In this study, anthropometric measurements (clinical measurements) will be applied in all patient groups; expected (to be difficult to provide airway patency as a result of detailed history, physical examination and evaluation tests performed by an experienced anesthesiologist), and unexpected (although it was not predicted that a difficulty was encountered). And ultrasounographic measurements will be applied in all patients. The aim of this study is to evaluate the predictive accuracy of ultrasonographic measurements.

In the preoperative period, the following clinical tests will be performed before the patient arrives in the operating room and when the patient arrives, the measurements will be made by ultrasonography.

1. Mallampati classification
2. Determination of mouth opening (interinsizer distance)
3. Thyromental distance
4. Sternomental distance

Preoperative evaluation of the patients and clinical results of the airway tests (mentioned above) will be recorded. The cervical soft tissue thickness will be measured and recorded at 3 levels (thyrohyoid membrane, vocal cord, hyoid bone) with the help of ultrasonography (mentioned above). In addition, since all patients will be under general anesthesia, laryngoscopic images (laryngoscopic evaluation according to Cormack Lehane classification) routinely recorded on the anesthesia follow-up sheet will be recorded.

Inclusion Criteria:

• patients under general anesthesia
• ASA 1-2-3

Exclusion Criteria:

• Patients who will undergo emergency surgery,
• pregnant women,
• children,
• patients who may have difficulty in airway management due to cervical instability,
• patients with trauma or malignancy in the neck region

ASA 1-2-3, 18-75 aged, patients undergoing general anesthesia