Bulging Fontanelle

Bulging FontanelleWe are all very smart people (objectively, this is a true statement).  Sometimes, however, we can outsmart ourselves.  Don’t strain yourself too much to determine how the laws of thermodynamics may have lead a neonate to be febrile; rather, just do the LP! Additionally, don’t do complex calculus on the results from the traumatic LP; just count the number of white blood cells and be conservative.  If you want to contemplate the utility of urine studies based on duration of illness, that is an excellent use of your neurons; however, overanalyzing what to do with the child who has a Bulging Fontanelle and Fever will not leave you feeling smarter.


Bulging Fontanelle: Basics

  • There are 6 Fontanelles, but only two are clinically apparent.
    • Anterior: 4-6 cm in dimension; closure – 4th – 26th month of life
    • Posterior: 1-2 cm in dimension; closure – 1st – 2nd month of life
    • Mastoid x 2, Sphenoid x 2
  • Position of child matters:
    • You should palpate the fontanelle with the child in upright position.
    • Feeling the fontanelle with child supine may cause it to feel full when it is not truly abnormal.
  • Position of the fontanelle matters:
    • The fontanelle should normally be slightly sunken relative to the upper table of the skull.
    • A fontanelle that is even with the upper level of the skull or above it is abnormal.
  • Pulsations are normal – usually represent peripheral pulses.


Bulging Fontanelle: Common Benign Causes

Before we get too crazy… let us be reasonable and consider some common causes… but, know that these should be transient.

  • Supine (or Trendelenburg) Position
    • Gravity works
    • Hydrostatic pressure will cause a supine child’s fontanelle to be “full.”
  • Coughing
  • Vomiting
  • Crying
  • Recent Vaccinations have also been associated with bulging fontanelle, but no causal link known and often determined after ruling out badness. [Sreedhar, 2013; Freedman, 2005]


Bulging Fontanelle: Super Bad

  • Meningitis/Meningoencephalitis
  • Space Occupying Lesion (ex, AVMs, tumors, intracranial abscess)
  • Intracranial Hemorrhage (ex, Non-accidental trauma, Trauma)
  • Hydrocephalus
  • Hypoxic-Ischemic Injury


Bulging Fontanelle: Other Badness


Bulging Fontanelle: Evaluation

  • Step 1: Be Reasonable.
    • Ensure that we are not dealing with one of the Common Benign Causes.
  • Step 2: Let’s not outsmart ourselves!
    • Yes, there are cases of benign idiopathic intracranial hypertension… [Goldberg, 2013; Barry, 1989]
    • Yes, there are potential non-emergent causes…
    • Yes, work-ups often reveal no significant pathology, thankfully, but the potential to miss mass or meningitis is real.
  • Step 3: Image brain.
    • In extremely well appearing and afebrile children, may consider close outpatient follow-up and possible MRI.
    • If you are even slightly uncertain about the wellness of the child, don’t outsmart yourself… get the image now.
      • One study found 36% of patients with bulging fontanelles had abnormal neuro-imaging. [Tu, 2005]
      • High risk factors were: Fever and Age < 2 months OR Abnormal Neuro Finding
  • Step 4: Consider the Lumbar Puncture
    • Yes, a small percentage of febrile children with bulging fontanelle have bacterial meningitis, but a more substantial percentage (26.7%) have viral meningitis. [Shacham, 2009]
    • Again… don’t outsmart yourself… if there is no contraindication, get the CSF. [Beri, 2011]
    • Measuring an opening pressure can also add valuable information.



Raju SS1, Chacko B. Transient bulging fontanelle after measles vaccination. Indian Pediatr. 2014 Aug;51(8):673. PMID: 25129011. [PubMed] [Read by QxMD]
Goldberg EM1. Fever and bulging fontanelle mimicking meningitis in an infant diagnosed with benign intracranial hypertension. Pediatr Emerg Care. 2013 Apr;29(4):513-4. PMID: 23558272. [PubMed] [Read by QxMD]

Shacham S1, Kozer E, Bahat H, Mordish Y, Goldman M. Bulging fontanelle in febrile infants: is lumbar puncture mandatory? Arch Dis Child. 2009 Sep;94(9):690-2. PMID: 19531528. [PubMed] [Read by QxMD]

Freedman SB1, Reed J, Burwen DR, Wise RP, Weiss A, Ball R. Transient bulging fontanelle after vaccination: case report and review of the vaccine adverse event reporting system. J Pediatr. 2005 Nov;147(5):640-4. PMID: 16291356. [PubMed] [Read by QxMD]

