・Case history
A 64-year-old man with no medical history received a positive stool test
for fecal occult blood. The patient showed no notable abnormal findings
on upper gastrointestinal endoscopy. He subsequently underwent
colonoscopy and was found to have a mass lesion approximately 2 cm in
diameter at the lower rectum (Figure 1). Endoscopic evaluation of lesion
invasion suggested infiltration into the deep submucosal layer. A biopsy
revealed a histopathological diagnosis of moderately differentiated
tubular adenocarcinoma. Rectal examination of the lesion showed that the
lower edge of the lesion was about 3 cm away from the dentate line and
had good mobility (Figure 1). No other gross lesions were noted after
examining the entire large intestine. No notable abnormal findings were
observed in terms of general biochemistry, complete blood count, or
coagulation test. Tumor markers, including carcinoembryonic antigen and
carbohydrate antigen 19-9 levels, were also within normal ranges.
Computed tomography showed no clear localization of the rectal mass and
no significant lymphadenopathy around the lower rectum. None of the
findings suggested obvious distant metastasis. Based on the mentioned
findings, we determined that surgical resection was indicated for this
lesion. Furthermore, based on the positional relationship between the
mass and the dentate line, we determined that ISR was appropriate and
decided to perform laparoscopic ISR considering that the patient had no
history of laparotomy. The patient was placed in the lithotomy position
intraoperatively with his head low. We started the surgery via the
transanal procedure. Accordingly, we applied the Lone Star RETRACTOR™
all around the anal canal and observed the inside of the rectum. As
shown in the preoperative examination findings, the dentate line was 3
cm away from the lower edge of the mass. We dissected all layers of the
rectum with a 2 cm margin from the inferior margin of the mass to the
anal side. We closed the rectal stump on the resected side with a
nodular suture, after which we entered the layer between the internal
and external sphincters and proceeded with the detachment of the pelvic
muscles to the extent that the prostate was palpable on the ventral side
and the coccyx on the dorsal side. After peeling to that depth, we
prepared three pieces of gauze, which was soaked in a liquid prepared by
dissolving 25 mg of ICG in 10 mL of water containing sodium arginine
with a concentration of 6 mg / ml, and then sufficiently squeezed out
the moisture and carefully spread it all around the deepest parts so
that they were in the same layer (Figure 2). Thereafter, we proceeded
with laparoscopic manipulation starting with five ports. We proceeded
with detachment from the inside of the sigmoid mesentery and dissected
the lymph nodes around the root of the inferior mesenteric artery (IMA).
We then dissected the IMA at the height immediately after the left colic
artery diverged and then performed rectal and mesenteric detachment. As
we peeled the rectum from the front of the sacrum and proceeded toward
the anus, we encountered the levator ani muscle. After switching the
scope to the near-infrared observation mode while further peeling toward
the anus and paying attention to the levator ani muscle, the luminescent
gauze was observed through the back of the tissue. As the fibrous tissue
was exfoliated, the fluorescent gauze gradually became see-through. When
the tissue was further incised with an electric knife at the site where
the fluorescence was strong, the gauze was finally exposed to the naked
eye. We then proceeded with rectal detachment to expose the entirety of
gauze while relying on fluorescent ICG and paying attention to the
prostate, seminal vesicles, and neurovascular bundle, which allowed us
to safely reach the detached layer from the anal side (Figure 3).
Thereafter, we returned to the transanal surgery once more. The
intestinal tract was dragged out of the anus and the sigmoid colon was
dissected to remove the specimen. Afterwards hat, the sigmoid colon and
the residual rectum were sutured with a total of 16 needles around the
circumference with a 4-0 monofilament absorbent thread in all layers and
anastomosed. We then confirmed the absence of intra-abdominal bleeding
via laparoscopy, after which a temporary ileal-covering stoma was
finally constructed and the surgery was completed. The operative time
and blood loss were 293 min and 5 mL, respectively.