Preoperative and Intraoperative Determinants of Incisional Bulge following Retroperitoneal Aortic Repair
Article Outline
Although the left flank retroperitoneal incision is a useful approach for many patients undergoing major aortic reconstruction for aneurysmal and occlusive disease, it has been associated with weakening of the flank muscles, resulting in bulges varying from slight asymmetry to huge hernias. The purpose of this study was to determine if the incidence of this complication correlated with identifiable preoperative or intraoperative factors. Fifty consecutive patients undergoing aortic reconstruction via the retroperitoneal approach were followed for 1 year postoperatively for evidence of disfiguring bulges. Bulges were scored as follows: normal/mild, <1-inch protrusion; moderate, protrusion 1–2 inches; severe, protrusion >2 inches and/or pain or true herniation. Preoperatively, patients were administered a questionnaire to elicit demographic and comorbidity data. Fifty-six percent of patients developed a bulge at 1 year. In 43% of these, the bulge was deemed mild and in 54% moderate. One patient developed a severe bulge. Among preoperative comorbidities, no statistically significant correlations were found on bivariate analysis. However, likelihood ratios for bulge development of 5.5 for renal disease and 3.1 for cancer were demonstrated. Conversely, peripheral vascular disease had a likelihood ratio of 0.21 for bulge formation and emphysema, 0.28. On logistic analysis, incision >15 cm and body mass index (BMI) >23 mg/kg2 were found to correlate strongly with bulge formation (p = 0.003, odds ratio = 9.1, and p = 0.018, odds ratio = 16.9, respectively). Together, these yielded a pseudo r2 of 0.32. BMI >23 mg/kg2 was found to yield the greatest explanatory power. These same two variables were found to correlate with severity of bulge: p = 0.02 for incision >15 cm and p = 0.006 for BMI >23. Of note, gender, age, and extension of the incision into the interspace were not significant on logistic analysis. Preoperatively, surgeons should warn obese patients and those requiring large incisions for extensive disease of their increased risk for poor healing. Intraoperatively, surgeons should aim to minimize incision length.
INTRODUCTION
Although the left flank incision has been lauded for providing greater exposure and minimizing immediate postoperative complications, it has also been associated with poor wound healing compared with the standard transabdominal incision. This retroperitoneal approach has been shown to lead to fewer postoperative respiratory and cardiac complications, reduced intubation time, lower narcotic requirement, decreased rates of ileus, earlier resumption of regular diet, shorter hospital stay, and lower overall cost.1, 2, 3, 4, 5, 6, 7, 8 Furthermore, the retroperitoneal approach has been credited with less blood loss and increased hemodynamic stability.3, 5, 7
However, most surgeons have held that the retroperitoneal approach contributes to a higher rate of incisional bulges and wound complications compared with the transabdominal approach. In fact, the literature conflicts on this point. In studies of midline incisions, investigators have found incisional hernia rates varying 16.5–28%.9, 10, 11, 12 However, Darling et al.4 found “annoying flank bulge” in only 5–7% of their patients undergoing the retroperitoneal approach. Others have found no statistical difference in the rates of incisional hernias or bulges when comparing the two approaches.2, 3 Only Sieunarine and colleagues13 found significantly more bulging, hernias and wound pain at 3 years postoperatively in their series of 100 patients randomized to the retroperitoneal approach compared with transabdominal. Fifteen patients had bulging and four had hernias in the retroperitoneal approach compared with one each in the transperitoneal approach (p < 0.001 and p = 0.20, respectively). This variation in the finding of postoperative incisional bulge and hernia can be attributed in part to definitions and clinical diligence.
This study follows a cohort of patients undergoing aortic surgery via left retroperitoneal incision in the manner first described by Rob.14 Our aims were threefold: (1) to catalog the incidence of wound complications, (2) to determine preoperatively those patients at greatest risk for bulge development with elective retroperitoneal incision, and (3) to delineate surgeon-controlled variables to minimize wound complications.
METHODS
Fifty-three consecutive nonrandomized patients underwent retroperitoneal aortic repair and were followed for 1 year to assess for abdominal bulge. All operations were performed at the Johns Hopkins Hospital by one of three staff surgeons. The aorta was approached through a retroperitoneal incision as described by Williams et al.15: patients were put in the right lateral decubitus position, the table was flexed and placed in Trendelenberg, the kidney rest was raised, and the left arm was suspended at chin level. A small incision was made first, from the tip of the tenth or eleventh rib and the umbilicus. Inadequate exposure sometimes necessitated extension of the incision, including into the tenth or eleventh intercostal space. Grounds for surgery included aortic aneurysm (infrarenal, juxtarenal, suprarenal) and aortoiliac occlusive disease. Exclusion criteria included previous left flank incision or preexisting left flank bulge. One patient died from congestive heart failure prior to completion of the study, and two did not complete the full 1-year follow-up, yielding a cohort of 50 patients.
