MEMORANDUM OPINION

JOHN S. ANDERSON, Justice.

This is an accelerated appeal from the trial court's denial of appellant's, University of Texas Medical Branch, plea to the jurisdiction. Appellee, Tinesha T. Thompson, filed suit against appellant, a government healthcare provider, for medical malpractice in appellant's treatment of appellee's appendicitis. Appellant, asserting appellee's claims do not invoke the Texas Tort Claims Act's limited waiver of sovereign immunity, filed a plea to the jurisdiction, which the trial court denied. We reverse and render judgment dismissing appellee's claims for want of subject-matter jurisdiction.

FACTUAL AND PROCEDURAL BACKGROUND

Appellee visited appellant's emergency room on three consecutive days in 2003. Appellee complains only about the care she received during the second of her three visits. Appellee first visited the emergency room on April 29, 2003 complaining of abdominal pain, nausea, and vomiting. She was diagnosed with gastritis and instructed to follow up with her primary-care physician. According to appellee's expert, Dr. Charles Stewart, appellant's physicians performed a reasonable evaluation of appellee on this first visit including appropriate laboratory and radiologic evaluation.

Appellee returned to appellant's emergency room the following day, this time by ambulance. Appellee reported a worsening condition including more vomiting and pain throughout her abdomen. Her examination revealed a high white-blood-cell count and a rapid heartbeat, but no additional radiographic studies were obtained. The attending physician prescribed appellee medication, and ultimately discharged her with instructions to eat a high-fiber diet, follow-up with a family medicine physician, and return to the emergency room if her symptoms worsened. Finally, before she was discharged, appellee was given an injectable form of pain medication that appellee alleges masked her symptoms.

Appellee's expert, Dr. Charles Stewart, believes appellant's physicians missed key signs of appellee's appendicitis on this second visit to the emergency room. Although Dr. Stewart found no fault with the laboratory work ordered during this second visit, he opined that a prudent physician would have requested another imaging study such as an ultrasound or a CT scan. Dr. Stewart stated that if the emergency room physician had ordered a CT scan during this second visit to the emergency room, in all medical likelihood the appendicitis would have been appropriately discovered during this visit. Dr. Stewart continued that appellant's inappropriate evaluation and discharge of appellee during this second visit delayed appropriate care and administration of antibiotics to decrease the effects of the ruptured appendix. Dr. Stewart concluded that "as a direct result of the . . . failure to adequately examine the [appellee], counsel the resident about the dangers of the patient who returns within 48 hours, and order appropriate imaging studies on this [appellee's] second visit, the [appellee] did, in fact, suffer an intraabdominal abscess that required additional hospitalization and procedures."

On the next day, appellee returned to the emergency room and following a CT scan, appellant performed an emergency repair of appellee's appendix. Dr. Stewart found no fault with appellant's treatment of appellee during this third visit to the emergency room.

Appellee filed suit against appellant alleging appellant's physicians and nurses harmed appellee by: (1) improperly administering injectable pharmaceuticals thereby masking the symptoms of appendicitis; (2) improperly permitting appellee's discharge from the hospital while she remained in a condition requiring emergency surgical intervention; and (3) failing to properly evaluate and treat appellee. In a plea to the jurisdiction, appellant asserted that appellee's claims do not invoke the Tort Claims Act's limited waiver of sovereign immunity. In response to appellant's plea to the jurisdiction, appellee asserted that appellant also committed negligence by (1) using x-ray equipment, because, according to appellee, x-rays are not capable of diagnosing appendicitis, and (2) misusing diagnostic equipment such as a stethoscope, blood pressure machines, and thermometers in a way that failed to recognize the signs and symptoms of appellee's illness. Appellee asserted that the tangible personal property used by appellant's physicians that invoked the Tort Claims Act's limited waiver of immunity were: pain medications, the x-ray machine, and various diagnostic equipment including a stethoscope, blood pressure machine, and a thermometer.

The trial court denied appellant's plea to the jurisdiction and this interlocutory appeal followed pursuant to Tex. Civ. Prac. Rem. Code Ann. § 51.014(a)(8) (Vernon Supp. 2005).

DISCUSSION

In one issue, appellant argues appellee's suit is barred by sovereign immunity.

I. Sovereign Immunity

In Texas, sovereign immunity deprives a trial court of subject matter jurisdiction for lawsuits in which the state or certain governmental units have been sued unless the state consents to suit. Tex. Dep't of Parks Wildlife v. Miranda, 133 S.W.3d 217, 224 (Tex. 2004). The Tort Claims Act provides a limited waiver of sovereign immunity, allowing suits to be brought against governmental units only in certain, narrowly defined circumstances. TEX. CIV. PRAC. REM. CODE ANN. § 101.021 (Vernon 2005); Tex. Dep't of Criminal Justice v. Miller, 51 S.W.3d 583, 587 (Tex. 2001). Thus, appellant is immune from suit unless the Tort Claims Act expressly waives immunity. Miranda, 133 S.W.3d at 224-25.

