What is the appropriate management for a patient presenting with right lower abdominal pain?

Management of Right Lower Abdominal Pain

Obtain CT abdomen and pelvis with IV contrast immediately as your initial imaging study for any adult patient presenting with right lower quadrant abdominal pain. 1, 2

Initial Diagnostic Imaging

• CT abdomen and pelvis with IV contrast is the definitive first-line imaging modality, achieving 95% sensitivity and 94% specificity for appendicitis while simultaneously identifying alternative diagnoses in 23-45% of cases. 1, 2

• The American College of Radiology explicitly recommends CT over other modalities for right lower quadrant pain evaluation, as it provides superior diagnostic accuracy compared to ultrasound and can detect the full spectrum of pathology including diverticulitis, bowel obstruction, malignancy, and vascular emergencies in a single study. 1, 2

• IV contrast is essential for optimal diagnostic performance; oral contrast may be added for better bowel visualization but is not mandatory and can delay diagnosis without improving accuracy. 1, 2

When Ultrasound May Be Considered First

• Ultrasound should only be considered as initial imaging in women of reproductive age when gynecologic pathology (ectopic pregnancy, ovarian torsion, tubo-ovarian abscess) is the primary clinical concern, not when appendicitis is suspected. 2

• Combined transabdominal and transvaginal ultrasound achieves 97.3% sensitivity and 91% specificity for gynecologic causes in women of reproductive age, but this performance is operator-dependent and dramatically decreases in obese patients. 2

• Critical limitation: ultrasound fails to visualize the appendix in 20-81% of cases, creating diagnostic uncertainty that necessitates CT anyway, resulting in diagnostic delay without avoiding radiation exposure. 2

• Ultrasound sensitivity for appendicitis ranges widely from 21% to 95.7% depending on operator experience, patient body habitus, and clinical presentation—this unreliability makes it unsuitable as first-line imaging when appendicitis is suspected. 2

Pre-Imaging Management Steps

While arranging CT imaging, immediately implement these measures:

• Establish NPO status and initiate IV fluid resuscitation to prepare for potential surgical intervention. 3

• Obtain surgical consultation immediately—do not wait for imaging results if clinical suspicion for appendicitis is high. 3

• Check complete blood count and inflammatory markers, but never delay imaging based on normal laboratory values, as serious pathology frequently presents with normal labs in elderly patients and early disease. 2, 3

• Perform beta-hCG testing in all women of reproductive age before imaging to exclude pregnancy and guide contrast decisions. 1

Differential Diagnosis Beyond Appendicitis

The broad differential for right lower quadrant pain includes:

• Gastrointestinal causes: Appendicitis (most common surgical cause), right-sided colonic diverticulitis (increasingly common with age and mimics appendicitis), Crohn disease, cecal diverticulitis, bowel obstruction, colorectal malignancy (accounts for 60% of large bowel obstructions in elderly). 2, 4, 5

• Gynecologic causes: Ectopic pregnancy, ovarian torsion, tubo-ovarian abscess, ruptured ovarian cyst, pelvic inflammatory disease. 1, 2

• Urologic causes: Nephrolithiasis, pyelonephritis, urinary tract infection. 2, 5

• Vascular causes: Mesenteric ischemia (critical consideration in elderly patients with cardiovascular disease). 2

• Other causes: Epiploic appendagitis, omental infarction, mesenteric adenitis, psoas abscess. 4, 5

Post-CT Management Algorithm

If CT confirms appendicitis:

• Initiate broad-spectrum IV antibiotics immediately (covering anaerobic bacteria including Bacteroides species—metronidazole plus a second agent for aerobic coverage). 3, 6
• Obtain immediate surgical consultation for appendectomy. 3

If CT identifies alternative diagnosis:

• Cecal or right-sided colonic diverticulitis: IV antibiotics, bowel rest, surgical consultation if complicated (perforation, abscess). 3
• Bowel obstruction: NPO, nasogastric decompression, IV fluids, surgical consultation. 2, 3
• Gynecologic pathology: Immediate gynecology consultation for suspected torsion or ectopic pregnancy. 3
• Inflammatory bowel disease: Gastroenterology consultation, consider IV steroids. 3

Critical Pitfalls to Avoid

• Do not use ultrasound first in obese patients, elderly patients, or when clinical suspicion for appendicitis is high—proceed directly to CT to avoid diagnostic delay. 2

• Atypical presentations are the norm in elderly patients, who frequently lack classic symptoms, have blunted inflammatory responses, and present later with higher perforation rates. 2

• Never assume normal laboratory values exclude serious pathology—many elderly patients with perforation or serious infection present with normal white blood cell counts. 2

• Do not delay imaging or surgical consultation to administer oral contrast—IV contrast alone provides excellent diagnostic accuracy without the time delay. 1, 2

• Conventional radiography has no role in evaluating acute right lower quadrant pain and should not be obtained. 1