Interoperability issue between necessary devices.

This is a prospective cohort study. Patients have an incisional or parastomal hernia with >20 cm fascial defect on pre-operative imaging who will undergo an anticipated open bilateral transversus abdominis release with retromuscular synthetic mesh will have their abdominal wall tension measured using a tension scale and their intra-abdominal pressure measured using a urinary catheter containing pressure sensors. The investigators aim to quantify the changes, as well as explore and describe the physiologic shifts that may be associated with these changes.

Inclusion Criteria:

• Patients ≥ 18 years of age
• Incisional or parastomal hernia with >20 cm fascial defect on pre-operative imaging
• Anticipated open bilateral transversus abdominis release with retro-muscular synthetic mesh placement

Exclusion Criteria:

• Pregnant patients
• Require a Legally Authorized Representative (LAR) to sign the informed consent form

Adult patients with an incisional or parastomal hernia with a >20 cm fascial defect on pre-operative imaging who undergo an anticipated open bilateral transversus abdominis release with retro-muscular synthetic mesh placement will be included. The investigators anticipate that patients with very large defects will experience the greatest changes in abdominal wall tension and intra-abdominal pressure.