puo1 pdf - د.حسنين

PUO

Dr. Hasanain

“ Pyrexia of Unknown

Origin ”

Total Lec: 29

Fever without a focus
(Pediatric Mystery)

LEARNING OBJECTIVES

1-  Define fever and FUO.
2-  Put a differential diagnosis.
3-  Master a panel of investigations.
4-  Decide when to start empirical therapy?

MCQ

The commonest cause of PUO is:

A-  A common disease presenting in an atypical way.
B-  A rare disease presenting in atypical way.
C-  A common disease presenting typically.
D- A rare disease presenting typically.

ANSWER A

•

A 10 - year old female, presented to the outpatient clinic with a 4 - week
history of fever (38.3 C – 39.5 C) and easy fatigability. She underwent a good
primary work up by the family physician prior to referral with failure to reach a
diagnosis. She is sitting now with her worried parents in the desk next to you
and ready to receive your questions and actions.

1-  How you define this complaint in view of duration?
2-  Put a differential diagnosis inside a general frame?
3-  What shall you ask in the context of history?
4-  What are the general and special sites you look for in physical

examination?

5- Set a panel of investigations you are planning to perform?
6- Start a treatment plan?

1- How you define this complaint in view of
duration?

DEFINITIONS

• Fever: A rectal temperature of ≥38 C. It

fluctuates in degree and timing.

• FWLS (Fever without localising sign): Fever

of acute onset, with duration of <1 wk and
without localizing signs.

• FUO (Fever of unknown origin): Fever

documented by a health care provider and
for which the cause could not be identified
after 3 wk of evaluation as an outpatient
or after 1 wk of evaluation in the hospital.

• Range of normal temperature

o Axillary 36 - 37.4

o Oral 36.7 - 37.7

o Rectal 36.9 - 37.9

PATHOGENESIS

Regulators:

1.  Thermo sensitive neurons in pre-optic and anterior hypothalamus
2.  Blood temperature
3.  Receptors in skin and muscles

Mechanisms:

1-  Pyrogens (endogenous and exogenous)
2-  Heat production exceeding loss
3-  Defective Heat loss

A. B. Continuous: Temperature remains above normal throughout the day and does

not fluctuate more than 1 °C in 24 hrs.Typhoid, lobar pneumonia,

C- Remittent: Temperature remains above normal throughout the day and fluctuates
more than 1 °C in 24 hours. SBE

D. Intermittent: The temperature elevation is present only for a certain period, later
cycling back to normal. Kala Azar

E. Undulant: fever is typically undulant, rising and falling like a wave Brucellosis

F. Relapsing: multiple episodes of fever occur and each may last up to 3 days.
Individuals may be free of fever for up to 2 weeks before it returns. Tick borne

Remember the sequelae

2- Put a differential diagnosis inside a general frame?

between 5 and 15% of FUO cases defy diagnosis, despite exhaustive studies.

CAUSES

1- Infections:

•  Bacterial
•  Systemic: Brucellosis, Salmonella, Tuberculosis
•  Localized infections: Osteomyelitis, Pneumonia and Sinusitis
•  Viruses: CMV, Hepatitis viruses ,HIV, IM (Epstein-Barr virus)
•  Parasitic Diseases: Malaria ,Toxoplasmosis
•  Fungal diseases

2- Rheumatologic diseases

• JRA, Rheumatic fever, SLE and drug fever.

3- Neoplasms

• Leukemia, Lymphoma, other malignancies.

4- Miscellaneous

• Familial Mediterranean fever, Kawasaki disease.

5- Undiagnosed

Always look for

Abscesses: Abdominal, brain, dental, hepatic, pelvic, perinephric, rectal, subphrenic,
psoas

APPROACH

The Best Approach

“there is no substitute for observing the patient, talking to him and thinking about
him”

3- What shall you ask in the context of history?

HISTORY

Fever specifications, sweating, antipyretics use and response, appearance, other
complaints (CNS, urinary,,,,), pain (severity, site), rash and distribution, arthralgia /
arthritis, travel, contact, animals, medications, hospitalization, immunizations,
ethnicity, exposure to contaminated food or water.

4- What are the general and special sites you look for in physical examination?

CAREFUL PHYSICAL EXAMINATION

General appearance and vital signs (heart rate, pressure, respiratory, temperature),
pallor, jaundice, clubbing, skin and scalp, eyes, sinuses, oropharynx, LN, abdomen,
musculoskeletal, genitourinary.

5- Set a panel of investigations you are planning to perform?

INVESTIGATIONS

Level 1:

CBC differentials, ESR, CRP, metabolic panel (RFT, LFT, elects), GUE, stool, C/S, LP,
CXR, US, TB, EBV, CMV, cultures.

Level 2:

Echo, CT, Bone scan, Serology, Autoimmune, Bone marrow

Level 3:

Tissue biopsy, Endoscopy

•

avoid indiscriminately ordering a large battery of tests.

6- Start a treatment plan?

Treatment

in general, NONE Until diagnosis

You should know that

1.  most children will get better
2.  most children have common illnesses
3.  it hasn’t killed them yet! So do not rush to antibiotic treatment.

Admit

1-  Reliability
2-  Toxicity
3-  Invasive investigations

Empirical therapy (little or no role in cases of classic fever of unknown origin) is
indicated only in:

1.  Nonsteroidal agents in presumed JIA
2.  Antituberculosis drugs in critically ill children with possible disseminated TB
3.  Clinically deteriorating with suspicion of bacteremia or sepsis.
4.  Immunocompromised

Antibiotics if used should be at targeted disease rather than blanket therapy with 4-5
antibiotics.

Take home message

•

FUO is more likely to be an unusual presentation of a common disorder than a
common presentation of a rare disorder.

•

Giving antibiotics to a child with FUO is like shooting a gun into dark room

Thank you

Fever without a focus
(Pediatric Mystery)

Hints

• As the duration of fever increases, infectious etiology decreases
• Malignancy and factitious fever should be considered with more prolonged

fever

• The most critical features of the evaluation of a patient with FUO is to take a

carefully history and to reassess the patient frequently.

• The Best Approach is “there is no substitute for observing the patient, talking

to him and thinking about him”

• It is important to look for uncommon presentation of common disease and to

perform a detailed physical examination

• Clinically challenging - get expert help! Clinical balance between trial

antimicrobial (often anti tuberculosis regimen) or corticosteroid trial.

• avoid indiscriminately ordering a large battery of tests.

Approach

Task

1- Intra abdominal abscess

History: Seven-year old male, PUO, Swinging in nature, with non specific localizing
abdominal pain and a prior history of appendicitis.

Physical examination: Febrile, Right iliac fossa mass