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                                                                    EXHIBIT 3.28

                                     BYLAWS

                                       OF

                          STURGIS, HENDERSON & PROCTOR
                           PATHOLOGY LABORATORY, P.A.

                     A MISSISSIPPI PROFESSIONAL CORPORATION


                               ARTICLE I. OFFICES

     The principal office of the corporation in the state of Mississippi shall
be located in Flowood, Mississippi. The corporation may have such other offices,
either within or without the state of Mississippi, as the Board of Directors may
designate or as the business of the corporation may require from time to time.

     The registered office of the corporation required by the Mississippi
Business Corporation Act to be maintained in the state of Mississippi may be,
but need not be, identical with the principal office in the state of
Mississippi, and the registered agent and the address of the registered office
may be changed from time to time by the Board of Directors.

                            ARTICLE II. SHAREHOLDERS

     Section 1.  ANNUAL MEETING. The annual meeting of the shareholders shall be
held on the first Monday in February each year, beginning with the year 1992, at
the hour of 6:00 p.m., for the purpose of electing directors and for the
transaction of such other business as may come before the meeting. If said day
is a legal holiday, then the meeting shall be held on the next regular working
day thereafter. If the election of directors shall not be held on the day
designated herein, at any annual meeting of the shareholders, or at any
adjournment thereof, the Board of Directors shall cause, the election to be held
at a special meeting of the shareholders as soon thereafter as conveniently may
be done.

     Section 2.  SPECIAL MEETINGS. Special meetings of the shareholders, for any
purpose or purposes, unless otherwise prescribed by statute, may be called by
the

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President or by the Board of Directors, and shall be called by the President at
the request of the holders of not less than one-tenth (1/10) of all the
outstanding shares of the corporation entitled to vote at the meeting.

     Section 3.  PLACE OF MEETING. The Board of Directors may designate any
place, either within or without the state of Mississippi, as the place of
meeting for any annual meeting or for any special meeting called by the Board of
Directors. A waiver of notice signed by all shareholders entitled to vote at a
meeting may designate any place, either within or without the state of
Mississippi, as the place for the holding of such meeting. If no designation is
made, or if a special meeting be otherwise called, the place of meeting shall be
the principal office of the corporation.

     Section 4.  NOTICE OF MEETING. Written or printed notice stating the place,
day and hour of the meeting and, in case of a special meeting, the purpose or
purposes for which the meeting is called, shall be delivered not less than ten
(10) nor more than sixty (60) days before the date of the meeting, either
personally or by mail, by or at the direction of the President, or the
Secretary, or the officer or persons calling the meeting, to each shareholder of
record entitled to vote at such meeting. If mailed, such notice shall be
addressed to the shareholder at his address as it appears on the stock transfer
books of the corporation, with postage thereon prepaid.

     Section 5.  FIXING OF RECORD DATE. For the purpose of determining
shareholders entitled to notice of or to vote at any meeting of shareholders or
any adjournment thereof, or shareholders entitled to receive payment of any
dividend, or in order to make a determination of shareholders for any other
proper purpose, the Board of Directors of the corporation may fix in advance a
date as a record date for any such determination of shareholders, such date in
any case to be not more than seventy (70) days and, in case of a meeting of
shareholders, not less than ten (10) days prior to the date on which the
particular action, requiring such determination of shareholders, is to be taken.
If no record date is fixed for the determination of shareholders entitled to
notice of or to vote at a meeting of shareholders, or shareholders entitled to
receive payment of a dividend, the date on which notice of meeting is mailed or
the date on which the resolution of the Board of Directors declaring such
dividend is adopted, as the case may be, shall be the record date for such
determination of shareholders. When a determination of shareholders entitled to
vote at any meeting of shareholders has been made as provided in this section,
such determination shall apply to any adjournment thereof.

