What is the role of Computed Tomography (CT) scan with or without contrast in evaluating right lower quadrant abdominal pain?

From the Guidelines

For right lower quadrant discomfort, CT with intravenous contrast is generally recommended as the preferred imaging approach. The contrast enhances visualization of inflammation, infection, and vascular structures, which is particularly helpful for diagnosing common causes of right lower quadrant pain such as appendicitis, diverticulitis, inflammatory bowel disease, and ovarian pathology 1. Oral contrast may also be administered depending on the clinical scenario, though many institutions now omit oral contrast for suspected appendicitis to expedite diagnosis. If the patient has contraindications to IV contrast (such as severe renal impairment or contrast allergy), a non-contrast CT can still provide valuable information, though with somewhat reduced sensitivity for certain conditions. The scan should include the entire abdomen and pelvis to ensure comprehensive evaluation of potential causes of the pain. Some key points to consider when ordering a CT for right lower quadrant discomfort include:

• The use of IV contrast increases the spectrum of detectable pathology in patients with nonlocalized pain 1
• Many institutions do not routinely use oral contrast because of the associated delay in scan acquisition and departmental throughput balanced against questionable diagnostic advantage 1
• CT with IV contrast adds diagnostic value and helps direct management, with studies showing that it can change leading diagnosis, admission status, and surgical plans in a significant proportion of patients 1
• The choice of imaging modality should be tailored for diagnosis of acute appendicitis in patients with a high degree of suspicion but should also allow diagnosis of other causes of RLQ pain to triage appropriate patient management 1 Patients should be instructed to fast for 4-6 hours prior to the exam if oral contrast will be used, and they should inform the radiologist about any allergies or kidney problems before receiving IV contrast.

From the Research

CT Scan for Right Lower Quadrant Discomfort

• The use of CT scans in evaluating right lower quadrant discomfort is a common practice, with studies suggesting its effectiveness in diagnosing acute appendicitis and other conditions 2, 3, 4, 5, 6.
• A study published in 2020 discussed the approach to evaluating patients with acute onset right lower quadrant pain and the choice of imaging modalities, including CT scans, ultrasound, and MRI 2.
• Another study from 2015 compared the use of ultrasonography and CT scans in diagnosing acute appendicitis, finding that dedicated appendiceal ultrasound should be used as a primary imaging modality, with CT scans serving as a problem-solving modality 3.
• The role of CT scans in reducing negative appendectomy rates and perforated appendicitis was explored in a 2007 study, which found a trend towards decreased rates of negative appendectomy and perforated appendices with mandatory CT imaging 4.
• A 2008 study investigated the effectiveness of CT scans without rectal contrast in diagnosing acute appendicitis, finding that CT scanning without rectal contrast is effective and makes rectal contrast unnecessary 5.
• The use of oral and intravenous contrast-enhanced CT scans in evaluating acute right lower quadrant pain was discussed in a 2003 study, which found that this technique facilitates diagnosis of appendicitis and other entities that may cause right lower quadrant pain 6.

Contrast Use in CT Scans

• The use of contrast in CT scans for right lower quadrant discomfort is a topic of discussion, with some studies suggesting that rectal contrast may not be necessary 5.
• A study from 2008 found that CT scanning without rectal contrast is effective for diagnosing acute appendicitis, with a sensitivity of 90%, specificity of 98%, and accuracy of 94% 5.
• Another study from 2003 discussed the use of oral and intravenous contrast-enhanced CT scans, finding that this technique facilitates diagnosis of appendicitis and other entities that may cause right lower quadrant pain 6.

Imaging Modalities

• The choice of imaging modality for right lower quadrant discomfort depends on various factors, including patient population and clinical presentation 2, 3.
• Ultrasound is a useful imaging modality, particularly in pediatric and pregnant patients, due to its lack of radiation 2, 3.
• MRI may also be used as an alternative to CT scans, especially in patients who cannot undergo CT scans or require further evaluation 2.