Page 59 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery

Endoscopic examination of the choana and nasopharynx
WARNING
is performed initially, because this is easy, rapid, unlikely to
VetBooks.ir may provide a diagnostic sample (Willard and Radlinsky, Nasal biopsy using any technique will result in
cause iatrogenic trauma and subsequent bleeding, and
haemorrhage that can be severe. Identification of
1999; McCarthy, 2005; Johnson et al., 2006). Examination
coagulopathies prior to nasal biopsy is essential
is most easily performed with a retroflexed endoscope but
a rigid telescope with a 120-degree lens may also be used.
Alternatively, non-endoscopically guided transnasal
Diagnosis of choanal atresia, nasopharyngeal stenosis,
caudal pharyngeal mass lesions, aberrant turbinates or biopsy can be used to obtain diagnostic samples. This is
the fastest and easiest technique, but false-negative
foreign bodies is possible.
results are possible. The distance to the medial canthus of
Anterior rhinoscopy can be performed with a flexible
endoscope or rigid telescope (5 mm in large dogs; 2–3 mm the eye is noted and marked on the biopsy instrument.
Biopsy instruments should not be inserted past this point,
in cats and small dogs) (Willard and Radlinsky, 1999;
to prevent iatrogenic damage to the cribriform plate and
McCarthy, 2005; Johnson et al., 2006). Suction during an brain. Cup biopsy forceps or alligator forceps can be
endoscopic examination is essential to clear blood and
used to grasp tissue blindly; alternatively, a piece of hard
tissue debris from the visual field. Flushing is recom-
plastic tubing or catheter cover cut at an angle can be
mended by some authors; sterile saline is instilled from forced into the nostril and the mass. The tube may
caudal to rostral using a Foley catheter passed over the
be connected to a large syringe to provide suction or used
soft palate or from rostral to caudal by delivery of the solu-
alone. The biopsy sample will be retained within the tube.
tion through the endoscope. Diagnostic samples may be The tube should be redirected and advanced several
collected from the flush.
times to obtain multiple samples.
Guided by imaging-derived localization of abnormal-
Flushing after the biopsy procedure can be used to
ities, the nasal passages should be assessed in a logical remove any tissue fragments left behind and to gather
and standard manner during rhinoscopy. The nasal meati
more tissue samples. A bulb syringe is used to instil
should be assessed for loss of turbinates or inflammatory the flushing solution with pressure into the nostril. For
or neoplastic growth, inflammation and the presence of cats, a small bulb syringe or a 10 ml syringe can be used.
foreign bodies. Samples are collected in a gauze sponge placed within the
Turbinate atrophy, with fungal plaques covering chron- pharynx. Flushing may also be performed regardless of
ically inflamed mucosa, is often visible rhinoscopically in whether or not a lesion is found endoscopically because
animals with Aspergillus spp. infections. The plaques flushing can dislodge occult foreign bodies or provide
usually appear as small flattened greenish-white struc- samples from unobserved lesions.
tures that adhere to the nasal mucosa, and these plaques Flushing can also be used as the sole biopsy tech-
may be mistaken for foreign bodies. If aspergillosis is nique. This is more successful if done using hydropulsion
suspected but not identified, sinusoscopy or trephination after a mass has been confirmed using a rhinoscope
has been found to be useful in identifying frontal sinus (Ashbaugh et al., 2011). To perform nasal hydropulsion,
involvement (Johnson et al., 2006). Fungal ‘balls’ or granu- one nostril is digitally occluded and a 20–60 ml regular
lomas, especially those caused by cryptococcosis, may luer tip syringe filled with sterile saline is inserted into the
also be found in the nasopharynx (Hunt et al., 2002). contralateral nostril. Prior to forcefully infusing the saline,
Some veterinary surgeons (veterinarians) recommend a towel is placed under the nose, the endotracheal tube
rhinoscopic debridement of fungal material prior to anti- cuff is checked for proper inflation and a Poole suction tip
fungal treatment. is placed at the opening to the oesophagus. Twenty to
sixty millilitres of saline is then rapidly injected under
pressure (<2 seconds). The procedure is repeated (2–3
Nasal biopsy times) until no additional tissue can be dislodged, then the
Nasal tumours usually result in an obvious mass protrud- entire nasal cavity is re-evaluated via rhinoscopy. Tissue
ing into one of the meati and can appear as pink, yellow- is collected from the towel, oral cavity and nasopharynx.
greyish or purple abnormal, often friable tissue that Thorough suctioning of the oropharynx, proximal oesoph-
bleeds easily. Inflammatory masses and polyps, fungal agus, larynx and the proximal trachea around the endo-
granulomas and tumours cannot always be differentiated tracheal tube is performed. Using this technique,
on the basis of radiographic and gross endoscopic diagnostic samples were dislodged from the nasal cavity
appearance, hence nasal biopsy is always indicated to in 90% of dogs and cats (37 of 41) with nasal tumours
obtain tissue samples for histopathological analysis. For (Ashbaugh et al., 2011). Additionally, imme diate relief of
dogs with a documented bleeding tendency or clinico- nasal obstruction was noted in some patients. Minor
pathologically documented def ciency in coagulation or expected postoperative complications include sneezing,
i
platelet function, blood typing and crossmatching (if reverse sneezing and mild epistaxis.
appro priate) should be performed prior to the biopsy of
nasal disease. The location of the biopsy should be PRACTICAL TIP
determined from previous imaging studies and rhino-
Always flush the nasal cavity after biopsy, even if no
scopy. The results of these studies should be available
for evaluation during the biopsy procedure and multiple lesion was identified
samples should be taken from the area of interest. The
most reliable way of taking representative samples is Endoscopic biopsy should be performed at the end of
using rhinoscopic guidance with cup forceps introduced an examination because the field of view is often obscured
into the nasal cavity alongside the endoscope. Cup for- by haemorrhage after the biopsy procedure.
ceps that are passed through the working channel of CT, MRI or ultrasonography can also be used to guide
flexible endoscopes often result in tiny biopsy samples a biopsy procedure. These techniques require general
l
and false-negative results. anaes thesia, special equipment and a thorough know edge

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