# Incorporating Imaging into the Diagnostic Workup of the Acute Abdomen

## Quick Answer

- Sequence imaging by patient stability and suspected pathology, starting with survey radiographs for most stable patients and moving to ultrasound or CT when radiographs are inconclusive.
- Use ultrasound as the primary cross-sectional tool for soft tissue evaluation, especially for gastrointestinal, urinary, and reproductive tract assessment.
- Reserve CT for unstable patients, complex trauma, or cases where radiography and ultrasound fail to identify a surgical lesion.

## Clinical Context and Imaging Principles

The acute abdomen represents one of the most time-sensitive presentations in veterinary emergency medicine. The term describes sudden onset abdominal pain, distension, vomiting, or other signs that suggest an intra-abdominal process requiring rapid diagnosis and intervention. The diagnostic challenge lies in distinguishing medical conditions that respond to supportive care from surgical emergencies that require immediate operative intervention. Imaging serves as the cornerstone of this distinction, providing objective evidence of the location, extent, and nature of the underlying pathology.

The imaging approach must balance diagnostic accuracy against the practical constraints of the emergency setting. Time, patient stability, available equipment, and the experience of the clinician all influence the choice of imaging modality. A systematic algorithm that sequences radiography, ultrasound, and CT based on these factors reduces the risk of missed diagnoses and unnecessary delays. The goal is not to perform every imaging test on every patient but to select the most appropriate test at the most appropriate time.

The clinical examination remains the starting point for all acute abdomen evaluations. Palpation, auscultation, and observation provide initial clues about the location and severity of the disease process. However, physical examination alone cannot reliably identify the specific cause of an acute abdomen. Imaging provides the objective confirmation needed to guide treatment decisions. The American Veterinary Medical Association emphasizes the importance of regular veterinary care and the role of diagnostic testing in establishing accurate diagnoses and treatment plans for companion animals.

The imaging algorithm presented in this article follows a stepwise approach that respects the stability of the patient and the diagnostic question at hand. The sequence begins with the least invasive and most readily available modality and progresses to more advanced imaging when needed. This approach minimizes the time to diagnosis while avoiding unnecessary procedures that could delay treatment or cause additional stress to the patient.

## At a Glance

The following table summarizes the primary imaging modalities used in the acute abdomen workup, their strengths, limitations, and typical clinical applications.

| Modality | Strengths | Limitations | Typical Applications |
|----------|-----------|-------------|----------------------|
| Radiography | Fast, widely available, low cost, no sedation required | Limited soft tissue detail, gas and fluid overlap, operator dependent | Detection of gastrointestinal obstruction, foreign bodies, free gas, organomegaly, and masses |
| Ultrasound | Excellent soft tissue detail, real time evaluation, no ionizing radiation | Operator dependent, requires patient cooperation, limited in obese patients or with gas distension | Evaluation of liver, spleen, kidneys, bladder, intestines, lymph nodes, free fluid, and masses |
| CT | High resolution, multiplanar reconstruction, excellent for trauma and complex cases | Requires anesthesia or heavy sedation, higher cost, less widely available | Evaluation of trauma, complex masses, vascular lesions, and cases where radiography and ultrasound are inconclusive |

The choice of modality depends on the clinical question, the stability of the patient, and the equipment available. Radiography provides a rapid overview of the abdomen and is the appropriate first step for most stable patients. Ultrasound provides detailed soft tissue evaluation and is the next step when radiography is inconclusive or when a specific organ system is suspected. CT provides the highest level of detail and is reserved for complex cases where other modalities have failed to provide a diagnosis.

## Initial Assessment and Patient Stabilization

Before any imaging is performed, the patient must be assessed and stabilized. The acute abdomen patient may present with shock, dehydration, electrolyte imbalances, or other life-threatening conditions that require immediate attention. The physical examination provides the first indication of the patient's stability and the urgency of the situation.

The initial assessment includes evaluation of the patient's cardiovascular status, respiratory function, and level of consciousness. The mucous membrane color, capillary refill time, heart rate, and pulse quality provide information about perfusion and the presence of shock. The respiratory rate and effort indicate whether the patient is able to maintain adequate oxygenation. The level of consciousness reflects the overall neurologic status and the severity of the systemic disease.

