Endostomal Three-dimensional Ultrasonography for Parastomal Hernia

Endostomal Three-dimensional Ultrasonography Compared to Clinical Examination, Computerized Tomography and Intraoperative Findings for Parastomal Hernia Diagnosis

The intention is to examine the role of ultrasonographic examination inside intestinal stomas in diagnosing parastomal hernia. Patients with a stoma since at least one year back who are being scheduled for abdominal surgery will be examined for eligibility according to the selection criteria. Included patients will undergo routine clinical examination, endostomal ultrasonography and computerized tomography scan of the abdomen. Findings will be correlated to findings during surgery (gold standard). Values for sensitivity, specificity, predictive values and likelihood ratio will be calculated.

Parastomal hernia (PSH) is one of the most common stoma complications, with an incidence of 30-50 % within just a couple of years of stoma creation. Surgical parastomal hernia repair is a morbid and complicated procedure, with a 30-day reoperation rate of 13 % and 30-day mortality rate of 6 % in population-based surveys. There is no established gold standard diagnostic modality. Routinely, patients are examined clinically in various positions with and without increased intra-abdominal pressure. It has been shown in previous studies that clinical examination has a very low inter-observer reliability. Computerized tomography is often performed in addition to clinical examination, but is not ideal in diagnosing PSH either, not only beacause of insufficient test characteristics but also since the examinations should ideally be performed with specific protocols, prone position and be reviewed by a dedicated radiologist. The risk of incorrectly diagnosing a PSH (false positive) is that patients might subsequently be exposed to complex and dangerous surgical interventions without any health benefit, while incorrectly ruling out a PSH (false negative) can cause the patient to have to live with potentially treatable symptoms, life-threatening bowel incarceration being the most severe potential complication.

Thus, improved diagnostic accuracy is required. A method that has been developed within our research group is endostomal tree-dimensional ultrasonography, which has preliminarily proven to be approximately as sensitive as CT, with a markedly higher specificity. A larger and less selected study needs to be conducted in order to reliably calculate test characteristics, predictive values and likelihood ratio.

Inclusion Criteria:

• End colostomy or end ileostomy since ≥ 1 year
• Planned for laparotomy or laparoscopy
• Age ≥ 18
• Speaks and reads Swedish language
• Informed consent

Exclusion Criteria:

• Known parastomal hernia only indication for laparotomy or laparoscopy