What is the diagnosis and treatment for an elderly female patient with sharp pain in the back near the kidneys and hematochezia (blood in stool)?

Diagnostic Approach for Elderly Female with Sharp Back Pain Near Kidneys and Hematochezia

This patient requires immediate CT scan with IV contrast to differentiate between life-threatening causes including complicated diverticulitis, bowel ischemia, perforated viscus, and renal pathology—all of which present with overlapping symptoms in elderly patients and carry mortality rates up to 8% when diagnosis is delayed. 1, 2

Immediate Diagnostic Workup

Critical Laboratory Tests

• Complete blood count to assess for leukocytosis (>10,000/mm³ suggests bowel ischemia or peritonitis, though 43% of elderly patients with serious pathology lack leukocytosis) 1, 2
• Serum lactate as a marker of tissue hypoperfusion and bowel ischemia—elevated levels correlate with transmural necrosis and mortality 2
• C-reactive protein and procalcitonin to assess severity of intra-abdominal pathology, though up to 39% of patients with complicated diverticulitis have CRP <175 mg/L 3, 2
• BUN/creatinine to evaluate for acute kidney injury from dehydration or renal pathology 1, 2
• Blood typing and cross-matching for potential transfusion if hematochezia is severe 1

Imaging Strategy

CT scan of abdomen and pelvis with IV contrast is mandatory as first-line imaging, with sensitivity >95% for detecting diverticulitis, bowel perforation, ischemia, and renal masses 1, 3, 2. This imaging influences treatment plans in 65% of elderly patients and changes surgical management in 48% of cases 1, 3. The high prevalence of chronic kidney disease in elderly patients (39.4% in those aged 60+) should not discourage IV contrast use, as recent meta-analyses show no increased risk of contrast-induced acute kidney injury in this population 1.

Primary Differential Diagnoses

Life-Threatening Causes Requiring Immediate Intervention

Complicated diverticulitis with perforation or abscess presents with back pain radiating from the left lower quadrant, but only 50% of elderly patients have typical lower quadrant pain, 17% have fever, and 43% lack leukocytosis 1, 2. CT findings include pericolonic fat stranding, bowel wall thickening >5mm, and rim-enhancing fluid collections (abscesses in ~35% of cases) 3. Distant intraperitoneal free air on CT correlates with need for operative management and should never be managed conservatively 1, 3.

Acute mesenteric ischemia presents with pain out of proportion to physical examination findings—the hallmark feature—and demands immediate imaging, particularly in elderly patients with cardiovascular disease or atrial fibrillation 2. Mortality increases with every hour of diagnostic delay 2.

Perforated viscus with peritonitis presents with abdominal rigidity and requires immediate surgical consultation 2. Elderly patients are more likely to present with complicated disease requiring urgent surgery 2.

Renal Pathology Mimicking Bowel Disease

Renal cell carcinoma with hemorrhage can present with flank pain and hematuria, but the blood may be misattributed to lower GI bleeding 4. One-third of patients have metastatic disease at presentation, and skeletal metastases are purely lytic 4.

Page kidney (subcapsular hematoma) presents with severe flank pain, hematuria, and secondary hypertension from compression of renal parenchyma activating the renin-angiotensin-aldosterone system 5. This can occur spontaneously without trauma in elderly patients 5.

Lower GI Bleeding Sources

Hemorrhoids or anorectal varices require differentiation via anoscopy or proctoscopy, as hemorrhoids are confined to the anal canal while varices cross the dentate line 1. However, up to 15% of patients with serious hematochezia have an upper GI source, and 8% with presumed diverticular bleeding have upper sources 1.

Colorectal cancer accounts for 60% of large bowel obstructions and carries a 2.4-11% risk in patients presenting with rectal bleeding 1, 2. CT findings suggesting malignancy include pericolonic lymphadenopathy >1cm 3.

Mandatory Physical Examination Components

• Digital rectal examination to detect rectal mass, fecal impaction, blood, or rectal prolapse—approximately 40% of rectal carcinomas are palpable 1, 2
• Examination of all hernia orifices to detect incarcerated hernias causing obstruction 2
• Assessment for peritoneal signs including abdominal rigidity, though sensitivity for detecting strangulation is only 48% even in experienced hands 1
• Vital signs monitoring for orthostatic hypotension or shock 1, 2

Management Algorithm Based on CT Findings

Uncomplicated Diverticulitis (WSES Stage 0)

• Conservative management without antibiotics in immunocompetent patients without sepsis 3, 2
• Hospital admission for observation given advanced age 2

Localized Complicated Diverticulitis (WSES Stage 1a)

• Broad-spectrum antibiotics covering E. coli, Enterobacteriales, and Clostridiales 2
• Intravenous fluid resuscitation with isotonic dextrose-saline and supplemental potassium 2

Abscess Present (WSES Stage 1b-2a)

• Broad-spectrum antibiotics plus percutaneous drainage if abscess >4cm 3, 2
• Short course antibiotics (3-5 days) after adequate source control 2

Diffuse Peritonitis or Free Air (WSES Stage 3-4)

• Immediate surgical consultation for source control—this is not optional 3, 2
• Both Hartmann procedure and resection with primary anastomosis are reasonable surgical options 2

Renal Pathology Identified

• Urology consultation for renal mass or subcapsular hematoma 5
• Hypertension management with ACE inhibitor if Page kidney diagnosed 5
• Consider nephrectomy for renal cell carcinoma with metastatic disease 4

Critical Clinical Pitfalls to Avoid

Never assume hematochezia originates from the lower GI tract without upper endoscopy if the source is unclear, as 15% of serious hematochezia cases have upper GI sources 1.

Do not delay CT imaging based on normal laboratory values—elderly patients frequently lack typical inflammatory markers despite life-threatening pathology 1, 2.

Pain out of proportion to examination findings mandates immediate imaging for mesenteric ischemia, as mortality increases hourly with delayed diagnosis 2.

Progressive muscle weakness is a red flag for metastatic disease requiring advanced imaging beyond plain radiographs 4.

Resuscitation and Supportive Care

• Maintain hemoglobin >7 g/dL and mean arterial pressure >65 mmHg during resuscitation, but avoid fluid overload 1
• Correct coagulopathy (INR >1.5) with fresh frozen plasma and vitamin K 1
• Correct thrombocytopenia (<50,000/µL) with platelet transfusion 1
• Nasogastric tube placement to prevent aspiration pneumonia and decompress proximal bowel 2
• Foley catheter to monitor urine output as marker of perfusion 2

Pain Management

• Intravenous acetaminophen 1g every 6 hours as first-line in multimodal approach 2
• Reserve opioids for breakthrough pain only at lowest effective dose for shortest duration 2

Disposition

Hospital admission is mandatory given advanced age, inability to exclude surgical pathology, and potential for rapid deterioration 2. Intensive care unit admission is warranted if hemodynamic instability persists despite resuscitation, transfusion requirement exceeds 2 units, or continuous active bleeding occurs 1.