What does bilous Nasogastric Tube (NGT) output look like?

What Bilious Nasogastric Tube Output Looks Like

Bilious NGT output appears as yellow-green to dark green fluid, reflecting the presence of bile acids that have refluxed from the duodenum into the stomach.

Visual Characteristics

• Color ranges from yellow-green to dark green or brownish-green, depending on bile concentration and mixture with gastric contents 1, 2
• The fluid may appear frothy or contain particulate matter when mixed with gastric secretions and food residue 2
• Consistency is typically liquid, though viscosity varies based on the proportion of bile to gastric juice 3

Clinical Context and Significance

When Bilious Output Indicates Pathology

• Bilious output becomes clinically significant when volumes exceed 500-1000 mL per 24 hours, requiring aggressive fluid and electrolyte replacement 4
• In postoperative patients, persistent bilious output beyond 5 days suggests mechanical obstruction, intra-abdominal abscess, or anastomotic leak and warrants CT imaging 4
• The presence of bile at endoscopy or in gastric aspirates does not necessarily indicate pathology, as approximately 23% of patients undergoing routine endoscopy have bile in their stomachs without clinical significance 1

Distinguishing Normal from Pathological Bile Reflux

• Fasting bile reflux (FBR) greater than 120 μmol/hour is associated with symptomatic duodenogastric reflux, particularly in patients complaining of bile regurgitation or vomiting 2
• Bile acid concentrations alone do not correlate with mucosal injury severity or clinical symptoms 1
• Patients with gallstones or post-cholecystectomy have increased duodenogastric bile reflux, which may explain some postcholecystectomy symptoms 3

Common Clinical Scenarios

Mechanically Ventilated Patients

• Pathological bile reflux occurs in approximately 48% of mechanically ventilated patients with NGTs, contributing to erosive esophagitis despite acid-suppressive therapy 5
• The severity of esophagitis correlates with gastric residual volume and duration of bile reflux, which increases with the number of organ failures 5

Small Bowel Obstruction

• Bilious vomiting or NGT output is a cardinal sign of small bowel obstruction, though NGT placement should be reserved for patients with active emesis rather than routine use 6
• Routine NGT decompression in SBO without active vomiting increases pneumonia risk, respiratory failure, and hospital length of stay 6

Critical Management Points

• Quantify output volume over 24 hours and assess for dehydration signs (tachycardia, hypotension, decreased urine output) when bilious output is significant 4
• Replace losses with balanced crystalloids at 1:1 ratio initially, monitoring electrolytes every 6-12 hours as gastric losses are rich in hydrogen, chloride, and potassium 4
• Investigate underlying causes with CT imaging if high bilious output persists beyond 5 days postoperatively 4

Common Pitfall to Avoid

• Do not rely on bilious output volume alone to guide management, as high output may reflect excessive fluid administration rather than true pathology 4
• Avoid using 0.9% saline for replacement; use balanced crystalloids to prevent hyperchloremic metabolic acidosis 4