Pulmonary embolism rule-out criteria
The pulmonary embolism rule-out criteria (PERC) helps assess people in whom pulmonary embolism is suspected, but unlikely. Unlike the Wells score and Geneva score, which are clinical prediction rules intended to risk stratify people with suspected PE, the PERC rule is designed to rule out the risk of PE in people when the physician has already stratified them into a low-risk category.People in this low risk category without any of these criteria may undergo no further testing for PE: low oxygen saturations – SaO2 <95%, unilateral leg swelling, coughing up blood, prior DVT or PE, recent surgery or trauma, age >50, hormone use, fast heart rate. The rationale behind this decision is that further testing (specifically CT angiogram of the chest) may cause more harm (from radiation exposure and contrast dye) than the risk of PE. The PERC rule has a sensitivity of 97.4% and specificity of 21.9% with a false negative rate of 1.0% (16/1666). Blood tests
In people with a low or moderate suspicion of PE, a normal D-dimer level (shown in a blood test) is enough to exclude the possibility of thrombotic PE, with a three-month risk of thromboembolic events being 0.14%. D-dimer is highly sensitive but not specific (specificity around 50%). In other words, a positive D-dimer is not synonymous with PE, but a negative D-dimer is, with a good degree of certainty, an indication of absence of a PE. A low pretest probability is also valuable in ruling out PE.
Plateau iris is a less common medical condition of the eye resulting from anterior displacement of the peripheral iris by the ciliary body causing angle closure glaucoma. First line treatment for all causes of narrow angle glaucoma is laser iridotomy. If narrow angle glaucoma persists after iridotomy then it is called plateau iris syndrome and subsequently managed either medically (miotics) or surgically (laser peripheral iridoplasty). Plateau iris is a less common form of narrow angle glaucoma and is sometimes discovered after an iridotomy causes a rapid increase in eye pressure. Since this condition is not common, most ophthalmologists are unfamiliar with, and have little experience with, the anatomy of and treatments for this condition. References
Further reading
Wand, M; Grant, WM; Simmons, RJ; Hutchinson, BT (January 1977). "Plateau iris syndrome". Transactions. Section on Ophthalmology. American Academy of Ophthalmology and Otolaryngology. 83 (1): 122–130. PMID 898466. NAID 10029605696. Pavlin, Charles J.; Ritch, Robert; Foster, F. Stuart (April 1992). "Ultrasound Biomicroscopy in Plateau Iris Syndrome". American Journal of Ophthalmology. 113 (4): 390–395. doi:10.1016/s0002-9394(14)76160-4. PMID 1558112. Ritch, Robert (April 1992). "Plateau Iris Is Caused by Abnormally Positioned Ciliary Processes". Journal of Glaucoma. 1 (1): 23–26. doi:10.1097/00061198-199204000-00006. S2CID 72047734. Diniz Filho, Alberto; Cronemberger, Sebastião; Mérula, Rafael Vidal; Calixto, Nassim (October 2008). "Plateau iris". Arquivos Brasileiros de Oftalmologia. 71 (5): 752–758. doi:10.1590/S0004-27492008000500029. PMID 19039479. Ritch, Robert; Tham, Clement C.Y; Lam, Dennis S.C (January 2004). "Long-term success of argon laser peripheral iridoplasty in the management of plateau iris syndrome". Ophthalmology. 111 (1): 104–108. doi:10.1016/j.ophtha.2003.05.001. PMID 14711720.