Peritonitis Surgery

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### Introduction to Peritonitis - **Definition:** An acute inflammatory reaction of the serous membrane (peritoneum) that lines the abdominal cavity and covers the visceral organs. It is a severe condition often associated with significant morbidity and mortality if not promptly managed. - **Anatomy & Physiology Pearls:** - Peritoneum: Large, semi-permeable membrane (~1.7 m² surface area, similar to skin). - Parietal peritoneum: Sensitive to pain, temperature, touch (somatic innervation). - Visceral peritoneum: Insensitive to touch/temperature, responds to stretch (autonomic innervation). - Functions: Lubrication, immune response, fluid absorption/exchange. - **Pathophysiology:** 1. **Initial insult:** Contamination (bacterial, chemical) or tissue injury. 2. **Inflammatory cascade:** Release of cytokines (IL-1, TNF-alpha), chemokines, prostaglandins. 3. **Vascular changes:** Vasodilation, increased capillary permeability, leading to fluid shift into the peritoneal cavity (third-spacing), causing hypovolemia and ascites. 4. **Cellular response:** Neutrophil infiltration, fibrin deposition (leading to adhesions). 5. **Systemic effects:** Sepsis, SIRS (Systemic Inflammatory Response Syndrome), MODS (Multiple Organ Dysfunction Syndrome) due to absorption of toxins and inflammatory mediators into the bloodstream. - **Etiology (Causes):** - **Primary Peritonitis (Spontaneous Bacterial Peritonitis - SBP):** - No obvious perforation or intra-abdominal source. - Most common in patients with cirrhosis and ascites (translocation of gut bacteria). - Less common causes: Nephrotic syndrome, SLE, peritoneal dialysis. - **Secondary Peritonitis:** (Most common surgical emergency) - **Perforation of hollow viscus:** Peptic ulcer, appendicitis, diverticulitis, bowel ischemia/infarction, inflammatory bowel disease (Crohn's, UC), foreign body, trauma, malignancy. - **Inflammation without perforation:** Acute pancreatitis (chemical peritonitis), cholecystitis, salpingitis. - **Post-operative:** Anastomotic leak, surgical contamination. - **Tertiary Peritonitis:** - Persistent or recurrent infection after initial treatment for secondary peritonitis. - Often involves immunocompromised patients, resistant organisms, or inadequate source control. - Characterized by low-grade inflammation, often with fungal or atypical bacterial infections. - **Severity Assessment Scores:** - **Mannheim Peritonitis Index (MPI):** Score based on age, sex, organ failure, extent of peritonitis, source, and duration of symptoms. Predicts mortality. - **APACHE II (Acute Physiology and Chronic Health Evaluation II):** General severity of illness score, used in ICU settings. - **SOFA (Sequential Organ Failure Assessment):** Tracks organ dysfunction over time. ### Clinical Presentation - **Cardinal Symptoms:** - **Abdominal Pain:** Typically acute onset, severe, diffuse, constant, and exacerbated by movement, coughing, or palpation. - **Nausea and Vomiting:** Common, often reflex-induced due to peritoneal irritation and ileus. - **Fever and Chills:** Indicative of systemic infection and inflammatory response. - **Abdominal Distension:** Due to paralytic ileus (bowel stasis) and accumulation of fluid/gas. - **Altered Bowel Habits:** Constipation (due to ileus) or sometimes diarrhea. - **Key Physical Signs:** - **Generalized Abdominal Tenderness:** Elicited on light palpation. - **Rebound Tenderness (Blumberg's Sign):** Pain upon sudden release of deep palpation, highly suggestive of peritoneal irritation. - **Guarding:** Involuntary contraction of abdominal muscles on palpation, a protective reflex. - **Rigidity (Board-like Abdomen):** Severe, constant muscle spasm, indicating diffuse peritonitis. - **Absent or Decreased Bowel Sounds:** Reflects paralytic ileus. - **Percussion Tenderness:** Pain on light percussion of the abdomen. - **Systemic Signs of Sepsis/Shock:** - **Tachycardia:** Heart rate > 90 bpm. - **Hypotension:** Systolic BP 20 breaths/min. - **Oliguria:** Urine output ### Diagnosis - **Clinical Suspicion:** High index of suspicion based on history and physical exam is paramount. - **Laboratory Investigations:** - **Complete Blood Count (CBC):** - **Leukocytosis:** WBC > 10,000/µL, often with a "left shift" (increased band neutrophils), indicating bacterial infection. - **Anemia:** May be present from chronic disease or acute blood loss. - **Electrolytes, Renal Function (BUN, Creatinine):** - Assess hydration status, electrolyte imbalances (e.g., hyperkalemia in bowel ischemia), and kidney