What are the potential causes and treatment options for an older adult with a history of joint disease or trauma, who is experiencing severe pain and hematochezia one month after hip replacement surgery?

Severe Pain and Blood in Stool One Month Post-Hip Replacement

This patient requires immediate evaluation for a gastrointestinal complication, most likely NSAID-induced peptic ulcer disease or diverticular bleeding, while simultaneously addressing inadequate postoperative pain control with a multimodal analgesic approach that avoids NSAIDs.

Immediate Diagnostic Evaluation

Gastrointestinal Assessment

• Hematochezia at one month post-hip replacement is a serious complication requiring urgent colonoscopy, as this is the first-line diagnostic modality with 78% diagnostic yield for identifying the site and cause of severe lower GI bleeding 1
• Diverticular disease is the most common cause of severe hematochezia (30% of cases), with right-sided diverticular bleeding accounting for 44% of diverticular cases in some populations 1
• Acute abdominal complications after hip surgery, though rare, include perforated peptic ulcer (most common), acute cholecystitis, volvulus, and colonic pseudo-obstruction, typically presenting 3-10 days postoperatively but can occur later 2
• Check for recent NSAID use, as NSAIDs are contraindicated in elderly hip fracture patients due to renal dysfunction risk and GI bleeding, yet are commonly prescribed despite guidelines 3

Laboratory Workup

• Obtain complete blood count to assess for anemia and need for transfusion (transfuse if hemoglobin <8 g/dL with symptoms or <7 g/dL if asymptomatic) 3
• Check renal function, as elderly patients have reduced glomerular filtration rate affecting drug excretion 4
• Obtain ESR and CRP to rule out late prosthetic joint infection, which can present with pain and may be subtle in onset 5

Pain Management Strategy

First-Line Multimodal Approach

• Administer intravenous acetaminophen 1000 mg every 6 hours as the cornerstone of pain management, scheduled around-the-clock rather than as-needed 3, 4
• Immediately discontinue any NSAIDs if being used, as they are contraindicated in elderly patients with renal dysfunction and carry significant GI bleeding risk 3, 4
• Consider peripheral nerve blocks if pain is localized to the hip region, as these reduce opioid requirements 3, 4

Adjunctive Pharmacological Options

• Add gabapentinoids for neuropathic pain components 3, 4
• Apply topical lidocaine patches for localized pain 3, 4
• Consider low-dose ketamine if pain is severe and refractory, as it provides comparable analgesia to opioids with fewer cardiovascular side effects 4

Opioid Management (If Necessary)

• Reserve opioids strictly for breakthrough pain only, using the shortest duration and lowest effective dose 3, 4
• Implement progressive dose reduction due to high risk of morphine accumulation leading to over-sedation, respiratory depression, and delirium in elderly patients 3
• Reduce both dose and frequency by half in patients with renal dysfunction 3
• Avoid codeine entirely, as it is constipating, emetic, and associated with perioperative cognitive dysfunction 3

Evaluation for Other Pain Sources

Prosthetic-Related Complications

• Review serial radiographs comparing to immediate postoperative films to identify loosening, component malposition, or periprosthetic fracture (2.23% prevalence at one year) 5, 6
• Consider aspiration under fluoroscopic guidance if ESR and CRP are both elevated, as late hematogenous infection can present with pain 5
• Evaluate for prosthesis dislocation (1.11% prevalence at one year, higher in fracture patients at 9.2%) 6, 7
• Assess for psoas tendon impingement if pain is worse with active hip flexion, confirmed by CT scan 5

Alternative Pain Sources

• Evaluate lumbar spine pathology (spinal stenosis, degenerative disk disease) as these commonly present as hip pain 5
• Compare current pain characteristics to preoperative symptoms to determine if this represents inadequate surgical correction versus new pathology 5

Critical Management Pitfalls

• 42% of patients over 70 receive inadequate analgesia despite reporting moderate to high pain levels, leading to delayed mobilization, chronic pain, and delirium 3
• Both inadequate analgesia AND excessive opioid use increase postoperative delirium risk in elderly patients 4
• Mortality related to severe hematochezia is 5%, with 16% requiring surgery, though 81% of bleeding stops spontaneously 1
• Acute abdominal complications after hip surgery are rare but "almost exclusively lead to life-threatening situations" requiring early identification by both orthopedic and general surgery teams 2
• Never exceed 4 g/24 hours of acetaminophen, particularly when using combination products, and educate patients on acetaminophen content in all medications 4

Immediate Action Plan

1. Admit for urgent gastroenterology consultation and colonoscopy to identify bleeding source
2. Stop all NSAIDs immediately if being used
3. Initiate scheduled IV acetaminophen 1000 mg every 6 hours as first-line pain control
4. Check hemoglobin and transfuse if indicated based on symptoms and level
5. Obtain orthopedic radiographs and inflammatory markers to rule out prosthetic complications
6. Add gabapentinoids and consider regional blocks for breakthrough pain rather than escalating opioids