What is the best course of action for a 79-year-old male patient with an infrarenal aortic aneurysm (40x40mm), possible proctitis, elevated C-Reactive Protein (CRP) (239), and abnormal white blood cell count (elevated neutrophils and lymphocytes), who is currently afebrile, passing urine, but experiencing some urinary difficulties, after self-discharging from the emergency department (A&E) following administration of Intravenous (IV) fluids?

Immediate Management of 79-Year-Old with Infrarenal AAA, Suspected Proctitis, and Systemic Inflammation

This patient requires urgent hospital readmission for intravenous antibiotics and further investigation of the suspected proctitis/intra-abdominal infection, as the markedly elevated CRP (239) with leukocytosis suggests active infection that poses immediate risk, while the 40mm AAA itself does not require intervention and is not the primary concern. 1, 2

Critical Priority: Address the Infection, Not the Aneurysm

The 40mm infrarenal AAA is not an indication for intervention and should not drive your immediate management decisions:

• Intervention for asymptomatic infrarenal AAAs measuring <50mm in men is contraindicated (Class III recommendation) 1, 3, 2
• The annual rupture risk for a 40mm AAA is <1%, far lower than any operative mortality risk 3, 2
• This aneurysm requires surveillance only, with imaging every 12 months 2

The real threat is the suspected intra-abdominal infection indicated by:

• CRP of 239 (markedly elevated)
• Elevated white cells, neutrophils, and lymphocytes
• CT findings of mesorectal fat stranding suggesting proctitis
• Diverticulosis (potential source of infection)

Immediate Actions Required in GP Setting

Arrange urgent hospital readmission today for the following reasons:

1. Systemic Infection Management

• The patient requires intravenous broad-spectrum antibiotics to cover gastrointestinal flora (including anaerobes) given the suspected proctitis and diverticulosis 4, 5
• Start empiric coverage for gram-negative organisms and anaerobes while awaiting blood cultures 4, 5
• The combination of mesorectal fat stranding and markedly elevated inflammatory markers suggests active colonic/rectal pathology requiring urgent investigation

2. Rule Out Mycotic (Infected) Aneurysm

• This is the most dangerous scenario: the combination of AAA + systemic infection + elevated inflammatory markers raises concern for mycotic aneurysm 4, 5
• Mycotic infrarenal AAAs have 39-100% mortality without appropriate surgical management 5
• Blood cultures are essential (positive in 65% of mycotic aneurysms, with Salmonella being most common at 27-35%) 4, 5
• If mycotic aneurysm is confirmed, open surgical repair is the first choice for hemodynamically stable patients (0% mortality vs 100% mortality with conservative management alone) 5

3. Investigate the Proctitis

• The patient needs urgent colonoscopy or flexible sigmoidoscopy to evaluate the mesorectal fat stranding 1
• Possible diagnoses include infectious proctitis, inflammatory bowel disease, ischemic colitis, or diverticulitis
• Tissue cultures and biopsies are needed to guide antibiotic therapy

4. Assess for Complicated Diverticulitis

• Diverticulosis with elevated inflammatory markers may indicate diverticulitis 2
• CT showed no frank diverticulitis, but clinical correlation is needed
• Complicated diverticulitis can lead to abscess formation or perforation

Specific Instructions for Hospital Referral

Contact the acute medical team immediately and communicate:

1. Primary concern: Suspected intra-abdominal infection (proctitis vs diverticulitis) with systemic inflammatory response (CRP 239, leukocytosis)
2. Secondary concern: Need to exclude mycotic aneurysm given proximity of infection to known AAA
3. Patient requires:
   • IV antibiotics (broad-spectrum covering GI flora and anaerobes)
   • Blood cultures before antibiotics if possible
   • Repeat inflammatory markers
   • Gastroenterology/colorectal surgery consultation for endoscopic evaluation
   • Vascular surgery consultation if mycotic aneurysm suspected

What NOT to Do

• Do not refer to vascular surgery for the AAA itself - a 40mm aneurysm does not meet criteria for intervention 1, 3, 2
• Do not delay hospital admission - the infection risk is immediate, while AAA rupture risk is <1% annually 3, 2
• Do not treat with oral antibiotics in the community - the severity of inflammation (CRP 239) requires IV therapy and investigation 4, 5
• Do not assume the urinary symptoms are unrelated - they may indicate systemic sepsis or referred pain from intra-abdominal pathology

Regarding the Urinary Symptoms

The patient reports "the flow is not correct" but is passing urine:

• This is likely secondary to systemic illness or referred pain from the intra-abdominal pathology
• Less likely to be direct AAA compression (40mm is too small)
• Obtain urinalysis to exclude concurrent UTI contributing to sepsis
• Assess post-void residual if urinary retention suspected

Follow-Up After Acute Management

Once the infection is treated and the patient is stable:

• Arrange surveillance ultrasound for the AAA in 12 months 2
• Smoking cessation counseling if applicable (reduces AAA expansion risk) 2
• Blood pressure optimization (reduces AAA expansion risk) 2
• Consider beta-blocker therapy to reduce AAA expansion rate 2

The bottom line: This patient's immediate mortality risk comes from the infection, not the aneurysm. Urgent hospital readmission for IV antibiotics, blood cultures, and investigation of the proctitis is mandatory.