Low Anterior Resection

A low anterior resection is performed to treat cancer of the rectum (the lowest part of the large bowel) when the cancer does not involve the anal sphincter muscles. You may have radiotherapy or chemoradiation (chemotherapy and radiotherapy) to shrink the cancer beforehand to make the cancer easier to remove and decrease the chances of it coming back later on.

During this procedure, the part of your rectum containing the cancer is removed, usually with part of the sigmoid colon as well. Blood vessels and lymph nodes supplying the affected area are also removed. The two healthy ends of the remaining colon and rectum are then sewn or stapled together to form a join called an anastomosis. Sometimes it is necessary to divert faeces to the outside of the body (an ileostomy) to allow recovery. For patients with weakened anal muscles, a slightly different procedure is performed to remove the cancer and avoid the risk of bowel incontinence after surgery. You will have the opportunity to discuss fully all the risks and benefits of your operation with me before signing your consent form.

Resection with Anastomosis

In nearly all cases, a low anterior resection is planned as a minimally invasive (laparoscopic or robotic) procedure. The operation is performed using instruments inserted through several small cuts on your lower abdomen.These cuts are about 1–1.5 cm long, but one cut (near the pubic bone) is longer because the diseased portion of the rectum needs to be brought through to the outside of the body and removed without damaging the remaining parts of the rectum and sigmoid colon.

A small video camera is passed through one of the cuts so that the inside of the abdomen can be seen on a TV monitor, and special surgical tools are passed through the other cuts to free the rectum and colon from the surrounding tissue. Carbon dioxide gas is used to slowly inflate the abdomen and give a clearer view of the rectum and sigmoid colon.

There are many delicate structures near the rectum that need to be protected and this is achieved by precision surgery. The blood vessels to the rectum and sigmoid colon are sealed and cut by special surgical instruments so the amount of blood loss is minimal.

A surgical drain is sometimes placed near the anastomosis. This is a thin tube that comes through the abdominal wall to the outside. As a last step, the wounds are closed with dissolvable stitches, followed by application of surgical glue that makes the wounds watertight.

You will be given a long-acting antibiotic in the anaesthetic room and an injection of local anaesthetic before you leave the operating theatre. The whole surgical procedure takes 1–4 hours, depending on complexity and patient factors.

There is a 5% chance of a planned low anterior resection that starts as a laparoscopic procedure needing to be switched to an open one. This involves making a single long (25 cm) incision on the lower abdomen to access the rectum and using surgical tools directly to free the rectum from the surrounding tissue and cut out a portion of the rectum and sigmoid colon. Again, the procedure takes 1–4 hours, depending on complexity and patient factors. This is most likely to occur in patients who are obese and in those who are found to have an obstruction or have adhesions from previous surgery.

The portion of rectum that has been removed is sent to the pathology department where the pathologist carefully examines it.

A low anterior resection is done under general anaesthesia, so you will be asleep and feel no pain. You will need to fast from midnight on the night before if your surgery is scheduled for the morning, or from 7 am if it is scheduled for the afternoon.

Full bowel preparation at home is needed before a low anterior resection. This entails you taking a special laxative to clear your bowel completely on the day before your surgery. You will receive detailed instructions on how to do this before your procedure. The preparation may also include a low-fibre diet. The following website explains in detail what you can eat and drink on a low-fibre diet ( You will be given detailed instructions on what you need to do and the medication needed in advance of your admission.

After your operation

After your surgery, you will be taken to the recovery area and then to the ward. When you wake up, you will have several tubes attached to your body, including an intravenous infusion tube in your arm to give you fluids and any necessary drugs, a catheter in your bladder to drain urine, and a drainage tube coming from the operation site to remove any oozing fluid. Most or all of these tubes are removed after 24 hours. Supplementary oxygen is given by nasal prongs. Antibiotics are not generally necessary after a low anterior resection, but are given in some circumstances, particularly if the surgery has been performed as an emergency.

Some discomfort is common after surgery when your local anaesthetic wears off. The anaesthetist will decide on the method of postoperative pain relief that is best for you. Oral painkillers are all that is needed in most patients, but some require intravenous analgesia and a small number need an epidural. An epidural is often useful in emergency surgery where an open operation has been performed. It is rarely needed for laparoscopic or robotic surgery. Intravenous analgesia can be provided by a patient-controlled analgesia device, where a drip in your arm is connected to a syringe of pain-killing medication within a box. When the patient presses a button, a small dose of medication is pushed into the drip. There is a lockout that make it impossible to overdose. When you are discharged, you will be given pain medication to take home. It is best to keep taking this medication until the discomfort is manageable.

You can eat and drink as you wish after the operation, and if there is no problem with drinking, the drip providing fluid will be stopped. Some patients feel a little nauseous after eating and drinking soon after their surgery. In these patients, we wait a little longer before introducing food and fluid and keep the fluid drip going. You will be mobilised on the day following your surgery. The stay in hospital after a low anterior resection is around 3–5 days, but you may need to stay in longer if, for example, the join in the bowel leaks or the bowel is slow to start working again after surgery. If you have been given a temporary stoma to divert the faeces, you will stay in hospital until you are happy you can manage this stoma by yourself (5–8 days).

Many people find that their bowel function returns to normal within about 3 days, and they can resume their normal diet at that time. Eating a balanced diet after your operation will aid your recovery. You may also be given medication to thicken or loosen your stools as needed.

You will not be able to drive when you are discharged from hospital, so it is important to arrange a friend or relative to take you home. When patients can resume driving after this type of surgery is determined on a case-by-case basis. This is usually 2 weeks, but will be discussed with you after your surgery. Most people need longer before they can safely, forcefully, and quickly press the emergency footbrake to avoid a potential incident whilst driving. Please let your insurance company know when you have been given the all-clear to resume driving.

When you get home

Many people feel tired and weak after major surgery of this type, and full recovery may take up to 2 months. When you get home, you will need someone to help with meals, housework, and shopping. For the first week or two you may tire easily, so try to alternate short periods of light activity and rest in bed, taking care not to spend too much time lying down because of the risk of developing a blood clot in your legs (deep venous thrombosis).

Do not lift anything heavy, such as children, groceries or washing, or do strenuous work like digging the garden or lawn mowing for the first 6 weeks. You may resume intercourse when you wish.

You may get some pain off and on around your wound for several months, especially as you start to move and exercise more. This is to be expected. Taking a mild painkiller regularly will help with this. If the pain does not seem to improve or you are worried, contact your GP or our colorectal nurses.

How soon you can return to work following this type of surgery depends on what type of work you do, and this will be discussed with you after your operation.

The laboratory report is usually available within 2 weeks of the operation and will be discussed with you, along with any further treatment needed, at your next appointment, which will be 2 weeks after your procedure. If you have any questions or concerns about your surgery, please contact my office.

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