Rectal Adenocarcinoma Resected via a Rectal Eversion and Submucosal Resection Technique
Signalment: 11-year-old, MN Siberian husky cross
History:
This dog presented to our ER service with a 6-week history of bloody diarrhea and intermittent bleeding from his rectum. On rectal exam, a mass was palpable on the dorsal aspect of the rectum. There were no abnormalities on either APOCUS or TPOCUS.
Physical exam findings:
9.6 mm x 9.6 mm subcutaneous mass on the dorsomedial aspect of the left carpus. No other abnormalities noted.
Diagnostic and clinical staging tests:
Fine-needle aspirate: poorly exfoliative mast cell tumor (MCT)
CBC: mild anemia (PCV 35%)
Serum biochemistry: increased ALT (250 U/L) and ALP (269 U/L)
Three-view thoracic radiographs: no evidence of lung metastasis
Abdominal and thoracic CT scan: focal enteropathy in the descending colon to rectum, no evidence of intra-abdominal or intra-thoracic metastasis, normal thorax, and several non-specific and insignificant findings in the abdomen
Treatment:
Following induction of anesthesia, the dog was positioned in sternal recumbency and the tail was elevated. The rectal mucosa was everted with five 3-0 PDS stay sutures. Once the mass was exteriorized, a subcmucosal resection was performed with approximately 5 mm lateral margins. The rectal mucosa was then sutured with a single layer of 3-0 Monocryl in a simple continuous suture pattern.
Outcome:
Grade I rectal adenocarcinoma with complete histologic (R0) excision, 4.7 mm histologic tumor-free lateral margins and 3.0 mm deep margins
No evidence of local recurrence 4 months postoperatively
Notes:
There are three different surgical approaches for management of rectal carcinomas: rectal pull-through, rectal mass resection via a dorsal inverted U-approach, or rectal eversion and submucosal resection. Rectal resection and anastomosis via a dorsal inverted U-approach is only indicated for focal lesions in the region of the dorsal rectum. Rectal pull-through procedures are associated with a high risk of fecal incontinence and rectal stricture formation (see https://pubmed.ncbi.nlm.nih.gov/25181273/). The trend is to be more conservative with resection of rectal masses, typically through a rectal eversion (or transanal) and submucosal resection approach. The results for this approach are surprisingly good despite being more conservative. In one study of 93 dogs treated with the approach, the local recurrence rate was 21% and the majority of these were treated with repeat submucosal resection. For dogs with rectal carcinomas, the median survival time was not reached with 1-, 2-, and 5-year survival rates of 95%, 89%, and 73% respectively.
Tags: #rectalcarcinoma #transanal #rectaleversion #submucosalresection
The rectal mass was exteriorized by progressively everting the rectal mucosa using 3-0 PDS stay sutures.
Once exteriorized, an incision was made into the rectal mucosa and the rectal mucosa was undermined deep to the rectal mass. The mass was then resected by incising around the mass and the rectal mucosa with Metzenbaum scissors with approximately 5 mm lateral margins.
Once resected, bleeding was controlled with electrosurgery and then the rectal mucosal incision was closed in a single layer with a simple continuous suture pattern using 3-0 Monocryl.
The completed closure of the rectal mucosal defect.
The appearance following release of the stay sutures. The discharge instructions for these cases are one of the easiest to follow because there is no exercise restriction and no sutures to remove!