The patient's hydration status is assessed through skin turgor, mucous membrane moisture, and the presence of sunken eyes. The abdomen is evaluated for distension, pain, and the presence of fluid. The patient's history, including the onset and progression of signs, the presence of vomiting or diarrhea, and any known exposure to toxins or foreign bodies, provides important context for the imaging findings.

The patient must be stabilized before imaging is performed. Intravenous fluid therapy is initiated to correct dehydration and maintain blood pressure. Pain management is provided to reduce the patient's discomfort and facilitate the imaging procedure. The patient's electrolyte and acid-base status is evaluated and corrected as needed. The patient's blood glucose is checked and treated if abnormal.

The decision to perform imaging is based on the patient's stability and the clinical suspicion. A stable patient with a suspected surgical condition may undergo radiography and ultrasound before surgery. An unstable patient with a suspected surgical condition may require immediate surgery without imaging, or imaging may be performed during the surgical preparation period. The clinician must balance the need for diagnostic information against the risk of delaying surgery.

## Radiography in the Acute Abdomen

Radiography is the most commonly used imaging modality for the acute abdomen. It is widely available, relatively inexpensive, and provides a rapid overview of the abdominal cavity. The radiograph is obtained with the patient in the lateral and ventrodorsal positions, and the images are evaluated for the presence of free gas, obstruction, foreign bodies, organomegaly, and masses.

The radiograph provides information about the size, shape, and position of the abdominal organs. The liver, spleen, kidneys, and bladder are visible on the radiograph, and their size and position can be evaluated. The stomach and intestines are visible, and the presence of gas or fluid within them can be assessed. The radiograph also provides information about the presence of free gas in the abdominal cavity, which is a sign of a perforated viscus.

The radiograph is particularly useful for the detection of gastrointestinal obstruction. The presence of a foreign body, a mass, or a stricture can cause the intestines to become distended with gas and fluid. The radiograph shows the distended loops of the intestine and the location of the obstruction. The radiograph can also detect the presence of a foreign body, such as a bone, a toy, or a piece of fabric, which may be visible as a radiopaque object.

The radiograph is also useful for the detection of free gas in the abdominal cavity. Free gas is a sign of a perforated viscus, such as a perforated stomach or intestine. The free gas is visible as a gas bubble under the diaphragm or in the abdominal cavity. The radiograph can also detect the presence of a pneumoperitoneum, which is a sign of a ruptured viscus.

The radiograph has limitations. It provides limited soft tissue detail, and the organs may be obscured by gas or fluid. The radiograph cannot distinguish between different types of soft tissue masses, and it cannot detect the presence of a small amount of free fluid. The radiograph is also limited in its ability to evaluate the pancreas, the adrenal glands, and the lymph nodes.

The radiograph is the first step in the imaging algorithm for most patients with an acute abdomen. It provides a rapid overview of the abdominal cavity and can identify the most common causes of the acute abdomen, including obstruction, foreign bodies, and free gas. If the radiograph is inconclusive, the next step is ultrasound.

## Ultrasound in the Acute Abdomen

Ultrasound is the most useful imaging modality for the evaluation of the soft tissue structures of the abdominal cavity. It provides high-resolution images of the liver, spleen, kidneys, bladder, and other organs. It can detect the presence of the fluid, masses, and the changes in the organ architecture that are associated with the disease.

The ultrasound is performed with the patient in the dorsal or lateral position. The transducer is placed on the abdomen and the images are obtained in the sagittal and transverse planes. The ultrasound provides real-time images, which allows the clinician to evaluate the movement of the organs and the presence of the fluid.

The ultrasound is particularly useful for the evaluation of the liver, spleen, and kidneys. The liver is evaluated for the presence of the masses, the changes in the echotexture, and the dilation of the bile ducts. The spleen is evaluated for the presence of the masses, the changes in the echotexture, and the presence of the fluid. The kidneys are evaluated for the presence of the masses, the changes in the echotexture, and the obstruction of the urinary tract.

The ultrasound is also useful for the evaluation of the pancreas. The pancreas is a difficult organ to evaluate with the radiograph, but the ultrasound can detect the presence of the pancreatitis, the masses, and the fluid. The ultrasound can also evaluate the adrenal glands, which are difficult to see with the radiograph.

The ultrasound is the most sensitive imaging modality for the detection of the free fluid in the abdominal cavity. The free fluid is visible as an anechoic area between the organs. The ultrasound can also detect the presence of the fluid in the chest, which is a sign of the heart failure or the other disease.

