Exhibit 3.166

                          CERTIFICATE OF INCORPORATION
                                       OF
                      EM-CODE REIMBURSEMENT SOLUTIONS, INC.
                    Pursuant to the provisions of Section 102
                      of the General Corporation Law of the
                                State of Delaware

      I, the undersigned, for the purpose of creating and organizing a
corporation under the provisions of and subject to the requirements of the
General Corporation Law of the State of Delaware, do HEREBY CERTIFY as follows

      FIRST:   Name. The name of the corporation (the "Corporation") is:
               EM-CODE REIMBURSEMENT SOLUTIONS, INC.

      SECOND:  Effective Date. The incorporation of the Corporation pursuant
               hereto shall be effective upon filing this Certificate of
               Incorporation with the Delaware Secretary of State.

      THIRD:   Registered Agent. The address of the registered office of the
               Corporation in the State of Delaware is 9 East Loockerman Street,
               in the city of Dover, Delaware 19901, county of Kent. The name of
               the registered agent at such address is National Registered
               Agents, Inc.

      FOURTH:  Purpose. The purposes for which the Corporation is formed are to
               engage in any lawful act or activity for which corporations may
               be organized under the Delaware General Corporation Law.

      FIFTH:   Authorized Shares. The aggregate number of shares of stock which
               the Corporation shall have authority to issue is One Thousand
               (1,000) shares of Common Stock, par value $.01

      SIXTH:   Incorporator. The name and mailing address of the sole
               incorporator of the Corporation are as follow:

               Paulette G. Lockwood
               1717 Main Street, Suite 5200
               Dallas, Texas 75201

      SEVENTH: In furtherance and not in limitation of the powers conferred by
               the laws of the State of Delaware, the Board of Directors of the
               Corporation is expressly authorized and empowered to make, alter
               or repeal the Bylaws of the Corporation, subject to the power of
               the stockholders of the Corporation to alter or repeal any Bylaws
               made by the Board of Directors. Election of Directors need not be
               by written ballot.



      EIGHTH:  The Corporation reserves the right at any time and from time to
               time to amend, alter, change or repeal any provision contained in
               this Certificate of Incorporation in the manner now or hereafter
               prescribed by law, and rights, preferences and privileges of
               whatsoever nature conferred upon stockholders, directors, or any
               other persons whomsoever by and pursuant to this Certificate of
               Incorporation in its present form or as hereafter amended are
               granted subject to the right reserved in this Article.

      NINTH:   No person shall be personally liable to the Corporation or its
               stockholders for monetary damages for breach of fiduciary duty as
               a director, provided, however, that the foregoing shall not
               eliminate or limit the liability of a director (1) for any breach
               of the director's duty of loyalty to the Corporation or its
               stockholders, (2) for acts or omissions not in good faith or
               which involve intentional misconduct or a knowing violation of
               law, (3) under Section 174 of the General Corporation Law of the
               State of Delaware, or (4) for any transaction from which the
               director derived an improper personal benefit. If the General
               Corporation Law of the State of Delaware is amended to authorized
               corporate action further eliminating or limiting the personal
               liability of Directors, then the liability of a director of the
               Corporation shall be eliminated or limited to the fullest extent
               permitted by the General Corporation Law of the State of
               Delaware, as so amended. Any repeal or modification of the
               provisions of this Article Ninth by the stockholders of the
               Corporation shall not adversely affect any right or protection of
               a director of the Corporation existing at the time of such repeal
               or modification.

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      IN WITNESS WHEREOF, the undersigned, being the incorporator hereinabove
named, for the purpose of forming a corporation pursuant to the General
Corporation Law of the State of Delaware, does make this Certificate, hereby
declaring, certifying and acknowledging under penalties of perjury that the
facts herein stated are true and that this Certificate of Incorporation is her
act and deed, and accordingly has hereunto set her hand, this 16th day of
October,1998.

                                                  /s/ Paulette G. Lockwood
                                                ------------------------------
                                              Paulette G. Lockwood, Incorporator

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             CERTIFICATE OF CHANGE OF LOCATION OF REGISTERED OFFICE
                             AND OF REGISTERED AGENT

It is hereby certified that:

      1. The name of the corporation (hereinafter called the "corporation") is
              EM-CODE REIMBURSEMENT SOLUTIONS, INC.

      2. The registered office of the corporation within the State of Delaware
is hereby changed to 2711 Centerville Road, Suite 400, City of Wilmington 19808,
County of New Castle.

      3. The registered agent of the corporation within the State of Delaware is
hereby changed to Corporation Service Company, the business office of which is
identical with the registered office of the corporation as hereby changed.

      4. The corporation has authorized the changes hereinbefore set forth by
resolution of its Board of Directors.

Signed on January 29, 2003

"/s/" Robyn E. Bakalar
-------------------------------------
Robyn E. Bakalar, Assistant Secretary

DE BC D-COA CERTIFICATE OF CHANGE 09/00 (#163)

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