diverticulitis accounts for approximately 8% of right lower quadrant pain cases 3
Intestinal obstruction is present in approximately 3% of cases 3
Ureteral stone/nephrolithiasis is a common cause requiring differentiation from appendicitis 1, 4
Infectious enterocolitis, including typhlitis and inflammatory terminal ileitis, is a consideration in the differential diagnosis 3
Colitis, including inflammatory bowel disease, is also a potential cause of right-sided abdominal pain 3

Perforated appendicitis has high morbidity and mortality if diagnosis is delayed; imaging does not increase perforation rates 1, 2
Mesenteric ischemia requires consideration of lactate and D-dimer, though these lack specificity 5, 6
Ectopic pregnancy must be excluded in all women of reproductive age before imaging, with beta-hCG testing being mandatory 5, 6

Location specificity, such as right lower quadrant pain, strongly suggests appendicitis, but clinical determination alone has unacceptably high negative appendectomy rates (up to 25%) 2, 4
Clinical scoring tools, like the Alvarado score, have not improved diagnostic accuracy and show mixed results for guiding CT use 2, 4
Complete blood count, comprehensive metabolic panel, urinalysis, serum lipase, and beta-hCG are all part of the mandatory laboratory workup 5, 6
CT abdomen/pelvis with IV contrast is the imaging modality of choice for right lower quadrant pain, with 95% sensitivity and 94% specificity for appendicitis [3, @28@]

Failing to obtain pregnancy testing before any imaging in women of reproductive age can lead to delayed diagnosis of ectopic pregnancy and unnecessary radiation exposure 5, 6, 7
Over-reliance on clinical examination alone results in negative appendectomy rates as high as 25% without imaging 2, 4
Delaying imaging in equivocal cases can impact diagnostic accuracy, as CT use has increased to reflect improved diagnostic accuracy without increasing perforation rates 3