     Section 6.  VOTING RECORD. The officer or agent having charge of the stock
transfer books for shares of the corporation shall make a complete record of the
shareholders entitled to vote at each meeting of shareholders or any adjournment
thereof, arranged in alphabetical order, with the address of and the number of
shares held by each. Such record shall be available for inspection by any
shareholder beginning two (2) business days after notice of the meeting is given
for which the list

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was prepared and continuing through the meeting, at the corporation's principal
office or at a place identified in the meeting notice in the city where the
meeting will be held. On written demand, the record shall be subject to the
inspection of any shareholder at any time during the period it is available for
inspection. The record shall be available for inspection at the meeting or any
adjournment thereof.

     Section 7.  QUORUM. A majority of the outstanding shares of the corporation
entitled to vote, represented in person or by proxy, shall constitute a quorum
at a meeting of shareholders. If less than a majority of the outstanding shares
are represented at a meeting, a majority of the shares so represented may
adjourn the meeting from time to time without further notice. At such adjourned
meeting at which a quorum shall be present or represented, any business may be
transacted which might have been transacted at the meeting as originally
notified. The shareholders present at a duly organized meeting may continue to
transact business until adjournment, notwithstanding the withdrawal of enough
shareholders to leave less than a quorum.

     Sections 8. PROXIES. At all meetings of shareholders, a shareholder may
vote by proxy executed in writing by the shareholder or by his duly authorized
attorney in fact. Such proxy shall be filed with the Secretary of the
corporation before or at the time of the meeting. No proxy shall be valid after
eleven (11) months from the date of its execution, unless otherwise provided in
the proxy.

     Section 9.  VOTING OF SHARES. Each outstanding share of common stock shall
be entitled to one (1) vote upon each matter submitted to a vote at a meeting of
the shareholders.

     Section 10. INFORMAL ACTION BY SHAREHOLDER. Any action required to be taken
at a meeting of the shareholders, or any other action which may be taken at a
meeting of the shareholders, may be taken without a meeting if one or more
consents in writing, setting forth the action so taken, shall be signed by all
of the shareholders entitled to vote with respect to the subject matter thereof.
The signature of any shareholder upon the minutes of a meeting shall be deemed
such consent in writing to all action reflected to have been taken at said
meeting by said minutes.

                         ARTICLE III. BOARD OF DIRECTORS

     Section 1.  GENERAL POWERS. The business and affairs of the corporation
shall be managed by its Board of Directors.

     Section 2.  NUMBER, TENURE AND QUALIFICATIONS. The number of directors of
the corporation shall be not less than one (1), but the shareholders may elect
additional directors as they may desire so long as there is an odd number
thereof. A The holders of majority of the outstanding shares of stock entitled
to vote may at

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any time peremptorily terminate the term of office of all or any of the
directors by a vote at a meeting called for such purpose or by a written
statement filed with the Secretary or, in his absence, with any other officer.

     Section 3.  REGULAR MEETINGS. A regular meeting of the Board of Directors
shall be held without other notice than this Bylaw immediately after, and at the
same place as, the annual meeting of the shareholders. The Board of Directors
may provide, by resolution, the time and place, either within or without the
state of Mississippi, for the holding of additional regular meetings without
notice other than such resolution.

     Section 4.  SPECIAL MEETINGS. Special meetings of the Board of Directors
may be called by, or at the request of, the President or any two (2) directors.
The person or persons authorized to call special meetings of the Board of
Directors may fix any reasonable place, either within or without the state of
Mississippi, as the place of holding any special meeting of the Board of
Directors called by them.

     Section 5.  NOTICE. Notice of any special meeting shall be given at least
two (2) days previously by written notice delivered personally or mailed to each
director at his business address, or by telegram. If mailed, such notice shall
be deemed to be delivered when deposited in the United States mail so addressed,
with postage thereon prepaid. If notice be given by telegram, such notice shall
be deemed to be delivered when the telegram is delivered to the telegraph
company. Any director may waive notice of any meeting. The attendance of a
director at a meeting shall constitute a waiver of notice of such meeting,
except where a director attends a meeting for the express purpose of objecting
to the transaction of any business because the meeting is not lawfully called or
convened. Neither the business to be transacted at, nor the purpose of, any
regular or special meeting of the Board of Directors need be specified in the
notice or waiver of notice of such meeting.

