Batch Sectioning Reveals Internal Wrinkles

One batch of variable-diameter triple lumen nasojejunal tubes had passed the complete routine inspection process.Every unit has passed the required checks, including visual inspection, air-flow testing, and hydrostatic pressure testing.

The finished products were already packed and waiting for shipment. Meanwhile, the sales team was under pressure from the customer to meet the delivery schedule.

Under the established quality-control procedure, however, destructive section sampling was still required.

When an engineer cut the tubing longitudinally and placed the samples on the inspection bench, a problem became visible.

A small number of tubes had subtle wrinkles hidden inside the transition section.

The outside surface was smooth. Routine airflow and pressure tests could not detect the issue.

But the team understood the potential concern. If such a tube were used clinically, protein residues in the feeding solution could gradually accumulate in these tiny internal irregularities over time, potentially contributing to blockage.

The internal review quickly became a difficult decision.

One option was to manually remove the defective pieces and ship the rest of the batch. That would protect the delivery schedule and limit the immediate loss.

Quality control and R&D took a different view.

The internal wrinkles could not be reliably identified from the outside. Manual sorting could not guarantee that every affected tube would be removed.

The final decision was straightforward: no sorting, no downgrade—the entire batch was reprocessed.

Production was temporarily stopped. Engineers stayed on the factory floor through two consecutive nights, repeatedly adjusting the extrusion equipment and fine-tuning the dynamic control parameters around the transition-section tooling.

The goal was not simply to detect the defect after production. It was to address the manufacturing conditions that could create it in the first place.

The delivery schedule had to be pushed back. The factory absorbed the additional material and labor costs, along with the pressure of managing customer expectations.

But we were not willing to pass an invisible quality concern downstream to distributors or clinical users.

Clinical Leakage Feedback Leads to a New Testing SOP

Another example started with feedback from a frontline nurse.

In a small number of cases, minor leakage was observed around the connector after the tubing had been subjected to negative-pressure suction and repeated bending.

The first assumption was that the connector component might be responsible.

The team tested several batches of connector components. The occasional leakage still occurred.

Instead of closing the issue there, R&D decided to reproduce the actual conditions encountered in an ICU environment.

The team went beyond the static leak testing required by the applicable standard and repeatedly simulated bending and negative-pressure cycles.

After extensive testing, the underlying mechanism became clearer.

When the tube was bent under load, the transition section could undergo extremely small deformation that was not visible to the naked eye. The resulting stress could travel along the tube toward the connector assembly, potentially affecting the seal and leading to leakage.

The current standard did not require this specific combined bending-plus-negative-pressure test condition.

Our approach was simple: if that is how the product is used clinically, that is how we should test it.

The factory subsequently updated its internal inspection SOP. Combined simulations involving negative pressure, bending, and twisting were formally added to the required testing process.

The additional testing time and equipment wear will never appear on a product brochure or in a specification table.

But these extra controls are intended to help OEM customers and distributors reduce the risk of downstream complaints.

Raw Material Control: When Borderline TPU Is Rejected

The balance between delivery schedules and quality requirements can also arise before production even begins.

In one case, a batch of medical-grade TPU arrived with its measured properties close to the limits of the factory’s internal acceptance criteria.

Production calculated that, by adjusting extrusion temperature and machine speed, it would still be possible to manufacture finished tubes that met the appearance and routine inspection requirements while keeping the order on schedule.

R&D strongly disagreed.

Variable-diameter extrusion from three lumens to one is highly sensitive to the uniformity of the material melt. Material operating near the internal acceptance boundary may not show an obvious problem during production, but it could amplify potential wall-thickness variations around the transition section.

Even if the finished products passed outgoing inspection, the long-term risk under indwelling clinical conditions would be difficult to quantify.

The decision was ultimately made to reject the entire batch of raw material.

Production was stopped until a new batch arrived.

The order was delayed, and the production schedule had to be reorganized.

But our principle is clear:

Delivery schedules can be discussed and adjusted. Long-term clinical safety is not something we compromise on.

These decisions rarely make it into marketing materials.

A distributor reviewing inspection reports or examining finished samples may never see what happened behind the scenes.

Yet the ability of a nasojejunal tube to perform consistently throughout its intended indwelling period can depend on precisely these invisible quality decisions.