The Acute Abdomen – Decision Making in the First Few Hours

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Presenter: Amanda Boag MA VETMB DipACVIM DACVECC FHEA MRCVS, Clinical Director at Vets Now

European Specialist in Emergency and Critical Care, Amanda Boag delivered a ‘must see’ webinar for any vet working in small animal practice today. Most vets will encounter the acute abdomen patient at several points point in their career and this webinar offers the tools to deal with this often stressful scenario as effectively and as successfully as possible.

Amanda advised on the practical and logical approach to the acute abdomen patient and explained that a balance needs to be struck between diagnosing a patient and stabilising them. The initial approach should firstly incorporate a cardiovascular and respiratory assessment by checking critical parameters such as heart rate, mucous membrane colour, pulse quality, respiratory rate and respiratory depth. Discordant findings such as bright red mucus membranes and a high heart rate should ring alarm bells and alert the clinician to a possible underlying septic or distributive cause, whereas weak pulses in the presence of bradycardia could indicate the presence of a hyperkalaemia causing condition, such as Addison’s disease.

Neurological assessment of the obtunded animal is also necessary and Amanda advised in her experience spinal pain can often be misinterpreted as abdominal pain and as a result should always be considered as a possible differential in the cardiovascularly stable obtunded patient. However if severe abdominal pain is present in an obtunded patient which is cardiovascularly unstable, the clinician should always be highly suspicious of septic peritonitis.

Abdominal palpation is another key diagnostic tool when performing a patient’s physical examination but care needs to be taken to ensure ‘splinting’ (the tensing of abdominal muscles) only takes place as a result of true abdominal pain rather than through the rough handling of a patient’s abdomen. Amanda advises just stroking the abdomen initially and then gradually applying pressure rather than going straight for firm palpation. Elevation of the front legs can also be particularly useful in deep chested dogs as cranial structures and foreign bodies within the abdomen can drop down and be more easily palpated.

Once a ‘capsule’ history has been obtained and a major body systems and abdominal examination has been performed, the patient needs to be stabilised by first placing an intravenous catheter. A blood sample can then be obtained prior to administering fluid therapy which can be initiated based on physical examination findings. Amanda also advised there is no rationale for withholding analgesia with opioids being her first line drug of choice. Antibiosis may also be necessary but it is important to consider whether a useful sample such as abdominal fluid can be obtained prior to starting antibiotic therapy. The administration of anti-emetics is a topic for debate amongst clinicians as it has the potential to mask the progression of vomiting and this may prevent the need for surgery being recognised. Amanda advised that, in her opinion, she would only utilise anti-emetic therapy when she is confident the underlying condition is unlikely to be surgical.

Whether to perform surgery or not  is one of the key questions to be asked when working up an acute abdomen patient and Amanda explained we can get significantly closer to an answer by analysing any abdominal free fluid present. Sometimes just a small amount of abdominal fluid is present which can be impossible to tap, but this hurdle can be overcome by performing a diagnostic peritoneal lavage (DPL). Amanda explained this can be achieved by placing an intravenous catheter through the abdominal wall and introducing 10ml/kg of warmed sterile saline into the abdominal cavity. The catheter is then removed and the patient moved around so the fluid disperses. A blind abdominal tap can then be performed in the right cranial quadrant of the patient’s abdomen where any fluid obtained can then be analysed.

Analysis of abdominal fluid whether obtained with or without a DPL can produce some really useful information and should always be performed. Cytology of this fluid is key, as the presence of just one cell with intracellular bacteria would indicate that surgery is absolutely necessary. Biochemical analysis can also be very useful and should always include glucose levels which if lower than that of the patient’s blood sample could indicate the presence of septic peritonitis. Higher levels of BUN, creatinine, and potassium compared with the patient’s blood sample also indicates uroabdomen, and is another useful indicator for surgery. However Amanda warns against false positives for uroabdomen if IV fluids have been given rapidly to a patient which could significantly dilute the levels of urea and creatinine in the blood. Bile peritonitis is also indicated if bilirubin levels are higher in abdominal fluid compared to the patient’s blood and is another indicator for surgery.

Amanda ended this webinar by once again re-enforcing the key question which needs to be made regardless of the specific diagnosis ‘to cut or not to cut’? She explained there are unfortunately no hard or fast rules to answer this question but in time she hopes scoring systems will be developed to help. In the meantime vets have to rely on the patient’s history, physical examination and the results of a number of diagnostics tests discussed within this webinar. The vet’s experience and ‘gut’ feel also needs to be taken into account and there will be times we get it right and times we get it wrong. Amanda cited a number of examples where surgery could easily be performed when it was not in fact necessary including the dog with parvovirus enteritis, and the patient with spinal pain.

Performing the occasional ex lap with insignificant findings will for all of us be inevitable but Amanda advised the risk to the patient of being too cautious and not performing surgery where necessary is far greater than performing an ex-lap on a non-surgical patient. For this reason surely performing too many surgeries is better than performing too few but with the tools provided to us by this webinar, hopefully (most of the time) we will follow the right path and make the right decision.

The Stethoscope (MRCVS)

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