The infant heel stick, also known as the heel prick test or the infant blood spot test, is a routine procedure performed on newborns shortly after birth. This test involves pricking the baby’s heel to collect a small blood sample, which is then used to screen for a variety of conditions. This article provides information on the newborn heel stick, what it screens for, and its potential benefits, risks, and considerations. It also provides some tips on soothing and comforting babies through the heel stick.
What Is the Infant Heel Stick Test?
The heel stick involves using a small, sterile lancet to make a quick puncture in the infant’s heel, typically on the outer edge. A few drops of blood are collected on a special filter paper, which is then sent to a laboratory for analysis (1). While the procedure does cause brief discomfort, it typically lasts only a few minutes and most babies are quickly comforted.
The blood collected is tested for a wide range of conditions, with the exact number and type of conditions varying by state. In the United States, newborn screening programs generally test for anywhere from 29 to more than 50 various conditions (1). These screenings are state-mandated – though you can opt out – and designed to identify disorders that, if left untreated, could lead to serious health problems, developmental delays, and more.
Potential Benefits of the Infant Heel Stick Test
The primary purpose of the heel stick test is to identify newborns at risk for certain conditions before symptoms appear (1). Early diagnosis and intervention can greatly improve outcomes for affected babies (1). As with all medical interventions, it’s important to be aware of the potential benefits and risks so parents can make an educated decision for their children. The potential benefits of the heel stick test are listed below.
1. The Heel Stick Test May Allow For Early Detection of Metabolic Disorders (1).
The heel stick test screens for various metabolic disorders, such as phenylketonuria (PKU) and medium-chain acyl-CoA dehydrogenase deficiency (MCADD). These conditions can lead to severe cognitive impairments or life-threatening episodes if left untreated. Early detection allows for immediate dietary adjustments and/or treatments that support normal development and can prevent long term disability or complications.
2. The Heel Stick Test May Allow for Identification of Genetic Disorders (1).
The test also detects genetic disorders, like cystic fibrosis and sickle cell disease. Early intervention can significantly improve the quality of life for affected infants by managing symptoms before they become severe and by preventing complications.
3. The Heel Stick Test Screens for Endocrine Disorders (1).
The heel stick test includes screening for endocrine disorders, like congenital hypothyroidism, where early treatment with hormone replacement can prevent intellectual disability and support normal growth.
4. The Heel Stick Has The Potential To Contribute to Science and Research.
Blood samples from the heel stick test can be used for research to help improve the health of future babies. For example, studies have used de-identified blood spots to investigate the relationship between viral infection at birth and autism later in life (2). For some parents, this is a potential downside – more about privacy concerns below.
Commonly Screened Conditions
I always recommend that parents take some time to understand the medical procedures and tests that may affect their children. When it comes to the newborn heel stick test, the specific conditions screened for vary by state. Click here to see the conditions that each state screens for.
While many of the conditions screened for are extremely rare, the newborn heel stick does detect about 3,000 positives per year (1). Below, you’ll find more information on the five conditions that are most commonly detected by the newborn heel prick.
1. Phenylketonuria (PKU)
PKU is a genetic disorder that affects the metabolism of phenylalanine, an amino acid found in many foods. It is caused by a deficiency in the enzyme phenylalanine hydroxylase (3).
Symptoms: If untreated, phenylalanine accumulates in the blood, potentially leading to severe intellectual disabilities, developmental delays, and behavioral problems (3). If treatment begins within the first 2-3 weeks of life and is strictly followed, the child isn’t expected to experience any symptoms and can live a normal, healthy life.
Treatment: A strict lifelong diet low in phenylalanine is prescribed to prevent the harmful effects of PKU. Special formulas and foods are used to provide adequate nutrition while avoiding phenylalanine (3).
2. Congenital Hypothyroidism
Congenital hypothyroidism is a condition where the thyroid gland is underactive at birth, leading to insufficient production of thyroid hormones necessary for brain development and growth (4).
Symptoms: Without treatment, congenital hypothyroidism can lead to intellectual disability, and other serious health issues. Symptoms may not be obvious at birth (4).
Treatment: Early and lifelong treatment with thyroid hormone replacement (levothyroxine) supports normal development (4).
3. Cystic Fibrosis (CF)
Cystic fibrosis is a genetic disorder that affects the lungs and digestive system, leading to the production of thick, sticky mucus that can cause severe respiratory and digestive issues (5).
Symptoms: Symptoms include persistent cough, frequent lung infections, and difficulty breathing. Some infants may show signs of bowel obstruction soon after birth (5).
Treatment: There is no cure for cystic fibrosis; instead, treatment focuses on managing symptoms and preventing complications through airway clearance techniques, enzyme supplements, and specialized diets (5).
