Imaging in Suspected Complicated Appendicitis
A 27-year-old woman with a body mass index of 38 kg/m² has had right iliac fossa pain, nausea and anorexia for six days. Temperature is 37.9 °C, heart rate 96 beats/min, white cell count 13 × 10⁹/L, and a urine pregnancy test is negative. She has right iliac fossa tenderness without a palpable mass. Which of the following is the most appropriate next investigation?
- A.Contrast-enhanced abdominal CTCorrect
- B.Transabdominal pelvic ultrasound
- C.Diagnostic laparoscopy
- D.Immediate open appendectomy
Explanation
The clinical picture of right iliac fossa pain, anorexia, nausea and leukocytosis suggests appendicitis, but three features create enough diagnostic uncertainty to justify definitive imaging before any operation. First, gynecological disease such as tubo-ovarian abscess, ovarian torsion or pelvic inflammatory disease mimics appendicitis closely in a young woman. Second, obesity limits the reliability of both abdominal palpation and graded compression ultrasound, because the acoustic window is poor and the appendix is often not visualized. Third, a six-day history raises the probability of complicated disease, meaning perforation, a phlegmon or a contained abscess, and that distinction changes management from immediate appendectomy to antibiotics with or without drainage. Contrast-enhanced CT is the most accurate modality for appendicitis in non-pregnant adults, with sensitivity and specificity above 90 percent, and it simultaneously evaluates the pelvis and urinary tract for alternative diagnoses. Ultrasound remains first line in children and pregnant women, where avoiding radiation matters more, but is a poor choice in this body habitus. Diagnostic laparoscopy and open appendectomy are treatments, and committing to either without knowing whether an abscess is present risks an operation in a hostile inflamed field. Imaging first therefore produces the safest management roadmap.
Why each option
- A.
- Correct. Contrast-enhanced CT is the most accurate test for appendicitis in non-pregnant adults, is unaffected by obesity, and identifies perforation, abscess and gynecological mimics.
- B.
- Ultrasound is first line in children and pregnancy, but at a body mass index of 38 kg/m² the appendix is frequently not visualized and a negative study would not exclude disease.
- C.
- Diagnostic laparoscopy is invasive and would be undertaken blind; a large contained abscess is better drained percutaneously than approached surgically.
- D.
- Immediate open appendectomy skips the crucial question of whether this is complicated disease, and operating on a phlegmon carries a high risk of bowel injury.
Reference: WSES Jerusalem guidelines for diagnosis and treatment of acute appendicitis, 2020 update
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