In addition, there's connecting service from Canada, Europe, South America and the Far East. Commuter service between San Juan, St. Croix and St. Thomas is also available. Commuter airlines can transport you between islands in as little as 17 minutes.n addition, there's connecting service from Canada, Europe, South America and the Far East. Commuter service between San Juan, St. Croix and St. Thomas is also available. Commuter airlines can transport you between islands in as little as 17 minutes.
A rough estimate is that it takes about 14 hours for blood to be broken down within the intestinal lumen; therefore if transit time is less than 14 hours the patient will have hematochezia, and if greater than 14 hours the patient will exhibit melena.
Fecal Occult Blood Testing. It is normal to lose 0.5 to 1.5 mL of blood daily in the gastrointestinal tract,3 and melena usually is identified when more than 150 mL of blood are lost in the upper gastrointestinal tract.3 FOBTs have sufficient sensitivity to detect bleeding that is not visible in the stool.