The ultrasound has limitations. It is operator dependent, and the quality of the images depends on the experience of the operator. The ultrasound is limited by the presence of the gas in the intestines, which can obscure the underlying organs. The ultrasound is also limited in the evaluation of the obese patients, where the fat can interfere with the transmission of the sound waves.

The ultrasound is the second step in the imaging algorithm for most patients with an acute abdomen. It is used when the radiograph is inconclusive or when a specific organ system is suspected. The ultrasound can provide the detailed information about the soft tissue structures that the radiograph cannot provide.

## Computed Tomography in the Acute Abdomen

Computed tomography (CT) is the most advanced imaging modality for the evaluation of the acute abdomen. It provides high-resolution, cross-sectional images of the abdominal cavity, and it can detect the presence of the masses, the fluid, and the lesions that are not visible with the radiograph or the ultrasound.

The CT is performed with the patient under anesthesia or sedation. The patient is placed in the CT scanner and the images are obtained in the axial plane. The images can be reconstructed in the sagittal and coronal planes, which provides a more complete view of the abdominal cavity.

The CT is particularly useful for the evaluation of the complex cases, where the radiograph and the ultrasound have failed to provide a diagnosis. The CT can detect the presence of the masses, the fluid, and the lesions that are not visible with the other modalities. The CT can also evaluate the presence of the obstruction, the perforation, and the other surgical conditions.

The CT is also useful for the evaluation of the trauma patient. The CT can detect the presence of the free fluid, the free gas, and the injuries to the organs. The CT can also evaluate the presence of the fractures and the other injuries to the bones.

The CT has limitations. It requires anesthesia or sedation, which can be a risk for the unstable patient. The CT is more expensive than the radiograph or the ultrasound, and it is not available in all veterinary practices. The CT also exposes the patient to the radiation, which is a concern for the patient and the staff.

The CT is the third step in the imaging algorithm for most patients with an acute abdomen. It is used when the radiograph and the ultrasound have failed to provide a diagnosis, or when the patient is unstable and the CT can be performed quickly. The CT can provide the information that is needed to make the diagnosis and to plan the treatment.

## Imaging Algorithm for the Acute Abdomen

The imaging algorithm for the acute abdomen is a stepwise approach that sequences the radiograph, the ultrasound, and the CT based on the patient's stability and the suspected pathology. The algorithm is designed to minimize the time for the diagnosis and to minimize the risk of the missed diagnosis.

The algorithm begins with the patient's stability. If the patient is unstable, the imaging is performed only if it can be done quickly and safely. If the patient is stable, the imaging is performed in a stepwise manner.

The first step is the radiograph. The radiograph is performed in the stable patient with the acute abdomen. The radiograph provides a baseline overview of the abdominal cavity and can identify the most common causes of the acute abdomen.

If the radiograph is inconclusive, the next step is the ultrasound. The ultrasound is performed to evaluate the soft tissue structures of the abdominal cavity. The ultrasound can provide the diagnosis that the radiograph cannot provide.

If the ultrasound is inconclusive, the next step is the CT. The CT is performed to provide the high-resolution images of the abdominal cavity. The CT can provide the diagnosis that the radiograph and the ultrasound cannot provide.

The algorithm is not a rigid protocol. The clinician can modify the algorithm based on the patient's condition and the clinical suspicion. For example, if the patient has a suspected obstruction, the radiograph may be the only imaging that is needed. If the patient has a suspected mass, the ultrasound may be the first imaging that is performed.

The algorithm is designed to be efficient and effective. It provides a systematic approach to the imaging of the acute abdomen, and it reduces the risk of the missed diagnosis. The algorithm is based on the evidence and the clinical experience, and it is updated as new evidence becomes available.

## Practical Implementation and Assessment Steps

The implementation of the imaging algorithm requires a systematic approach to the patient's care. The following steps provide a framework for the clinician to follow.

