The acute abdomen

Veterinary-focused assessment with sonography for trauma-airway, breathing, circulation, disability and exposure: a prospective observational study in 64 canine trauma patients

OBJECTIVE

To describe the technique and findings of the 'veterinary focused assessment with sonography for trauma-airway, breathing, circulation, disability and exposure' protocol in dogs suffering from trauma.

MATERIALS AND METHODS

Prospective observational study on a new point-of-care ultrasound protocol on 64 dogs suffering from trauma and comparison of findings with radiology.

RESULTS

Comparison of the results of this new ultrasound protocol for trauma patients with radiography findings for pneumothorax, pleural effusion, alveolar-interstitial syndrome and abdominal effusion revealed positive agreement of 89, 83, 100 and 87% and negative agreement of 76, 83, 76 and 92%, respectively. Novel findings of the 'veterinary focused assessment with sonography for trauma-airway, breathing, circulation, disability and exposure' exam, which were not previously reported for dogs undergoing focused assessment with sonography for trauma, included alveolar-interstitial syndrome (suggestive of pulmonary contusions), diaphragmatic hernia, retroperitoneal effusion and tracheal injury. Our new technique may also help identify increased intracranial pressure via changes in optic nerve sheath diameter and haemodynamic instability through the evaluation of the caudal vena cava and cardiac function.

CLINICAL SIGNIFICANCE

The described ultrasound examination protocol can be rapidly performed on dogs suffering from trauma during resuscitation and it may detect injuries previously undetectable using other veterinary point-of-care ultrasound protocols.

Correlation between Preoperative Ultrasonographic Findings and Clinical, Intraoperative, Cytopathological, and Histopathological Diagnosis of Acute Abdomen Syndrome in 50 Dogs and Cats

Acute abdomen syndrome is an emergency in small animal practice that requires rapid diagnosis to determine the appropriate treatment. No studies have correlated the preoperative abdominal ultrasonography (US) findings with the clinical, surgical, cytopathologic, and histopathologic findings. This retrospective study was designed to evaluate abdominal US in the diagnosis of acute abdomen syndrome using surgery as a "criterion standard". The most frequently misinterpreted lesions with US were also identified. The study included 50 dogs and cats with physical examination, an US diagnosis, US guided fine-needle aspiration cytology, intraoperative findings, and histopathology. Intraoperatively, 49 primary and 43 secondary lesions were identified. The sensitivity, specificity, and positive and negative predictive values for US were calculated. There was a good agreement between the US diagnosis and intraoperative findings of 86.9% (80/92), for both primary and secondary lesions (p < 0.0001). Cytology and histopathology examinations corroborated the US in 86.4% (n = 64/74) of primary and 66.2% of secondary (n = 49/79) lesions. Using US as the "criterion standard", the sensitivity of abdominal palpation for identification of ascites and masses was 32.4% and 43.7%, respectively, while the specificity was 93.7% and 94.4%, respectively. Abdominal US is a useful preoperative modality for diagnosing acute abdominal diseases in dogs and cats. Care should be taken with interpretation of gastrointestinal perforation, omental tumors, and common bile duct rupture, as these lesions are frequently misinterpreted with US.

Radiographic techniques and interpretation of the acute abdomen

Radiography is a familiar and available imaging modality for the evaluation of patients with acute abdominal distress. Potential causes for acute abdominal distress include the hepatobiliary system, spleen, urogenital tract, and gastrointestinal tract. Radiographic signs associated with specific conditions are described, including gastric-dilation volvulus, urinary bladder rupture, ureteral rupture, urethral rupture, pancreatitis, and small intestinal obstruction. Additionally, contrast procedures that can be beneficial in evaluating the patient with acute abdomen, including positive contrast cystography, urethrography, excretory urography, and peritoneography, are described.

Ultrasonography of the acute abdomen

For many years, ultrasonography has been considered to be one of the most valuable imaging techniques for evaluation of the abdominal cavity and its organs. In most cases, abdominal ultrasonography helps obtain information that leads to a definitive diagnosis. Ultrasonography is also valuable to narrow the list of differential diagnoses obtained with other diagnostic techniques. This article discusses the role of ultrasound for the diagnosis of the most common diseases that can produce clinical signs of acute abdominal pain. Abdominal organs that can be evaluated using ultrasound include the liver, biliary system, pancreas, stomach, small intestine, kidney, urinary bladder, uterus, and prostate. Pathologies of the abdominal cavity and retroperitoneal space can be also diagnosed with ultrasonography. Interventional ultrasound techniques are useful to either assist in getting the definitive diagnosis or to treat certain pathologic conditions.

Cytology and fluid analysis of the acute abdomen

In patients with acute abdominal pain, abdominal paracentesis and diagnostic peritoneal lavage often yield fluid samples for cytologic and biochemical evaluation. Cytology of the effusion from a patient with acute abdominal disease can be a crucial tool for the rapid diagnosis necessary for initiation of timely and appropriate therapy. Appropriate sample collection, handling, and preparation are essential to obtain an accurate diagnosis. Analysis of the fluid sample should include gross examination of the effusion, measurement of total nucleated cell count, packed red blood cell volume, and protein concentration, as well as examination for the presence of other cells, bacteria, food particles, or plant material. Biochemical evaluation should proceed based on the clinician's index of suspicion for a particular disease process. Abdominal effusions are generally classified as transudate, modified transudate, or exudate, depending on the total nucleated cell count and protein concentration. Cytology of all fluids collected should be performed systematically, utilizing progressively higher magnifications with a microscope. Specific diseases with associated abdominal effusions include septic peritonitis, nonseptic peritonitis, hemoabdomen, uroabdomen, pancreatitis, bile peritonitis, chylous effusion, and neoplasia. A complete description of sample preparation and evaluation is reviewed.

Triage and approach to the acute abdomen

The presentation of a patient with acute abdominal pain often is both a diagnostic and therapeutic challenge for the veterinary practitioner. Rapid physical examination and assessment of the patient's cardiovascular status are critical to initiating appropriate and often aggressive medical management as diagnostic tests are being performed. A number of diagnostic tests can be performed, including complete blood count, serum biochemistry profile, serum amylase and lipase, abdominal radiographs, abdominal ultrasound, abdominal paracentesis or diagnostic peritoneal lavage, cytology, and fluid analysis. In some cases, surgical exploration may be indicated, depending on each patient's clinical signs and response to therapy. Of the most important aspects of medical management of the patient with acute abdominal pain is to maintain oxygen delivery to tissues and to treat aggressively for pain or discomfort. The initial triage and approach to the patient with acute abdomen are discussed.

The acute abdomen: a surgeon's approach to diagnosis and treatment

Clinical approach to a patient with acute abdominal distress involves decision making: whether to take a patient to surgery, or manage the patient medically. A thorough and systematic approach requires the use of diagnostic imaging modalities, including radiology and ultrasonography, performing diagnostic peritoneal lavage or abdominal paracentesis techniques, and bloodwork evaluation, including complete blood count and serum biochemistry profiles. In some cases, the results of diagnostic tests may lead to surgical versus medical management, particularly when a patient fails to respond to medical management alone. In other cases, such as GDV syndrome, penetrating abdominal wounds, pyometra, or uncontrolled abdominal hemorrhage, rapid surgical management is necessary for patient survival. This article describes a systematic approach to a small animal patient with acute abdomen.