     Section 6.  QUORUM. A majority of the directors shall constitute a quorum
for the transaction of business at any meeting of the Board of Directors, but if
less than a majority are present, the meeting may be adjourned from time to time
without further notice.

     Section 7.  MANNER OF ACTING. The act of the majority of the directors
present at a meeting at which a quorum is present shall be the act of the Board
of Directors.

     Section 8.  INFORMAL ACTION BY DIRECTORS. Any action required to be taken
at a meeting of the directors or any other action which may be taken at a
meeting of directors, may be taken without an actual meeting if one or more
consents in writing, setting forth the action so taken, shall be signed by all
of the directors entitled to vote with respect to the subject matter thereof.
The signature of any director upon the

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minutes of a meeting shall be deemed such consent in writing to the action
reflected to have been taken at such meeting by such minutes.

     Section 9.  DISPENSING WITH BOARD OF DIRECTORS. By unanimous consent of all
of the shareholders of the corporation, evidenced by either written agreement,
minutes of a shareholder meeting at which all shareholders are represented and
unanimously approve of the action or a written unanimous consent executed by the
shareholders in lieu of a meeting, the shareholders may dispense with the Board
of Directors of the corporation in accordance with Miss. Code Ann. Section
79-4-8.01(c) (1972). If the shareholders elect to dispense with the Board of
Directors, all duties, responsibilities, rights, authority and obligations
imposed on and enjoyed by the Board of Directors of the corporation by the
Articles of Incorporation or Bylaws of the corporation or at law or in equity
shall be imposed on and enjoyed by the shareholders of the corporation. In votes
by shareholders acting in lieu of the Board of Directors, each outstanding share
of common stock shall be entitled to one (1) vote upon each matter submitted to
a vote at a meeting of the shareholders. A shareholder may disclaim the duties,
responsibilities, rights, authority and obligations conferred under this
provision solely by granting jointly to all of the other shareholders of the
corporation his proxy to vote his shares at meetings of shareholders (or by the
execution of consents of shareholders in lieu of a meeting) at which action is
taken which, but for the provisions of this Section, would be taken by a board
of directors of a corporation, rather than shareholders. In such event^ the
shares subject to this proxy shall be voted by such remaining shareholders in
the same proportion as the remaining shareholders vote their shares on the issue
in question.

                              ARTICLE IV. OFFICERS

     Section 1.  NUMBER. The officers of the corporation shall be a President,
one or more Vice Presidents (the number thereof to be determined by the Board of
Directors) a Secretary, and a Treasurer. Such other officers and assistant
officers as may be deemed necessary may be elected by the Board of Directors.
Any two or more offices may be held by the same person.

     Section 2.  ELECTION AND TERM OF OFFICE. The officers of the corporation to
be elected by the Board of Directors shall be elected annually at a meeting of
the Board of Directors held after each annual meeting of the shareholders. If
the election of officers shall not be held at such meeting, such election shall
be held as soon thereafter as conveniently may be done. Each officer shall hold
office until his successor shall have been duly elected and shall have qualified
or until his death, or until he shall resign or shall have been removed in the
manner hereinafter provided.

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     Section 3.  REMOVAL. Any officer or agent elected or appointed by the Board
of Directors may be removed by the Board of Directors whenever in its judgment
the best interests of the corporation would be served thereby, but such removal
shall be without prejudice to the contract rights, if any, of the person so
removed.

     Section 4.  VACANCIES. A vacancy in any office because of death,
resignation, removal, disqualification or otherwise, may be filled by the Board
of Directors for the unexpired portion of the terms.

     Section 5.  SALARIES. The salaries of the officers shall be fixed from time
to time by the Board of Directors and no officers shall be prevented from
receiving such salary by reason of the fact that they are also directors of the
corporation.