Green AM, Walsh CB. Investigational protocols and physician liability. J Clin Psychopharmacol. 1992 Jun;12(3):210-2. PMID: 1629389. [PubMed] [Read by QxMD]
Barry W, Lenney W, Hatcher G. Bulging fontanelles in infants without meningitis. Arch Dis Child. 1989 Apr;64(4):635-6. PMID: 2751342. [PubMed] [Read by QxMD]
Silver W, Kuskin L, Goldenberg L. Bulging anterior fontanelle. Sign of congestive heart failure in infants. Clin Pediatr (Phila). 1970 Jan;9(1):42-3. PMID: 5410370. [PubMed] [Read by QxMD]
Sean M. Fox
Sean M. Fox

I enjoy taking care of patients and I finding it endlessly rewarding to help train others to do the same. I trained at the Combined Emergency Medicine and Pediatrics residency program at University of Maryland, where I had the tremendous fortune of learning from world renowned educators and clinicians. Now I have the unbelievable honor of working with an unbelievably gifted group of practitioners at Carolinas Medical Center. I strive every day to inspire my residents as much as they inspire me.

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  1. Good Morning, my 7 month old son has a bulging fontanelle. He is a healthy and happy baby with no other symptoms. Is this normal? Should I be concerned?

    • My 7month old and I are currently in the ER on suspicion of something bad but all her tests came back good. She is also happy and healthy. They can’t tell me why it’s like that.

  2. My son is 2 years and 6 months old, he seems to have a bulging fontanelle since he was about 1, iw that possible ?

  3. Hi, my 4month old has a bulging fontanelle we went to the ER and were admitted with the suspicion of meningitis, they did a LP on her and it came out clear of any bacteria or virus however a week before this her Pediatrician took samples of her stools since she had diarrhea, her results showed a culture… At the hospital they had her on antibiotics and her fontanelle went down we were discharged a day ago but this morning I realized that her fontanelle began to bulge again… Should a require a CT scan and MRI??

    • Obviously, I cannot discuss individual, patient specific medical advice. Any time you have concerns about your child, you should discuss them honestly with your child’s care providers.
      All the best,

  4. Last week, our 6mo old son had his well child check and received his 6mo immunizations along with the first flu shot – he is current on all immunizations, and the only new one was the influenza. He developed a low fever, tmax 101.3 and I administered one dose of acetaminophen because he was uncomfortable. Through the night, he moaned in his sleep. I nursed him through the night as is his normal routine, and I did not turn on the light which is my normal routine. Upon awakening in the morning, I noticed he had a very noticeable Bulging Fontanelle – it looked cone-like. He seemed very uncomfortable, with a high pitched cry, with postural changes; seemingly most uncomfortable when lying supine. I took him to Urgent Care at the office where his Pediatrician also works. The Urgent Care MD did an assessment, asked his pediatrician to assess my son, and she agreed that his demeanor and fontanelle were very different from the previous day. I took him to the children’s hospital per our pediatrician’s recommendation. There, they did bloodwork – almost all normal. CRP was elevated at 4. WBC was 6.2 on Monday and 13.44 on Tuesday, but still WNL. U/S of fontanelle was negative, CSF was negative, blood culture was negative, CSF resulted with a “rare WBC” – but there has been no follow up or explanation for that.
    My son’s fontanelle seems to fluctuate now from being truly sunken to even with his skull. He still cries, at times, with postural changes. Is there something else you’d recommend looking for, or another test that you would recommend. I think the doctors were content with the negative results, and maybe that is reasonable because it ruled out the immediate “bad” diagnoses. I’m still concerned. He’s our 4th child, and I don’t think I am overreacting by wanting more proof that everything is well with him, before we write this off as an immunization adverse reaction. Is it reasonable to request imaging?

    • Ms. Sanchez,
      I am sorry that you have been so worried about your son! Obviously, I cannot give out specific medical advice for an individual. I would recommend that you further discuss your concerns with your primary care team so that they can review what their evaluation has allowed them to rule out… and perhaps what still needs to be considered. It is quite normal, however, to have the fontanelle change from flat to full based on position and crying, etc, but please clarify with your team.
      All the best,

  5. I suddenly notice that my daughter has a swollen fontanelle and I don’t know what’s the cause and what to do pls help

    • Joy,
      If she is doing well, then contact your pediatrician.

      If she is not doing well, then still contact your pediatrician, but be prepared that you may be directed to the ED.

      Hope all is well,

  6. Hi. My baby’s fontanelle becomes bulgy after long hour of sleep and get backs to normal few minutes after she woke up.. Anyone experience the same?

