OBJECTIVE: We aimed at determining whether a negative single complete compression ultrasonography (CUS) of the lower limbs veins is a safe and accurate diagnostic method to rule out the diagnosis of deep venous thrombosis in pregnant and early postpartum women. DESIGN: Hospital-based retrospective study. SETTING: The gynaecology and vascular ultrasound units of three general hospitals in western France. PATIENTS: We identified from the hospitals databases all pregnant or up to three months postpartum women who underwent CUS for a suspicion of deep venous thrombosis between January 2002 and December 2004. METHODS: Questionnaires were sent to all women with a negative CUS. Their medical records were also checked. MAIN OUTCOME MEASURES: We assessed the three-month thromboembolic risk and its 95% percent confidence interval in women left untreated on the basis of a negative single complete CUS of the lower limbs. RESULTS: During the study period, 162 pregnant or postpartum women underwent CUS for a suspicion of deep venous thrombosis. It was positive in 44 (27%). The 118 women who had a negative CUS were sent the questionnaire. Information about the three-month follow-up was found for 107 patients (91%). None of them experienced a thromboembolic event during follow-up: 0.0% (95% CI: 0.0-3.6). CONCLUSIONS: Single complete CUS of lower limbs veins appears to be a safe method to rule out the diagnosis of deep venous thrombosis in pregnant or early postpartum women. This has to be confirmed by a prospective management study with a formal follow-up.