function, especially in hypovolemic shock. - **Liver Function Tests (LFTs):** - Essential in suspected SBP to assess liver function and severity of cirrhosis. - **Blood Cultures:** - To identify causative organisms and guide antibiotic therapy, especially in septic patients. - **Lactate Level:** - Elevated in tissue hypoperfusion, sepsis, and shock. A rising lactate indicates worsening clinical status. - **C-Reactive Protein (CRP) & Procalcitonin:** - Non-specific inflammatory markers; elevated levels support bacterial infection and inflammation. Procalcitonin is more specific for bacterial sepsis. - **Coagulation Profile (PT/INR, PTT):** - Assess clotting status, important pre-operatively and in severe sepsis. - **Arterial Blood Gas (ABG):** - Assess acid-base status, oxygenation, and ventilation. Metabolic acidosis is common in sepsis. - **Imaging Studies:** - **Plain Abdominal Radiographs (X-rays):** - **Erect Chest X-ray/Abdominal X-ray:** Can detect "free air" under the diaphragm (pneumoperitoneum), pathognomonic for hollow viscus perforation. May also show dilated bowel loops in ileus or obstruction. - **Computed Tomography (CT) Scan of Abdomen and Pelvis with Intravenous Contrast:** - **Gold Standard for Secondary Peritonitis.** - **High sensitivity and specificity.** - **Identifies the source:** Perforated appendix, diverticulum, ulcer, bowel wall thickening, abscesses, fluid collections. - **Assesses extent of disease:** Diffuse peritonitis vs. localized collections. - **Guides surgical planning.** - **Ultrasound (US):** - Useful for detecting ascites (especially in SBP), localized fluid collections, gallbladder pathology, and gynecological causes. - Less useful for detecting free air or diffuse peritonitis due to overlying bowel gas. - **Diagnostic Peritoneal Lavage (DPL):** - Less common now due to improved imaging. - Can be used in trauma or unstable patients where intra-abdominal injury is suspected. - Positive if >10 mL gross blood, >100,000 RBC/mm³, >500 WBC/mm³, or presence of bile/food particles. - **Diagnostic Paracentesis (for SBP):** - **Indication:** Any patient with ascites and suspected infection. - **Analysis of Ascitic Fluid:** - **Cell Count:** Polymorphonuclear (PMN) leukocyte count > 250 cells/mm³ is diagnostic for SBP. - **Culture:** Send for aerobic and anaerobic cultures. - **Protein, Albumin, Glucose, LDH:** Helps differentiate SBP from secondary bacterial peritonitis (SBP typically has low protein, high SAAG; secondary peritonitis often higher protein, lower SAAG). - **Mnemonic for Diagnostic Workup:** **"L-I-P-S-A"** - **L**abs (CBC, LFTs, Cultures, Lactate) - **I**maging (CT, X-ray, US) - **P**hysical exam - **S**BP-specific (Paracentesis) - **A**BGs (Acid-base status) ### Management Principles (Surgical Focus) - **Time is Tissue:** Prompt diagnosis and intervention are critical to reduce morbidity and mortality. - **Initial Resuscitation (Pre-operative):** **"The Golden Hour"** - **A-B-C-D-E Approach:** - **A**irway: Secure if needed (intubation for respiratory distress or altered mental status). - **B**reathing: Supplemental oxygen, mechanical ventilation if necessary. - **C**irculation: - **Intravenous Fluid Resuscitation:** Aggressive administration of crystalloids (e.g., Lactated Ringer's) to counteract third-spacing and combat hypovolemic shock. Administer 1-2 liters rapidly, then titrate. - **Vasopressors:** If hypotension persists despite adequate fluid resuscitation (e.g., Norepinephrine). - **Central Venous Access:** For fluid administration, CVP monitoring. - **D**isability: Neurological assessment, correct hypoglycemia. - **E**xposure: Full patient examination, maintain normothermia. - **Urinary Catheter:** To monitor urine output (indicator of renal perfusion). Aim for >0.5 mL/kg/hr. - **Nasogastric Tube:** For gastric decompression to prevent vomiting, aspiration, and reduce abdominal distension (especially in ileus). - **Broad-Spectrum Intravenous Antibiotics:** - **Empiric Therapy:** Initiate immediately after cultures are drawn (within 1 hour). - **Coverage:** Must cover Gram-positive, Gram-negative, and anaerobic bacteria. - **Common Regimens:** - Piperacillin/Tazobactam (Zosyn) - Carbapenem (e.g., Meropenem, Imipenem) - Cephalosporin (e.g., Cefepime) + Metronidazole - Fluoroquinolone (e.g., Ciprofloxacin) + Metronidazole - **Adjust based on severity, local resistance patterns, and patient allergies.** - **Targeted Therapy:** Adjust antibiotics based on culture and sensitivity results once available. - **Duration:** Typically 4-7 days post-source control for uncomplicated cases, longer for severe or tertiary peritonitis. - **Source Control (Surgical Intervention):** **THE DEFINITIVE TREATMENT FOR SECONDARY PERITONITIS.