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Apt-Downey test

What is this test?

This test assesses blood in the stool or emesis (vomit) of infants. It is used to help differentiate the baby's blood from the mother’s blood[1][2][3]. This test is used when bleeding in the baby's gastrointestinal tract is suspected[1][2][4].

Why do I need this test?

Laboratory tests may be done for many reasons. Tests are performed for routine health screenings or if a disease or toxicity is suspected. Lab tests may be used to determine if a medical condition is improving or worsening. Lab tests may also be used to measure the success or failure of a medication or treatment plan. Lab tests may be ordered for professional or legal reasons. The following is a possible reason why this test may be done:

When and how often should I have this test?

When and how often laboratory tests are done may depend on many factors. The timing of laboratory tests may rely on the results or completion of other tests, procedures, or treatments. Lab tests may be performed immediately in an emergency, or tests may be delayed as a condition is treated or monitored. A test may be suggested or become necessary when certain signs or symptoms appear.

Due to changes in the way the body naturally functions through the course of a day, lab tests may need to be performed at a certain time of day. If your baby was prepared for a test by changing his food or fluid intake, lab tests may be timed in accordance with those changes. Timing of tests may be based on increased and decreased levels of medications, drugs or other substances in the body.

The age or gender of the person being tested may affect when and how often a lab test is required. Chronic or progressive conditions may need ongoing monitoring through the use of lab tests. Conditions that worsen and improve may also need frequent monitoring. Certain tests may be repeated to obtain a series of results, or tests may need to be repeated to confirm or disprove results. Timing and frequency of lab tests may vary if they are performed for professional or legal reasons.

How should I get ready for the test?

Before the stool sample is collected, tell the healthcare worker if your baby has a medical condition or is receiving a medication or supplement that causes the bloody stool.

How is the test done?

A sample of stool may be collected for this test. Emesis may be collected if your baby is vomiting.

For a stool sample collected at home, place the baby's stool into a container provided by the healthcare worker. Avoid adding urine, water, tissues, or toilet paper to the sample. Collect the largest amount of stool possible for the test[2]. If stool is unavailable, the healthcare worker may use a blood-stained diaper for this test[1].

How will the test feel?

This test usually causes no discomfort.

What should I do after the test?

After giving a stool sample in a healthcare facility, close the container if it has a lid, and place the container where the healthcare worker instructed. Clean your hands with soap and water. If you have been asked to collect the stool sample while at home, follow the directions provided.

Stool or emesis samples should be tested as soon as possible after they are collected, ideally within 30 minutes[5][1].

What are the risks?

Stool: Giving a stool sample is generally considered safe. Talk to your healthcare worker if you have questions or concerns about this test.

What are normal results for this test?

Ask your healthcare worker for the normal results of this test.

What follow up should I do after this test?

Ask your healthcare worker how you will be informed of the test results. You may be asked to call for results, schedule an appointment to discuss results, or notified of results by mail. Follow up care varies depending on many factors related to your test. Sometimes there is no follow up after you have been notified of test results. At other times follow up may be suggested or necessary. Some examples of follow up care include changes to medication or treatment plans, referral to a specialist, more or less frequent monitoring, and additional tests or procedures. Talk with your healthcare worker about any concerns or questions you have regarding follow up care or instructions.

References:

[1] McRury JM & Barry RC: A modified Apt test: a new look at an old test.. Pediatr Emerg Care 1994; 10:189-191.

[2] Liu N, Wu AH, & Wong SS: Improved quantitative Apt test for detecting fetal hemoglobin in bloody stools of newborns. Clin Chem 1993; 39(11):2326-2329. Available from URL: http://www.clinchem.org/cgi/reprint/39/11/2326. As accessed 1/27/2005.

[3] Crook M: Haemoglobin in stools from neonates: measurement by a modified Apt-test. Med Lab Sci 1991; 48(4):346-347.

[4] Apt L & Downey WS Jr: "Melena" neonatorum: the swallowed blood syndrome.. J Pediatr 1955; 47:6-12.

[5] Henry JB: Clinical Diagnosis and Management by Laboratory Methods, 20th ed. Saunders, 2001.


Last Updated: 6/12/2013

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