     Section 6.  DUTIES. The duties of each of said officers shall be the duties
usually instant to such offices of a corporation.

     Section 7.  VOTING OF STOCK. Unless otherwise directed by the Board of
Directors, the President in his discretion may vote or give proxies covering all
stock and shares of beneficial interest owned by the corporation.

                ARTICLE V. CONTRACTS, LOANS, CHECKS AND DEPOSITS

     Section 1.  CONTRACTS. The Board of Directors may authorize any officer or
officers, or agent or agents, to enter into any contract or execute and deliver
any instrument in the name of and on behalf of the corporation, and such
authority may be general or confined to specific instances.

     Section 2.  LOANS. No loans shall be contracted on behalf of the
corporation and no evidences of indebtedness shall be issued in its name unless
authorized by a resolution of the Board of Directors. Such authority may be
general or confined to specific instances. The corporation shall not make any
loan to its officers and directors.

     Section 3.  CHECKS, DRAFTS, ETC. All checks, drafts, or other orders for
the payment of money, notes or other evidences of indebtedness issued in the
name of the corporation, shall be signed in such manner as shall from time to
time be determined by resolution of the Board of Directors.

     Section 4.  DEPOSITS. All funds of the corporation not otherwise employed
shall be deposited from time to time to the credit of the corporation in such
banks, trust companies or other depositaries as the Board of Directors may
select.

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                              ARTICLE VI. DIVIDENDS

     The Board of Directors may from time to time declare, and the corporation
may pay, dividends oN its outstanding shares in the manner and upon the terms
and conditions provided by law and its Articles of Incorporation.

                                ARTICLE VII. SEAL

     The Board of Directors shall provide a corporate seal which shall be
circular in form and shall have inscribed thereon the name of the corporation,
and which shall be in the form as hereon impressed:

                         ARTICLE VIII. WAIVER OF NOTICE

     Whenever any notice is required to be given to any shareholder or director
of the corporation under the provisions of these Bylaws or under the provisions
of the Articles of Incorporation or under the provisions of the Mississippi
Business Corporation Act, a waiver thereof in writing, signed by the person or
persons entitled to such notice, whether before or after the time stated
therein, shall be deemed equivalent to the giving of such notice. The signature
of any shareholder or director to the minutes of a meeting shall be deemed a
waiver of any notice required of the holding of such meeting or the business
transacted therein.

                             ARTICLE IX. AMENDMENTS

     These Bylaws may be altered, amended or repealed and new Bylaws may be
adopted by the Board of Directors or by the Shareholders at any regular or
special meeting.

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                       ARTICLE X. CERTIFICATES FOR SHARES
                               AND THEIR TRANSFER

     Section 1.  CERTIFICATES FOR SHARES. Each holder of shares of stock in this
corporation shall be entitled to a certificate under the seal of the
corporation, signed by the President or a Vice President and the Secretary or
Assistant Secretary. Certificates of stock shall be numbered progressively
beginning with the number one, and shall be issued in order of such number. The
stock certificates for this corporation shall be in the form hereinafter placed.

     Each of said certificates shall have typed or printed on the face thereof
the following: "The transferability and negotiability of the shares of stock
evidenced by this certificate are restricted by a Buy-Sell Agreement between the
Shareholders of the corporation, a copy of which is maintained at the
corporation's offices and is available for inspection."

     Section 2.  TRANSFER. Stock shall be transferred on the books of the
corporation and the corporation shall be bound by such transfers only after the
duly issued certificate shall have been tendered to the corporation with a duly
executed bill of sale or assignment of the shares or a portion of the shares
evidenced thereby. In the event of a lost certificate, the corporation may
require such bond or indemnity from the holder of such certificate or
certificates as the directors may determine.

                             ARTICLE XI. FISCAL YEAR

     The fiscal year of the corporation shall end on the 31st day of December of
each year.

