The Unwell Neonate and Infant – PEM Induction

Author, update and questions: Meriel Tolhurst-Cleaver / Codes: / Editor: Thomas Webster / Reviewer: Mia Thomas / Published: 12/09/2018

The neonatal period (<28 days of age) and young infancy (< 3months ) is the most common time for presentation of congenital conditions and the highest susceptibility for infection. But, unfortunately, young babies are renowned for their vague presentations and lack of localising clinical signs. In fact, they can be a bit of a diagnostic nightmare! So, in order to avoid panicking when faced with a sick baby, keep in mind these big 5 diagnoses not to be missed, how to spot them and a few tips about management.

Warning: this is an overview and summary of how to approach an unwell infant and covers a lot of big and broad topics. Please do check out the further reading and references delve deeper into on each of them.


You must always consider sepsis in any unwell infant (<3 months)! You really need to have a low threshold for performing a full septic screen (blood cultures, urine culture and CSF culture) and commencing on empirical intravenous antibiotics. Any infant (<3 months) presenting with a fever (>38 C) will definitely qualify for this (as per NICE guidance), but please also consider this management in any baby who presents with non-specific symptoms and signs, as they may not mount a febrile response to infection.

Its useful to ask about birth risk factors for neonatal infection (these include suspected or confirmed infection in another baby in the case of multiple pregnancy, maternal fever or known infection in labour, prolonged rupture of membranes over 24 hours and Group B Streptococcus infection confirmed in this pregnancy). Premature birth (less than 37 weeks gestation) following spontaneous labour is a risk factor in and of itself, and prolonged rupture of membranes for more than 18 hours before a preterm birth also constitutes a risk factor. If any of these are present you should be even more suspicious and it would lower your threshold for a full septic screen (for example in a neonate who has not had a fever but is generally unwell). However, do not be falsely reassured if there are no risk factors present.

Presentation of sepsis in a young baby may include irritability, off feeds, vomiting and diarrhoea, lethargy (not waking for feeds), floppiness, not wetting nappies, high pitched cry, rapid or shallow breathing, apnoea, seizures or abnormal movements. Clinical features on examination may include tachycardia, tachypnoea, fever (>38 C) or hypothermia, hypotension, poor perfusion, respiratory distress (grunting, recessions, nasal flaring), distended abdomen, bulging or tense fontanelle, pallor, mottled skin and decreased conscious level.

Management involves a full septic screen (as above) and commencement on empirical antibiotics (as per local antibiotic guideline). These should be given within 1 hour of sepsis being identified. Antibiotics should NOT be delayed whilst waiting for a lumbar puncture if there is nobody available to perform it (or it fails). Get parents and nurses to attempt to catch a clean urine sample whilst they are waiting for investigations and during procedures to avoid the need for a catheter or supra-pubic aspiration. Sepsis 6 guidelines also recommend sending a lactate, using oxygen to keep saturations >94%, giving a fluid challenge if needed and measuring the urine output (NB. This doesnt necessarily have to be via a catheter as many units will weigh nappies to measure output). While you will be routinely sending inflammatory markers and renal function, remember to also check the blood glucose as these babies can easily become hypoglycaemic if they have had decreased feeding and increased metabolic demand from sepsis!

Sounds straightforward? It rarely is! If you want to read more, Edward Snelson has written posts about it here and here and NICE guidelines can be found here.


Congenital heart disease often presents in early infancy. Do not be complacent – many are NOT picked up on antenatal scans or on the initial baby check so a baby can present to ED with no known cardiac history.

Red flags in the history include poor weight gain, breathlessness (especially during feeding), sweating (again may be during feeding), blue episodes or episodes of pallor. Clinical features may include tachycardia, tachypnoea (which is common and respiratory distress may be present, but tachypnoea without respiratory distress is considered a red flag for cardiac disease), cyanosis (remember peripheral cyanosis can be normal e.g. if cold but central cyanosis is always pathological), pallor, enlarged liver, bi-basal fine crepitations, heart murmur or absent femoral pulses. You can also check for differences in saturations and blood pressure between the right arm (pre-ductal) and right leg (post-ductal).

