Acute abdomen: investigation

• Acute onset of abdominal pain.
• Prompt diagnosis and immediate medical or surgical intervention necessary to prevent deterioration of patient.
  Follow the diagnostic tree for Acute abdominal pain Acute abdominal pain.

• Abdominal pain/abdominal splinting.
• Vomiting.
• Diarrhea.
• Postural changes.
• Gait changes: stiff stilted gait.
• Reluctance to move.
• Hiding from owners.
• Anorexia.
• Lethargy.
• Shock.

• Depends on severity of primary disease and rapidity of therapy and definitive diagnosis.
• All ages:
  • Foreign body.
  • Gastrointestinal obstruction Intestine: obstruction.
  • Intussusception Intussusception.
  • Panleukopenia viral enteritis (young kittens) Feline panleucopenia virus disease.
  • Severe parasitic infection (young cats).
  • Abdominal trauma Abdomen: trauma.
• Older cats:
  • Neoplasia causing abdominal effusion or abdominal hemorrhage.

• Depends on primary cause.
• Sources of abdominal pain include the following systems:
  • Urogenital, eg ureteric obstruction due to ureterolithiasis Urolithiasis.
  • Gastrointestinal, eg small intestinal obstruction.
  • Splenic.
  • Hepatobiliary.
  • Pancreatic.
  • Peritoneal.
• Displacement, obstruction or distention, inflammation or infection, perforation or rupture, and/or vascular compromise in any of these systems can result in somatic or visceral pain and the presentation of an acute abdomen.

• Abdominal pain caused by distention/stretch, inflammation or ischemia of solid or hollow abdominal organs, mesentery or parietal peritoneum.
• Ischemia and inflammation can also result in activation of pain receptors via the release of mediators such as bradykinin, serotonin, histamine and eicosanoids.

• Acute onset.

• Signalment and history can aid in helping focus on most likely diagnosis.

• Immediate questions to ask yourself:
  • Does the patient require IMMEDIATE resuscitation?
  • Does the patient require invasive cardiorespiratory monitoring?
  • Are diagnostic tests necessary?
  • Does the patient require urgent surgery?
  • Does the patient require a surgical work-up?

• Ask client specific questions:
  • Toxin exposure? (ethylene glycol Ethylene glycol poisoning, other).
  • Garbage ingestion or dietary indiscretion (deliberate or accidental).
  • Foreign body exposure?
  • Possibility of trauma?
  • Nature and character of vomit? In relation to meals/eating?
  • Vaccination status.
  • Health status of other animals or humans in household?
  • Type, dose and duration of any drugs (NSAIDs Analgesia: NSAID, steroids, acetaminophen, diazepam Diazepam)?
  • Recent heat cycle in unspayed female cats?

Physical examination

• Perform a thorough physical examination.
  Perform abdominal examination LAST, as it can be painful and may lead you to miss vital clinical signs.

Head

• Eyes:
  • Sunken, anisocoria (trauma or toxin), mentation, seizures (metabolic or toxin).
• Tongue:
  • Look carefully under the tongue for the presence of string/linear foreign bodies. As it may cut in deep under the tongue careful inspection is needed.
• Fur around muzzle:
  • Look for evidence of excessive salivation (nausea).
  • Look at fur around muzzle for evidence of vomit or toxin (Wood's lamp used to detect ethylene glycol. Ethylene glycol may fluoresce under a black light/Wood's lamp Wood''s lamp test).
• Mucous membranes:
  • Color.
  • Tachyness.
  • Capillary refill time.
  • Rapid CRT with endotoxin/sepsis.
  • Prolonged CRT with hypovolemic shock.

Thoracic auscultation

• Lungs Respiratory: disease - clinical investigation:
  • Normal or harsh/crackles (aspiration pneumonitis secondary to vomiting?).
  • Respiratory rate and effort.
• Cardiac Heart: disease - clinical investigation:
  • Murmurs?
  • Arrhythmias? (severe bradycardia if hyperkalemia and atrial standstill present with urinary tract obstruction or rupture).
  • Pulse quality and character/synchrony.
    • Bounding pulses with endotoxic/septic shock Shock: septic.
    • Poor pulse quality with hypovolemic shock.
  • Vomiting may precede signs of cardiac disease by several days.

Neurological examination

• In stable patients, perform complete neurological examination Neurological examination:
  • Cranial nerves: decreased function.
  • Gait abnormalities: intervertebral disk disease can be mistaken for abdominal pain Intervertebral disk disease.
  • Mentation: dull depressed with shock, trauma, seizures, toxins.

Fur/hair/coat/skin

• Look carefully for evidence of penetrating trauma, blood on haircoat.
• Look carefully for evidence of bruising or hemorrhage.
• Look carefully at skin around umbilicus for discoloration.
  May appear red in color with intra-abdominal hemorrhage.
• Look at feet and prepuce/vulva for ethylene glycol with Wood's Lamp.

Abdominal examination

• Abdominal examination consists of 4 parts:
  • Visual inspection.
  • Auscultation.
  • Percussion.
  • Ballottement/palpation.

