EXHIBIT 3.243

CERTIFICATE OF FORMATION

OF

CSMC, LLC

Under Section 18-201 of the

Delaware Limited Liability Company Act

FIRST: The name of the limited liability company is CSMC, LLC (the “Company”).

SECOND: The address of the registered office of the Company in the State of Delaware is 1013 Centre Road, Wilmington, Delaware 19805.

THIRD: The name and address of the Company’s registered agent for service of process is Corporation Service Company, 1013 Centre Road, Wilmington, Delaware 19805.

IN WITNESS WHEREOF, the undersigned has executed this Certificate of Formation as of October 30, 1998.

By: /s/ John M. Franck
Name: John M. Franck II
Title: Authorized Person

STATE OF DELAWARE
SECRETARY OF STATE
DIVISION OF CORPORATIONS
FILED 03:30 PM 05/07/1999
991183201 — 2964231

CERTIFICATE OF MERGER

OF

COLLEGE STATION REAL ESTATE, LLC

INTO

CSMC, LLC

Pursuant to Section 18.209 of the

Delaware Limited Liability Company Act

The undersigned limited liability company DOES HEREBY CERTIFY:

FIRST: The name and the state of formation or organization of each of the constituent entities to the merger are as follows:

Name State of Formation or Organization

CSMC, LLC (“LLC 1”)     Delaware

College Station Real Estate, LLC (“LLC2”) Delaware

SECOND: An Agreement and Plan of Merger between the constituent entities to the merger (the “Merger Agreement”) has been approved and executed by each of the constituent entities in the merger.

THIRD: LLC 2 shall be merged with and into LLC 1, with LLC 1 being the surviving entity (the “Surviving Entity”) in the merger, and the name of the Surviving Entity shall be CSMC, LLC.

FOURTH: The Certificate of Formation of LLC 1 at the effective date of the merger shall be the Certificate of Formation of the Surviving Entity.

FIFTH: The executed Merger Agreement is on file at the principal place of business of the Surviving Entity. The address of the Surviving Entity is One Park Plaza, Nashville, Tennessee 37201.

SIXTH: A copy of the Merger Agreement will be furnished by the Surviving Entity, on request and without cost, to any member of the constituent entities.

SEVENTH: This Certificate of Merger shall be effective on May 7, 1999.

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IN WITNESS WHEREOF, this Certificate of Merger has been executed on this 6th day of May, 1999.

CSMC, LLC

By: /s/ Ronald Lee Grubbs, Jr.
Ronald Lee Grubbs, Jr.
Vice President

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