---
kind: "section"
citation: "49 C.F.R. § 40.155"
title: "49"
number: "40.155"
heading: "What does the MRO do when a negative or positive test result is also dilute?"
url: "https://uscodex.org/cfr/49/40.155"
---

# §40.155. What does the MRO do when a negative or positive test result is also dilute?

- (a) When the laboratory reports that a specimen is dilute, you must, as the MRO, report to the DER that the specimen, in addition to being negative or positive, is dilute.
- (b) You must check the “dilute” box (Step 6) on Copy 2 of the CCF.
- (c) When you report a dilute specimen to the DER, you must explain to the DER the employer's obligations and choices under [§ 40.197](/cfr/49/40.197.md), to include the requirement for an immediate recollection under direct observation if the creatinine concentration of a negative-dilute specimen was greater than or equal to 2mg/dL but less than or equal to 5mg/dL.
- (d) If the employee's recollection under direct observation, in [paragraph (c)](#c) of this section, results in another negative-dilute, as the MRO, you must:
  - (1) **Review the CCF to ensure that there is documentation that the recollection was directly observed.**
  - (2) If the CCF documentation shows that the recollection was directly observed as required, report this result to the DER as a negative-dilute result.
  - (3) If CCF documentation indicates that the recollection was not directly observed as required, do not report a result but again explain to the DER that there must be an immediate recollection under direct observation.

## Notes

### Amendments

[65 FR 79526, Dec. 19, 2000, as amended at 66 FR 41952, Aug. 9, 2001; 68 FR 31626, May 28, 2003; 69 FR 64867, Nov. 9, 2004; 73 FR 35971, June 25, 2008]

### Authority

Authority: 49 U.S.C. 102, 301, 322, 5331, 20140, 31306, and 54101 et seq.

### Source

Source: 65 FR 79526, Dec. 19, 2000, unless otherwise noted.

### Amendments

[65 FR 79526, Dec. 19, 2000, as amended at 66 FR 41952, Aug. 9, 2001; 68 FR 31626, May 28, 2003; 69 FR 64867, Nov. 9, 2004; 73 FR 35971, June 25, 2008]