How should a 54-year-old female be treated on post-operative day 1 after total knee replacement (TKR) with abdominal distension, no stool or flatus passage since yesterday, a soft non-tender abdomen, and present bowel sounds?

Management of Post-Operative Day 1 Ileus After Total Knee Replacement

Immediate Conservative Management

This patient has a post-operative ileus (POI), which is expected after major surgery and should be managed conservatively with bowel rest, nasogastric decompression if vomiting occurs, intravenous fluid resuscitation, and early mobilization. 1, 2

Initial Supportive Measures

• Begin intravenous crystalloid fluid replacement immediately to correct dehydration from third-spacing and NPO status 1, 2
• Insert a Foley catheter to monitor urine output as a marker of adequate resuscitation 1, 2
• Maintain bowel rest (NPO status) until bowel function returns 1
• Administer anti-emetics if nausea or vomiting develops (ondansetron preferred to avoid prokinetic agents that could worsen distension) 1

Nasogastric Tube Consideration

• Place a nasogastric tube ONLY if the patient develops vomiting to prevent aspiration pneumonia and decompress the proximal bowel 1, 2
• In this case, since the patient is not vomiting and the abdomen is soft and non-tender, nasogastric decompression is NOT indicated at this time 1

Critical Assessment to Rule Out Mechanical Obstruction

The presence of bowel sounds and soft, non-tender abdomen suggests simple ileus rather than mechanical obstruction, but you must remain vigilant for red flags 1, 2:

• Monitor for peritoneal signs (rigidity, rebound tenderness, guarding) which would indicate ischemia or perforation 1
• Check vital signs frequently for tachycardia, tachypnea, fever, or hypotension suggesting complications 1
• Obtain laboratory studies: complete blood count, metabolic panel, and lactate level to exclude ischemia (elevated lactate, leukocytosis, metabolic acidosis are concerning) 1, 2

Imaging Decision

• Plain abdominal X-ray is reasonable as a first-line study to assess bowel gas pattern and exclude free air, though it has only 50-60% diagnostic accuracy for obstruction 1
• CT abdomen/pelvis with IV contrast should be obtained if: the patient develops peritoneal signs, persistent vomiting, worsening distension, fever, or elevated lactate 1, 2
• Do NOT give oral contrast as it delays diagnosis, increases aspiration risk, and can mask bowel wall enhancement abnormalities 1, 2

Medication Management

Avoid Constipating and Prokinetic Agents

• Review and discontinue any opioids if possible, or reduce to the minimum effective dose, as they are the primary cause of post-operative ileus 1
• Avoid or discontinue cyclizine and other anticholinergic antiemetics as they worsen ileus 1
• Do NOT use prokinetic agents (metoclopramide, domperidone) in the acute setting as they can worsen pain and distension in mechanical obstruction 1

Laxative Therapy - NOT Indicated Yet

• Do NOT start laxatives on POD 1 with no flatus or stool, as this is expected post-operative ileus 1
• Laxatives become appropriate only after 3-4 days if constipation persists once bowel sounds return and the patient is tolerating oral intake 1

Early Mobilization

• Encourage early ambulation and physical activity as soon as medically safe, as this is the most effective intervention to restore bowel function after surgery 1

Monitoring and Reassessment

• Perform serial abdominal examinations every 4-6 hours to detect any change in tenderness, distension, or development of peritoneal signs 1, 2
• Monitor nasogastric output volume if tube is placed (high output >500 mL/day suggests more proximal obstruction) 1
• Reassess daily for return of flatus and bowel movements, which typically occurs by POD 3-5 1

When to Escalate Care

Obtain urgent surgical consultation if any of the following develop 1, 2:

• Peritoneal signs (rigidity, rebound tenderness, involuntary guarding)
• Hemodynamic instability despite fluid resuscitation
• Persistent or worsening distension with severe pain
• Feculent vomiting (suggests distal obstruction)
• Elevated lactate >4 mmol/L or metabolic acidosis
• CT findings of closed-loop obstruction, bowel wall thickening, decreased enhancement, pneumatosis, or mesenteric venous gas

Expected Timeline

• Most post-operative ileus resolves spontaneously within 3-5 days with conservative management 1, 3
• If no improvement by day 5-7, consider water-soluble contrast study to differentiate partial from complete obstruction and potentially provide therapeutic benefit 1

Common Pitfall to Avoid

Do not aggressively treat with laxatives or prokinetics on POD 1 - this is normal post-operative ileus that requires time, hydration, mobilization, and opioid minimization, not pharmacologic bowel stimulation 1