Abdominal Pain: Laboratory Test Pearls and Pitfalls

1
Abdominal Pain Laboratory Test Pearls and
Pitfalls

• Joe Lex, MD, FAAEM
• Temple University Hospital
• Philadelphia, PA USA
• Education Chair, American Academy of Emergency
  Medicine

2
Abdominal Pain

• 10 of Emergency Department visits
• 40 diagnosed as nonspecific
• 50 of those admitted discharged with change in
  diagnosis

3
Differential Includes

• Diabetic ketoacidosis
• Alcoholic ketoacidosis
• Uremia
• Sickle cell disease
• Porphyria
• Systemic lupus

• Vasculitis
• Glaucoma
• Hypertension
• Scorpion sting
• Methanol poisoning
• Black widow spider bite

4
Differential Includes

• Heavy metal toxicity
• Acute coronary syndrome
• Pneumonia
• Pulmonary embolism
• Testicular torsion

• Herniated thoracic disc
• Streptococcal pharyngitis
• Rocky Mountain spotted fever
• Mononucleosis
• Etc.

5
Differential Includes

• and those are just the extraabdominal causes of
  abdominal pain
• Id be happy with a test that could tell me that
  the source of pain was really the abdomen.

6
Literature Suggests We Get

• White blood cells
• Electrolytes
• Glucose
• Renal functions
• Liver functions
• Amylase / lipase
• Pregnancy test

• Urinalysis
• C-reactive protein
• Procalcitonin
• Lactate
• Phosphorus
• Leukocyte elastase
• Others??

LABS
7
Literature Suggests We Get
LABS
8
First and Foremost

• Female ovaries pregnancy
• When patients said
• My last period was on time.
• I dont think Im pregnant.
• I cant possibly be pregnant.
• 10 were pregnant.

PREGNANCY
Ramoska EA, et al. Ann Emerg Med. 1989
Jan18(1)48-50.
9
Abdominal Pain
10
Right Upper Quadrant
11
Gall Bladder
G B
12
Gall Stones / Colic

• No pathognomonic study
• Lab studies should all be normal
• ? ALT / AST think hepatitis
• ? alkaline phosphatase / bilirubin think common
  bile duct obstruction
• ? amylase / lipase think pancreatitis

G B
13
Common Duct Stones

• ? serum bilirubin in 32
• ? aminotransferases in 34
• ? alkaline phosphatase in 22
• Common duct stones in 17.4
• Best predictive value for duct stone ? alkaline
  phosphatase (46)

G B
Jarvinen H. Ann Clin Res. 1978 Dec10(6)323-7.
14
Common Duct Stones

• ? bilirubin and alkaline phosphatase associated
  with common duct stones
• Combination of bilirubin level gt 3.0 and alkaline
  phosphatase gt250 gt75 chance of common duct
  stone
• ? serum or urine amylase little, if any, value

G B
Saltzstein EC, et al. Surg Gynecol Obstet. 1982
Mar154(3)381-4.
15
Cholecystitis

• 40 patients pathologically confirmed acute
  cholecystitis
• Fever at presentation 10
• Leukocytosis at presentation 60
• No single / combination of clinical / laboratory
  findings at time of presentation identified all
  patients

G B
Singer AJ, et al. Ann Emerg Med. 1996
Sep28(3)267-72.
16
Cholecystitis

• Acute cholecystitis nongangrene
• 71 lack fever
• 32 lack leukocytosis
• 28 lack fever and leukocytosis

• Acute cholecystitis gangrene
• 59 lack fever
• 27 lack leukocytosis
• 6 lack fever and leukocytosis

G B
Gruber PJ, et al. Ann Emerg Med. 1996
Sep28(3)273-7.
17
Hepatitis
Liver
18
Hepatitis

• ALT usually gtAST
• Both 10 100 times normal
• ? prothrombin time first sign of complicated
  course
• WBC / differential not helpful

Liver
19
Spot Urine Dipstick

• 70 74 sensitive for serum bilirubin
• 43 53 sensitive for other liver enzyme
  abnormalities
• 77 87 specific for hepatitis

Liver
Kupka T, et al. Ann Emerg Med. 1987
Nov16(11)1231-5.
20
Spot Urine Dipstick

• 83 86 positive predictive values for detecting
  at least one LFT abnormality
• 85 negative predictive value for serum bilirubin
  elevations, but lower for other LFTs

Liver
Kupka T, et al. Ann Emerg Med. 1987
Nov16(11)1231-5.
21
Typical AST / ALT Values
Liver
Johnston DE. Am Fam Physician. 1999 Apr
1559(8)2223-30.
22
Abdominal Pain
23
Right Lower Quadrant
24
Appendix
25
White Cells and Appendicitis

• Typical range 12,00018,000 / mm3
• Leukocytosis in 75 80
• Immature white cells in 75 80
• Same as in gastroenteritis, pelvic inflammatory
  disease, ruptured ovarian cyst, ectopic
  pregnancy, etc.

RULE IN?
26
White Cells and Appendicitis

• Progressive increase in white cell count over
  time unreliable
• Elderly (gt60!) with appendicitis normal white
  cell count 45 of time

Scott JH 3rd, et al. J Urol. 1983
May129(5)1015.
RULE IN?
Thimsen DA, et al. Am Surg. 1989
Jul55(7)466-8.
Freund HR, et al. Am Surg. 1984
Oct50(10)573-6.
27
White Cells and Appendicitis

• Proportion of patients with elevated white cell
  count and perforation equal to proportion
  perforated with normal white cell count

RULE IN?
Coleman C, et al. Am Surg. 1998
Oct64(10)983-5.
Young DV. Am J Surg. 1989 Apr157(4)428-30.
Graham JM, et al. Am J Surg. 1980
Feb139(2)247-50.
28
White Cells and Appendicitis

• White cell count normal early in 80, eventually
  rises over 24 hours

Doraiswamy NV. Br J Surg. 1977 May64(5)342-4.
RULE IN?
Hoffmann J, et al. Br J Surg. 1989
Aug76(8)774-9.

