Fontanelles - sunken
Sunken fontanelles; Soft spot - sunken
Sunken fontanelles are an obvious curving in of the "soft spot" in an infant's head.
Considerations
The skull is made up of many bones. There are 8 bones in the skull itself and 14 bones in the face area. They join together to form a solid, bony cavity that protects and supports the brain. The areas where the bones join together are called the sutures.
The bones are not joined together firmly at birth. This allows the head to change shape to help it pass through the birth canal. The sutures gradually gain minerals and harden, firmly joining the skull bones together. This process is called ossification.
In an infant, the space where two sutures join forms a membrane-covered "soft spot" called a fontanelle (fontanel). The fontanelles allow the brain and skull to grow during an infant's first year.
There are normally several fontanelles on a newborn's skull. They are located mainly at the top, back, and sides of the head. Like the sutures, fontanelles harden over time and become closed, solid, bony areas.
- The fontanelle in the back of the head (posterior fontanelle) most often closes by the time an infant is 1 or 2 months old.
-
The fontanelle at the top of the head (
anterior
fontanelle) most often closes within 7 to 19 months.
Anterior
Anterior means "in front of" or "the front surface of. " It usually refers to the front side of the body. For example, your knee caps are on the ant...
The fontanelles should feel firm and should curve inward slightly to the touch. A noticeably sunken fontanelle is a sign that the infant does not have enough fluid in his or her body.
Causes
-
Dehydration
(not enough fluid in the body)
Dehydration
Dehydration occurs when your body does not have as much water and fluids as it should. Dehydration can be mild, moderate, or severe, based on how muc...
-
Malnutrition
Malnutrition
Malnutrition is the condition that occurs when your body does not get enough nutrients.
When to Contact a Medical Professional
A sunken fontanelle can be a medical emergency. A health care provider should check the infant right away.
What to Expect at Your Office Visit
The provider will perform a physical exam and ask questions about the child's symptoms and medical history, such as:
Physical exam
During a physical examination, a health care provider studies your body to determine if you do or do not have a physical problem. A physical examinat...
- When did you first notice that the fontanelle looked sunken?
- How severe is it? How would you describe it?
- Which "soft spots" are affected?
- What other symptoms are present?
-
Has the baby been ill, especially with
vomiting
,
diarrhea
, or excessive sweating?
Vomiting
Nausea is feeling an urge to vomit. It is often called "being sick to your stomach. "Vomiting or throwing-up is forcing the contents of the stomach ...
-
Is the
skin turgor
poor?
Skin turgor
Skin turgor is the skin's elasticity. It is the ability of skin to change shape and return to normal.
- Is the baby thirsty?
- Is the baby alert?
- Are the baby's eyes dry?
- Is the baby's mouth moist?
Tests may include:
-
Blood chemistries
Blood chemistries
A comprehensive metabolic panel is a group of blood tests. They provide an overall picture of your body's chemical balance and metabolism. Metaboli...
-
CBC
CBC
A complete blood count (CBC) test measures the following:The number of red blood cells (RBC count)The number of white blood cells (WBC count)The tota...
-
Urinalysis
Urinalysis
Urinalysis is the physical, chemical, and microscopic examination of urine. It involves a number of tests to detect and measure various compounds th...
- Tests to check the baby's nutritional status
You might be referred to a place that can provide intravenous (IV) fluids if the sunken fontanelle is caused by dehydration.
References
Carlo W. The newborn infant. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics . 19th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 88.
-
Skull of a newborn - illustration
The "sutures" or anatomical lines where the bony plates of the skull join together can be easily felt in the newborn infant. The diamond shaped space on the top of the skull and the smaller space further to the back are often referred to as the "soft spot" in young infants.
Skull of a newborn
illustration
-
Sunken fontanelles (superior view) - illustration
The fontanelles should feel firm and very slightly concave to the touch. A noticeably sunken fontanelle is a sign that the infant does not have enough fluid in its body.
Sunken fontanelles (superior view)
illustration
-
Skull of a newborn - illustration
The "sutures" or anatomical lines where the bony plates of the skull join together can be easily felt in the newborn infant. The diamond shaped space on the top of the skull and the smaller space further to the back are often referred to as the "soft spot" in young infants.
Skull of a newborn
illustration
-
Sunken fontanelles (superior view) - illustration
The fontanelles should feel firm and very slightly concave to the touch. A noticeably sunken fontanelle is a sign that the infant does not have enough fluid in its body.
Sunken fontanelles (superior view)
illustration
Review Date: 2/5/2015
Reviewed By: Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.