Secondary Abdominal Approaches
Alternative surgical approaches to access the most oral limits of the
descending colon include left paramedian (De Oliveira et al 2009)
or left flank laparotomy (Turek et al 2019). In both instances,
an initial ventral midline celiotomy was used for exploration, diagnosis
and localization of the obstruction, and determination that it was not
accessible through a ventral midline approach. In the De Oliveiraet al (2009) report, sufficient exposure of the affected
descending colon for enterotomy through the secondary paramedian
approach was facilitated by elevating the obstructed segment of the oral
descending colon by a surgeon with their arm through the ventral midline
incision. The details of the location and surgical technique left flank
laparotomy approach in Turek et al (2019) were not sufficiently
described to determine if it was a paramedian approach while the horse
was in dorsal recumbency or if the horse was repositioned into right
lateral recumbency (after closing the original celiotomy incision).
Other reports describing flank laparotomy for descending colon lesions
were based on financial or patient constraints and flank laparotomy was
not performed to improve access to the oral or aboral limits of the
descending colon (Herbert et al 2021). A right flank laparotomy
was used to access an obstruction within the descending duodenum when a
ventral midline approach was not successful (Durham 1998).
For very aboral descending colon obstructions, either a paramedian
approach or a parainguinal approach (Barrett and Munstermann 2013; Tureket al 2019) can be used to improve access for exteriorization.
Similar to the secondary paramedian approach described by De Oliveiraet al (2009), elevation of the descending colon to a parainguinal
or parainguinal incision can be facilitated by a surgeon with their arm
through the ventral midline incision. Barrett and Munstermann (2013)
utilized a right parainguinal approach for their surgery; however, they
comment that a left parainguinal approach may be more advantageous based
on the descending colon anatomy (Barrett and Munstermann 2013; Klohnen
2013). The sidedness for the parainguinal incision could be determined
in surgery via a ventral midline celiotomy or through manipulation of a
palpable obstruction via rectal palpation based on which side allows
easier elevation, as well as the preferences of the surgeon (which
depends on their handedness and where they stand relative to the horse
(caudal or craniolateral)).