** - **Principle:** Eliminate the source of contamination, remove infected material, and prevent ongoing contamination. - **Timing:** Emergent surgery once the patient is hemodynamically stable. Delaying surgery for more than 6-12 hours in secondary peritonitis significantly increases mortality. ### Surgical Approach - **Pre-operative Considerations:** - **Informed Consent:** Discuss risks, benefits, alternatives (including potential for stoma, ICU stay). - **Anesthesia Consultation:** High-risk patients often require careful anesthetic management. - **Blood Products:** Type and cross-match blood, especially in unstable patients or anticipated major blood loss. - **Surgical Access:** - **Laparotomy (Open Abdomen Surgery):** - **Incision:** Midline vertical incision from xiphoid to pubis is preferred. It offers rapid access, excellent exposure to all abdominal quadrants, and can be easily extended. - **Exploration:** Systematic exploration of the entire abdominal cavity to identify all sources of contamination and assess the extent of peritonitis. - **Laparoscopy (Minimally Invasive Surgery):** - **Role:** Increasingly used for diagnostic purposes and treatment of selected, stable patients with localized peritonitis (e.g., early perforated appendicitis, some cases of perforated diverticulitis, cholecystitis). - **Advantages:** Less pain, shorter hospital stay, faster recovery, reduced adhesion formation. - **Limitations:** Not suitable for hemodynamically unstable patients, diffuse severe peritonitis, extensive adhesions, or when the source is unclear/difficult to access laparoscopically. Risk of bowel injury. - **Intra-operative Steps (The "3 D's" + Repair):** 1. **D**iagnose and **D**efine the Source: * Systematic exploration: Start with the suspected area, then examine all organs (stomach, duodenum, small bowel, colon, appendix, gallbladder, liver, spleen, gynecological organs). * Identify the exact point of perforation, inflammation, or necrosis. 2. **D**efinitive Source Control (Repair/Resection): * **Perforated Peptic Ulcer:** * Small, anterior perforation: Primary closure with omental patch (Graham patch) to reinforce the repair. Vagotomy (truncal or highly selective) + pyloroplasty may be considered for recurrent ulcers, but not in acute emergency. * Large/posterior perforation: May require partial gastrectomy or diversion. * **Appendicitis:** Appendectomy (open or laparoscopic). * **Diverticulitis with Perforation:** * **Hinchey Stage III (purulent peritonitis) or IV (fecal peritonitis):** Usually requires resection of the involved colon segment. * **Hartmann's Procedure:** Resection of diseased colon, creation of end colostomy, and closure of distal rectal stump. Common in unstable patients or severe contamination. Reversal in 3-6 months. * **Primary Anastomosis with Loop Ileostomy:** Resection and rejoining of colon, with a temporary ileostomy to protect the anastomosis. Considered in more stable patients with less contamination. * **Laparoscopic Lavage:** Controversial, may be considered in selected stable patients with purulent peritonitis (Hinchey III) without gross fecal contamination. * **Bowel Ischemia/Perforation:** * Resection of non-viable (necrotic) bowel. * Primary anastomosis (rejoining the bowel) if conditions are favorable (stable patient, minimal contamination, good blood supply to remaining ends, no tension). * Stoma formation (ileostomy or colostomy) if primary anastomosis is too risky. * **Trauma:** Repair of specific organ injuries. 3. **D**ebridement and **D**econtamination: * **Peritoneal Lavage:** Copious irrigation with warm normal saline (several liters) to dilute and remove pus, fibrin, particulate matter, and bacteria. * **Suction:** Thorough suctioning of all fluid and debris, especially from dependent areas (pelvis, paracolic gutters, subphrenic spaces). * **Fibrin Removal:** Gentle manual removal of large fibrin clots. - **Drainage:** - **Role:** Controversial. Generally, drains are NOT routinely placed in diffuse peritonitis if adequate source control and lavage have been achieved. - **Indications:** - Localized collections/abscesses that cannot be completely debrided. - Pancreatic necrosis or ongoing leakage (e.g., pancreatic fistula). - Protection of a high-risk anastomosis (debated). - **Placement:** Placed in dependent areas, away from anastomoses, exited through a separate stab incision. Closed suction drains are preferred. - **Abdominal Wall