  7. Hello, my 6mth old grandson has been going back and forth to the ER, for the last two days and has to return tomorrow for his 3rd antibiotic treatment.He went to ER Saturday morning due to 103 fever and his soft bulging up and down. They have ran blood work twice, and no findings but they are treating him as if it is some kind of virus. They don’t have a name for this virus, is it safe for them to keep sending him home and not keeping him for observation. His face has broken out bad, they said because of his fever… Tonight they gave him his treatment and sent him back home with a 102 fever. Remind you this is the 3rd day but nobody can tell my daughter anything. They said he had a CT scan and it was negative. I feel like Something is wrong with the baby head. Can you please help us with some answers. When she carried him they said he had 10% of fluid on his brain and 12%on the other side, but when she gave birth they did and ultrasound and x-rays and everything was normal. We need help!

  8. Hi I just have a question. You said in one of your previous responces that if the soft spot if bulging while sitting, there should be physical abnormalities. What lind of abnormalities?

    • As the Morsel points out… the mere presence of a bulging fontanelle does not equal a diagnosis… but should be taken in context of the other physical and historic findings.

  9. My baby is 7 months old and is teething she has a swollen soft spot with no fever I’m a first time mom and I’m really concerned she has gotten slightly more sleepy yesterday (April 12) and I noticed the soft spot April 11 around bedtime I’ve kept an eye on it and it still hasn’t went down

    • I, obviously, cannot give out individual medical advice… but it is always reasonable, when you are concerned about your child, to have a conversation with your child’s physician.

      • My baby is 17 months old she was born with A bulging fontanel. The docters never told us that is abnormal. She still has it. Should we be worried?

  10. My daughter had a head injury when she was 9 mo old a subdermal haemorrhage i think is what its called. Now shes 3 and it seems like the top of her head behind where her soft spot is bulging. Its been this way since it happened. Shes very smart and is not delayed at all. She did develop a lazy eye shortly after the accident. Should i be worried. The dr. Says no need for a xray i disagree. What do you think am i being overly worried?

    • I, obliviously, cannot give specific medical recommendations to individuals. I will say that X-rays of the skull are seldom helpful. I would discuss your concerns openly with your child’s physician.

      I wish you all of the best,

  11. Hi my son’s fontanelle when he asleep it’s bulging and wen he wakes up it’s normal is there a problem . He was addmited once and they did all kind of test even a lumber punsher and he didn’t have meningitis.

    • Thank you for your comment. Officially, I cannot provide medical advice; however, as was noted in the post, Gravity Works… so when an infant is lying down, the “column of water” (Cerebral Spinal Fluid) will cause a bulging of the fontanelle and that is normal. When an infant sits/ is held up right, then the pressure should decrease and the fontanelle should return to the normal position. It is when the fontanelle is bulging while in upright position, or when it is associated with other physical abnormalities, that this should raise the most concern.

  12. I have legal guardianship of a three year old niece and her 4 siblings.
    Yesterday they had a mandatory visit with their bio mother. The 15 yr old and mother got in a fight, n the bio mom pushed 3yrold hard into the arm of couch. She has been complaining of headaches since returning. Her soft spot on top of her head is very firm and seems to be bulging since last combing her hair. Any thoughts!? I can’t seem to find any answers online other then trama can cause bulging. What should I do!?????

    • Holly N, officially I cannot give medical advice out over the Internet. I will say that it would be unusual for a 3 year old to have an open fontanelle still (the front one usually has closed by 2 years of age). If you are concerned, you should bring the child to the primary care physicians.
      Thank you, Sean

      • My baby is 17 months old she was born with A bulging fontanel. The docters never told us that is abnormal. She still has it. Should we be worried?

    • Did you ever figure out anything? My 3 year old Fontanelle has felt hard and swollen the last few weeks. We took her to two drs and all said she was fine. But it’s concerning and has appeared out of no where

  13. Interestingly, I just read your morsel as I had a 7week old patient present with enlarging posterior fontanelle to our ED – when you refer to neuroimaging, is CT adequate? And also, does this apply to posterior fontanelle issues also?

    • Yes, posterior fontanelle fullness would lead to similar considerations as anterior fontanelle fullness. As for imaging… It somewhat depends on your suspicion for the underlying cause as well as ease of outpatient imaging. If concern high for possible hemorrhage, I’d get CT. U/S is another option as the ventricles can be imaged via the open fontanelle, but may not view all areas well. Others advocate for MRI… I’d reserve this for lower concern for acute issues.

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