The specific Tort Claims Act provision under which appellee alleges waiver provides that a "governmental unit in the state is liable for . . . personal injury and death so caused by a condition or use of tangible personal or real property if the governmental unit would, were it a private person, be liable to the claimant according to Texas law." Tex. Civ. Prac. Rem. Code Ann. 101.021(2) (Vernon 2005).

II. Standard of Review

Whether a court has subject matter jurisdiction is a question of law. Miranda, 133 S.W.3d at 226. Appellate courts reviewing a challenge to a trial court's subject matter jurisdiction review the trial court's ruling de novo. Id. at 228. When reviewing a plea to the jurisdiction in which the pleading requirement has been met and evidence has been submitted to support the plea that implicates the merits of the case, we take as true all evidence favorable to the nonmovant. Id. Further, we indulge every reasonable inference and resolve any doubts in the nonmovant's favor. Id. III. Appellee's Suit is Barred by Sovereign Immunity

Appellee's suit does not invoke the limited waiver of immunity found in the Tort Claims Act for two reasons. First, appellee's allegations do not meet the Tort Claims Act's requirement that tangible state personal property cause appellee's injury. See TEX. CIV. PRAC. REM. CODE ANN. § 101.021(2). Second, the substance of appellee's claim is that appellant failed to timely diagnose and treat appellee's appendicitis.

A. Tangible State Personal Property Did Not Cause Appellee's Injury

The Tort Claims Act's plain language limits its waiver of sovereign immunity to only those personal injuries caused by a condition or use of tangible personal or real property. Id. The mere involvement of property in circumstances leading to an injury is insufficient to meet this causation requirement. Dallas County Mental Health Mental Retardation v. Bossley, 968 S.W.2d 339, 342-43 (Tex. 1998). Instead, the property must be the instrumentality of the harm. Robinson v. Univ. of Tex. Med. Branch at Galveston, 171 S.W.3d 365, 369 (Tex.App.-Houston [14th] 2005, no pet.). In Miller, a case with remarkably similar facts, the plaintiff sued the state alleging that her husband's government employed doctor invoked the Tort Claims Act's waiver of immunity by prescribing drugs that masked his symptoms and misusing diagnostic tools in such a way that the doctor failed to timely diagnose his meningitis. Miller, 51 S.W.3d at 587. The Texas Supreme Court held that the use of property alleged by the plaintiff did not invoke the Tort Claims Act's waiver of immunity. Id. at 588. The supreme court continued that mere involvement of tangible personal property in the treatment is not enough to waive immunity; instead, that property must have actually caused the injury. Id. Because it did not, there was no waiver of sovereign immunity. Id. at 589.

In the case at bar, appellee alleges she was given symptom-masking drugs and the appellant's emergency room personnel did not properly use medical diagnostic tools to timely diagnose her appendicitis. These allegations do not meet the Tort Claims Act's causation requirement because none of the property involved in appellee's medical treatment actually harmed appellee.

B. Appellee's True Complaint, that Appellant Failed to Timely Diagnose and Treat Her Appendicitis, Does Not Waive Immunity

In determining whether sovereign immunity has been waived, courts look to the real substance of a plaintiff's cause of action, not the plaintiff's characterization of her claims. See, e.g., Dallas Area Rapid Transit v. Whitley, 104 S.W.3d 540, 543 (Tex. 2003); Bossley, 968 S.W.2d at 343. Here, the real substance of appellee's suit is that appellant's emergency room medical staff failed to timely detect and treat appellee's appendicitis and these failures resulted in pain and injury that would not have occurre

In determining whether sovereign immunity has been waived, courts look to the real substance of a plaintiff=s cause of action, not the plaintiff=s characterization of her claims. See, e.g., Dallas Area Rapid Transit v. Whitley, 104 S.W.3d 540, 543 (Tex. 2003); Bossley, 968 S.W.2d at 343. Here, the real substance of appellee=s suit is that appellant=s emergency room medical staff failed to timely detect and treat appellee=s appendicitis and these failures resulted in pain and injury that would not have occurred if she had been timely and properly diagnosed and treated. However, a state entity=s failure to act does not invoke the Tort Claims Act=s limited waiver of immunity. See Kassen v. Hatley, 887 S.W.2d 4, 14 (Tex. 1994). As the real substance of appellee=s cause of action is a failure to act, appellee=s suit does not invoke the Tort Claims Act=s waiver of immunity.

Conclusion

We sustain appellant=s issue and reverse the trial court=s denial of appellant=s plea to the jurisdiction and render judgment dismissing appellee=s suit for want of subject-matter jurisdiction.