Rectum amputation with swing flapMedical editor Stein G. Larsen MD
Oslo University Hospital
A rectum amputation, or abdomino perineal resection (APR), is performed when tumor is situated so low that the sphincter muscle or pelvic floor is infiltrated. In a rectum amputation, the rectum, as well as the anal canal and some of the pelvic floor muscles are removed. The sigmoideum is then used to make a stoma.
If the distance to the tumor is short, an extended rectum amputation (also called a cylindrical rectum amputation) is performed. More of the pelvic floor is removed for this procedure. The defect in the pelvic floor or perianal skin must often be reconstructed with a net or swing flap consisting of muscle and skin. At the Radium Hospital, this is done in collaboration with a plastic surgeon.
There is a higher frequency of local recurrence after a rectum amputation than a after a low anterior resection. The cause of this is somewhat unclear. In the lower part of the rectum, it is very narrow or there is no mesorectal fat. The tumor will therefore quickly infiltrate the pelvic floor muscle if infiltrating the rectal wall. If the infiltration is not macroscopic, this dissection can easily occur in the layer between the rectum and pelvic floor. The tumor may then be perforated and cancer cells released. By stopping the resection toward the pelvic floor from the abdomen earlier, this can be avoided. A cylindrical dissection must be performed in all cases for large, low tumors (T3/T4).
Previously, rectum amputations were performed on 50-60% of rectal cancer cases. After introduction of the total mesorectal resection (TME), the frequency has been reduced to 20-30%. At some foreign treatment centers, about 90% are anastomosized. The percentage depends on how many are irradiated before surgery and whether the most advanced tumors are treated at the hospital or not. It is somewhat unclear how many patients have stool incontinence after very low surgery. Many surgeons therefore prefer a rectum amputation or Hartmann's operation if anal function is reduced.
During the reconstruction phase of the operation, the stoma is made.
- Localized rectal cancer.
- Tumor situated very low and infiltrating the pelvic floor muscle such that the pelvic floor muscle must be removed.
- Palliation in patients with relatively long expected survival time despite distant metastases.
- The patient is prepared for a permanent stoma and its location is marked on the skin.
- Bowel emptying is not necessary if anastomosis is ruled out from the start.
- Thrombosis prophylaxis
- Antibiotic prophylaxis
- Epidural catheter is installed for postoperative pain treatment.
- A bladder catheter is inserted (Foley catheter).
- The patient lies horizontal on the operation table. When the perineal phase will be performed, the patient is turned over to his/her abdomen and the hips are elevated.
- The operation is carried out under general anesthesia.
- The sigmoid colon is mobilized from any adhesions so that a tension-free stoma can be constructed.
- Sharp mesorectal dissection is performed.
- The dissection from above is stopped at the base of the coccygeus, at the attachment of the levator ani muscle on the internal lateral obturator muscle, and as far down behind the vagina/prostate as feasible.
- Coccygeus is separated from the sacrum.
- A sigmoideostomy is made.
- The musculo-cutaneous swing flap (vertical rectus abdominus (VRAM)) is dissected and turned into the pelvis.
- A large compress is placed in front of the sacrum to hold the bowels out of the pelvis and the flap in place.
- A vacuum drain is placed in the pelvis.
- The abdomen is closed.
- The patient is turned to the prone position.
- The anal opening is closed with a purse-string suture and a perianal incision is made in the skin extending up over the coccygeus.
- The dissection goes in the ischiorectal tissue dorsally to the base of the coccygeus and laterally to the attached internal obturator muscle.
- The levator ani muscle is followed from the coccygeus laterally and loosened from the internal obturator muscle.
- The rectum is mobilized and the vesicles/prostate/vagina are identified and dissected from the rectum.
- The urethral catheter is palpated in men and the urethra is avoided.
- The specimen is removed.
- VRAM flap (Vertical rectal abdominal muscle flap) is sutured laterally to the rest of the pelvic floor muscles and in the defect in the perineal skin.
- Vacuum drain is placed deep to the VRAM flap.
- The patient may drink and eat on the first postoperative day.
- The epidural catheter is removed usually on the 2nd-3rd day and the patient obtains an oral analgesic.
- The abdominal drain is removed when there is no longer fresh blood, usually on the 2nd-3rd day. The swing flap drain should be removed when the draining volume is less than 200 ml/day.
- The bladder catheter is kept until the bladder empties spontaneously to prevent a large bladder from pressing on the swing flap thereby reducing its circulation and possible necrosis of the flap.
- Due to the swing flap, the patient should stay in bed for one week and avoid lying in the supine position.
- The patient is usually discharged after 3 weeks.
Complications from surgery
- For rectal amputations, the postoperative mortality rate is 0-3%.
- Cardiopulmonary complications depend on the patient's general health status, the duration and extensiveness of surgery.
- Postoperative ileus occurs in about 5 %.
- Ventral hernias in the abdominal inscision occur relatively frequently.
- Separation of the musculocutanous flap from the skin
- Necrosis of the musculocutaneous swing flap may occur.
Damage to the autonomic nerves in the pelvis can cause:
- bladder paralysis—often temporary
- erection and ejaculation problems
- vaginal dryness