Peritonitis and Intra-Abdominal Abscess Jej Krige

OPEN ACCESS TEXTBOOK OF GENERAL SURGERY PERITONITIS AND INTRA-ABDOMINAL ABSCESS JEJ KRIGE INTRODUCTION Intra-abdominal sepsis, including sensory innervation. The peritoneal peritonitis and abscess formation, cavity forms the potential space present serious and potentially life- threatening events in the management Between the parietal and visceral of surgical patients with significant layers and is divided into the general resultant morbidity and mortality. peritoneal cavity or greater sac, and Twenty percent of patients presenting the lesser sac which communicate via with generalised suppurative peritonitis the foramen of Winslow. The and over 50% of high risk patients with anatomic surface area of the post-operative intra-abdominal sepsis peritoneum in adults is about 1.7 sq. die despite intensive treatment. Major meters and approximates the total recent advances have occurred in the body surface area. conceptual understanding of the pathogenesis, diagnostic The parietal peritoneum has a somatic methodology, antibiotic therapy and afferent nerve supply and is sensitive application of non-invasive technology to all forms of stimuli. Irritation of the in intra-abdominal sepsis. As a parietal peritoneum produces sharp, consequence, the management of well localized, discriminate pain with intra-abdominal infection requires a tenderness, involuntary guarding and careful interdisciplinary approach, with rigidity of the abdominal muscles if the close collaboration between surgeon, stimulus is sufficiently intense. The physician, radiologist, bacteriologist parietal peritoneum on the and anaesthetist. undersurface of the diaphragm is supplied centrally by the phrenic This chapter outlines the relevant nerves and peripherally by lower anatomy and physiology, intercostal nerves. Irritation of the pathogenesis, clinical features, peritoneum over the central portion of diagnostic approach and management the diaphragm results in referred pain of primary and secondary bacterial in the distribution of the cutaneous peritonitis and intra-abdominal branches of the third, fourth and fifth abscess. cervical nerves over the shoulder region. ANATOMY The peritoneum is the largest serous The visceral peritoneum receives membrane in the body and consists of afferent innervation only from the a single layer of mesothelial cells autonomic nervous system and is supported on a connective tissue relative insensitive to tactile, thermal base. The parietal peritoneum lines and chemical stimuli. Stimuli from the the anterior, lateral and posterior visceral peritoneum characteristically abdominal walls, the undersurface of are poorly localized and are perceived the diaphragm and the pelvis and is as a dull pain. The visceral afferent reinforced by transversalis fascia. The nerves have no receptors to mediate visceral peritoneum is reflected on the pain and temperature, but are intra-abdominal viscera, mesentery sensitive to bowel ischaemia and and omentum, creating a closed cavity distention or traction on the except for the open ends of the mesentery. fallopian tubes. Although the parietal and visceral surfaces are part of the PHYSIOLOGY same membrane, the distinction is The peritoneum consists of a single relevant with regard to differences in surface layer of mesothelial cells supported on a basement membrane DEFINITION and a deeper well-vascularized Peritonitis is the acute inflammatory connective tissue layer containing response of the visceral and parietal collagen and elastic fibres, fat cells, peritoneum to bacterial, chemical, reticulum cells and macrophages. The radiation or foreign body injury. The peritoneal cavity contains less than two major clinical categories of 50ml of clear fluid consisting of water, peritonitis are based on etiology: electrolytes and solutes derived from interstitial fluid and plasma. Normal 1) Primary peritonitis is an infection of peritoneal fluid has a specific gravity of the peritoneum occurring de novo less than 1,016 and less than 3 grams without obvious intra-abdominal per ml of protein, predominantly pathology. albumen. Fibrinogen is not present and the fluid will not clot. Much of the 2) Secondary bacterial peritonitis is a peritoneal membrane acts as a purulent inflammation of the passive, semi-permeable barrier to the peritoneum due to contamination bidirectional diffusion of water and following a complication of a pre- most solutes. Normal peritoneal fluid existing primary intra-abdominal contains less than 3000 cells per ml3 process such as perforated peptic with 50% lymphocytes, 40% macrophages, a few eosinophils, mast ulcer, ruptured appendix, a cells and occasional desquamated disrupted anastomotic suture line mesothelial cells. Bacteria are absent. or as consequence of bacterial Peritoneal fluid