1.  Perform a thorough physical examination and assess the patient's stability.
2.  Stabilize the patient with intravenous fluids, pain management, and other supportive care as needed.
3.  Obtain a complete history, including the onset and progression of symptoms, the presence of vomiting or diarrhea, and any exposure to toxins or foreign bodies.
4.  Perform the radiograph as the first imaging modality in the stable patient.
5.  Evaluate the radiograph for the presence of the obstruction, the foreign body, the free gas, the organomegaly, and the mass.
6.  If the radiograph is inconclusive, perform the ultrasound.
7.  Evaluate the ultrasound for the presence of the fluid, the mass, the organomegaly, and the lesions.
8.  If the ultrasound is inconclusive, perform the CT.
9.  Evaluate the CT for the presence of the mass, the obstruction, the perforation, and the other surgical conditions.
10. Based on the imaging findings, determine the need for the surgery or the medical management.

The assessment steps are designed to be practical and to be implemented in the clinical setting. The steps are based on the evidence and the clinical experience, and they are updated as the new evidence becomes available.

## Records and Measurements

The imaging findings must be documented in the patient's medical record. The record should include the date and time of the imaging, the modality used, the views obtained, and the findings. The record should also include the interpretation of the findings and the recommendations for the treatment.

The measurements of the organs and the lesions should be recorded. The measurements provide the baseline for the monitoring of the disease and the response to the treatment. The measurements include the size of the liver, the spleen, the kidneys, and the other organs. The measurements also include the size of the masses and the lesions.

The imaging findings should be compared with the clinical findings and the laboratory findings. The comparison provides the information about the accuracy of the imaging and the diagnosis. The comparison also provides the information about the progression of the disease and the response to the treatment.

The records should be maintained in a secure and confidential manner. The records should be available to the clinician and the other members of the healthcare team. The records should be retained for the period required by the law and the regulations.

## Common Failure Patterns

The imaging of the acute abdomen can fail to provide a diagnosis in some cases. The failure can be due to the limitations of the imaging modality, the operator error, or the patient's condition.

The radiograph can fail to detect the presence of the obstruction, the mass, or the free gas. The radiograph can also fail to detect the presence of the fluid, which is a sign of the peritonitis or the other disease.

The ultrasound can fail to detect the presence of the mass, the lesion, or the fluid. The ultrasound can also fail to detect the presence of the obstruction, which is a sign of the surgical condition.

The CT can fail to detect the presence of the mass, the lesion, or the fluid. The CT can also fail to detect the presence of the obstruction, which is a sign of the surgical condition.

The failure of the imaging can be due to the operator's error. The operator may not be able to obtain the images of the quality, or the operator may not be able to interpret the images correctly. The operator's error can be reduced by the training and the experience.

The failure of the imaging can also be due to the patient's condition. The patient may be too unstable to undergo the imaging, or the patient may be too obese to obtain the images of the quality. The patient's condition can be improved by the stabilization and the preparation.

The failure of the imaging can be reduced by the use of the algorithm and the systematic approach. The algorithm provides the framework for the imaging, and the systematic approach reduces the risk of the missed diagnosis.

## Welfare and Safety Context

The imaging of the acute abdomen is a diagnostic procedure that is performed to improve the health and the welfare of the patient. The imaging is performed with the goal of the diagnosis and the treatment, and it is performed in a manner that minimizes the risk of the patient.

The imaging of the acute abdomen is a safe procedure when it is performed by the trained and the experienced clinician. The radiograph and the ultrasound are non-invasive and do not require the anesthesia. The CT requires the anesthesia, which is a risk of the patient.

The imaging of the acute abdomen is a procedure that is performed with the consent of the owner. The owner is informed of the risks and the benefits of the imaging, and the owner is given the opportunity to ask the questions.

The imaging of the acute abdomen is a procedure that is performed in the best interest of the patient. The imaging is performed to provide the diagnosis and to plan the treatment. The imaging is performed to reduce the risk of the missed diagnosis and to improve the outcome of the patient.

The World Organisation for Animal Health emphasizes the importance of the animal health and the welfare in the veterinary practice [6]. The imaging of the acute abdomen is a part of the veterinary practice that is performed to improve the health and the welfare of the patient.

## Limitations and Professional Escalation Criteria

The imaging of the acute abdomen has limitations. The imaging cannot provide a diagnosis in all cases. The imaging can be limited by the patient's condition, the operator's experience, and the equipment available.

The imaging of the acute abdomen is a diagnostic procedure that is performed by the clinician. The clinician is responsible for the interpretation of the imaging and the recommendation of the treatment. The clinician should be aware of the limitations of the imaging and the need for the escalation.

