I have abdominal pain that started after lunch, accompanied by low‑grade fever, bloating, pressure and mild tenderness on palpation, with temporary relief from a hot shower—what should I do?

Immediate Evaluation and Management of Post-Prandial Abdominal Pain with Low-Grade Fever

You need a contrast-enhanced CT scan of your abdomen and pelvis immediately to rule out acute diverticulitis, cholecystitis, appendicitis, or other serious intra-abdominal infection that requires urgent intervention. Your constellation of symptoms—abdominal pain starting after lunch, low-grade fever beginning at 5:30 PM, bloating, pressure, and mild tenderness—represents a classic presentation of acute intra-abdominal infection that cannot be reliably diagnosed by clinical examination alone. 1, 2

Why Imaging Cannot Be Delayed

• Clinical assessment alone misdiagnoses acute abdominal pathology in 34–68% of cases, making symptom-based diagnosis dangerously unreliable. 2
• The classic triad of localized abdominal pain, fever, and leukocytosis occurs in only 25% of diverticulitis cases, meaning most patients with serious infection present exactly as you have—with vague symptoms that seem mild. 2
• CT abdomen and pelvis with IV contrast achieves 98% diagnostic accuracy and is rated 8/9 (usually appropriate) by the American College of Radiology for evaluating acute abdominal pain with fever. 1, 2

Critical Red Flags in Your Presentation

• Low-grade fever starting in the evening is a hallmark of intra-abdominal infection and indicates bacterial translocation or localized peritonitis that may progress to sepsis. 1
• Mild tenderness on palpation suggests peritoneal irritation, which can rapidly evolve into diffuse peritonitis if an abscess ruptures or perforation occurs. 1
• Bloating and pressure combined with fever raises concern for bowel obstruction with secondary infection, which carries a 90% rate of inability to pass gas or stool when complete. 1
• Temporary relief from hot shower does not exclude serious pathology—patients with spontaneous bacterial peritonitis or early diverticulitis frequently report transient symptom improvement that masks progressive infection. 1

Immediate Actions Required

• Go to the emergency department now if you develop any of the following: inability to pass gas or stool, vomiting, worsening pain, abdominal rigidity, confusion, rapid heartbeat, or inability to tolerate oral fluids. 1, 2
• Do not eat or drink anything until you have been evaluated, as you may require emergency surgery or percutaneous drainage if imaging reveals an abscess or perforation. 1
• Request CT abdomen and pelvis with IV contrast as your first imaging study—do not accept plain X-rays or ultrasound as substitutes, as they have sensitivities of only 10–20% for detecting the complications you may have. 1

Most Likely Diagnoses Based on Your Symptoms

Acute Diverticulitis (Most Common in Adults)

• Acute sigmoid diverticulitis is the leading cause of left-sided abdominal pain in adults, particularly those over 50, and presents with exactly your symptom pattern: post-prandial pain, evening fever, bloating, and mild tenderness. 2
• CT will show pericolonic fat stranding, bowel wall thickening, and any complications such as abscess (requiring drainage if ≥4 cm) or perforation (requiring emergency surgery). 2
• If CT confirms uncomplicated diverticulitis and you are immunocompetent, you will likely be managed conservatively without antibiotics for up to 7 days, as antibiotics do not improve outcomes in uncomplicated cases. 2

Acute Cholecystitis

• Right upper quadrant pain after eating (especially fatty meals), fever, and tenderness suggest gallbladder inflammation, which requires early cholecystectomy within 7–10 days if confirmed. 1
• Ultrasound is the investigation of choice for suspected cholecystitis, showing pericholecystic fluid, gallbladder wall edema, and impacted stones. 1
• If cholecystitis is complicated (gangrenous, perforated, or with abscess), you will need laparoscopic cholecystectomy plus antibiotics for 4 days if immunocompetent, or up to 7 days if immunocompromised. 1

Appendicitis (If Pain is Right-Sided)

• The 24-hour progression from diffuse pain to localized right lower quadrant tenderness, combined with fever, follows the classic appendicitis pattern and requires immediate surgical consultation. 3
• CT has 94% sensitivity for appendicitis and will guide whether you need emergency appendectomy or can be managed with antibiotics alone. 3

Spontaneous Bacterial Peritonitis (If You Have Cirrhosis)

• If you have known liver disease with ascites, your symptoms could represent spontaneous bacterial peritonitis, which is diagnosed by paracentesis showing >250 neutrophils/mm³ and requires immediate empiric antibiotics. 1
• Up to one-third of patients with spontaneous infections are entirely asymptomatic or present only with vague abdominal discomfort and low-grade fever, making diagnostic paracentesis mandatory in any cirrhotic patient admitted with your symptoms. 1

What Happens After CT Imaging

If CT Shows Uncomplicated Diverticulitis

• Conservative management without antibiotics is recommended if you are immunocompetent, with clear liquid diet advancement and oral analgesics for pain control. 2
• Antibiotics (Ertapenem 1 g daily or Eravacycline 1 mg/kg every 12 hours) for maximum 7 days are reserved only if you are immunocompromised or elderly. 2

If CT Shows Complicated Diverticulitis with Abscess

• Abscess <4 cm: 7-day course of antibiotics alone without drainage. 2
• Abscess ≥4 cm: percutaneous drainage plus antibiotics for 4 days. 2
• If signs of infection persist beyond 7 days, repeat CT is mandatory to assess for inadequate source control. 2

If CT Shows Perforation or Diffuse Peritonitis

• Emergency surgical consultation for primary resection and anastomosis (if clinically stable) or Hartmann's procedure (if critically ill). 2
• Broad-spectrum carbapenem therapy (Meropenem 1 g every 6 hours by extended infusion) must be started immediately if septic shock develops. 1, 2

If CT Shows Cholecystitis

• Early laparoscopic cholecystectomy within 7–10 days is the definitive treatment for uncomplicated cholecystitis, with one-shot antibiotic prophylaxis and no post-operative antibiotics needed. 1
• For complicated cholecystitis, you will need cholecystectomy plus antibiotics for 4 days (if immunocompetent with adequate source control) or up to 7 days (if immunocompromised or critically ill). 1

Common Pitfalls to Avoid

• Do not assume your symptoms are "just indigestion" because they started after lunch—acute cholecystitis, diverticulitis, and appendicitis all commonly present post-prandially due to increased bowel motility and gallbladder contraction. 1, 2
• Do not wait to see if symptoms resolve overnight—every hour of delay in diagnosing and treating intra-abdominal infection increases mortality by 10% in patients who develop septic shock. 1
• Do not accept reassurance based on "mild" tenderness—peritoneal signs can be subtle early in the disease course, and progression to diffuse peritonitis can occur within hours. 1
• Do not undergo colonoscopy during an acute episode if diverticulitis is suspected, as colonic distention increases perforation risk; colonoscopy should be postponed 6–8 weeks after symptom resolution. 2

When Conservative Outpatient Management May Be Considered

• If CT confirms uncomplicated diverticulitis, you have no peritoneal signs, you can tolerate oral intake, and you are immunocompetent, outpatient management without antibiotics is appropriate. 2
• You must return immediately if fever worsens, pain becomes severe, you develop vomiting or inability to pass stool, or symptoms persist beyond 2–3 days. 2
• Repeat CT abdomen/pelvis with IV contrast is mandatory if symptoms do not improve within 2–3 days of conservative management. 2