has minimal contamination from external antibacterial activity, mediated both via sources (eg. penetrating injury). the complement system and the lymphocyte population in the fluid. Secondary bacterial peritonitis is more The number of granulocytes is common and of greater surgical significantly increased in the presence significance than primary peritonitis; of inflammation. Peritoneal aspiration accurate differentiation between the may be of value for culture and two types is crucial for optimal chemical analysis to facilitate the management. diagnosis of inflammatory conditions, tumours or intraperitoneal trauma. PRIMARY PERITONITIS The principal route of absorption and clearance of fluids and particulate Children matter from the peritoneal cavity is by Primary peritonitis is uncommon, lymphatics. Reverse flow is prevented accounting for less than 1% of all by one-way valves within the thoracic cases of peritonitis and predominantly lymphatic system. Experimentally, affects girls younger than 10 years of particulate matter including red cells age. The bacterial involved are and bacteria, are recoverable from the primarily pneumococci and Group A thoracic lymph within 6 minutes and streptococci. Less commonly, gram- from the blood within 12 minutes after negative bacilli and Group B intraperitoneal injection. Absorption of streptococci are found. A useful fluid by the diaphragmatic lymphatics diagnostic feature in differentiating the produces a cephalad flow of peritoneal usually monobacterial spontaneous fluid which is promoted by increased peritonitis from the polymicrobial flora respiratory movement. The rapid of secondary peritonitis is the single peritoneal clearance of particulate species of bacteria cultured. About matter and fluid functions as the one half of cases of pneumococcal essential first line of defence following peritonitis occur in children with initial peritoneal contamination. nephrosis. The causative bacteria gain access to the peritoneum by a haematogenous route or uncommonly, progressive encephalopathy or via the fallopian tubes. diminishing renal function. A diagnositc ascitic tap is necessary to The clinical manifestations are those determine the presence of bacteria, of acute diffuse peritonitis. A pre- neutrophils, protein, glucose and pH of existing upper respiratory infection, the ascitic fluid. Gram stains are pneumonia or otitis media may mask positive however only in one-third of the initial onset of peritonitis. Severe, culture proven cases. Careful aerobic generalized abdominal pain is the and anaerobic cultures isolate a single predominant symptom. High fever, organism in 80% of patients with SBP; often with chills, irritability, vomiting the most frequent organisms and diarrhoea are common. On recovered are E.Coli and examination, the child appears ill, pneumococci. Anaerobes are virtually pyrexial with a temperature of 400C, never isolated. The ascitic fluid WBC and an elevated pulse rate. The is generally 500ml3 with more than 75 abdomen is diffusely tender and neutrophils/ml3. A peritoneal acidosis ascites with shifting dullness may be with a pH of less than 7.3 is due to demonstrated. Bowel sounds are lactic acid production by the infecting hypoactive or absent. The white blood organisms. While the bacterial count reveals a leucocytosis of 20,000 infection may be effectively treated to 40,000 ml3 with a with suitable antibiotics, the prognosis polymorphonuclear predominance and is poor and exceeds 80% due to a shift to the left. Heavy albuminuria is progressive liver decompensation, present in cases superimposed on renal failure, encephalopathy and nephrosis. Blood culture is usually haemorrhage. positive for streptococci or pneumococci. A peritoneal aspirate SECONDARY BACTERIAL under local anaesthesia with an PERITONITIS immediate Gram stain is important to differentiate primary peritonitis in Secondary bacterial peritonitis is an which surgical intervention is contra- acute suppurative inflammatory indicated from peritonitis secondary to process of the peritoneal cavity arising a perforated appendix where prompt as a consequence of either: surgery is necessary. If only cocci are · Primary disease of the abdominal seen on the smear, conservative viscera therapy is appropriate. A mixed · Penetrating or blunt trauma bacterial flora on the smear demands an exploratory laparotomy. · Previous intra-abdominal surgery Adults Aetiology Spontaneous bacterial peritonitis Secondary peritonitis may complicate (SBP) is an infective complication almost any abdominal condition caused by enteric organisms and including inflammatory, traumatic, usually occurs in alcoholic cirrhotic obstructive or neoplastic processes patients with ascites. (Table 1). Perforation following Characteristically,

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