A 25-year-old pregnant woman at 18 weeks gestation requires investigation for suspected appendicitis. Ultrasound is inconclusive. Which statement best reflects the safety and guidance on further imaging in this clinical scenario?

• A CT abdomen-pelvis should be avoided entirely; the patient should be managed clinically without imaging
• B A single abdominal radiograph is equivalent to MRI for appendicitis diagnosis in pregnancy
• C MRI without gadolinium is the preferred next investigation; if CT is required it should be performed without delay as diagnostic benefit outweighs radiation risk ✓
• D PET-CT is the most accurate modality and should be used in preference to CT or MRI in pregnancy

Explanation

When ultrasound is inconclusive for appendicitis in pregnancy, MRI without gadolinium contrast is the recommended next-line investigation due to absence of ionising radiation, excellent soft tissue contrast, and good diagnostic accuracy for appendicitis and its complications. MRI is safe in the second and third trimesters; first trimester is also generally considered safe but avoided if possible. Gadolinium crosses the placenta and is classified as Category C — use only if essential. If MRI is unavailable or clinically inappropriate, CT should not be withheld, as the consequences of a perforated appendix to mother and fetus substantially outweigh the radiation risk from a single CT scan (typically 20-30 mGy fetal dose). PET-CT is never appropriate in pregnancy.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.