If you have any concerns that an unwell baby may have a cardiac defect have a low threshold for performing saturations and blood pressure on the right arm and right leg and performing a chest xray and ECG. Speak to your local General Paediatric team or Paediatric Cardiologists early. You must have a low threshold for commencing prostaglandins (Prostin) in any grey or cyanotic infant presenting less than 1 month of age in order to keep a patent ductus arteriosus (PDA) open in a duct-dependant lesion! Remember that almost of all of these suspected cardiac babies will need empirical treatment for sepsis as well given their presentation. Bear in mind they may well not be stable enough to perform a lumbar puncture, in which case this can be deferred to a later date and antibiotics administered promptly following blood and urine cultures. Fluid resuscitation may be needed but should be given in 10ml/kg aliquots with careful reassessment after each bolus to assess for any deterioration or signs of fluid overload.

You can find a detailed RCEM learning reference section on congenital heart disease here and EM cases podcast here.


Inborn errors of metabolism often present in the first few months of life and we should always try to bear this in mind in an unwell young infant. Pointers from the history may include consanguineous parents, previous miscarriages or sudden infant death in the family and known family history of metabolic conditions. The presentation of metabolic disorders if often very unclear, which means you must keep a high index of suspicion. A baby may present encephalopathic, with seizures, poor weight gain or poor growth, vomiting or just generally unwell.

If you have any suspicions of a metabolic problem then perform these screening tests: glucose, ketones, lactate and ammonia. The glucose and ketones can be done on a bedside machine, send a gas (to include a lactate) and an ammonia sample (this must be a free flowing venous sample and sent immediately to the lab on ice). Stop all feeds and commence IV fluid resuscitation (as needed) and maintenance fluids that must include dextrose (normally 10%). If any of these are abnormal or you need more advice then contact your local tertiary Paediatric Metabolic team for advice. This website is also a really excellent resource and includes lots of advice for emergency management of metabolic conditions.

We have a blog on metabolic babies here.

Non-accidental Injury

Have a high index of suspicion for non-accidental injury (NAI) in a baby that presents generally unwell, or possibly with a decreased level of consciousness, lethargy, irritability or any signs of trauma such as swelling or bruising. Red flags from talking to the parents may include a bizarre, inconsistent or vague history of events or an unusual affect or interaction with the baby. Remember “babies that don’t cruise shouldn’t bruise” and the mechanism of injury must be developmentally appropriate (e.g. a baby who can’t yet roll cannot roll off a sofa). You need to strip all babies off completely to examine them, including examining in the nappy area. Any bruising or sign of trauma in a non-mobile child is abnormal and needs careful consideration, and potentially investigation if there are any concerns of NAI.

Also be aware of known risk factors for NAI such as parental drug and alcohol abuse or mental health issues and domestic violence. Ask whether the family is known to social services. You need to ask these difficult questions routinely, the more you do this, the less awkward it will feel. You may want to preface this section of your history by saying “these are a few standard questions we ask everyone”.

Ensure you are familiar with your local pathway for management of suspected NAI, as it varies between trusts. In this age group it normally involves a referral to social care and your local Paediatric or safeguarding team, and possibly the police. Emergency department management must include any necessary resuscitation and treatment regardless of the suspicion of NAI. Initial investigations in the ED will depend on clinical presentation, and investigations will be limited to those required to diagnose the underlying problem. Once the child is clinically stable, further investigations will be performed by the safeguarding clinicians and may include a CT head scan to look for intracranial bleeding, bloods (especially FBC and clotting studies), a skeletal survey and ophthalmology review to look for retinal haemorrhages.

NAI is so important – you may notice we’ve covered it again, later on in this iBook!

