Acute Abdominal Pain - Adults

Related Subjects:Acute Cholecystitis |Acute Appendicitis |Chronic Peritonitis |Abdominal Aortic Aneurysm |Ectopic Pregnancy |Acute Cholangitis |Acute Abdominal Pain/Peritonitis |Assessing Abdominal Pain |Penetrating Abdominal Trauma

🫀 Peritonitis is a surgical emergency caused by inflammation of the peritoneum, often due to perforated abdominal organs (e.g., appendicitis, diverticulitis, peptic ulcer, ruptured AAA). ⚠️ Immediate attention to ABC (airway, breathing, circulation) is critical. 🚨 In elderly, immunocompromised, or steroid-treated patients, signs may be subtle or absent. ⏱️ Early diagnosis and surgical intervention reduce morbidity and mortality.

ℹ️ About

• 🌊 Generalised Peritonitis: Due to perforated viscus → widespread inflammation.
• 🦠 Acute Suppurative: Pus formation from bacterial infection → classic acute abdomen presentation.

🧪 Aetiology

• 🩸 Inflammation of Peritoneum: Triggered by infection, chemical irritation, or trauma.
• ⚠️ Causes: Leakage of gastric contents, bile, blood, or bacteria into peritoneal cavity.
• 🧪 Aseptic vs. Septic: Sterile irritants (bile, acid, pancreatic juice) may become secondarily infected.

📊 Classifications

• ⏱️ Acute vs. Chronic: Acute = emergency; Chronic (e.g., TB) = slow onset.
• 🔍 Primary vs. Secondary:
  • Primary = haematogenous spread (e.g., SBP in cirrhosis).
  • Secondary = intra-abdominal source (perforated organ, postop leak).
• 🧫 Septic vs. Aseptic: Bacterial vs. sterile causes (e.g., pancreatitis).

🚨 Causes of Acute Peritonitis

• 🍽️ GI perforations: Appendicitis rupture, diverticulitis, perforated ulcers.
• 💚 Biliary/hepatic: Gallbladder rupture, bile leak.
• 🤕 Trauma: Penetrating injuries, anastomotic leaks.
• 👩‍🍼 Gynaecological: Ectopic pregnancy rupture, pelvic infection.
• 🧴 Spontaneous Bacterial Peritonitis: In cirrhotic ascites.
• 🌍 Infectious: TB, typhoid, dialysis-related peritonitis.

🧫 Microbiology

• Gram−: E. coli, Klebsiella, Bacteroides fragilis
• Gram+: Streptococcus, Enterococcus
• Fungal: Candida (esp. immunosuppressed)
• Chronic: Mycobacterium tuberculosis

🩺 Clinical Features

• 😖 Severe sudden abdominal pain ± shoulder tip pain (diaphragmatic irritation)
• 🤮 Nausea, vomiting, distension
• 🛡️ Rigid “board-like” abdomen, guarding, rebound
• 📈 Fever, tachycardia, hypotension
• 💥 Septic shock in severe cases

🔎 Investigations

• 🧪 FBC (↑WCC), CRP, U&E, LFTs, lactate, amylase, blood cultures
• ❤️ ECG (exclude MI, look for AF/embolus)
• 👩‍🍼 β-hCG in women of childbearing age
• 🩻 CXR (free air under diaphragm)
• 🖥️ CT (gold standard for diagnosis and localisation)
• 🩺 USS (abscess/biliary pathology)

⚠️ Complications

• 🦠 Sepsis & septic shock
• 🔥 SIRS → ARDS, AKI
• ⛔ Paralytic ileus
• 💔 Multiorgan failure, death

⚡ Acute Abdominal Pain in Adults — Causes, Features, Investigations & Management

Causes of acute abdominal pain can be grouped by system. This table summarises key conditions with their classic presentation, investigations, and first-line management.

✅ Key Clinical Advice

• Always assess and stabilise with ABCDE before focusing on diagnosis.
• In unstable patients → urgent surgical review, do not delay for imaging.
• Consider broad differentials; elderly and immunosuppressed may have atypical presentations.