                          ARTICLE XII. EMERGENCY BYLAWS

     The Emergency Bylaws provided in this Article XIII shall be operative
during any emergency in the conduct of the business of the corporation resulting
from a catastrophic event that prevents a quorum of the Directors from being
readily assembled, notwithstanding any different provision in the preceding
Articles of the Bylaws or in the Articles of Incorporation of the corporation or
in the Mississippi Business Corporation Act. To the extent not inconsistent with
the provisions of this Article, the Bylaws provided in the preceding Articles
shall remain in effect during such emergency and upon its termination the
Emergency Bylaws shall cease to be operative.

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     During any such emergency:

     (a)  A meeting of the Board of Directors may be called by any officer or
director of the corporation. Notice of the time and place of the meeting shall
be given by the person calling the meeting to such of the directors as it may be
feasible to reach by any available means of communication. Such notice shall be
given at such time in advance of the meeting as circumstances permit in the
judgment of the person calling the meeting.

     (b)  At any such meeting of the Board of Directors, a quorum shall consist
of one.

     (c)  The Board of Directors, either before or during any such emergency,
may provide, or from time to time modify, lines of succession in the event that
during such an emergency any or all officers or agents of the corporation shall
for any reason be rendered incapable of discharging their duties.

     (d)  The Board of Directors, either before or during any such emergency,
may, effective in the emergency, change the head office or designate several
alternative head offices or regional offices, or authorize the officers so to
do.

     No officer, director or employee acting in accordance with these Emergency
Bylaws shall be subject to repeal or change by further action of the Board of
Directors or by action of the shareholders, but no such repeal or change shall
modify the provisions of the next preceding paragraph with regard to action
taken prior to the time of such repeal or change. Any amendment of these
Emergency Bylaws may make any further or different provision that may be
practical and necessary for the circumstances of the emergency.

                          ARTICLE XIII. INDEMNIFICATION

     Section 1.  AUTHORITY TO INDEMNIFY. The corporation may indemnify any
person who was or is a party or is threatened to be made a party to any
threatened, pending or completed action, suit or proceeding, whether civil,
criminal, administrative or investigative, by reason of the fact that he is or
was a director, officer, employee or agent of the corporation, or is or was
serving at the request of the corporation as a director, officer, employee or
agent of another corporation, partnership, joint venture, trust or other
enterprise, against expenses (including attorneys' fees), judgments, fines and
amounts paid in settlement actually and reasonably incurred by him in connection
with such action, suit or proceeding if he conducted himself in good faith and
(i) in the case of conduct in his official capacity with the corporation, in a
manner he reasonably believed to be in the best interests of the corporation, or
(ii) in all other cases, that his conduct was at least not opposed

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to its best interests and, with respect to any criminal action or proceeding by
judgment, order, settlement, conviction, or upon a plea of nolo contendere or
its equivalent, is not, of itself, determinative that the person did not meet
the standard of conduct described in this Section.

     Section 2.  LIMIT ON INDEMNIFICATION AUTHORITY. The corporation may not
indemnify any person under this Article: (1) in connection with a proceeding by
or in the right of the corporation in which the director was adjudged liable to
the corporation; or (2) in connection with any other proceeding charging
improper personal benefit to him, whether or not involving action in his
official capacity, in which he was adjudged liable on the basis that personal
benefit was improperly received by him.

     Section 3.  INDEMNIFICATION WHERE DIRECTOR OR OFFICER SUCCESSFULLY DEFENDS
ACTION. To the extent that a director, officer, employee or agent of the
corporation has been successful on the merits or otherwise in defense of any
action, suit or proceeding referred to in Sections 1 and 2 of this Article, he
shall be indemnified against expenses (including attorneys' fees) actually and
reasonably incurred by him in connection therewith.

