Clinical Exercise: McBurney Incision Appendectomy
Scenario:
A 40 year old patient is carried into the emergency room on a stretcher in a position with the knees drawn up and hips flexed. The patient complains of pain localized to the lower right quadrant of the abdomen and his holding the posture to reduce movement and associated pain.
Diagnosis/Considerations:
You conduct a surface examination of the abdomen observing rebound tenderness when the abdomen is pressed and localization of pain at the lower right quadrant is typical of classically presenting acute appendicitis (you will hear more about abdominal surface examination from Dr. Colgan in an upcoming lecture).
The patient is immediately admitted to surgery and of a variety of surgical approaches you select the McBurney incision for the procedure. This incision is commonly used for open appendectomy, heals rapidly, and generally has good cosmetic results.
Mechanism:
Acute appendicitis is the result of inflammation of the inner lining of the vermiform appendix. This condition is common and requires urgent surgical intervention. Delayed intervention is associated with increased morbidity and left untreated has the potential for severe complications including perforation of the appendix, sepsis, and risk of death.
Appendicitis typically occurs as the result of an infection, but can also be the result of an obstruction to the appendix lumen. The only current curative treatment is surgical removal of the appendix.
The appendix is a small 'worm like' extension of the cecum with a size ranging anywhere from 2-20cm in length (typically 5-8cm). The taenia coli muscle bands along the ascending colon converge on the posteromedial side of the cecum at the base of the appendix. Thus, following those bands is a useful way for the surgeon to find the appendix.
Treatment (perform these steps on the donor in a mock-procedure):
PREPARATION: Send a member of your team to the instrument supply tables to fetch a suture packet.
Note: The goal of this clinical exercise is not to actually find (or remove) the appendix, but instead the goal is to appreciate the limited field of view that a surgical intervention has relative to the dissection that you are currently performing. Thus, if you do not find the appendix you will be able to see the structure later in the laboratory session.
Also note that since acute appendicitis is a relatively common condition there is a good chance that your donor may have had the appendix removed when they were younger and there will not be an appendix to find.
1) Replace the muscle and skin flaps of the donor to approximately their normal position
Make the incisions below on the side that you had opened the muscle layers of the external abdominal oblique and inguinal canal.
2) Make an incision through the skin and fascia 5-6cm long parallel to the inguinal ligament trajectory at the 'McBurney point' exposing the muscle wall.
This point is one third of the distance from the anterior superior iliac spine to the umbilicus.
This incision should be approximately in line with where your previous incision in the external abdominal oblique was located.
3) Use the skin spreader (Weitlaner Retractor) to spread and hold the skin incision open and move the external abdominal oblique fibers apart.
You have already made an incision in these fibers so a blunt movement is all that is needed (in the living the muscle fibers can also be bluntly separated).
4) Bluntly separating fibers of the internal abdominal oblique and transversus abdominis muscles exposes the transversalis fascia.
5) Using forceps lift the transversalis fascia and with scissors make a 5-6cm incision through the transversalis fascia and peritoneum giving an opening into the abdominal cavity.
6) Have part of the team hold the opening wide with probes such that the team can examine through the opening and move structures with a blunt probe or finger.
What you are seeing is the caecum region of the large intestine. Do not cut/tear anything you are seeing, just move structures with a blunt probe.
7) Examine towards the inferior end of the caecum looking for a long thin protrusion that would be the appendix.
Note how difficult the field of view is through a surgical sized opening relative to the wide dissection fields you have been using in the anatomy class.
8) Reflect the skin out of the way and have a second look through the McBurney incision for the caecum and appendix.
9) When finished exploring through the opening, using your suturing skill close just the opening in the muscle layers of the abdominal wall with 3-4 sutures evenly spaced.
Neat even spacing of your sutures would assist the muscle wall to heal in the living.
NOTE: when finished suturing ensure that all suture needles are collected into one of your trays and transported to the sharps containers for safe disposal.
Outcome:
The appendix was removed alleviating the acute condition. The patient recovers from the surgery and there is minimal scarring from the incision.
Images from eMedicine