Giant ventral incisional hernias with loss of domain: what the radiologist needs to know

Clinical History

A 75-year-old obese woman had a history of remote psychiatric disease, surgically resected breast carcinoma (over ten years) and open cholecystectomy 9 years earlier. Currently, she was hospitalised because of anaemia from bleeding endometrial atrophy, with stable vital signs.
The key physical finding was represented by a large incisional ventral hernia.

Imaging Findings

The patient was being considered for combined hysterectomy and ventral abdominal hernia repair using a prosthetic mesh.
Unenhanced multidetector CT (Figs 1 and 2) confirmed a giant incisional hernia at the ventral abdominal wall, containing abdominal fat, colon and small bowel loops, associated with atrophied rectus muscles. Easy CT measurement of the hernia sac volume (HSV, 2267 cm3) and abdominal compartment volume (ACV, 6937 cm3) using the approximate ellipsoid volume formula resulted in a HSV / ACV ratio of 32.6%, consistent with loss of domain. Additionally, the diameters and angle of the abdominal wall defect were measured in the CT report.
Surgery was ultimately postponed because of sepsis from urinary infection and rhabdomyolysis following accidental fall.

Discussion

Incisional hernias (IHs) involve protrusion of abdominal fat and viscera through a post-surgical defect in the abdominal wall, and are nowadays becoming more prevalent due to the overweight epidemic and the growing complexity of surgeries. The combined effect of obesity and associated cardiorespiratory and metabolic comorbidities increase the risk of IH development, the complexity of surgical repair, and the rate of postoperative complications. Currently, a significant proportion (approximately 11%) of all hernia repair procedures is performed to manage giant ventral IHs (GVIHs), which severely impact the patients’ quality of life. Unfortunately, no consensus definition exists and a GVIH is variably diagnosed on the basis of maximum hernia sac width exceeding 10-15 cm, or of a large hernia sac volume (over 100-200 cm3). GVIH repair is technically challenging and burdened with unacceptable high postsurgical mortality (up to 5%), morbidity (34-50%) and recurrence rates (up to 50%), proportionally increasing with hernia size [1, 2].
Additionally, surgeons recently rely on the concept of “loss of domain” (LOD) which is calculated as the hernia sac-to abdominal cavity volume ratio. GVIHs with LOD >30% are associated with prolonged postoperative hospitalisation and frequent recurrence. The most dreaded early complication is abdominal compartment syndrome, which results from forcing back abdominal viscera from long-standing GVIH into a smaller abdominal cavity, causing impaired blood flow and cardiopulmonary failure [3].
As a result, radiologists are increasingly requested to preoperatively assess IHs, in order to improve success of surgical repair. As this typical case exemplifies, multidetector CT with optional intravenous contrast and/or oral bowel opacification is beneficial for preoperative surgical planning. The technologist should ensure to include the entire abdominal girth in the field-of-view, and reconstruct images along three (namely axial, coronal and sagittal) planes. In a few minutes, the attending radiologist can add value to the report by measuring hernia sac and abdominal cavity diameters and calculating HSV, ACV (Fig.1) and LOD which represents the HSV / ACV ratio. Additionally, the abdominal defect diameters and angle should be measured (Fig.2), the bulk and symmetry of the abdominal wall musculature can be observed [4-8].
In fact, CT findings are useful to predict the need for complex surgical techniques for abdominal wall reconstruction. For instance, progressive pneumoperitoneum is strongly suggested for LOD>25% with better results compared to standard on-lay mesh repair. On the other hand, wide-angle (>20°) GVHIs are approached using combined midline fascial reapproximation, anterior component separation and sublay prosthetic mesh [3, 9, 10].

Differential Diagnosis List

Final Diagnosis

Giant ventral incisional hernia with loss of domain

URL:	https://www.eurorad.org/case/15283
DOI:	10.1594/EURORAD/CASE.15283
ISSN:	1563-4086