The escalation criteria are the conditions that require the referral to the specialist or the advanced imaging. The escalation criteria include the following:

- The patient is unstable and the imaging cannot be performed.
- The imaging is inconclusive and the patient is not improving.
- The imaging is inconclusive and the patient is deteriorating.
- The imaging is inconclusive and the patient has a suspected surgical condition.
- The imaging is inconclusive and the patient has a suspected mass or a lesion.

The escalation criteria are the conditions that require the referral to the specialist. The specialist is the veterinarian who has the advanced training and the experience in the imaging of the acute abdomen. The specialist can provide the advanced imaging and the treatment of the patient.

The escalation criteria are the conditions that require the referral to the advanced imaging. The advanced imaging includes the CT, the MRI, and the other imaging modalities. The advanced imaging can provide the diagnosis that the radiograph and the ultrasound cannot provide.

The escalation criteria are the conditions that require the referral to the surgery. The surgery is the treatment of the surgical conditions, such as the obstruction, the perforation, and the mass. The surgery is performed by the surgeon, who has the advanced training and the experience in the surgery of the acute abdomen.

## Decision Framework for Imaging Sequence Based on Clinical Probability and Resource Availability

The stepwise algorithm of radiography, ultrasound, and CT provides a useful foundation, but emergency clinicians face a more complex reality. Patient stability, suspected pathology, and available equipment rarely align in a simple sequence. A practical decision framework must incorporate clinical probability scoring, resource triage, and explicit triggers for modality escalation. This section presents a structured approach that emergency clinicians can apply at the bedside to reduce time to diagnosis and avoid the common pitfall of completing a full imaging sequence when a single targeted study would suffice.

### Probability Stratification Before Image Selection

The first decision point occurs before any imaging is performed. The clinician assigns the patient to one of three probability categories based on the physical examination, history, and preliminary laboratory findings. This stratification determines whether the patient proceeds directly to a specific modality or follows the standard sequence.

**High probability of surgical disease.** Patients with progressive abdominal distension, severe pain on palpation, suspected foreign body ingestion, or evidence of peritonitis fall into this category. For these patients, the clinician should consider whether radiography alone can answer the surgical question. If the radiograph clearly demonstrates a mechanical obstruction, free gas, or a radiopaque foreign body, the patient proceeds to surgery without additional imaging. The American Veterinary Medical Association notes that timely diagnosis and treatment planning are central to effective veterinary care, and avoiding unnecessary diagnostic steps supports this goal.

**Moderate probability of surgical disease.** Patients with vomiting, mild abdominal pain, or nonspecific signs fall into this category. These patients benefit from the standard sequence of radiography followed by ultrasound. The radiograph provides a rapid overview, and the ultrasound adds soft tissue detail when the radiograph is inconclusive. This group represents the majority of acute abdomen presentations and the sequence works well for them.

**Low probability of surgical disease.** Patients with mild signs, a clear medical history such as recent dietary indiscretion, or a known medical condition such as pancreatitis fall into this category. For these patients, the clinician may proceed directly to ultrasound if soft tissue evaluation is needed, or may begin with radiography to rule out free gas and obstruction. The low probability category allows the clinician to avoid the full sequence when the clinical picture suggests a medical instead of surgical process.

### Resource Triage and Equipment Availability

The decision framework must account for the reality that not all emergency practices have the same imaging capabilities. A practice with in-house ultrasound and radiography but no CT will follow a different sequence than a referral center with all three modalities available. The framework should be adapted to the available resources while maintaining the same diagnostic goals.

**Radiography-only practices.** In practices without ultrasound or CT, the radiograph is the sole imaging modality. The clinician must maximize the information obtained from the radiograph by obtaining both lateral and ventrodorsal views and by using additional projections when needed. The clinician should also recognize the limitations of radiography and have clear escalation criteria for referral to a practice with advanced imaging capabilities.

**Radiography and ultrasound practices.** Most general and emergency practices have both radiography and ultrasound. The sequence of radiograph followed by ultrasound works well in this setting. The clinician should be proficient in abdominal ultrasound and should have a clear protocol for the evaluation of the liver, spleen, kidneys, bladder, and gastrointestinal tract. The ultrasound can provide the diagnosis that the radiograph cannot provide, and the combination of the two modalities is sufficient for most acute abdomen cases.

