CT Versus Ultrasound in Young Women With Right Iliac Fossa Pain: A Single-Centre Retrospective Study

Acute right iliac fossa (RIF) pain is a common presentation in premenopausal women. Compared with men, women are less likely to undergo abdominopelvic computed tomography (CT) and are twice as likely to have a negative diagnostic laparoscopy for appendicitis. However, CT exposes patients to significant ionising radiation-2 years of background exposure-raising lifetime cancer risk to one in 3700. Imaging decisions in this cohort are therefore clinically complex. This study investigated whether rates of negative diagnostic laparoscopy differ between women who underwent no imaging, ultrasound (US), or CT.

We retrospectively reviewed women aged 16-55 years presenting with acute RIF pain over a 2-year period at a tertiary referral centre who underwent laparoscopic appendicectomy. Data collected included imaging modality and findings, histopathological diagnosis, initial fever, WCC and CRP. The reference standard was histopathologically confirmed appendicitis. Diagnostic performance of CT and US was assessed using positive predictive value (PPV) and sensitivity.

We identified 502 women, of whom 421 underwent imaging. CT only was performed in 238 patients, US only in 177, both modalities in 6, and 81 had no imaging. US scans were more frequently inconclusive than CT (130 vs. 11). Appendicitis was confirmed histologically in 68.1% of unscanned patients, 48.1% following US and 86.6% following CT. CT demonstrated higher diagnostic accuracy (PPV 92.5%, sensitivity 96.4%) than US (PPV 75.0%, sensitivity 35.5%). Negative appendicectomy rates were significantly higher following US. Raised CRP and WCC correlated with positive histopathology and CT results but less consistently with positive US. Fever was rare (11) and did not correlate with any of the groups.

In young women, the risk of negative laparoscopy must be balanced against radiation exposure from CT. CT or clinical assessment alone may reduce unnecessary appendicectomies compared with US.