Closure:** - **Primary Closure:** Standard closure of the abdominal fascia and skin. - **Temporary Abdominal Closure (TAC) / Open Abdomen:** - **Indications:** - **Damage Control Surgery:** In critically ill patients (e.g., severe sepsis, coagulopathy), to complete source control and resuscitation in a staged manner. - **Abdominal Compartment Syndrome:** To decompress the abdomen. - **Anticipated "Second Look" Laparotomy:** To assess bowel viability or ensure complete source control. - **Massive Bowel Edema:** To prevent abdominal compartment syndrome. - **Ongoing Contamination:** To allow for repeated lavage. - **Methods:** Vacuum-assisted closure (VAC) systems, Bogota bag, mesh, zipper. - **Goal:** Protect abdominal contents, prevent evisceration, allow for repeated access, and facilitate delayed primary closure or skin grafting. - **Risks:** Increased fluid loss, fistula formation, delayed fascial closure. - **Mnemonic for Surgical Steps:** **"S-C-L-D-C"** - **S**tabilize (resuscitation) - **S**ource Control (repair/resect) - **L**avage (peritoneal wash) - **D**rain (if indicated) - **C**lose (primary or temporary closure) ### Postoperative Care - **Intensive Care Unit (ICU) Management:** - Many patients with severe peritonitis require ICU admission for close monitoring and organ support. - **Hemodynamic Monitoring:** Continuous BP, HR, CVP, sometimes arterial line, PA catheter. - **Ventilatory Support:** Mechanical ventilation often required for respiratory failure. - **Fluid & Electrolyte Balance:** Careful management of IV fluids, correction of electrolyte derangements (hypokalemia, hypomagnesemia often seen). - **Renal Support:** Dialysis/CRRT if acute kidney injury develops. - **Continued Antibiotic Therapy:** - Continue broad-spectrum antibiotics, adjusting based on cultures. - Duration typically 4-7 days after adequate source control for uncomplicated cases; longer for severe, complicated, or tertiary peritonitis (up to 10-14 days or longer until clinical improvement). - **Nutritional Support:** - **Early Enteral Nutrition:** If the gut is functional and anastomosis is secure, start enteral feeds as soon as possible to maintain gut integrity and immune function. - **Parenteral Nutrition (TPN):** If enteral feeding is not possible or contraindicated for prolonged periods. - **Pain Management:** - Aggressive pain control with IV opioids, epidural analgesia (if no contraindications) to facilitate deep breathing and mobility. - **Monitoring for Complications:** - **Sepsis/Septic Shock:** Persistent fever, tachycardia, hypotension, organ dysfunction. - **Intra-abdominal Abscess:** Persistent fever, localized pain, leukocytosis. Requires drainage (percutaneous or surgical). - **Anastomotic Leak:** Catastrophic complication after bowel resection. Presents with increasing abdominal pain, fever, tachycardia, purulent or feculent drain output, leukocytosis. Requires re-exploration. - **Acute Kidney Injury (AKI):** Monitor urine output and creatinine. - **Acute Respiratory Distress Syndrome (ARDS):** Monitor oxygenation. - **Wound Infection/Dehiscence:** Inspect wound daily. - **Fistula Formation:** Enterocutaneous fistula (leakage of bowel contents through skin). - **Abdominal Compartment Syndrome:** Increased intra-abdominal pressure leading to organ dysfunction. - **Deep Vein Thrombosis (DVT) / Pulmonary Embolism (PE):** Prophylaxis is crucial. - **Mnemonic for Post-Op Complications:** **"A-B-C-D-E-F-S"** - **A**bscess (intra-abdominal) - **B**owel (anastomotic **L**eak, **I**leus, **F**istula) - **C**ardiovascular (sepsis, shock, DVT/PE) - **D**ehiscence (wound) - **E**lectrolytes (imbalance) - **F**ever (persistent infection) - **S**epsis (ongoing Systemic Inflammatory Response Syndrome) ### Prognosis - **Mortality:** Highly variable, ranging from 50%, depending on: - **Underlying cause:** Perforated ulcer vs. ischemic bowel. - **Patient factors:** Age, comorbidities (cardiac, renal, liver disease, immunosuppression). - **Severity of peritonitis:** Diffuse fecal vs. localized purulent. - **Presence of organ failure:** MODS carries a very high mortality. - **Time to definitive source control:** Delayed surgery increases mortality significantly. - **Adequacy of source control and resuscitation.** - **Long-term Complications:** - **Adhesions:** Can lead to chronic pain or small bowel obstruction. - **Incisional Hernia:** Risk after laparotomy. - **Stoma-related complications:** If stoma created. - **Recurrent infections/abscesses.** - **Prevention of SBP:** Prophylactic antibiotics (e.g., Norfloxacin) in high-risk cirrhotic patients.