Pleural effusions & chylothorax

Sort the fluid first - transudate or exudate - then recognise the commonest neonatal effusion: chylothorax.

TRANSUDATE vs EXUDATE · CHYLE = LYMPHOCYTES + TRIGLYCERIDES

FIRST SORT THE FLUID

Transudate or exudate?

Pleural fluid is first split into transudate (a hydrostatic/oncotic imbalance) and exudate (inflammation or infection). In the newborn, the single commonest effusion is a chylothorax, which is handled separately below.

Feature	Transudate	Exudate
Protein	<3 g/dL	>3 g/dL
LDH	<200 IU	>200 IU
Pleural:serum LDH	<0.6	>0.6
Glucose	Same as serum	Less than serum
pH	>7.40	<7.40
White cells	<1000/mm³	>1000/mm³
Typical cause	Heart failure, hypoproteinaemia, non-immune hydrops, iatrogenic	Infection / inflammation

THE NEONATAL ONE

Chylothorax

Why it happens

Fluid balance

A thin pleural film is normally kept constant by balanced capillary filtration and lymphatic reabsorption; an effusion forms when production outstrips drainage.

Three fluid types

Transudate (hydrostatic/oncotic imbalance - hydrops, cardiac, renal), exudate (infection or inflammation), or chyle - the commonest in the newborn.

Thoracic duct

Carries chyle - lymph rich in long-chain fats, lymphocytes, protein and immunoglobulin - from the gut and lower body to the venous system.

Chylothorax

Obstruction, malformation or a leak of the thoracic duct / lymphatics lets chyle collect in the pleural space.

Congenital vs traumatic

Congenital lymphatic dysplasia (often syndromic) vs trauma - birth, or after cardiac / thoracic surgery.

Associations

More common with chromosomal anomalies and syndromes - trisomy 21, Noonan, Turner.

If early/large

Compresses the developing lung (pulmonary hypoplasia) and can drive hydrops, polyhydramnios and preterm labour.

Making the diagnosis

Fluid cells

Lymphocyte-predominant

Triglycerides

High, especially after feeding

Appearance

Clear if the baby has not fed; milky once enteral (long-chain) fat is given

Watch for

Repeated drainage causes lymphopaenia (and immunoglobulin/protein loss)

Management ladderDrain if there is respiratory compromise. Reduce chyle flow by feeding a formula rich in medium-chain triglycerides (absorbed via portal blood, not lymph) or resting the gut on TPN. Replace significant albumin/immunoglobulin losses. For persistent leaks, try octreotide; thoracic duct ligation or pleurodesis is reserved for severe, refractory cases. Large fetal effusions/hydrops may warrant thoracocentesis or a thoraco-amniotic shunt.

Nursing considerations

Monitor work of breathing and SpO2; assist with and observe chest drains.
Document drain volume and character (milky after feeds suggests chyle); watch for protein and lymphocyte losses.
Support nutrition - MCT feeds or TPN as planned; careful fluid balance.
Support the family, especially if drainage is prolonged.

SIDE BY SIDE

Hydrothorax vs chylothorax

Feature	Hydrothorax	Chylothorax
Fluid	Transudate or exudate	Lymph / chyle
Cause	Hydrostatic/oncotic imbalance or inflammation	Lymphatic obstruction / leak
Appearance	Variable	Clear if unfed, milky after feeds
Key labs	Protein, LDH, glucose, pH	Lymphocytes, triglycerides
Management	Treat the cause; drain if needed	Drain, MCT / TPN, octreotide; ligation if severe

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Effusion in a newborn? Tap it. Transudate vs exudate uses protein, LDH, glucose and pH. A lymphocyte-rich, triglyceride-high tap that turns milky after feeds is a chylothorax - drain it, switch to MCT or TPN, and reach for octreotide before surgery.

Educational summary for clinical teaching. Fluid thresholds are guides - interpret alongside the clinical picture and your laboratory's reference ranges.

Pleural effusions & chylothorax

Transudate or exudate?

Chylothorax

Hydrothorax vs chylothorax

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