<GOOD
HEALTH HOSPITAL>
CLINICAL LABORATORY PROCEDURE MANUAL
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Subject:
NITRAZINE |
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Effective
Date: 5/29/99 |
Category: |
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Supersedes:
8/11/97 |
Distributed
to: L&D |
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Prepared: |
Reviewed: |
Approved: |
Date: |
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Reviewed: |
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PURPOSE
Nitrazine
(Phenaphthazine ) paper is used to measure the vaginal pH of
expectant mothers.
PRINCIPLE
Nitrazine
paper is impregnated with an indicator dye Phenaphthazine. The
color changes as pH changes, giving a broad range of colors from
yellow through blue.
SUPPLIES
Phenaphthazine
reagent strip.
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STORAGE
Store
Phenaphthazine reagent strips at room temperature.
PATIENT
PREPARATION
No
patient preparation other than that required by a written
protocol.
PROCEDURE
Standard
Precautions must be adhered to by testing personnel.
Obtain
a strip of Nitrazine paper approximately three inches long
from the dispenser.
Wrap
the paper around the ends of the fingers of one hand.
Insert
the fingers and paper into the birth canal.
Remove
the paper and excess fluid.
Compare
the resulting color to the paper dispenser’s pH scale.
Record
results on the patient chart.
Reports
results as:
6.5
-6.5 =positive.
6.0 and below = negative.
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Criteria
for Unacceptable Specimens:
The
specimen is estimated to be stable for 2-5 minutes at room.
Contamination with blood will interfere with the reading. Bloody
specimens should be read with caution, as it is difficult to
interpret the color reaction.
EXPECTED
VALUES
Normal
vaginal pH is acidic (below 7.0). pH results above 7.0 ( basic)
indicate that amniotic fluid is present. Bring results to the
attention of the attending physician.
QUALITY
CONTROL
Supplies:
pH
calibrating buffers; pH 6.0 and pH 8.0 Store buffers at room
temperature. Buffers are stable until the expiration date on the
bottles.
Policy:
Both
controls are run once each day of use.
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Procedure:
1.
Add one drop of buffer to Nitrazine test paper.
2.
Compare color to the paper dispenser's pH scale. The pH must be
within 0.5 of the designated pH to be acceptable.
3.
Document all results on the Control Sheet. If controls are out
of range do not report any patient results until corrective
action has been taken:
Repeat
the procedure
Repeat
using a different Nitrazine test packet
If
controls are still out of range, call the Laboratory for
assistance
SPECIFIC
PERFORMANCE CHARACTERISTICS
The
Nitrazine paper measures pH values generally to within 1 pH unit
in the range of 4.5-7.5 visually.
REFERENCES
Apothecon,
Princeton, NJ, Nitrazine Paper, p0083-00, p0084-00 52520.
Communication from Bristol-Myers Squibb Company, March 28,1997.
Hellman, L.M., et. al., Williams Obstetrics. 14th
edition, New York, Appleton-Century-Crofts; 1971, p 405-406.