Prior to surgery, patients were administered a questionnaire cataloging their demographics, comorbidities, and type of aortic disease. Postoperative recovery, including incidence of bulge, was assessed at regular intervals by senior surgeons and at 1 year. Bulge severity was graded as follows: mild, asymmetry with protrusion <1 inch; moderate, protrusion 1–2 inches; severe, protrusion >2 inches and/or pain on straining. In most cases, the bulges were classified by two senior surgeons, yielding agreement in bulge severity. The results included here reflect the bulge estimation at 1 year postoperatively.
RESULTS
In this study of 50 consecutive nonrandomized patients undergoing aortic reconstruction via retroperitoneal approach, 44% healed well while the rest developed some flank bulging. No hernias required surgical intervention, although one did develop a severe hernia (Table I). Of the patients with imperfect healing, 42.9% had bulges deemed mild (asymmetry with protrusion <1 inch).
Table I. Patient categories
| Bulge | Count | Percent |
|---|---|---|
| None | 22 | 44 |
| Mild | 12 | 24 |
| Moderate | 15 | 30 |
| Severe | 1 | 2 |
Demographic variables and comorbidities were studied in an effort to predict preoperatively which patients would be more likely to develop bulges (Table II). There was no statistical difference in age among the two groups. Fifty-nine percent of men developed a bulge, while 45.5% of women did. Some comorbidities were associated with higher rates of bulge; these included renal disease (likelihood ratio 5.5), cancer (likelihood ratio 3.1), and history of coronary artery bypass grafting, obesity, or non-insulin-dependent diabetes mellitus (likelihood ratios 2.1). Conversely, some comborbidities showed a negative correlation with the development of bulge: peripheral vascular disease had a likelihood ratio of 0.21 for bulge formation and emphysema, 0.28. However, on bivariate analysis, no comorbidities were found to have statistical significance. On the other hand, body mass index (BMI) yielded significant results: the average BMI for patients who developed bulges was 28.0 kg/m2 compared with 24.8 kg/m2 for those who did not (p = 0.0325).
Table II. Demographic variables and comorbidities
| Bulge | No bulge | Likelihood ratio | p | |
|---|---|---|---|---|
| Age (years) | 69.8 | 71.5 | NA | 0.485 |
| Men | 59.0% | 41.0% | ||
| Women | 45.5% | 4.5% | ||
| BMI (kg/m2) | 28.0 | 24.8 | NA | 0.0325 |
| Renal disease | 28% | 5% | 5.5 | |
| Cancer | 31% | 10% | 3.1 | |
| Elevated creatinine | 24% | 10% | 2.4 | |
| Obese | 83% | 40% | 2.1 | |
| Non-insulin-dependent diabetes mellitus | 10% | 5% | 2.1 | |
| Erectile disfunction | 45% | 25% | 1.8 | |
| Hyperlipidemia | 69% | 40% | 1.7 | |
| Angioplasty | 21% | 15% | 1.4 | |
| Iliac disease | 21% | 15% | 1.4 | |
| Elevated blood urea nitrogen | 24% | 20% | 1.2 | |
| Hypertension | 76% | 80% | 0.95 | |
| Coronary artery disease | 48% | 60% | 0.80 | |
| Insulin-dependent diabetes mellitus | 3% | 5% | 0.69 | |
| Chronic obstructive pulmonary disease | 4% | 25% | 0.55 | |
| Stroke | 10% | 20% | 0.52 | |
| Carotid disease | 3% | 10% | 0.34 | |
| Myocardial infarction | 31% | 100% | 0.31 | |
| Emphysema | 7% | 25% | 0.28 | |
| Peripheral vascular disease | 10% | 50% | 0.21 | |
| Coronary artery bypass graft | 31% | 15% | 2.1 | |
| Peripheral vascular surgery | 10% | 10% | 1.0 | |
| Other vascular procedures | 41% | 40% | 1.0 | |
| Carotid endarterectomy | 7% | 0% | NA | |
| Smoking history | 93% | 100% | 0.93 | |
| Heavy alcohol use | 14% | 20% | 0.69 | |
| Smoking pack-years | 39.0 | 43.0 | NA | 0.571 |
| Preoperative psychological score (max 5) | 3.46 | 3.81 | NA | 0.365 |
| Preoperative physical score (max 5) | 3.19 | 3.62 | NA | 0.227 |
| Incision length (cm) | 24.3 | 16.3 | NA | 6.36 × 10−5 |
| Estimated blood loss (cc) | 1978 | 1850 | NA | 0.702 |
| Operative time (hr:min) | 3:04 | 2:49 | NA | 0.299 |
| Aortoiliac occlusive disease | 29% | 71% | 0.40 | |
| AAA | 61% | 39% | 1.59 | |
| AAA size (cm) | 5.86 | 5.38 | NA | 0.124 |
| Length of stay (days) | 7.14 | 7.05 | NA | 0.932 |
The average incision length for those patients who developed bulges was 24.3 cm compared with 16.3 cm for those who did not (p = 6.36 × 10−6). Predictably, those patients with higher BMIs required longer incisions. Nonobese patients required an average incision length of 17.5 cm compared with 22.0 cm for the obese (p = 0.0180). Figure 1 demonstrates a strong positive correlation between these two variables (r = 0.42).