     Section 4.  DETERMINATION REQUIRED PRIOR TO INDEMNIFICATION. Any
indemnification under Sections 1 and 2 of this Article (unless ordered by a
court) shall be made by the corporation only as authorized in the specific case
upon a determination that indemnification of the director, officer, employee or
agent is proper in the circumstances because he has met the applicable standard
of conduct set forth in Sections 1 and 2 of this Article. Such determination
shall be made:

     (1)  by the Board of Directors by majority vote of a quorum consisting of
          directors not at the time parties to the proceeding;

     (2)  if a quorum cannot be obtained under subdivision 1, by majority vote
          of a committee duly designated by the Board of Directors (in which
          designation directors who are parties may participate), consisting
          solely of two (2) or more directors not at the time parties to the
          proceeding;

     (3)  by special legal counsel:

          i.  selected by the Board of Directors or its committee in the manner
              prescribed in subdivision (1) or (2); or

          ii. if a quorum of the Board of Directors cannot be obtained under
              subdivision (1) and a committee cannot be designated under
              subdivision (2), selected by a majority vote of the full Board of

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              Directors (in which selection directors who are parties may
              participate); or

     (4)  by the shareholders, but shares owned by or voted under the control of
          persons who are at the time parties to the proceeding may not be voted
          on the determination.

Authorization of indemnification and evaluation as to reasonableness of expenses
shall be made in the same manner as the determination that indemnification is
permissible, except that if that the determination is made by special legal
counsel, authorization of indemnification and evaluation as to reasonableness of
expenses shall be made by those entitled under Subsection (3) to select counsel.

     Section 5.  ADVANCES. Expenses incurred by a director, officer, employee or
agent of the corporation in defending a civil or criminal action, suit or
proceeding shall be paid by the corporation in advance of the final disposition
of such action, suit or proceeding if:

     (1)  the person furnishes the corporation with a written affirmation of his
          good faith belief that he has met the standard of conduct described in
          Sections 1 and 2 of this Article;

     (2)  the person furnishes the corporation a written undertaking, executed
          personally or on his behalf, to repay the advance if it is ultimately
          determined that he did not meet the standards of conduct; and

     (3)  a determination is made that the facts then known to those making the
          determination would not preclude indemnification under this Article.

The undertaking described in subparagraph (2) above must be an unlimited general
obligation of the person giving the undertaking but need not be secured and may
be accepted without reference to financial ability to make repayment.
Determinations and authorizations of payments under this Section shall be made
in the manner described in Section 4 of this Article.

     Section 6.  GENERAL. The indemnification and advancement of expenses
provided by, or granted pursuant to, the other Sections of this Article shall
not be deemed exclusive of any other rights to which those seeking
indemnification may be entitled under any bylaw, agreement, vote of stockholders
or disinterested directors or otherwise, both as to action in his official
capacity and as to action in another capacity while holding such office.

     Section 7.  INSURANCE. The corporation may purchase and maintain insurance
on behalf of any person who is or was a director, officer, employee or agent of
the

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corporation, or is or was serving at the request of the corporation as a
director, officer, employee or agent of another corporation, partnership, joint
venture, trust or other enterprise against any liability asserted against him
and incurred by him in any such capacity, or arising out of his status as such,
whether or not the corporation would have the power to indemnify him against
such liability under this Article.

     Sections 8. DEFINITIONS. For purposes of this Article, the following words
or phrases shall have the meanings assigned to them in Miss. Code Ann. Section
79-4-8.50 (1972), as amended: "corporation," "director," "expenses,"
"liability," "official capacity," "party," and "proceeding."

     Section 9.  SEVERABILITY. If any provision of this Article or the
application thereof to any person or circumstance shall, to any extent, be
invalid or unenforceable, the remainder of this Article or the application of
this Article to persons or circumstances other than those to which it is held
invalid or unenforceable, shall not be affected thereby and each provision shall
be valid and shall be enforced to the fullest extent permitted by law.

                             SECRETARY'S CERTIFICATE

     I hereby certify that the foregoing Bylaws are the Bylaws of Sturgis,
Henderson & Proctor Pathology Laboratory, P.A. as adopted by Unanimous Consent
of the Shareholders of the corporation on the 1st day of July, 1992.

                                                              /s/ [ILLEGIBLE]
                                                              ---------------
                                                              Secretary

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