Finding the fever

Jed is a thriving 8 month old brought in by his parents with a fever of 38.8^oC; he’s tachycardic and grumpy. His fever began twelve hours ago, and aside from crankiness, he is otherwise well. He is fully immunized and there are no sick contacts at home. You get a call from your Mixed Emergency Department intern (it’s their first week) saying they can’t find a source for a fever…

Bottom Line

A thorough physical examination is essential to define a source of fever.

Learn and consider the NICE Guidelines traffic light system.

Have a very high index of suspicion in any child under 3 months presenting with a fever.

Common causes of occult infection are bacteraemia, urinary tract infection and pneumonia.

Always think about meningitis and sepsis.

Look everywhere!

A fever without source is “a fever occurring for less than a week without an adequate explanation after a careful history and thorough physical examination“.

So, for that thorough physical examination, where are the essential places to look? Where should you look for the source of fever?

The infectious sources of fever arise from cavities that you can extract a bodily fluid from. In short, anywhere there is goo! Think of those places where you can get a sample of fluid, and look there.

Firstly, the brain. Think “Does this patient have meningitis?“; it’s a good question to consider this in any paediatric patient. Recall the signs and symptoms and actively seek them out. Examine for photophobia, Kernig’s, nuchal rigidity and lethargy remembering there’s a lower likelihood of these symptoms being present in younger children. Also remember that infants may present as irritable or feeding poorly. Palpate the fontanelle (with the child at 45^o) for bulging. Consider the age of the patient; babies under three months are at a much higher risk of meningitis.

Next, think “Does this child appear septic? Bacteraemia is present in between 2-15% of febrile children under 3 months. Despite the introduction of the effective 7-valent (and now 13-valent) streptococcus pneumoniae vaccine, bacteraemia still occurs and can lead to focal infections – including meningitis – in around 10% of children, depending on the bacteria. Mortality differs depending on the pathogen, around 1% in pneumococcal, 4% of Neisseria meningitidis; an unidentified bacteraemia can have catastrophic outcomes. Blood cultures are really important if you’re going to start empiric antibiotics!

Urinary tract infections are common in kids! Catching a urine sample can be challenging in a child who’s a bit dry. At the earliest convenience, give the child a wash down and have a parent or keen helper catch a clean urine sample. It’s often unhelpful sending a bag-caught urine for culture, as the false positive rate isn’t worth the hassle (or distraction). Instead, either go straight for a clean catch, in-out catheter or if the child is unwell do a suprapubic aspirate. If the bag urine is already caught, a dipstick for leuks/nitrites may be of use, but ultimately, an uncontaminated sample is essential. Check out the NICE UTI guidelines.

Examine the lungs and have a good hunt for any work of breathing. The constellation of fever, tachypnoea and cough increases the likelihood of a pneumonic focus. Any changes on auscultation can be suggestive of bronchiolitis, pneumonitis, reactive airways disease, pneumonia or other lung pathology as it relates to the child’s age, so really take your time to listen to the front and back of their chest.

Always examine the ears, nose and throat; it’s a paediatric skill and we see more of these than everyone except the ENTs. Whilst you’re there have a look in the mouth and at the eyes, too!

Nose and rhinorrhoea – copius rhinorrhoea can be a strong sign of upper respiratory viruses. Although a very common cause for fevers in children, beware of ascribing all fevers in a child with rhinorrhoea to a “viral URTI”, without considering the other sources of fever.

Ears – otitis media can cause fevers, or be secondary to a respiratory tract infection. It goes without saying that every child’s ears must be examined. A good pointer is that child with a non-tender pinna and non-tender tragus is less likely to have an otitis externa, but you do need to look.

Throat – Consider the many causes of tonsillitis including Group A haemolytic strep infection. Fevers and a barking cough sounds like croup, but epiglottitis, bacterial tracehitis and inhaled or lodged foreign body can all give you fevers and a toxic appearance. Rarer diagnoses such as a retropharyngeal abscess are worth considering too.

Whilst we’re in the neighbourhood, have a look in the rest of the oral cavity for dental abscesses or lesions. Remember, teething doesn’t give you a fever!

Palpate the lymph nodes – lymphadenitis or malignancy may be hovering in a big, palpable node in the cervical chain, or the inguinal or axillary nodes. The nodes may herald the location of infection, so consider the area of drainage to each node.

In the abdomen – appendicitis, intussusception or gut perforation can make you febrile, as can a raft of other abdominal causes. You must lay hands on the child’s abdomen! Check for hernias, torted testis and palpate the flanks for tenderness. If they have diarrhoea or even just loose stools, catch one – you can send it for rota, adeno and norovirus or other infectious causes of diarrhoea; if there’s blood or mucous, consider haemolytic uraemia syndrome, salmonella, campylobacter and so on.

Thoroughly inspect every inch of the child’s skin – search for signs of local and systemic infection such as pus, cellulitis, rashes, petechiae.  Localised infection, such as furunculitis or boils, contaminated lacerations, grazes or puncture sites may be a source for fevers, or entry points for osteomyelitis. Don’t forget to check the back for abscesses!

Document any rashes comprehensively, avoiding diffuse terms like ‘maculo-paupular’ or ‘viral rash’. Say where and what it is; the dermatologists have a superb array of adjectives for use.

Impetigo, varicella zoster or herpes zoster can also cause fevers and systemic illness.  Don’t forget the genitals or the perianal area, Group A Strep or foreign bodies can be hiding away there.

Whilst the top and pants are off examine the bones and joints, really noting any red, painful or under mobilised joints. Children are at much higher risk of septic arthritis and osteomyelitis.

In high risk populations, think about rheumatic heart disease and double check those heart sounds.

Eyes – you’ve likely already checked for photophobia early on by flicking on the lights and checking the pupils. If the eyes are mucky, swab them and send it to the lab.

Check the conjunctivae for injection as well as the surrounding tissue for any hint of orbital or periorbital cellulitis. Insect bites or grazes around the area can be the only clue to an entry point.

Remember, in a well-appearing but febrile child, the causes of occult infection to consider are pneumonia, UTI and bacteraemia. Although most children will have a self-limiting, non-specific viral illness, it’s safe and appropriate to consider and exclude bacterial sources. In summary, if there’s goo, look there for the source of that fever.  If you’ve looked in all of these places and still have nothing to hang your hat on, then you’re looking at a true “fever without source”. Treat empirically, considering the age and appearance of the child.

This is not an exhaustive list of the causes of fever, it’s more an approach to make sure you’re looking in all the places that fever can be hiding.

Finally, make sure you check out Tessa Davis’ Life in the Fast Lane post on the NICE Guidelines for Fever and when to be really worried.

References

Tessa Davis via Life In the Fast Lane : Nice Fever Guidelines in Kids

NICE Guidelines – Feverish illness in children

NICE Guidelines – Urinary tract infection in children

Sepsis Kills

Uptodate: Fever without a source in children 3 to 36 months of age