Field Diagnosis of Choanal Atresia



Video available online

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to view videos of these procedures.





Figure 34.1 Sagittal section through the head of an alpaca cria demonstrating the atretic tissue occluding the nasopharynx.

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Figure 34.2 Obstruction of the nasopharynx results in breathing patterns associated with flaring of the nostrils and opening of the mouth.

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EQUIPMENT NEEDED


The following equipment is needed: 12-mL syringe, red rubber feeding tube (10 to 14 French), loose cotton, mirror, normal saline, pediatric bronchoscope (optional), radiographic equipment (optional), and radiopaque contrast material (optional).


RESTRAINT/POSITION


Sternal recumbency (cushed posture) or lateral recumbency is used. Sedation is not recommended unless orotracheal intubation is also done.


TECHNICAL DESCRIPTION OF PROCEDURE/METHOD


Crias suspected of being affected with choanal atresia can be difficult to make an accurate diagnosis because of the small size of the head and nasopharynx and because of the location of the obstruction. The obstruction is normally located 8- to 10-cm caudal to the nares and at the level of the medial canthus of the eye. If clinical signs are consistent with choanal atresia, then confirmatory tests should be done before euthanasia is opted. There are six readily performed clinical tests to determine if complete obstruction of the nasal passageway is present. These tests are most useful when complete (bilateral) choanal atresia exists. In the rare cases of unilateral choanal atresia, false test results can easily occur with the exception of endoscopy.


Follow these steps:



1. Hold loose cotton fibers (pulled from a cotton ball) in front of the nares and observe for movement. This test has a high risk of false negatives (air movement present) and false positives (air movement absent) because of ambient conditions.

2. Place a mirror immediately in front of each nares and observe for fogging on the mirror. This test has a high risk of false positives (fogging absent) because of ambient conditions.

3. Pass a small red rubber feeding tube (catheter) along the ventral and common meatus of the nasopharynx (Video 34.2: Red rubber catheter test for choanal atresia). If the nasopharynx is open, the tube can be passed into the esophagus or trachea. If the nasopharynx is obstructed, the tube will stop, usually at the level of the eye. This test has a risk of false negatives (tube coils up in the nasopharynx and gives impression of being passed) and false positives (tube displaces into the dorsal meatus and stops in the dorsal pharyngeal recess).

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Nov 6, 2016 | Posted by in GENERAL | Comments Off on Field Diagnosis of Choanal Atresia

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