Conventional policy mandates exploration of retroperitoneal hematomas presumed to contain penetrating injuries of the inferior vena cava (IVC). In clinical practice this maneuver frequently results in torrential blood loss, suggesting the injury may be best managed without exploration and IVC suturing. The present study was undertaken to define the natural history of untreated IVC perforations, and to assess venous access with such injuries. Twelve adolescent Hampshire pigs (20-25 kg) underwent halothane anesthesia and laparotomy. The infrarenal IVC was isolated temporarily and a posterior cruciate incision, equivalent to 50% of the IVC circumference, made via anterior venotomy. Animals were resuscitated with Ringer's lactate. Technetium sulfur colloid was injected 20 min postlaparotomy closure via either a jugular or femoral venous cannula, and count activity measured over the IVC injury site using a mobile gamma camera. The procedure was repeated via the counterpart limb. Background from the first injection was subtracted, and count ratios integrated from 16 to 19 min postinjection. Extravasation following lower extremity infusion was not significantly different from that following central venous administration. One pig succumbed to cryptogenic peritonitis one wk postinjury. The remaining animals were killed at periods ranging from 3 to 12 wk. No animal had clinical evidence of delayed bleeding, pulmonary embolus, or other venous sequelae during the observation period. At autopsy all vena cavae were normal caliber without evidence or pseudoaneurysm of thrombosis. This swine study confirms the efficacy of lower extremity venous access with contained IVC injury, and suggests that isolated retroperitoneal IVC injuries may be treated nonoperatively in very selected patients.