Fig. 1.
BMI (kg/m2) versus incision length (cm) for all patients. The trend line is shown, along with its equations and R value.
Numerous factors did not differ significantly between patients who developed bulges and those who did not. These included length of stay, estimated blood loss, pack-years of smoking, age, preoperative psychological score, preoperative physical score, operative time, and abdominal aortic aneurysm (AAA) size (Table II).
On logistic analysis, incision length >15 cm and BMI >23 mg/kg2 were found to correlate strongly with bulge formation (p = 0.003, odds ratio = 9.1, and p = 0.018, odds ratio = 16.9, respectively). Together, these yielded a pseudo r2 of 0.32. BMI ≥ 23 mg/kg2 was found to yield the greatest explanatory power (compared with the traditional threshold of 25 mg/kg2 for overweight).
These same two variables were found also to correlate with severity of bulge: p = 0.02 for incision >15 cm and p = 0.006 for BMI ≥ 23. Incision length >15 cm had a coefficient of 0.682; each centimeter of incision length resulted in a 0.682 unit increase on the severity scale of bulge. Similarly, increase in BMI by 1 kg/m2 yielded a 0.753 unit increase in bulge severity. The r2 for these two variables was 0.3471, meaning that 34.71% of the variance in bulge severity could be explained by these variables alone. Of note, gender, age, and extension of the incision into the interspace were not significant on logistic analysis.
DISCUSSION
We had three goals in this study of 50 patients undergoing aortic reconstruction via the retroperitoneal approach: (1) to catalog the incidence of wound complications, (2) to determine preoperatively those patients at greatest risk for postoperative bulges with elective retroperitoneal incision, and (3) to delineate surgeon-controlled variables to minimize wound complications.
In this study, 56% of patients developed bulges after retroperitoneal repair. This exceeds the rates generally quoted in the literature of 5–30%.2, 3, 4, 13 However, 43% of our bulges were deemed mild (asymmetry with protrusion <1 inch).
BMI emerged as a risk factor for subsequent bulging, allowing the surgeon to have a frank discussion of potential complications with the obese patient prior to undertaking aortic reconstruction. When controlled for obesity, incision length also emerged as a significant promoter of bulge formation. Predictably, higher BMI necessitated a longer incision, as demonstrated in Figure 1. The average incision length for obese patients was greater (22.0 cm) compared with nonobese patients (17.5 cm), p = 0.0180. Thus, the obese patient is at higher risk for incisional bulge not only by way of body mass but also by requiring a longer incision.
Type of aortic disease also emerged as a risk factor in incisional bulge development. In keeping with the findings of previous investigators,9, 10, 11, 16, 17, 18 a higher proportion of patients with aneurysmal aortic disease developed bulges (61.4%) compared to those with aortoiliac occlusive disease (28.6%), p = 0.138. Other researchers have found increased type III collagen turnover in patients with AAA versus aortoocclusive disease.19, 20, 21, 22 That patients with higher rates of type III collagen turnover have been noted to have a predilection for hernia formation in general23, 24 provides an etiological link between AAAs and the development of incisional bulges. However, we also found a significant difference in incision length for patients undergoing AAA repair (21.3 cm) versus surgery for aortic occlusive disease (16.0 cm), p = 0.0003.
