Body CT during pregnancy: utilization trends, examination indications, and fetal radiation doses

The objective of our study was to analyze body CT utilization trends, indications, fetal radiation doses, and scanning parameters associated with high fetal radiation doses (defined as > 30 mGy).

A retrospective review of all chest and abdominopelvic CT examinations performed between 1998 and 2005 of patients known to be pregnant was conducted. Demographics, gestational age, examination indication, and scan parameters were recorded. Fetal radiation dose was calculated for those abdominopelvic examinations with direct fetal irradiation.

From a database of more than 170,000 chest and more than 180,000 abdominopelvic CT examinations, 74 chest and 86 abdominopelvic examinations of pregnant patients were identified. Chest CT use increased on average 75%/y/1,000 deliveries in pregnancy versus 19%/y increase in all patients (p = 0.2700). Abdominopelvic CT utilization increase was on average 22%/y/1,000 deliveries in pregnant patients versus 13%/y increase in all patients (p = 0.1865). The most common indication for chest CT during pregnancy was suspected pulmonary embolism (85%, 63/74) and for abdominopelvic CT, suspected appendicitis (58%, 50/86). The average fetal dose from abdominopelvic CT was 24.8 mGy (range, 6.7-56 mGy); one examination exceeded the 50-mGy threshold for increased risk of childhood cancer. Scanning parameters associated with a dose of more than 30 mGy were a pitch of less than 1 (p = 0.0080) and more than one series acquisition (p = 0.0136).

Growth of CT during pregnancy reflects the trend of increased CT utilization in the general population. Avoiding use of CT in pregnant patients with suspected appendicitis would significantly decrease fetal radiation exposure. Abdominopelvic CT during pregnancy should be carefully planned and monitored so as not to exceed the fetal radiation dose for negligible risk.