Retrospective Observational Study of Computed Tomography-Based Vascular Risk Assessment During Needle Drainage of Peritonsillar Abscess

Summary

The purpose of this protocol is to measure the distances of peritonsillar abscesses from the Internal Carotid Artery (ICA), External Carotid Artery, and Internal Jugular Vein using contrast-enhanced Computed Tomography, to detect ICA course anomalies, and to assess the risk of vascular injury during drainage quantitatively.

Abstract

Peritonsillar abscess (PTA) is a common deep neck infection in which bedside drainage is performed close to major cervical vessels. Although catastrophic vascular complications are rare, clinicians have limited quantitative information on how far the internal carotid artery (ICA), external carotid artery (ECA), and internal jugular vein (IJV) lie from the abscess in individual patients. This protocol describes a contrast-enhanced computed tomography (CT)-based workflow to confirm unilateral PTA, acquire neck CT images under standard clinical settings, measure linear distances from the anterior and posterior abscess capsule to the ipsilateral ICA, ECA, and IJV, compare these distances with the contralateral healthy side as an internal control, and classify the theoretical risk of ICA injury during needle drainage using a modified Pfeiffer system. The procedure includes patient selection, safety screening for iodinated contrast, contrast-enhanced CT acquisition, standardized axial image review by a head and neck radiologist, and structured data recording and analysis. In a retrospective cohort of 94 adult patients, PTA consistently displaced the ICA, ECA, and IJV away from the tonsillar space, increasing both anterior and posterior distances compared with the healthy side. The mean posterior PTA-ICA distance was approximately 14 mm, whereas the contralateral tonsil-ICA distance was about 9 mm. ICA course anomalies (tortuosity or coiling) were detected in a minority of patients, and roughly one in seven cases met moderate-risk criteria because of shorter distances and/or aberrant ICA anatomy. Age, sex, and abscess volume did not significantly alter these relationships. This CT-based protocol provides a reproducible method to quantify PTA-vessel distances and identify patients with potentially higher vascular risk anatomy prior to drainage. It supports cautious, controlled-depth needle aspiration in most cases and highlights scenarios in which image-guided or operating-room drainage may be preferable.

Introduction

Peritonsillar abscess (PTA) is a collection of pus between the palatine tonsillar capsule and the superior pharyngeal constrictor muscle, most often arising as a complication of acute tonsillitis. It is the most common deep neck infection and a frequent otolaryngologic emergency, particularly in young adults, with an incidence of approximately 18-30 cases per 100,000 population and a peak in the 20-40-year age group¹. Patients typically present with severe unilateral sore throat, fever, hot-potato voice, trismus, dysphagia, and pooling of saliva. Prompt recognition and drainage, together with appropriate antibiotics, are essential to prevent ai....

Protocol

This protocol was applied in a retrospective observational cohort of patients with unilateral peritonsillar abscess (PTA) who underwent contrast-enhanced neck CT as part of their standard diagnostic work-up. The Dicle University Ethics Committee approved this retrospective observational study, which was carried out at a tertiary care facility (Approval number: 06/05/2021, 310). Every procedure followed the Declaration of Helsinki. Given the retrospective nature of the analysis, all participants provided written informed consent at the time of treatment for the use of their data in research.

Study design and patient selection

Results

Following these steps yields a reproducible, CT-based protocol for quantifying PTA-vessel distances, detecting ICA course anomalies, and classifying the theoretical risk of vascular injury during needle drainage in patients with peritonsillar abscess.

In routine clinical practice, contrast-enhanced CT is reserved for patients in whom the diagnosis is uncertain or the intraoral examination is limited (e.g., marked trismus, severe.......

Discussion

Although clinically significant vascular injury during PTA drainage is exceedingly rare, the possibility of ICA puncture remains a major concern among clinicians^15,17. The findings here provide quantitative evidence that PTA generally increases the distance between the tonsillar region and the surrounding vascular structures, particularly the ICA, thereby creating an additional tissue buffer during drainage. The mean posterior PTA-ICA distance was 14.1 ± 3.5.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
18–20 G Intravenous Cannula	BD (Becton, Dickinson and Company)	Varies by size
Contrast Injector System	Medrad (Bayer Healthcare)	Stellant CT
Digital Caliper Tool (PACS)	GE Healthcare	AW Server
Head and Neck CT Workstation	GE Healthcare	AW Server
Iodinated Contrast Agent (Nonionic)	Bayer Healthcare	Ultravist 300
Multidetector CT Scanner (64-slice)	GE Healthcare	Revolution EVO
PACS Software	GE Healthcare	Centricity PACS
Saline Flush (0.9% NaCl)	Baxter	FKE1323
SPSS Statistics Software	IBM	Version 21.0