4. Sickle Cell Disease
Sickle cell disease is an inherited disorder where red blood cells are abnormally shaped, leading to blockages in blood flow and reduced oxygen delivery to tissues (6).
Symptoms: Common symptoms include severe pain episodes, anemia, fatigue, and frequent infections. Complications can include organ damage and stroke (6).
Treatment: Management includes pain relief, hydration, blood transfusions, and preventive antibiotics. Bone marrow transplants may offer a potential cure for some patients (6).
5. Medium-Chain Acyl-CoA Dehydrogenase Deficiency (MCADD)
MCADD is a metabolic disorder that affects the body’s ability to break down medium-chain fatty acids into energy, which can be life-threatening during fasting or illness (7).
Symptoms: Symptoms can include vomiting, lethargy, low blood sugar, and seizures. If untreated, MCADD can lead to sudden death, particularly during periods of fasting (7).
Treatment: Treatment involves avoiding fasting and providing a high-carbohydrate diet during illness. Supplements like L-carnitine may be used to help the body process fats (7).
How the Heel Prick Test Is Performed
The heel prick test does involve a small puncture, and while this is likely to be briefly uncomfortable for your baby, it is essential for collecting the necessary blood sample. Outlined below are the steps of a heel prick test.
- Prick: A healthcare provider will use a sterile lancet to make a small puncture on the outer edge of the baby’s heel. Sometimes, your healthcare provider will use a small heating pad to gently warm your baby’s heel prior to the poke. This will allow for easier blood collection.
- Blood Collection: After the initial prick, the healthcare provider will gently squeeze the baby’s heel to encourage blood flow, collecting the necessary drops of blood on a special filter paper.
- Aftercare: The small wound is usually wiped clean, and a bandage may be applied to minimize any bleeding.
Tips for Comforting Your Baby
As a parent, seeing your baby experience discomfort can be distressing, but there are several ways you can help soothe and comfort your baby during and after the test:
- Breastfeeding: Breastfeeding during or immediately after the procedure can provide comfort and reduce the baby’s pain response. A 2022 study showed that breastfeeding was more effective for heel prick pain management than all other methods tested, including a lidocaine cream (8).
- Skin-to-Skin Contact: There is no need to interrupt skin-to-skin to perform the infant heel prick. Holding your baby skin-to-skin can offer comfort and reassurance (8), helping to calm them more quickly.
- Swaddling: If you are unable to hold your baby skin to skin, swaddling your baby can help them feel secure and calm both during and after the procedure.
- Pacifier: If your baby uses a pacifier (8), offering it during the procedure can help soothe them.
Being prepared for the procedure and understanding its importance can help reduce your own anxiety as a parent. Knowing how to comfort your baby during and after the heel prick can make the experience less distressing for both of you.
Potential Risks, Considerations, and Privacy Concerns
The infant heel stick is a very safe procedure with minimal risks. However, it’s important to be aware of the potential downsides to this procedure.
Temporary Discomfort
Many parents are concerned about the pain and discomfort their baby might experience during the procedure. While it’s true that this is not a pleasant procedure, the discomfort is usually brief and quickly resolved with comforting techniques (8).
Minor Bruising
Occasionally, a small bruise may form at the puncture site. This is not usually a cause for concern.
Infection
Infection is possible, and there are a few documented cases of staph infections post infant heel pricks, but this is extremely rare (9).
Test Is Not Officially Diagnostic
The results of the screening test do not establish an official diagnosis, but serve to identify a subset of patients who warrant further testing. Sometimes, the initial test results may be inconclusive, requiring a repeat heel stick to obtain a clearer result.
Test Can Yield False Positives
False positives happen in about 0.05% of cases (10), though for some specific diseases that rate is higher. For example, the screening for PKU has a 90% false-positive rate (11), meaning that of the babies who test positive for this, only 10% of infants with an initial positive result actually have the disorder. A repeat test is required if the initial test is positive.
Privacy Concerns
There is growing concern among parents regarding the storage and use of blood samples collected during the heel stick test (12). In some states, these samples are kept for research purposes, and there are questions about how long these samples are stored and whether parents’ requests for their destruction are honored (13).
The newborn heel prick is one of the standard medical procedures that are routinely performed on newborns.
To learn more about newborn standard of care medical interventions, read these articles: Understanding Newborn Antibiotic Eye Ointment, Why Infants Get Vitamin K1 At Birth, Understanding the RhoGAM Shot: A Guide for Expectant Mothers, Delayed Umbilical Cord Clamping: The Benefits & Risks, All About Vernix: Should It Be Washed Off? and Hepatitis B.
