Background
Acute appendicitis (AA), a common intra-abdominal surgical pathology, requires a comprehensive understanding of its presentation, evaluation, diagnosis, and overall operative management. In the United States, the annual incidence of AA is approximately 9.4 per 10,000 population, [1] with a mortality of 0.2-0.8%. [2] The morbidity and mortality are related to the presenting stage of the disease and are substantially higher in cases of perforation.
Briefly, the pathophysiology and progressive timeline of AA are attributed to the following:
-
Luminal obstruction causing distention
-
Ineffective venous and lymphatic drainage
-
Bacterial invasion
-
Perforation with associated leakage of contents into the peritoneal cavity
The presentation, evaluation, and diagnosis of AA are notoriously inconsistent, with a multitude of factors contributing to these discrepancies. The classic history consists of anorexia and periumbilical pain, followed by nausea, right-lower-quadrant (RLQ) pain, and vomiting, as well as leukocytosis. [3] The history and physical examination should provide enough clinical information to diagnose AA, with the use of imaging modalities as adjuncts in the assessment.
Treatment consists of providing aggressive intravenous fluid resuscitation and antibiotics, placing the patient on nil per os (NPO) status, providing pain control, and obtaining a general surgical consultation for definitive operative management. Increasing evidence suggests that in many patients with uncomplicated acute AA, antibiotic therapy may be as effective as surgical treatment. [4, 5] Endoscopic retrograde appendicitis therapy (ERAT) also appears to be a promising noninvasive treatment modality for uncomplicated AA. [6]
The operative approach to AA consists of appendectomy (surgical removal of the vermiform appendix); however, the choice between an open and a laparoscopic operation continues to be debated in the medical literature. [7, 8, 9] The RLQ incision of open appendectomy has persisted essentially unchanged since it was pioneered by McBurney in the 19th century. [10] The use of laparoscopy in the surgical management of AA was first described in 1983, and there is an ongoing trend toward increased use of this approach. [11]
As with other laparoscopic surgical procedures, the literature describes decreased pain, earlier resumption of diet, and decreased length of hospital stay for laparoscopic appendectomy versus the equivalent open procedure. [9, 12, 13] However, this must be objectively considered in the light of the current state of the open procedure, which already engenders minimal risk and is associated with an extremely short hospital stay and a low complication rate. Additional disadvantages of laparoscopy include increased cost and longer operating times.
The authors' institution, a residency training facility, uses the laparoscopic approach to AA (as do most US facilities), but surgeons must continue to understand and be capable of successfully performing open appendectomy. Open appendectomy is described in this article; for a description of the laparoscopic approach, see Laparoscopic Appendectomy.
Indications
Ever since being described by McBurney, [10] open appendectomy has been a well-established and widely performed operation indicated for patients with AA. Open appendectomy carries minimal risk and has an extremely short length of hospital stay. [7, 9, 14]
Open appendectomy is indicated when the surgeon or patient prefers an open procedure to a laparoscopic procedure or when the laparoscopic approach is contraindicated. Developing preoperative criteria is crucial in deciding the ideal operative approach for individual patients with AA. [15] Young age (pediatric patients), morbid obesity, and pregnancy are no longer specific indications for an open procedure. [16, 8, 17, 18, 19, 20, 21, 22, 23, 24, 25]
Contraindications
Contraindications for the laparoscopic approach include the lack of surgical expertise and necessary equipment, severe pulmonary disorders (eg, chronic obstructive pulmonary disease [COPD] and interstitial lung diseases), a bleeding diathesis, severe heart failure, portal hypertension, intolerance of (ie, hypotension due to) Trendelenburg positioning, poor visualization, and severe adhesive disease from previous abdominal surgical procedures. [15]
Technical Considerations
Anatomy
The appendix is an elongated outpouching of the cecum found at its posteromedial aspect, about 2.5 cm below the ileocecal valve. It is derived embryologically from the midgut, first noted between weeks 5 and 8 of gestation. [26] It subsequently becomes fixed in the RLQ of the abdomen as the gut rotates during development. [26]
Histologically, the walls of the appendix contain not only mucus-secreting goblet cells but also lymphoid tissue (developed during weeks 14 and 15 of gestation), implying immune function in early development. [26] Nevertheless, no specific function in the adult could be determined.
The base of the appendix can be identified during surgery by following the convergence of the taeniae coli toward the inferior portion of the cecum, forming a continuous muscular layer surrounding the appendix. The position of the appendicular tip is inconstant and can be situated in the following locations [27] :
-
Retrocecal (65%)
-
Descending pelvic (31%)
-
Transverse and retrocecal (2.5%)
-
Ascending, paracecal, and preileal (1%)
-
Ascending, paracecal, and postileal (0.4%)
The variance in location explains the vast array of presentations.
The blood supply of the appendix is derived from the appendicular artery, originating from the iliac ramus in 35% of cases, the division of the ileocolic artery in 28%, the anterior cecal artery in 20%, the posterior cecal artery in 12%, the ileocolic artery in 3%, and the ascending colic ramus in 2%. [28] The venous drainage parallels that of the arterial supply.
Structures associated with the appendix include the mesoappendix and the fold of Treves. The mesoappendix contains the appendicular nerves and vasculature; this structure is ligated during an appendectomy. The fold of Treves, another useful anatomic landmark in locating the appendix during surgery, not only represents an avascular structure but also is the only epiploic appendage located at the antimesenteric border of the small intestine. [29] In addition, it serves as a marker indicating the junction of the ileum and the cecum.
-
Open appendectomy. Skin incision is based on McBurney point, which lies one third of distance along imaginary line between right anterior superior iliac spine (ASIS) and umbilicus. Incision is made through this point perpendicular to this line (McBurney-McArthur) or horizontally (Lanz). Incision extends 3-5 cm along skin creases.
-
Open appendectomy. Dissection through both superficial (Camper) and deep (Scarpa) fascia. External oblique aponeurosis is exposed and incised in direction of fibers.
-
Open appendectomy. External oblique muscle is split bluntly by using alternating Kelly clamps and Roux retractors.
-
Open appendectomy. Sequence of muscle splitting and retraction is repeated with fascia of both internal oblique muscle and transversus abdominis to expose transversalis fascia and peritoneum.
-
Open appendectomy. Transversalis fascia and peritoneum are grasped with 2 straight clamps, with palpation between surgeon's fingers, and with care taken to avoid entrapment of any underlying structures. Incision is made with Metzenbaum scissors, and peritoneal cavity is entered.
-
Open appendectomy. In antegrade approach, ascending colon and its taeniae coli are identified and followed to their convergence, identifying base of appendix. Appendix-mesoappendix complex is freed from its adjacent, often inflamed, tissue and delivered into wound. Mesoappendix, containing appendiceal artery, is ligated (3-0 Vicryl 2 times) and separated from appendix.
-
Open appendectomy. Completion of appendectomy by division of appendix between 2 ligatures, closer to cecum.
