Description of the condition
Abdominal aortic aneurysm (AAA) is an abnormal enlargement in diameter of the aorta. With the ageing of the population, the prevalence of abdominal aortic aneurysm is increasing. The incidence rate is very high among men aged between 65 and 79 years, reaching 5% to 10% (Vardulaki 1999). Untreated AAAs are likely to increase in size and may eventually rupture. Rupture of the abdominal aorta is the most serious complication, which presents as a surgical emergency. Approximately 6000 men a year die from ruptured aortic aneurysm in England and Wales, accounting for about 2% of deaths in men (Earnshaw 2004). Elective surgical or endovascular repair of aortic aneurysms aims to prevent death from rupture.
Description of the intervention
Dubost performed the first successful excision of an abdominal aortic aneurysm via the retroperitoneal route in 1951 (Dubost 1952). However, the retroperitoneal approach, as it was reported by Oudot (Oudot 1951), offered limited exposure. In the following years, most surgeons preferred to use the transperitoneal approach or transabdominal aortic replacement for open infrarenal abdominal aortic aneurysm repair (Creech 1966). The retroperitoneal approach was not forgotten. In 1963, Rob wrote a detailed description of the retroperitoneal approach including its advantages, such as easier postoperative course, and its disadvantages, such as limited exposure (Rob 1963). In 1980, Williams reported an extended retroperitoneal approach, which offers a better exposure not only of the infrarenal but also of the pararenal and suprarenal aorta (Williams 1980). Endovascular repair is now the new choice method to treat abdominal aortic aneurysm as described by a number of reviews and meta-analyses comparing endovascular versus open surgery (Adriaensen 2002; Wilt 2006), although these reviews do not address the different approaches for open surgery. The 30 day mortality for elective endovascular aneurysm repair is lower than for open repair, but long-term mortality has been shown to be similar (Jetty 2010). Because endovascular repair is associated with higher costs, open surgical repair is still an important method for treating abdominal aortic aneurysms.
How the intervention might work
The transperitoneal approach is a very simple approach which allows surgical evaluation of the whole intra-abdominal cavity to deal with concomitant surgical disease such as colon carcinoma. The inferior mesenteric artery and eventually the polar renal arteries could also be repaired, which can be incorporated in an infrarenal aortic graft. The transperitoneal approach is thought to be better for venous anomalies (Nevelsteen 2005). An equal transperitoneal aortic approach to the abdominal aorta can be attained through midline and transverse abdominal incisions. Because there are no statistically significant differences in morbidity through transverse and midline abdominal incisions, the type of incision used can be left to the surgeon's preference (Lacy 1994). However, the transperitoneal approach usually involves intestinal manipulation, mesenteric traction, and blood contamination of the peritoneal cavity, all of which may lead to impaired intestinal motility (Arya 2009). In order to avoid these complications, many doctors prefer to use the retroperitoneal approach. Compared with the transperitoneal approach, the retroperitoneal approach does not require opening the whole intra-abdominal cavity, however it is time consuming and would not be better for emergency cases (Nevelsteen 2005). Although one study reported that respiratory function after aortic aneurysm repair was similar between the two groups (Volta 2003), other studies have reported that patients who had abdominal aortic aneurysm repair using the retroperitoneal approach had fewer postoperative respiratory complications, reduced incidence of intestinal obstruction, reduced intubation time, and decreased hospital stay and costs (Helsby 1975; Leather 1989; Taheri 1983). Moreover, several similar prospective randomized studies of the two approaches for aortic surgery have been performed, with conflicting results (Cambria 1990; Sieunarine 1997; Taheri 1983).
Why it is important to do this review
This review will draw together the available evidence to assess the advantages and disadvantages of the transperitoneal versus retroperitoneal approach for open abdominal aortic aneurysm repair.