The more extensive the bypass operation, the greater the risk for complications and nutrition deficiencies. Patients with extensive bypasses of the normal digestive process require not only close monitoring, but also life-long use of special foods and medications. Ten to 20 percent of patients who have weight loss operations require follow-up operations to correct complications.
Abdominal hernias are the most common complications that require follow-up surgery.
Less common complications include breakdown of the staple line and stretched stomach outlets. Vomiting may occur as a result of restrictive operations. It is caused by the small stomach pouch being overly stretched by food particles that have not been chewed well. The latter requires an emergency operation. Since gastric bypass operations cause food to skip the duodenum, where most iron and calcium are absorbed, these procedures imply a higher risk of resulting nutrition deficiencies than do restrictive procedures used alone.