**Full imaging capability.** Practices with CT available can use the full algorithm. The CT is reserved for cases where radiography and ultrasound are inconclusive, or for trauma patients where the CT provides a comprehensive evaluation of the abdomen. The CT is also useful for surgical planning in complex cases, such as large masses or vascular lesions.

### Time-Based Decision Points

Time pressure is a defining feature of the acute abdomen. The framework should include explicit time-based decision points that prompt the clinician to move to the next step or to escalate to surgery. These decision points prevent the clinician from spending excessive time on a single modality when the patient is deteriorating.

**The 30-minute radiograph review.** The radiograph should be obtained and reviewed within 30 minutes of the patient's presentation. If the radiograph provides a clear diagnosis, the clinician proceeds with the appropriate treatment. If the radiograph is inconclusive, the clinician moves to the next step without delay.

**The 60-minute ultrasound evaluation.** The ultrasound should be performed and interpreted within 60 minutes of the radiograph review. If the ultrasound provides a diagnosis, the clinician proceeds with the treatment. If the ultrasound is inconclusive and the patient is stable, the clinician may consider CT. If the patient is unstable or deteriorating, the clinician should escalate to surgery or referral.

**The 90-minute CT decision.** The CT should be performed within 90 minutes of the ultrasound review when it is indicated. The CT provides the highest level of detail and can identify lesions that are not visible with the other modalities. If the CT is inconclusive and the patient is deteriorating, the clinician should consider exploratory surgery or referral to a specialist.

### Clinical Probability Scoring System

A simple scoring system can help the clinician assign the patient to a probability category and guide the imaging sequence. The system uses the following criteria, each assigned a point value:

| Criterion | Points |
|-----------|--------|
| Abdominal pain on palpation | 1 |
| Abdominal distension | 1 |
| Vomiting | 1 |
| Fever | 1 |
| Tachycardia | 1 |
| Suspected foreign body ingestion | 2 |
| Free gas on radiograph | 3 |
| Peritonitis on examination | 3 |

A total score of 0 to 2 suggests a low probability of a surgical lesion. The clinician may begin with radiography and proceed to ultrasound if needed. A score of 3 to 5 suggests a moderate probability. The clinician follows the standard sequence of radiography and ultrasound. A score of 6 or higher suggests a high probability of a surgical lesion. The clinician should consider direct progression to surgery if the radiograph confirms the diagnosis, or to CT if the radiograph is inconclusive.

### Comparison of Imaging Sequences by Clinical Scenario

The following table compares the recommended imaging sequence for different clinical scenarios. The table provides a practical reference for the emergency clinician.

| Clinical Scenario | Recommended Sequence | Rationale |
|-------------------|----------------------|-----------|
| Suspected gastrointestinal obstruction | Radiograph, then ultrasound if inconclusive | Radiograph detects distended loops and foreign bodies. Ultrasound evaluates the intestinal wall and the presence of the foreign body. |
| Suspected peritonitis or free gas | Radiograph, then CT if inconclusive | Radiograph detects free gas. CT provides a more sensitive evaluation of the free gas and the source of the perforation. |
| Suspected pancreatitis | Ultrasound as the primary modality | Ultrasound provides the best evaluation of the pancreas and the surrounding tissues. Radiograph is less useful for the pancreas. |
| Suspected splenic mass or hemabdomen | Ultrasound, then CT if inconclusive | Ultrasound detects the mass and the free fluid. CT provides a more detailed evaluation of the mass and the vascular involvement. |
| Trauma patient | CT as the primary modality | CT provides a comprehensive evaluation of the abdominal organs, the free fluid, and the free gas. Radiograph and ultrasound may be performed first if the patient is unstable. |
| Suspected urinary tract obstruction | Ultrasound, then radiograph if inconclusive | Ultrasound detects the hydronephrosis and the bladder distension. Radiograph may detect the uroliths. |

### Documentation of the Decision Process

The decision framework should be documented in the patient's medical record. The record should include the clinical probability score, the imaging sequence used, the findings at each step, and the rationale for the decisions. This documentation provides a clear record of the diagnostic process and supports the clinical reasoning.

The record should also include the time of each imaging study and the time of the interpretation. The time records allow the clinician to evaluate the efficiency of the diagnostic process and to identify delays. The time records also support the escalation criteria, as the clinician can document the time at which the patient was deteriorating and the decision to escalate.

