To determine if internal bleeding is present a focused assessment with sonography (FAST) or diagnostic peritoneal lavage (DPL) can be used. Other diagnostic tests such as a computed tomography scan or various contrast studies can be used to more definitively classify the injury in both severity and location.[12] Local wound exploration is also another technique that may be utilized to determine how far the object penetrated.[13] Observation can be used in place of surgery as it can substitute an unnecessary surgery, which makes it the preferred treatment of penetrating trauma secondary to a stab wound when hypovolemia or shock is not present.[14] Laboratory diagnostic studies such as a hematocrit, white blood cell count and chemical tests such as liver function tests can also help to determine the efficiency of care .[15]