For further information you can see the NICE guidelines here and further RCEM teaching can be found here.


Surgical issues may also present in young infants. They may present with intestinal obstruction (for example due to malrotation and volvulus) and signs may include a distended abdomen, visible peristalsis, bilious vomiting, lethargy, decreased feeding or irritability. Bilious vomiting is very serious in a young infant and should never be ignored. Remember to always check the hernial orifices and testes as well!

In the first few days of life you need to consider Hirschsprung’s disease if an infant has failed to pass meconium within the first 24-48 hours of life. Always remember to check for a patent anus as well before you call the surgeons (just to save yourself a red face if it’s imperforate).

Also be aware of Necrotising Enterocolitis that can present in term babies as well as preterm, and after a few days of life. The baby may be septic or shocked, and may have apneas or respiratory distress. Their abdomen may be distended, shiny and they may have peri-umbilical flare.

Pyloric stenosis usually presents a bit later around 3-6 weeks of age with forceful vomiting (not bilious) after feeds, persistent hunger, dehydration, weight loss and irritability. This BMJ Best Practice piece is really useful to read further.

For all of these surgical conditions the basic management involves getting IV access, giving IV fluids and stopping feeds. Babies will also often require IV antibiotics this should be discussed with your local surgical team for your local guidelines. It is often also useful to insert an NG tube on free drainage and perform a chest and abdominal x-ray. Always liaise with your tertiary Paediatric Surgeons early if you are in a DGH, as you will probably need to arrange transfer for the baby and this can take time.

Take Home Points

  • Most unwell neonates and infants present with non-specific symptoms
  • ALWAYS consider sepsis – most unwell neonates and infants will need empirically treating for infection
  • When sending initial blood work a reasonable first line is FBC, U&Es, CRP, blood culture, venous gas (with lactate), glucose and ammonia
  • Consider cardiac and metabolic disease in any unwell baby – look for key red flags highlighted above
  • Keep a high index of suspicion for non-accidental injury.

References & Further Reading

  1. National Institute for Health and Care Excellence (NICE). Suspected sepsis: recognition, diagnosis and early management. [NG51] 2016. Last updated: 19 March 2024.
  2. The UK Sepsis trust. Education Resources Sepsis
  3. Paediatrics for Primary Care (and anyone else). Think Sepsis What does that mean?. 2017.
  4. Snelson E, Walsh H. Recognising Paediatric Sepsis. RCEMLearning, 2016. Updated: 26/03/2024
  5. National Institute for Health and Care Excellence (NICE). Neonatal infection: antibiotics for prevention and treatment. [NG195] 2021. Last updated: 19 March 2024.
  6. Jaffer F, Hosein  R. Congenital Heart Disease. RCEMLearning, 2020. Updated: 19/02/2024
  7. Helman, A, Joubert, G, Strobel, A. Congenital Heart Disease Emergencies. Emergency Medicine Cases. [Accessed 24th Feb 2024]
  8. British Inherited Metabolic Diseases Group (BIMDG)  Inherited Metabolic Diseases
  9. Snelson E. Metabolic Babies in the ED.. Easy As 1.. 2.. 3. RCEMLearning, 2016.
  10. National Institute for Health and Care Excellence (NICE). Child maltreatment: when to suspect maltreatment in under 18s. [CG89] 2009. Last updated: 09 October 2017.
  11. Abela N. Child Abuse. RCEMLearning, 2018.
  12. BMJ Best Practice  Hirschsprungs disease. Last reviewed: 2 Mar 2024
  13. Patient. Necrotising Enterocolitis. Last updated 30 Jan 2022. [Accessed 24th Feb 2024]
  14. BMJ Best Practice  Pyloric stenosis. Last reviewed: 2 Mar 2024
  15. Horeczko T. PEM Playbook The Undifferentiated Sick Infant. emDocs, 2016.

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