What is the appropriate emergency department assessment and management plan for an adult female with acute severe left lower quadrant pain that began one week after an episode of diarrhea, now experiencing constipation, a single episode of non‑bilious non‑bloody vomiting after taking bisacodyl, and dizziness, with no significant past medical history and a remote cesarean section?

Emergency Department Assessment and Management Plan for Acute Left Lower Quadrant Pain

Immediate Assessment

This patient requires urgent CT abdomen and pelvis with IV contrast as the primary diagnostic modality to establish the diagnosis and guide management. 1

Critical Initial Evaluation

• Rule out surgical emergencies immediately: Assess for peritoneal signs, hemodynamic instability, or signs of perforation/obstruction that would require immediate surgical consultation 1
• Obtain complete blood count and C-reactive protein: Elevated inflammatory markers in the setting of LLQ pain warrant diagnostic imaging; normal values should prompt reassessment in 12 hours 2
• Assess volume status: The patient has had diarrhea, vomiting, and reports dizziness—check orthostatic vital signs and initiate IV fluid resuscitation if indicated 1

Key Clinical Pitfall

The bisacodyl administration was inappropriate and potentially harmful in this clinical context. 1, 3 The patient presented with acute LLQ pain following diarrhea, and stimulant laxatives like bisacodyl can worsen abdominal pain (occurring in 24.7% of patients) and cause diarrhea (53.4% of patients), which may have precipitated the vomiting and dizziness 1. Bisacodyl is contraindicated in acute inflammatory bowel conditions and should never be given to patients with acute abdominal pain of unclear etiology 1.

Primary Diagnostic Imaging

CT Abdomen and Pelvis with IV Contrast

This is the most appropriate initial imaging study for this patient. 1

• Rationale: CT is the most useful examination for LLQ pain, providing accurate diagnosis regardless of patient sex or body habitus 1
• IV contrast is essential to characterize bowel wall pathology, pericolic abnormalities, vascular pathology, and intraabdominal fluid collections 1
• High sensitivity for critical findings: Detects extraluminal air indicating perforation, abscesses, and other complications requiring surgical intervention 1

Differential Diagnosis to Consider

The most likely diagnosis is acute sigmoid diverticulitis given the clinical presentation (LLQ pain following diarrhea in an adult), but CT will differentiate between: 1

• Acute colonic diverticulitis (most common cause of adult LLQ pain) 1
• Colitis or inflammatory bowel disease 1
• Epiploic appendagitis 1
• Bowel obstruction 1
• Gynecologic pathology (ovarian/fallopian tube pathology—particularly important given history of cesarean section) 1
• Perforated colon cancer (can mimic diverticulitis clinically and radiographically) 1
• Pyelonephritis or urolithiasis 1

Immediate Management While Awaiting Imaging

Supportive Care

• NPO status: Keep patient nothing by mouth until diagnosis is established 1
• IV fluid resuscitation: Normal saline bolus followed by maintenance fluids given history of diarrhea, vomiting, and dizziness 1
• Antiemetic therapy: Administer ondansetron 4-8 mg IV or prochlorperazine 10 mg IV for nausea/vomiting 1
• Pain control: Provide adequate analgesia with IV opioids or NSAIDs as appropriate (avoid NSAIDs if perforation suspected) 1

Laboratory Studies

• Complete blood count with differential 2
• Comprehensive metabolic panel (assess for dehydration, electrolyte abnormalities) 2
• C-reactive protein 2
• Urinalysis and urine pregnancy test (given reproductive age and gynecologic differential) 1
• Lipase if upper abdominal pain component 2

Post-Imaging Management Algorithm

If Uncomplicated Diverticulitis Confirmed

• Outpatient management may be appropriate if patient is hemodynamically stable, tolerating oral intake, has adequate pain control, and has reliable follow-up 1
• Initiate broad-spectrum antibiotics covering gram-negative and anaerobic organisms 1
• Clear liquid diet advancing as tolerated 1
• Arrange gastroenterology follow-up for colonoscopy 6-8 weeks after resolution (to exclude colon cancer, particularly if abscess, perforation, or fistula identified) 1

If Complicated Diverticulitis (Abscess, Perforation, Obstruction)

• Surgical consultation immediately 1
• Hospital admission for IV antibiotics and possible interventional radiology drainage or surgical intervention 1

If Alternative Diagnosis Identified

• Manage according to specific diagnosis (gynecologic consultation for ovarian pathology, urology for urolithiasis, etc.) 1

Critical Management Errors to Avoid

• Never administer stimulant laxatives (bisacodyl, senna) to patients with acute abdominal pain of unclear etiology—these are contraindicated in acute inflammatory bowel conditions and can worsen outcomes 1, 3
• Do not delay imaging in patients with elevated inflammatory markers—this increases risk of missed complications 2
• Do not perform contrast enema or colonoscopy acutely—these are contraindicated in suspected acute diverticulitis due to perforation risk 1