Finally, we aimed to demarcate surgeon-controlled variables that influenced the likelihood of postoperative bulging. Exclusive among these was incision length. Of note, extension of the incision into the intercostal space was not significant for bulge formation. Previous authors have maintained that intercostal incursion may damage the intercostal nerve, leading to denervation atrophy and tissue laxity.4, 25, 26
In summary, obese patients should be warned preoperatively of their heightened risk of postoperative incisional bulge. Intraoperatively, the surgeon should aim to minimize incision length.
REFERENCES
- . Infrarenal abdominal aortic disease: a review of the retroperitoneal approach . Br J Surg . 1991;78:6–9
- Comparison between the transabdominal and retroperitoneal approaches for aortic reconstruction in patients at high risk . J Vasc Surg . 1999;30:400–406
- Transabdominal versus retroperitoneal incision for abdominal aortic surgery. Report of a prospective randomized trial . J Vasc Surg . 1995;21:174–183
- . Current status of the use of retroperitoneal approach for reconstruction of the aorta and its braches . Ann Surg . 1996;224:501–508
- . Comparative analysis of retroperitoneal and transperitoneal aortic replacement for aneurysm . Surg Gynecol Obstet . 1989;168:387–393
- . Aorto-iliac reconstruction with special reference to the extraperitoneal approach . Br J Surg . 1975;62:596–600
- Hemodynamics and prostacyclin release in the early phases of aortic surgery: comparison of transabdominal and retroperitoneal approaches . J Vasc Surg . 1988;7:190–198
- . Left retroperitoneal approach using a retractor to repair abdominal aortic aneurysms: a comparison with the transperitoneal approach . Surg Today . 2002;32:577–580
- . Incisional hernias are more common in aneurysmal arterial disease . Eur J Vasc Endovasc Surg . 1996;12:196–200
- . Ventral hernia following abdominal aortic reconstruction . Am Surg . 1988;54:287–289
- . Incidence of abdominal wall hernia in aortic surgery . Am J Surg . 1998;175:400–402
- . Transverse abdominal incisions compared with midline incisions for elective infrarenal aortic reconstruction: predisposition to incisional hernia in patients with increased intraoperative blood loss . J Vasc Surg . 1994;20:27–33
- . Comparison of transperitoneal and retroperitoneal approaches for infrarenal aortic surgery: early and late results . J Cardiovasc Surg . 1997;5:71–76
- . Extraperitoneal approach to the abdominal aorta . Surgery . 1963;53:87–89
- . The extended retroperitoneal approach for the treatment of extensive atherosclerosis of the aorta and renal vessels . Surgery . 1980;88:846–855
- . Magnetic resonance imaging and abdominal wall hernias in aortic surgery . J Am Coll Surg . 2001;193:392–395
- Abdominal wall hernias in patients with abdominal aortic aneurysmal versus aortoiliac occlusive disease . Am J Surg . 1995;170:572–576
- Incidence of abdominal wall hernias in patients undergoing aortic surgery for aneurysm or occlusive disease . Vasa . 2002;31:111–114
- . Increased amounts of type III pN-collagen in human abdominal aortic aneurysms: evidence for impaired type III collagen fibrillogenesis . J Vasc Surg . 2000;32:1201–1207
- . Increased amount of type III pN-collagen in AAA when compared with AOD . Eur J Vasc Endovasc Surg . 2002;23:413–420
- Multiple defects in type III collagen synthesis are associated with the pathogenesis of abdominal aortic aneurysms . Ann N Y Acad Sci . 1996;800:216–228
- . Plasma and tissue levels of collagen types I and III markers in patients with abdominal aortic aneurysms . Int Angiol . 2000;19:64–68
- Increases in type III collagen gene expression and protein synthesis in patients with inguinal hernias . Ann Surg . 1993;218:754–760
- Recurrent inguinal hernia: disease of the collagen matrix? . World J Surg . 2002;26:401–408
- . The retroperitoneal incision – an evaluation of postoperative flank “bulge.” . Arch Surg . 1994;129:753–756
- . Midline retroperitoneal versus midline transperitoneal approach for abdominal aortic aneurysm repair . J Vasc Surg . 2000;32:219–223
PII: S0890-5096(06)60029-0
doi:10.1007/s10016-006-9021-3
© 2006 Annals of Vascular Surgery, Inc. Published by Elsevier Inc All rights reserved.
