Introduction:
Abdominoperineal resection (APR) a surgery to treat rectal cancers by removing the sigmoid colon, rectum, and anus (anal sphincter complex). Patients undergoing APR will need a permanent colostomy. A colostomy is a procedure that creates an opening in the large intestine through the abdomen for the stool to drain into a bag or pouch.
APR is done in conjunction with chemotherapy and radiotherapy, and different types of APR approaches are available to treat rectal cancers; in recent times, conventional open APR has been replaced with laparoscopic and robotic-assisted colorectal surgery, which offers less blood loss, reduced length of hospital stay, and minimal wound infection rate. Another new technique that has gained popularity is the extra levator abdominoperineal excision (ELAPE); due to its reduced recurrence and improved survival rate, ELAPE is accepted as the preferred technique for low rectal cancers.
What Is Rectal Cancer?
The rectum is the last 18 to 20 inches part of the large intestine located between the sigmoid colon and the anal canal. It is straight in shape and serves as the temporary storehouse for feces. When cancer begins in the rectum, it is known as rectal cancer. In patients with rectal cancer, the healthy cells in the rectum undergo mutations (changes in the deoxyribonucleic acid sequence) which signal the cells to grow uncontrollably. The mutated cells grow and combine to form a mass called a tumor.
The tumor continues to grow and destroys the surrounding healthy tissue causing abdominal pain, weakness, weight loss, etc.; if left untreated, it can lead to life-threatening conditions. Depending on the type and the extent of the cancer, the surgeon will perform either abdominoperineal resection (APR) or total mesorectal resection (TMR) of the tumor, either with or without adjuvant chemotherapy and radiation therapy.
What Are the Eligibility Criteria for APR?
It is indicated in patients who meet the below-mentioned criteria:
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The tumor involves the local structures like the external sphincter.
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The anal verge should be less than five centimeters. The anal verge is where the anal canal meets the outer skin.
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It is preferred for patients in whom it is impossible to achieve a negative distal margin. A negative distal margin is when no cancer cells are at the edge of the tissue, indicating that the entire cancer has been removed.
APR is also performed in Fournier’s gangrene, inflammatory bowel disease, and fecal incontinence patients. This procedure is not indicated in patients who suffer from comorbid conditions like obesity, poorly controlled diabetes, immunosuppression, frailty, etc. It is also not preferred in patients unfit for general anesthesia and at high risk for post-op complications.
What Tests Are Done Before APR?
All patients are thoroughly evaluated before the procedure. The first step is to diagnose the underlying medical condition for which APR is being performed. For example, if the clinician suspects rectal cancer based on the patient's symptoms, they will ask for a colonoscopy or a biopsy. After confirming rectal cancer, to evaluate the spread of rectal cancer, further investigations are done; they are:
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Complete Blood Count (CBC)- It gives the number of different types of cells in the body. A low red blood count in the CBC indicates blood loss due to the tumor, and a high white blood cell count suggests an infected tumor.
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Chemistry Panel to Measure Organ Function- Along with the red and white blood cells, the patient's blood sample can also be used to assess the function of different organs. For example, increased levels of albumin indicate liver involvement in cancer, and increased levels of creatinine suggest problems in the kidney due to the underlying pathology.
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Carcinoembryonic Antigen (CEA)- Carcinoembryonic antigen is a tumor marker found only in colorectal cancer patients. CEA testing helps to diagnose and monitor the treatment in patients with rectal cancer.
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Computed Tomographic (CT) Scan of the Chest- Helps to determine the extent of cancer spread in organs like lungs and liver.
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Magnetic Resonance Imaging (MRI) of the Pelvis- It is done to map out the outline of the surgical resection.
The surgeon might also request additional tests like electrocardiogram (ECG), spirometry, transthoracic echocardiogram (TTE), and cardiopulmonary exercise testing to evaluate cardiovascular and respiratory fitness. If the APR is done for Fourier gangrene or inflammatory bowel disease, the diagnostic test will be a computerized tomography (CT) scan and an endoscopy, respectively. CBC, chemistry panel, ECG, etc., are common tests before surgery and are not specific to APR.
How Is APR Done?
The procedure can be done through an open approach (which involves one large incision) or a laparoscopic approach (which includes several small incisions). Recently robot-assisted abdominoperineal resection is also being performed, which involves a robotic surgical system operated by the surgeon sitting in front of the control panel.
Irrespective of the approach, the procedure is done in three steps, they are:
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Abdominal Operation- After general anesthesia, a midline incision is made in the abdomen, and the surgeon will survey the abdomen and locate the tumor. The next step is to separate the blood vessels supplying the tumor and ligate them, followed by mobilization of the sigmoid colon and the rectum from the large intestine.
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Perineal Operation- The areas between the anus and the scrotum (in the case of males) or clitoris (in the case of females) are known as the perineal area. This is exposed by separating the buttocks, and an incision is made to expose the pelvic floor. The mobilized sigmoid colon, the rectum, the tumor, and the anal canal are brought through the perineal incision, and the anus is sutured off.
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Colostomy- A trephine (hole) is made in the skin that extends to the inner abdominal peritoneum. The free end of the large intestine transected from the sigmoid colon is extruded through the trephine. Its edges are sutures to the trephine border, thereby creating a stoma (opening). A pouch, also called an ostomy bag, is inserted through the opening, which collects the gas and stool. The bag must be worn at all times because there is no control over the waste elimination from the body.
What Are the Complications Of APR?
Abdominal perineal resection is an elaborated procedure that always includes postoperative complications, some of which are:
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Bleeding and delayed wound healing.
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Infection either from the stoma or the incision site.
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Perineal hernia, which is a hernia of the pelvic floor, is occasionally seen in patients and will need to be addressed with a hernia repair.
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Sexual and urinary dysfunction.
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Complications of anesthesia, like paresthesia, can also be seen occasionally.
Conclusion:
Abdominoperineal resection is a major surgery requiring extensive planning and an efficient multidisciplinary team. The team should comprise surgeons, oncologists, radiologists, histopathologists, and stoma care nurses. In addition, the patient should be counseled about nutrition and stoma care post-operatively. Recovery from APR takes time, resilience, and effort from the patient, and a better understanding of the procedure and complications helps the surgeon provide better patient outcomes.
