What is the appropriate management for a 22-year-old woman with nausea, vomiting, obstipation, and abdominal pain localized to the right lower quadrant, with a history of irregular menstrual periods and tenderness on pelvic examination?

Management of Right Lower Quadrant Pain in a Young Woman

This patient requires urgent CT abdomen and pelvis with IV contrast (without oral contrast) to establish the diagnosis, as the clinical presentation strongly suggests acute appendicitis but must differentiate from gynecologic pathology given her age and irregular menses. 1

Clinical Context and Diagnostic Approach

This 22-year-old woman presents with the classic migration pattern of appendicitis—diffuse abdominal pain that localizes to the right lower quadrant over 12 hours, accompanied by nausea, vomiting, and obstipation. 2 However, the pelvic examination finding of tenderness 4 cm lateral to the right ovary raises important differential considerations including:

• Acute appendicitis (most likely given pain migration pattern)
• Ovarian pathology (torsion, ruptured cyst, tubo-ovarian abscess)
• Ectopic pregnancy (must be excluded given irregular menses)
• Pelvic inflammatory disease

1

Immediate Diagnostic Imaging

CT Abdomen and Pelvis - The Definitive Study

CT abdomen and pelvis with IV contrast (without enteral contrast) is the single most appropriate initial imaging study for this patient. 1

Key performance characteristics:

• Sensitivity: 95% (95% CI: 0.93-0.96)
• Specificity: 94% (95% CI: 0.92-0.95) for appendicitis 1
• Contrast-enhanced CT without enteral contrast achieves 90-100% sensitivity and 94.8-100% specificity 1, 2

Critical advantages in this patient:

• Simultaneously evaluates for appendicitis AND gynecologic pathology 1
• In patients with RLQ pain, CT identifies non-appendiceal diagnoses (benign adnexal mass, ovarian pathology) in a significant proportion of cases 1
• Avoids delays associated with oral contrast administration, which is particularly important given 12-hour symptom duration and risk of perforation 1, 2

Why Not Ultrasound First?

While ultrasound is often recommended as first-line in young women of reproductive age, this patient's clinical presentation warrants proceeding directly to CT for several reasons:

• Ultrasound has significantly lower and more variable sensitivity (51.8-81.7%) and specificity (53.9-81.4%) compared to CT 1, 2
• The appendix is not visualized in 27.7-45% of ultrasound examinations, leading to indeterminate results 1
• Given the 12-hour duration and localized peritoneal signs (guarding, marked tenderness), this represents moderate-to-high clinical suspicion requiring definitive imaging 1
• An inconclusive ultrasound would necessitate CT anyway, causing treatment delay 3, 4

Pre-Imaging Essential Steps

Before imaging, immediately obtain:

1. Urine pregnancy test - Absolutely mandatory given irregular menses and reproductive age to exclude ectopic pregnancy 1
2. Complete blood count - Expected leukocytosis supports appendicitis diagnosis 1, 2
3. Urinalysis - Excludes urinary tract infection/nephrolithiasis 1

Surgical Consultation Timing

Obtain surgical consultation immediately while arranging imaging. 2 Do not delay surgical evaluation waiting for imaging results, as:

• The clinical presentation (pain migration, localized peritoneal signs, 12-hour duration) represents high probability of appendicitis 2
• Early surgical involvement reduces time to definitive treatment and perforation risk 2
• Surgeons can proceed directly to operation if CT confirms uncomplicated appendicitis 1

Management Algorithm Based on CT Results

If CT Confirms Appendicitis:

• Proceed immediately to appendectomy (laparoscopic preferred) 2
• Initiate IV antibiotics (cefoxitin 2g or equivalent) at time of diagnosis, not delayed until surgery 5
• NPO status and IV fluid resuscitation 2

If CT Shows Gynecologic Pathology:

• Ovarian torsion: Emergency gynecologic surgery 1
• Ruptured ovarian cyst: Conservative management vs. gynecology consultation based on hemodynamic stability 1
• Tubo-ovarian abscess: IV antibiotics and possible drainage 1

If CT is Negative/Indeterminate:

• Clinical reassessment and observation 1
• Consider MRI if high clinical suspicion persists (sensitivity and specificity 96% for appendicitis) 2

Critical Pitfalls to Avoid

Do not assume gynecologic pathology based solely on age and gender. The pain migration pattern (periumbilical to RLQ) is highly specific for appendicitis and occurs in only ~50% of appendicitis cases, making it a valuable diagnostic clue when present. 2

Do not delay imaging or surgery for oral contrast administration. Contrast-enhanced CT without enteral contrast is equally effective and avoids 2-4 hour delays that increase perforation risk. 1, 2

Do not rely on "classic" appendicitis presentation. Only 50% of appendicitis patients present with the full constellation of periumbilical pain migration, anorexia, nausea/vomiting, fever, and leukocytosis. 1, 2

Do not discharge without definitive diagnosis if CT is negative but clinical suspicion remains high. Admit for observation and serial examinations, as early appendicitis may not show CT findings. 1