Visual inspection

• Distention (hemoabdomen, mass effect).
• Deformity (mass effect, ascites).
• Bruising on skin.
• Discoloration around umbilicus (indicative of intraabdominal hemorrhage).
• Penetrating wounds.
• Look at penis for discoloration, sand or grit, suggesting urethral obstruction Urethra: obstruction .

Auscultation

• Increased borborygmi if acute obstruction, gastroenteritis, toxin.
• Decreased borborygmi if chronic obstruction, anorexia, peritonitis, ileus.

Percussion

• Hyperresonant with intraabdominal air.
• Hyporesonant if intraabdominal fluid.

Palpation/ballottement

• Masses.
• Organomegaly Abdominal organomegaly. Discrepancy in renal size is often seen in cats with ureteric obstruction.
• Plication of intestines (linear foreign body).
• Thickened intestines (FIP, lymphoma, parasites, inflammatory bowel disease).
• Fluid (FIP, hepatic failure, right sided cardiac disease).
• Large, firm urinary bladder  Feline lower urinary tract disease (FLUTD), Urethra: obstruction.
• Distention.
• Pain? Localized versus generalized?
• Rectal examination (always look at both ends, may be difficult in smaller cats). Feel for:
  • Masses.
  • Sublumbar lymph nodes.
  • Urethra.
  • Feces.
  • Hematochezia.
  • Melena.
  • Obstipation.
• Look at penis for discoloration, sand or grit, indicating urethral obstruction.
• Look at rectum externally for string/foreign body.

First wave diagnostics

• PCV/total solids Hematology: packed cell volume.
  • Decreased hematocrit with abdominal hemorrhage.
  • Increased Hct and total solids (TS) with dehydration.
• BUN Blood biochemistry: urea.
  • Increased with:
    • Prerenal azotemia Pre-renal azotemia.
    • Renal disease (acute toxin like ethylene glycol, acute ureteral or urethral obstruction).
  • Decreased with:
    • Severe hepatic failure.
• Glucose Blood biochemistry: glucose:
  • Decreased in sepsis.
• Electrolytes/acid base:
  • Hyperkalemia Hypokalemia with acute renal failure Kidney: acute renal failure.
  • Hyperphosphatemia Hyperphosphatemia with ethylene glycol intoxication, acute bowel ischemia.
  • Hypercalcemia Hypercalcemia: overview.
    • Renal failure.
  • Hyperlactatemia.
    • Poor perfusion, non-specific.
  • Hypochloremic Hypochloremia metabolic alkalosis.
    • Pyloric or upper duodenal obstruction.
• Complete blood count Hematology: complete blood count (CBC):
  • Leukocytosis with left shift.
  • Neutrophilia with sepsis.
  • Inflammation.
  • Neutropenia may be present if sequestration or decreased production (ie Panleucopenia viral enteritis).
  • Severity of left shift dependent on degree of inflammation.
• Serum biochemistry profile:
  • Non-specific changes according to affected systems.
• Amylase/lipase:
  • May be elevated with pancreatitis Pancreatitis.
  • Feline Trypsin-like immunoreactivity (fTLI) more specific and sensitive for pancreatitis Blood biochemistry: trypsin-like immunoreactivity.
• Coagulogram:
  • Elevated ACT, APTT, PT with suspect DIC Disseminated intravascular coagulation.
  • Thrombocytopenia with DIC.
  • Elevated fibrin degradation products with DIC.
  • Hepatic disease, neoplasia, vasculitis.
• Urinalysis:
  • Renal tubular casts, acute renal failure.
  • Calcium oxalate monohydrate crystals (ethylene glycol).
  • WBC's, bacteriuria, pyelonephritis, cystitis.
• FeLV/FIV serology Feline leukemia virus, Feline immunodeficiency virus.
• Toxoplasmosis:
  • Toxoplasma gondii  Toxoplasma gondii  has been identified in pancreas of cats with pancreatitis Toxoplasmosis.
• Abdominal radiographs Radiography: abdomen or computed tomography Computed tomography:
  • Loss of detail in abdomen:
    • Peritonitis Peritonitis.
    • Lack of intraabdominal fat.
    • Hemoabdomen.
    • Ascites (hepatic disease, right sided heart failure, FIP).
  • Free gas:
    • Ruptured viscus.
    • Penetrating wound.

Always perform abdominal radiographs before performing abdominocentesis, as iatrogenic pneumoperitoneum can occur during procedure.

Abdominal ultrasound

• Masses.
• Free fluid.
• Architecture and size of abdominal organs.

Abdominal ultrasound/AFAST scan Triage (Abdominal focused asssesement using sonography for trauma)

• Free fluid.
• Masses.
• Architecture and size of abdominal organs.
• Ultrasound guided abdominocentesis.

Abdominocentesis  Abdominocentesis

• Indications:
  • Loss of serosal detail on abdominal radiographs.
  • Penetrating injury, where penetration reaching the peritoneal cavity is unclear.
  • Persistent abdominal pain of unknown cause.
  • Post-operative complications following abdominal surgery.
  • Perform four quadrant abdominocentesis or ultrasound guided abdominocentesis.