The documentation should be maintained in a manner that is consistent with the practice's policies and the applicable regulations. The World Organisation for Animal Health emphasizes the importance of the animal health and the welfare in the veterinary practice, and the documentation of the diagnostic process supports the welfare of the patient by ensuring that the diagnosis is made in a timely manner.

### Troubleshooting the Imaging Sequence

The imaging sequence can fail to provide a diagnosis in some cases. The clinician should have a troubleshooting approach to identify the cause of the failure and to determine the next step.

**The radiograph is inconclusive.** The radiograph may be inconclusive due to the patient's body condition, the presence of the gas or the fluid, or the limitations of the modality. The clinician should consider the following troubleshooting steps:

- Obtain additional views, such as the right lateral and the left lateral views, to improve the evaluation of the stomach and the intestines.
- Repeat the radiograph after the patient has been stabilized and the gas or the fluid has been reduced.
- Proceed to the ultrasound or the CT if the radiograph remains inconclusive.

**The ultrasound is inconclusive.** The ultrasound may be inconclusive due to the operator's experience, the patient's body condition, or the presence of the gas. The clinician should consider the following troubleshooting steps:

- Repeat the ultrasound with a different transducer or a different approach.
- Use the ultrasound to guide the collection of the fluid or the tissue for the analysis.
- Proceed to the CT if the ultrasound remains inconclusive.

**The CT is inconclusive.** The CT may be inconclusive due to the lack of the contrast, the patient's movement, or the presence of the artifact. The clinician should consider the following troubleshooting steps:

- Repeat the CT with the contrast to improve the evaluation of the vascular structures and the masses.
- Use the CT to guide the biopsy or the aspiration of the lesion.
- Consider the surgical exploration if the CT remains inconclusive and the patient is deteriorating.

### The Role of the Clinician in the Decision Framework

The decision framework is a tool to support the clinician, not a replacement for the clinical judgment. The clinician must interpret the findings at each step and determine the appropriate next action. The clinician should be aware of the limitations of the imaging and the need for the escalation to the specialist or the advanced imaging.

The clinician should also be aware of the patient's condition and the response to the treatment. The patient's condition may change during the diagnostic process, and the clinician must be prepared to adjust the plan accordingly. The clinician should also be aware of the owner's expectations and the financial considerations, and the clinician should communicate the diagnostic plan and the findings to the owner in a clear and compassionate manner.

The American Animal Hospital Association provides guidance for the veterinary practice, and the clinician should follow the practice's protocols and the standards of care. The clinician should also be aware of the local regulations and the requirements for the veterinary practice, and the clinician should maintain the appropriate records and the documentation.

### The Role of the Imaging in the Clinical Decision

The imaging provides the objective evidence that supports the clinical decision. The imaging findings should be interpreted in the context of the clinical examination and the laboratory findings. The imaging findings should not be interpreted in isolation, and the clinician should consider the entire clinical picture when making the diagnosis and the treatment plan.

The imaging findings should be communicated to the owner in a clear and understandable manner. The owner should be informed of the findings, the implications for the patient, and the recommended treatment. The owner should also be informed of the limitations of the imaging and the need for the further testing or the referral.

The imaging findings should be documented in the medical record and should be available to the other members of the healthcare team. The documentation should include the findings, the interpretation, and the recommendations. The documentation should be maintained in a secure and confidential manner.

### The Clinical Decision and the Patient Outcome

The clinical decision framework is designed to improve the patient outcome by reducing the time to the diagnosis and the treatment. The framework provides a systematic approach to the imaging of the acute abdomen, and it reduces the risk of the missed diagnosis and the unnecessary delays. The framework is based on the evidence and the clinical experience, and it is updated as the new evidence becomes available.

The clinical decision framework is a practical tool that can be implemented in the emergency setting. The framework is designed to be flexible and to be adapted to the patient's condition and the available resources. The framework is also designed to be efficient and to minimize the time to the diagnosis and the treatment.

The clinical decision framework is a valuable addition to the diagnostic workup of the acute abdomen. It provides a structured approach to the imaging sequence, and it supports the clinician in making the timely and the accurate diagnosis. The framework is a practical tool that can be used in the emergency setting to improve the patient outcome and to reduce the risk of the missed diagnosis.

## Frequently Asked Questions

### What is the first imaging test for a patient with an acute abdomen?

The first imaging test is the radiograph. It provides a baseline overview of the abdominal cavity and can identify the most common causes of the acute abdomen, including the obstruction, the foreign body, and the free gas.

