"external drainage" is correct and usable in written English.
You can use it to refer to systems of drainage that are located outside a building or structure. For example, "The new office building has been equipped with external drainage systems to help manage water runoff."
This process is related with the transition from internal to external drainage of the Ebro basin.
Due to early graft failure, the patient underwent graftectomy, ligation of the portal vein, and external drainage of the common bile duct.
We hypothesize that smoothing of highlands by efficient glacial and periglacial erosion, coupled with potential river captures and conveyance of sediments via external drainage, can yield an apparently continuous low-relief plateau landscape formed diachronously at high elevation.
Surgical external drainage is an option if these procedures fail.
Pancreatic pseudocyst is usually treated by percutaneous external drainage, endoscopic internal or external drainage, or surgical internal drainage such as cystogastrostomy.
It was improved by endoscopic external drainage, and the stent was changed to an internal stent.
PTBD tube was changed to 12 Fr internal-external drainage tube and placed across the jejunal stenosis (Fig. 4b), followed by balloon dilation with 12 mm diameter (Fig. 4c).
Internal-external drainage was attempted in 30 interventions, and was successful in 19 (63%) interventions.
After removal of the introducer sheath, the final PTBD catheter (8.5 French Ultrathane® drainage catheter set, Cook Japan, Inc ., with multiple side holes positioned on both sides for internal-external drainage, was then advanced over the wire.
In addition, internal-external drainage was not performed in cases when a surgical resection had been already planned for treating jaundice in order to avoid unexpected tumor bleeding and other complications.
A catheter is placed with its distal end in the duodenum for internal-external-drainage.
