LABORATORY STUDIES

15. How is a complete blood count helpful?

Show answer
1. Hematocrit. If the hematocrit is high (> 45%), the patient is most likely dry or may have chronic obstructive pulmonary disease. If it is low (< 30%), the patient probably has a more chronic disease (associated with blood loss-always do a rectal and test the stool for blood).
2. White blood cell count.It takes hours for inflammation to release cytokines and elevate the white blood cell count. A normal white blood cell count is entirely consistent with significant abdominal trouble.

16. Is urinalysis necessary?

Show answer
Yes. White blood cells in the urine may redirect attention to the diagnosis of pyelonephritis or cystitis. Hematuria points to renal or ureteral stones. Because an inflamed appendix may lie directly on the right ureter, red and white blood cells may be found in the urine of patients with appendicitis.

17. What is a “three-way of the abdomen”?

Show answer
1. Upright chest radiograph. Look for free air under the diaphragm (perforated viscus) and pneumonia or pneumothorax.
2. Upright abdomen. Look for free air under the diaphragm and air-fluid levels (intestinal obstruction). Remember to look for sigmoid or rectal air (partial obstruction).
3. Supine abdomen. This radiograph tells nothing.

Most ureteral stones can be visualized. Only 10% of gallstones are radiopaque, and appendiceal fecaliths are rarely noted.
Honors: Air in the biliary system indicates a biliary-enteric fistula; this in association with intestinal air-fluid levels makes the diagnosis of gallstone ileus.
KEY POINTS: RADIOGRAPHIC EVALUATION FOR THE ACUTE ADBOMEN

1. May assist in diagnostic evaluation but should not supplant physical exam in evaluaton of an acute abdomen.
2. Three-way of the abdomen: look for free air under the diaphragm, intrathoracic pathology, air-fluid levels, dilated alimentary canal, distal air in rectum.
3. Ultrasound: useful for biliary, ob-gyn, and vascular assessments; may note intraperitoneal or retroperitoneal fluid collections.
4. Computed tomography: increasing use in clinical arena, with excellent visualization of abdominal structures. Drawbacks: cost, radiation exposure.

18. What is a sentinel loop?

Show answer
Except in children (who swallow everything, including air), small bowel gas is always pathologic. A single loop of small bowel gas adjacent to an inflamed organ (e.g., the pancreas) may point to the diseased organ.

19. Is ultrasound valuable?

Show answer
Yes, if the working diagnosis is cholecystitis, gallstones, ectopic pregnancy, ovarian cyst, abdominal aortic aneurysm, or intraperitoneal/retroperitoneal fluid.

20. Is abdominal computed tomography (CT) valuable?

Show answer
Yes, if the working diagnosis is an intra-abdominal abscess (sigmoid diverticulitis), pancreatitis, retroperitoneal bleeding (leaking abdominal aortic aneurysm; this patient should have gone straight to the operating room), or intrahepatic or splenic pathology.

21. What is a double-contrast CT scan?

Show answer
The bowel is delineated with barium or Gastrografin. The blood vessels are delineated with an iodinated vascular dye. The CT scan precisely displays the abdominal contents relative to vascular and intestinal landmarks. Contrast CT of pancreatitis is valuable to assess zones of perfusion or necrosis.