### When is the ultrasound used in the acute abdomen?

The ultrasound is used when the radiograph is inconclusive or when a specific organ system is suspected. It provides high-resolution images of the soft tissue structures and can detect the presence of the fluid, the mass, and the lesions.

### When is the CT used in the acute abdomen?

The CT is used when the radiograph and the ultrasound are inconclusive and the patient is stable enough to undergo the procedure. It provides high-resolution, cross-sectional images and can detect the presence of the masses, the fluid, and the lesions that are not visible with the other modalities.

### What are the limitations of the radiograph in the acute abdomen?

The radiograph has limited soft tissue detail and cannot detect the presence of the fluid, the masses, or the lesions in the soft tissue. It is also limited in the evaluation of the pancreas, the adrenal glands, and the lymph nodes.

### What are the limitations of the ultrasound in the acute abdomen?

The ultrasound is operator dependent and the quality of the images depends on the experience of the operator. It is limited by the presence of the gas in the abdomen, which can interfere with the imaging of the underlying organs.

### What are the limitations of the CT in the acute abdomen?

The CT requires anesthesia or general anesthesia, which is a risk for the unstable patient. It is also more expensive and less widely available than the radiograph or the ultrasound.

### What is the role of the imaging in the diagnosis of the acute abdomen?

The imaging provides the information needed to distinguish the medical conditions from the surgical conditions. It provides the evidence of the disease process and the location of the disease, which is needed to plan the treatment.

### What is the role of the clinician in the imaging of the acute abdomen?

The clinician is responsible for the interpretation of the imaging and the recommendation of the treatment. The clinician should be aware of the limitations of the imaging and the need for the escalation to the specialist or the advanced imaging.

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- [Veterinary Diagnostic Plan Development: A Step-by-Step Guide](/knowledge/veterinary-medicine/clinical-skills-training/veterinary-diagnostic-plan-development-step-by-step)
- [Equine Diagnostic Imaging: Radiography, Ultrasound, and Advanced Modalities](/knowledge/veterinary-medicine/equine-care/equine-diagnostic-imaging-radiography-ultrasound-advanced-modalities)
- [Toxicology in Emergency Practice: Common Poisons and Diagnostic Approach](/knowledge/veterinary-medicine/emergency-critical-care/toxicology-emergency-practice-common-poisons-diagnostic-approach)

## References and Further Reading

- [Pet Care](https://www.avma.org/resources-tools/pet-owners). American Veterinary Medical Association.
- [AAHA Guidelines](https://www.aaha.org/resources). American Animal Hospital Association.
- [Global Guidelines](https://wsava.org/global-guidelines). World Small Animal Veterinary Association.
- [Merck Veterinary Manual](https://www.merckvetmanual.com/). Merck Veterinary Manual.
- [Cornell University College of Veterinary Medicine](https://www.vet.cornell.edu/). Cornell University.
- [Animal Health and Welfare](https://www.woah.org/en/what-we-do/animal-health-and-welfare). World Organisation for Animal Health.
- [Using Artificial Intelligence to Predict Survivability Likelihood and Need for Surgery in Horses Presented With Acute Abdomen (Colic).](https://pubmed.ncbi.nlm.nih.gov/32534764). Journal of equine veterinary science, 2020.
- [Spectral detector computed tomography imaging of histologically confirmed splenic pathologies in 30 canine patients: a comparison of virtual non-contrast images and true unenhanced images.](https://doi.org/10.3389/fvets.2025.1645439). 2025.
- [Case Report: Partial neurectomy and limb-sparing treatment for SOX-10 expressing epithelioid malignant nerve sheath tumour of the tibial nerve.](https://doi.org/10.3389/fvets.2026.1773674). 2026.
- [Clinical features and imaging findings for a mediastinal hemangiosarcoma in a dog.](https://pubmed.ncbi.nlm.nih.gov/41586149). 2026.
- [Multimodal Imaging of Systemic Metastatic Myocardial and Vascular Calcification Associated with Renal Secondary Hyperparathyroidism in a Castrated Male Cat with End-Stage Chronic Kidney Disease: A Case Report.](https://doi.org/10.3390/ani16081169). 2026.

> This article is educational and is not a substitute for veterinary diagnosis or treatment. Contact a veterinarian for advice about an individual animal.