• White cell count does not effect surgeons
  decision to operate

English DC, et al. Am Surg. 1977
Jun43(6)399-402.
29
White Cells and Appendicitis

• White cell count and differential normal in 4
  11 of patients with appendicitis

RULE IN?
Arnbjornsson E, et al. Acta Chir Scand.
1983149(8)789-91.
Sasso RD, et al. Am J Surg. 1970
Nov120(5)563-6.
Raftery AT. Br J Surg. 1976 Feb63(2)143-4.
30
Other Laboratory Studies

• C-reactive protein and leukocyte elastase not
  consistently reliable to rule in or rule out
  appendicitis
• BUT

RULE IN?
Paajanen H, et al. J Am Coll Surg. 1997
Mar184(3)303-8.
Eriksson S, et al. Eur J Surg. 1995
Dec161(12)901-5.
31
Triple Test

• if white cell count lt9000 / mm3 AND
• if neutrophils lt75 of total white cells AND
• C-reactive protein lt0.6 mg/dL, THEN
• Negative predictive value approaches 100

RULE OUT?
Dueholm S, et al. Dis Colon Rectum. 1989
Oct32(10)855-9.
32
Urine and Appendicitis

• Proven appendicitis 20 30 have blood, white
  cells, or bacteria in urine
• Retrocecal appendicitis abnormal urine in 50

RULE OUT?
Arnbjornsson E. Am J Surg. 1988 Feb155(2)356-8.
Scott JH 3rd, et al. J Urol. 1983
May129(5)1015.
Jones WG, et al. J Urol. 1988 Jun139(6)1325-8.
Gardikis S, et al. Int Urol Nephrol.
200234(2)189-92.
33
Abdominal Pain
34
Epigastrium
35
Pancreas
36
Amylase Elevated in

• Pancreatitis
• Exctopic pregnancy
• Macroamylasemia
• Parotitis
• Renal failure

• Bowel obstruction or infarct
• Perforated ulcer
• Acute peritonitis
• Mesenteric ischemia
• Other causes

AMYLASE
Vissers RJ, et al. J Emerg Med. 1999
Nov-Dec17(6)1027-37
37
Amylase Not Very Sensitive

• Rises within 6 to 24 hours
• Peaks in 48 hours
• Normalizes in 5 to 7 days
• Sensitivity decreases after first 24 to 48 hours

AMYLASE
Ranson JH. World J Surg. 1997 Feb21(2)136-42.
38
Amylase Not Very Specific

• Amylase normal in 25 of patients with acute
  pancreatitis
• Highly specific if elevated 5 times above upper
  limit of normal

AMYLASE
Vissers RJ, et al. J Emerg Med. 1999
Nov-Dec17(6)1027-37
39
Lipase Sensitivity / Specificity

• Elevated in pancreatitis, bowel obstruction,
  perforated ulcer
• Just as sensitive as amylase
• Probably more specific than amylase (80 99)
• At five times upper limit of normal 60
  sensitive, 100 specific

LIPASE
Vissers RJ, et al. J Emerg Med. 1999
Nov-Dec17(6)1027-37
40
Biliary Pancreatitis Labs
PANCREAS
Tenner S, et al. Am J Gastroenterol. 1994
Oct89(10)1863-6.
41
Other Possible Markers

• Phospholipase A2
• C-reactive protein
• Interleukin-6
• Interleukin-8
• Trypsinogen
• Trypsin activation peptide

• Procarboxy-peptidase B activation peptide
• Serum amyloid A
• Procalcitonin
• Leukocyte elastase

PANCREAS
Rau B, et al. Dig Dis. 200422(3)247-57.
42
Ulcer Disease
ULCER
43
Helicobacter pylori
ULCER
False negative in 5 15
44
Abdominal Pain
45
Diffuse
46
Diffuse
47
Small Bowel Obstruction

• WBC not sensitive, not specific
• Hemoglobin high if dry, low if bleeding
• Amylase, lactate, creatine phosphokinase
  elevated late
• Electrolytes, renal function if prolonged volume
  loss

S B O
48
Small Bowel Obstruction

• History, physical, temperature, x-ray, white
  blood count, serum amylase cannot differentiate
  simple bowel obstruction from strangulated bowel

S B O
Deutsch AA, et al. Postgrad Med J. 1989
Jul65(765)463-7.
49
Small Bowel Ischemia

• Leukocytosis common, nonspecific
• Hemoconcentration, metabolic acidosis with base
  deficit, hyperamylasemia nonspecific, present in
  gt50
• Lactate 100 sensitive, 42 87 specific

Ischemia
Ruotolo RA, et al. Clin Geriatr Med. 1999
Aug15(3)527-57.
50
Nonspecific Abdominal Pain

• Most common in young
• Low social class
• Psychiatric disorders
• BUT
• If older than 50 years, 10 shown to have
  intra-abdominal cancer within next year

51
Other Causes Pain

• Diverticulitis
• Ruptured abdominal aortic aneurysm
• Perforated viscus
• Regional enteritis
• Psoas abscess
• Endometriosis

• Mittelschmerz
• Splenic rupture / infarct
• Cecal volvulus
• Gastric volvulus
• Sigmoid volvulus
• Rectus hematoma
• Etc.

Others
52
No Magic Bullet

• History and physical exam still most important
• Lab studies helpful if interpreted properly