Diagnostic peritoneal lavage

• Indicated when peritonitis or other effusive disease is suspected but other techniques have failed to provide a diagnostic sample Peritoneal fluid: analysis.

Fluid analysis

• Grossly:
  • Clear, turbid or flocculent, green, red.
• Cytology Peritoneal fluid: cytology: 
  • Bile.
  • WBC >2000/mm^3.
  • Neutrophils with or without bacteria.
• Biochemically:
  • Bilirubin Blood biochemistry: total bilirubin:
    • Greater than peripheral blood if biliary rupture, acute necrotizing cholecystitis.
  • Amylase Blood biochemistry: alpha amylase:
    • Greater than peripheral blood if pancreatitis.
  • Creatinine Blood biochemistry: creatinine:
    • Greater than peripheral blood with urinary rupture.
  • Aerobic and anaerobic culture.

See table 'Assessment of diagnostic peritoneal lavage fluid'    .

Procedural diagnosis

• Make decision based on:
  • Initial clinical signs.
  • Results of initial evaluation.
  • Response to initial therapy.

Definitive clinicopathologic diagnosis

• More accurate.
• Directs you at treating CAUSE, not just clinical signs.

Initial Stabilization

• Stabilize shock Shock: septic  Shock   Fluid therapy: for diarrhea  Fluid therapy: for acid-base imbalance  Fluid therapy: for electrolyte abnormality   Fluid therapy: for hemorrhage    Fluid therapy: for intestinal obstruction   Fluid therapy: for acute circulatory collapse   Blood transfusion .
• Intravenous crystalloid fluids, colloids, and blood products, as appropriate.
• Shock can be septic in origin or secondary to hypovolemia.
• Hypovolemic shock caused by:
  • Blood loss.
  • Third spacing.
  • Sepsis/endotoxin.
  • Vomiting/diarrhea.
  • GDV/mesenteric torsion.
• Oxygen.
• Broad spectrum antibiotics Therapeutics: antimicrobial drug.
• Analgesics after initial assessment Analgesia: overview.
• Patient has presented due to abdominal pain. Some practitioners believe that giving analgesics may mask ongoing signs. However, appropriate diagnostics must be performed to further evaluate patient. Ongoing pain can decrease response to shock therapy, therefore, analgesics are absolutely necessary for treatment following initial assessment.

See table 'Analgesics for treating acute abdomen'    .

• Perfusion parameters:
• Heart rate.
• Capillary refill time.
• Blood pressure.
• Mucous membrane color.
• Urine output.

Treatment

Non-surgical causes of acute abdomen

• Mild pancreatitis.
• Panleucopenia viral enteritis.
• Intervertebral disk disease.
• Hyperlipidemia Hyperlipidemia.
• Acute hepatic disease.
  • Cholangiohepatitis.
  • Hepatic lipidosis Liver: lipidosis.
  • Acute fulminant hepatic necrosis.
• Acute renal disease/pyelonephritis Pyelonephritis.
• Toxin ingestion.
• Gastroduodenal ulceration.
• Gastroenteritis.
• Colitis Colitis.
• Inflammatory bowel disease Inflammatory bowel disease: overview.

Indications for surgery

• Uncontrollable hemorrhage and inability to stabilize patient.
• Free gas on plain abdominal radiographs.
• Intracellular bacteria, fecal or vegetable/fiber material on DPL.
• Greater than 2000 cells/mm³ on DPL.
• Predominantly toxic neutrophils on DPL.
• Bilirubin in abdominal fluid or green abdominal fluid.
• Complete bowel obstruction or linear foreign body.
• Ureteric obstruction.
• Penetrating trauma/foreign body.
• Gunshot wound to abdomen.
• Evisceration.
• Abdominal impalement.

Refereed papers

• Recent references from PubMed and VetMedResource.
• Walters J M (2003) Abdominal paracentesis and diagnostic peritoneal lavage. Clin Tech Small Anim Pract 18 (1), 32-38 PubMed.

Other sources of information

• Boag A & Huges D (2008) Emergency management of the acute abdomen in dogs and cats. 1. Investigation and initial stabilisation. In Practice 26 (9), 476-83 VetMedResource.
• Mann F A (2000) Acute Abdomen: Evaluation an Emergency Treatment. Current Veterinary Therapy XIII. Ed J D Bonagura. WB Saunders Company, Philadelphia. pp160-164.
• Holt D & Brown D (1999) Acute abdomen and gastrointestinal emergencies. In: Manual of Canine and Feline Emergency and Critical Care. Eds L G King and R Hammond R. British Small Animal Veterinary Association, United Kingdom. pp. 127-144.
• Kleine L J (1997) Radiology of acute abdominal disorders of the dog and cat (Parts I and II). In: Emergency Medicine in Small Animal Practice: The Compendium Collection. Veterinary Learning Systems, Trenton, NJ. pp. 336-351.