FAQ: Can My Child Still Get the Heel Prick If I Decline Vitamin K?
Yes, your child can still undergo the heel prick test even if you choose to decline the vitamin K shot, or if you have opted for oral vitamin K. It is important to note that declining vitamin K may increase the risk of bleeding complications, as vitamin K is required for blood clotting (14). While the heel prick involves only a very small puncture, parents who are declining vitamin K for their newborn should be extra vigilant for any excessive bleeding.
Learn more about the vitamin K shot here: Why Infants Get Vitamin K1 At Birth.
Summary
The infant heel stick, or heel prick test, is a routine procedure that collects a small blood sample from a newborn’s heel to screen for a variety of serious, yet mostly treatable, conditions – like PKU, cystic fibrosis, and sickle cell disease. While the heel puncture causes brief discomfort, the benefits of early detection and intervention are significant, as they have the potential to prevent severe health issues and/or developmental delays. Parents can comfort their babies during the test with techniques like breastfeeding, skin-to-skin contact, and swaddling. Despite the benefits to this test, there are considerations – such as privacy concerns – regarding the storage of blood samples and the potential for false positives and bruising that are noteworthy.
References:
- Newborn Screening. (2023). Newborn screening process. Newbornscreening.hrsa.gov. https://newbornscreening.hrsa.gov/newborn-screening-process
- Lewis, M. H., & Goldenberg, A. J. (2015). Return of Results from Research Using Newborn Screening Dried Blood Samples. The Journal of law, medicine & ethics : a journal of the American Society of Law, Medicine & Ethics, 43(3), 559–568. https://doi.org/10.1111/jlme.12299
- Texas DSHS. (2018). Phenylketonuria (PKU). Texas.gov. https://www.dshs.texas.gov/newborn-screening-program/newborn-screening-parent-resources/phenylketonuria-pku
- Bowden, S.A., & Goldis, M. (2023). Congenital Hypothyroidism. [Updated 2023 Jun 5]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. https://www.ncbi.nlm.nih.gov/books/NBK558913/
- March of Dimes. (n.d.). Cystic fibrosis and your baby. Www.marchofdimes.org. https://www.marchofdimes.org/find-support/topics/planning-baby/cystic-fibrosis-and-your-baby
- Stanford Children’s Health. (2019). Stanford Children’s Health. Stanfordchildrens.org. https://www.stanfordchildrens.org/en/topic/default?id=sickle-cell-disease-in-children-90-P02327
- Merritt, J.L. 2nd, & Chang, I.J. (2000). Medium-Chain Acyl-Coenzyme A Dehydrogenase Deficiency. Apr 20 In: Adam MP, Feldman J, Mirzaa GM, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2024. https://www.ncbi.nlm.nih.gov/books/NBK1424/
- Napiórkowska-Orkisz, M., Gutysz-Wojnicka, A., Tanajewska, M., & Sadowska-Krawczenko, I. (2022). Evaluation of Methods to Minimize Pain in Newborns during Capillary Blood Sampling for Screening: A Randomized Clinical Trial. International journal of environmental research and public health, 19(2), 870. https://doi.org/10.3390/ijerph19020870
- Onesimo, R., Fioretti, M., Pili, S., Monaco, S., Romagnoli, C., & Fundarò, C. (2011). Is heel prick as safe as we think?. BMJ case reports, 2011, bcr0820114677. https://doi.org/10.1136/bcr.08.2011.4677
- Bahnsen, C. (2019). Raising the Bar on Newborn Screening Test Performance. Insights. https://news.mayocliniclabs.com/2019/08/29/raising-the-bar-on-newborn-screening-test-performance/
- Koch, R. K. (1999). Issues in Newborn Screening for Phenylketonuria. American Family Physician, 60(5), 1462–1466. https://www.aafp.org/pubs/afp/issues/1999/1001/p1462.html#afp19991001p1462-b6
- Cunningham, S., O’Doherty, K. C., Sénécal, K., Secko, D., & Avard, D. (2015). Public concerns regarding the storage and secondary uses of residual newborn bloodspots: an analysis of print media, legal cases, and public engagement activities. Journal of community genetics, 6(2), 117–128. https://doi.org/10.1007/s12687-014-0206-0
- Andrews, M. (2022). Privacy concerns prompt states to reexamine storing newborns’ heel blood tests. Www.cbsnews.com. https://www.cbsnews.com/news/newborn-baby-blood-tests-privacy-concerns/
- CDC. (2024). Protect Your Baby from Bleeds. Vitamin K Deficiency Bleeding. https://www.cdc.gov/vitamin-k-deficiency/fact-sheet/index.html
