Summary of Disorders of the Intestines: Acute Abdomen
An acute abdomen refers to the sudden onset of severe abdominal pain, often indicating an intra-abdominal disorder that requires immediate surgical intervention to prevent complications or save a patient's life. It's a general term encompassing various conditions causing severe abdominal pain and necessitates prompt diagnosis and treatment [i]. Understanding the types of abdominal pain, potential causes, associated signs and symptoms, and specific conditions is crucial for effective clinical management. This summary provides an overview of acute abdomen, focusing on key aspects relevant to medical professionals.
Types of Abdominal Pain
- Visceral Pain: Originates from the abdominal viscera (internal organs), which are innervated by autonomic nerve fibers [i]. It is typically triggered by distension or muscular contractions, resulting in vague, dull, and nauseating sensations [i].
- Somatic Pain: Arises from the parietal peritoneum, innervated by somatic nerves [i]. This type of pain is often a response to irritation from infections, chemical, or inflammatory processes, leading to sharp and well-localized discomfort [i].
- Referred Pain: Perceived at a location distant from the actual source due to the convergence of nerve fibers at the spinal cord [i]. For example, scapular pain from biliary colic or myocardial infarction pain felt in the neck, shoulders, and back [i].
Causes of Acute Abdomen
- Inflammatory: Conditions such as peritonitis and perforated appendicitis [i].
- Mechanical: Obstructions in the intestines caused by worms, food bolus, volvulus, or intussusception [i].
- Vascular: Perforated peptic ulcers, perforated diverticulitis, or perforated bowel [i].
- Neoplastic: Growths obstructing the movement of food along the gastrointestinal tract [i].
- Traumatic: Injuries such as ruptured spleen, ruptured aorta, or ruptured ectopic pregnancy [i].
- Congenital Defects: Hirschsprung's disease [i].
Signs and Symptoms
- Severe abdominal pain is a primary indicator [i].
- Nausea and vomiting due to gastrointestinal disturbance and excessive peristalsis [i].
- Distended abdomen [i].
- Constipation or diarrhea [i].
- Borborygymi (exaggerated bowel sounds) [i].
- Abdominal tenderness upon examination [i].
- Dehydration [i].
- Signs of shock due to excessive vomiting and/or diarrhea [i].
- Hard, woody abdomen due to hyper-excited peritoneum [i].
- Apparent abdominal contours due to actively peristaltic intestines [i].
- Guarding due to severe pain [i].
- Restlessness [i].
Mechanical vs. Non-Mechanical Obstruction
- Mechanical Obstruction (Small Bowel): Colicky pain, nausea, vomiting, constipation, distended abdomen, and borborygymi [i].
- Mechanical Obstruction (Large Bowel): Constipation, vomiting (later stage), constant hypostatic pain, nausea, sudden onset of colicky abdominal pains after constipation, and distended abdomen [i].
- Non-Mechanical Obstruction: Diffuse abdominal discomfort, abdominal distension, hiccups, constipation, frequent vomiting (gastric and bowel contents), and decreased bowel sounds [i].
Investigations
- History of sudden onset of severe abdominal pain [i].
- Physical examination to assess abdominal pain and distention [i].
- Imaging: X-ray (upright position), abdominal ultrasound, CT scan, and MRI [i].
- Laboratory Tests: Complete blood count and cross-matching [i].
Specific Conditions Causing Acute Abdomen
- Intestinal Obstruction: Disruption in the movement of gastrointestinal contents, characterized by abdominal pain, distension, and vomiting [i]. Can be dynamic (increased peristaltic activity against an obstruction) or adynamic (cessation of peristalsis) [i].
- Peritonitis: Inflammation of the peritoneum, often due to bacterial invasion or leakage of gastric contents/blood [i]. The peritoneum is divided into the parietal peritoneum (richly supplied with nerves, causing localized pain) and the visceral peritoneum (poorly supplied with nerves, causing vague pain) [i].
- Acute Appendicitis: Inflammation of the appendix, characterized by severe pain at McBurney's point and rebound tenderness [i]. Can be non-obstructive or obstructive [i].
- Hernia: Protrusion of a viscus through an abnormal opening or weakened area [i]. Types include inguinal, femoral, umbilical, and incisional hernias [i].
- Ulcerative Colitis: Chronic inflammatory disease of the mucosa and submucosa of the colon, rectum, and distal ileum [i].
- Diverticulitis: Infection and inflammation of diverticula (small pouches) in the colon, characterized by abdominal pain, fever, and nausea [i].
- Volvulus: Twisting or knotting of the intestines causing obstruction [i].
- Intussusception: Invagination of a portion of the intestine into itself [i].
- Gynaecological Causes: Such as ruptured ectopic pregnancy [i].
Emergency Pre-operative Care
- Aims: Focus on patient stabilization and preparation for surgery.
- Patient Admission/Environment: Ensure a safe and comfortable environment.
- Psychological Care: Provide support and reduce anxiety.
- Pre-operative Teaching: Explain the procedure and expected outcomes.
- Consent Form: Obtain informed consent.
- Observations: Monitor vital signs regularly.
- Investigations: Complete necessary diagnostic tests.
- Nutrition: Address nutritional needs as appropriate.
- Physical Preparation: Gastric preparation, bowel preparation, bladder preparation, local site/skin preparation, removal of jewelry/dentures, patient identification, pre-medication, gowning, transfer to theatre, post-operative bed, and communication with family [i].
Complications
- Sepsis [i].
- Shock (septic and hypovolemic) [i].
- Abdominal abscess [i].
- Renal failure [i].
- Respiratory complications [i].
- Strangulated hernia [i].
- Gangrenous bowel [i].
- Obstruction [i].
- Recurrence [i].
- Nutritional deficiencies [i].
- Perineal sepsis [i].
- Anal stricture [i].
- Perforated colon [i].
- Ascites [i].
Conclusion
Acute abdomen is a critical clinical presentation requiring rapid assessment and intervention. Understanding the various causes, types of pain, and associated symptoms is essential for accurate diagnosis and effective management. Specific conditions like intestinal obstruction, peritonitis, and appendicitis necessitate tailored approaches, while emergency pre-operative care aims to stabilize the patient for surgical intervention. Prompt and appropriate management can significantly improve patient outcomes and reduce morbidity and mortality. 