💊 Management

• 🔄 Resuscitation: ABCs, O₂, IV fluids, catheter for urine output.
• 💉 Antibiotics: Broad-spectrum IV (e.g., Tazocin ± metronidazole).
• 💊 Analgesia: IV morphine (2.5–5 mg), antiemetics.
• 🥛 NBM: Prepare for surgery.
• 🧑‍⚕️ Urgent surgical referral: Early laparotomy/laparoscopy.

🔪 Surgical Management

• Indicated for perforated viscus, bowel ischaemia, or generalised peritonitis.
• Procedures:
  • Exploratory laparotomy/laparoscopy
  • Resection of necrotic bowel, repair perforations
  • Peritoneal lavage, drain abscesses
• Continue IV antibiotics post-op.

⚡ Acute Abdominal Pain in Adults

Acute abdominal pain is a common emergency presentation. Causes vary by anatomical location. Careful history, examination, and prompt investigations guide diagnosis and management.

✅ Key Points

• Always assess ABCDE and resuscitate if unstable.
• Localise pain anatomically to guide differential diagnosis.
• Bloods + Urinalysis + Imaging form the core of investigation.
• Early surgical review is essential for suspected perforation, obstruction, ischaemia, or appendicitis.

📚 References

• Peritonitis: Pathophysiology & Management
• UpToDate: Acute Peritonitis
• Medscape: Peritonitis Overview

Case 1 – Perforated duodenal ulcer

A 48-year-old man with NSAID use develops sudden, severe epigastric pain radiating to the shoulder, rigid abdomen, and absent bowel sounds; vitals show tachycardia, low-grade fever, and mild hypotension. Erect CXR shows free subdiaphragmatic air. Manage with ABCDE, IV fluids, broad-spectrum antibiotics, PPI, NG tube, and urgent CT abdomen; refer for emergency surgery (laparoscopic Graham patch vs definitive ulcer surgery) and test/treat H. pylori after recovery.

Case 2 – Ruptured abdominal aortic aneurysm (AAA)

A 72-year-old man with smoking and hypertension presents with sudden tearing back/abdominal pain, hypotension, and a pulsatile abdominal mass. Avoid excessive fluids (permissive hypotension), give O₂, activate massive haemorrhage protocol, crossmatch, and call vascular surgery for immediate EVAR/open repair. POCUS/bedside ultrasound confirms large infrarenal AAA; do not delay for CT if unstable.

Case 3 – Ruptured ectopic pregnancy

A 30-year-old with 7 weeks’ amenorrhoea and vaginal spotting presents with worsening lower abdominal pain, dizziness, and shoulder tip pain; she is tachycardic and hypotensive with abdominal guarding. β-hCG positive; FAST scan shows free fluid. Resuscitate (O₂, IV access, bloods/crossmatch), consult gynae for urgent salpingectomy (or salpingostomy if appropriate), give anti-D if rhesus negative, and manage pain; differentials include ovarian torsion and ruptured corpus luteum.

Case 4 – Acute appendicitis

A 24-year-old develops periumbilical pain migrating to the RIF with anorexia, mild fever, and rebound tenderness; WBC/CRP raised. Ultrasound (slim female) or CT abdomen confirms inflamed, non-compressible appendix. Give IV fluids, analgesia, and broad-spectrum antibiotics; proceed to laparoscopic appendicectomy. Consider differentials (gynae, mesenteric adenitis); beware atypical retrocaecal pain.

Case 5 – Acute mesenteric ischaemia

A 78-year-old with AF has sudden, severe, diffuse abdominal pain out of proportion to scant early signs; lactate rising, metabolic acidosis. Urgent CTA shows SMA embolus. Resuscitate, start IV heparin and broad-spectrum antibiotics, involve vascular/HPB surgery for embolectomy/revascularisation ± bowel resection if non-viable; mortality is high—act fast.

Case 6 – Sigmoid volvulus

An 82-year-old in a care home presents with abdominal distension, pain, constipation, and tympany; X-ray shows the classic coffee-bean sign pointing to the RUQ. If no peritonitis/ischemia, perform flexible sigmoidoscopy with decompression and rectal tube; arrange definitive surgery (e.g., sigmoid colectomy) due to recurrence risk. If peritonitis or perforation, urgent laparotomy.