Imaging, Endoscopy, and Other Diagnostic Procedures for the Acute Abdomen

CHAPTER 83 Imaging, Endoscopy, and Other Diagnostic Procedures for the Acute Abdomen

Acute abdominal pain, or colic, is commonly seen in horses, and the clinical signs of colic are often similar, irrespective of the various underlying causes. Because the causes of colic are numerous and usually, but not exclusively, involve the gastrointestinal tract, accurate and timely diagnosis is crucial for initiating appropriate medical and surgical treatment and achieving a successful outcome. A complete and methodic diagnostic approach that encompasses information obtained through history and physical examination, clinicopathologic testing, and diagnostic imaging is essential to achieve this goal.



Abdominal Ultrasonography

Abdominal ultrasonography in foals and mature horses is extremely useful, not only in horses with acute abdominal pain but also in those with recurrent colic and weight loss. Ultrasonography enables evaluation of structures that are relatively inaccessible to examination by other diagnostic imaging techniques, such as radiography and endoscopy, and subsequently has become a mainstay in diagnostic testing in horses with colic. Abdominal ultrasonography not only provides valuable structural information but also permits characterization of peritoneal fluid location, volume, and consistency and may guide other diagnostic techniques, such as abdominocentesis and biopsy.

Abdominal ultrasonography can be performed transcutaneously or transrectally, and techniques vary in terms of preparation required, equipment needed, and structures that may be identified. A combination of both techniques may be required to obtain optimal results. Transcutaneous ultrasonography requires lower-frequency transducers; most commonly, frequencies of 2.5 to 5 MHz are needed, but probes operating at 5 to 10 MHz may be useful in foals and smaller, thinner, mature horses. Use of a higher frequency allows better anatomic detail and resolution but less tissue penetration, whereas use of a lower frequency allows deeper tissue penetration but lower resolution. Convex or sector transducers are most appropriate and allow easier access and positioning between ribs. Ideally the horse’s hair should be clipped, the skin cleansed thoroughly, and coupling gel applied, although images can be obtained in most horses without clipping. The entire abdomen and caudal part of the thorax should be imaged. Structures that may be imaged include the stomach, duodenum, jejunum, ileum, cecum, large colon, liver, spleen, and urogenital tract.

Transrectal ultrasonography is performed with a linear or small convex transducer with a frequency of 5 to 10 MHz. Preparation of the horse is similar for rectal palpation and necessitates adequate restraint, sedation, rectal relaxation, lubrication, and evacuation of feces from the rectum. Structures that may be imaged are similar to those that may be palpated during rectal palpation.

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May 28, 2016 | Posted by in EQUINE MEDICINE | Comments Off on Imaging, Endoscopy, and Other Diagnostic Procedures for the Acute Abdomen

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