Peritonsillar Abscess in the ED: Diagnosis, Drainage, and Targeted Antibiotic Therapy

You're on your emergency medicine rotation when a 30-year-old patient checks in with a chief complaint of the worst sore throat of their life. For the past three days, they've had a fever, fatigue, and a sore throat that has become progressively more painful, especially on one side.

Is this just a severe case of pharyngitis, or is there something more serious lurking in the back of the throat? A severe unilateral sore throat should make you think beyond the basics, and a peritonsillar abscess (PTA) should be at the top of your differential. Let's walk through a classic case and break down exactly what you need to know to nail the diagnosis and management.

A Classic Case in the ED

Our 30-year-old patient looks uncomfortable. Their vitals are: BP 140/70 mmHg, HR 90/min, RR 22/min, SpO2 98% on room air, and a temperature of 100.0°F (37.8°C).

They are alert and oriented, but their speech is slightly muffled and has a nasal quality—the classic "hot potato voice"— as if they're trying to talk with a hot potato in their mouth.

When you ask them to open their mouth, you notice they can't open it very wide (trismus). With a tongue depressor and a good light source, you see the key finding: the right palatal arch is red, swollen, and bulging downward, pushing the uvula over to the left side. This asymmetry is the hallmark of a peritonsillar abscess.

Given the high clinical suspicion, you consult your ENT colleague on call. Together, you perform bedside incision and drainage of the abscess, obtaining purulent fluid that is sent for culture. The patient receives a single 8 mg IV dose of dexamethasone  and a dose of amoxicillin-clavulanate.

After a few hours of observation, their pain and trismus have improved significantly. They are discharged home with a 10-day course of oral antibiotics and strict instructions to follow up with ENT the next day. At their follow-up, the patient is feeling much better, able to eat and drink comfortably, and requires no further intervention.

What Exactly is a Peritonsillar Abscess (PTA)?

A peritonsillar abscess is the most common deep neck space infection seen in young adults. It's a collection of pus that forms in the loose connective tissue between the tonsillar capsule and the superior pharyngeal constrictor muscle.

It's typically a polymicrobial infection, most often caused by Group A Streptococcus along with oral anaerobes like Fusobacterium and Prevotella. While it can be a complication of bacterial or even viral tonsillitis, the abscess itself is always a bacterial process that requires drainage and antibiotics.

If left untreated, a PTA can spread to other deep neck spaces, leading to life-threatening complications like descending mediastinitis, retropharyngeal abscess, Ludwig angina, or Lemierre syndrome. This is why prompt diagnosis and treatment of PTA are critical.

PTA Diagnosis and Treatment: The Clinical Approach

Spotting the Signs: Key Symptoms and Exam Findings

The diagnosis is primarily clinical. Look for the classic triad:

• Severe unilateral sore throat

• Fever

• Trismus (difficulty opening the jaw due to inflammation of the pterygoid muscles)

Other key findings include:

• "Hot potato voice": A muffled, nasal-sounding voice.

• Dysphagia and Odynophagia: Difficulty and pain with swallowing, often causing drooling.

• Physical Exam: Unilateral swelling of the soft palate and tonsillar pillar, with deviation of the uvula to the contralateral (unaffected) side.

Diagnostic Tools: When the Exam Isn't Enough

In most cases, the physical exam is all you need. However, if the diagnosis is uncertain or the patient has severe trismus preventing a good view, imaging can help.

• Intraoral POCUS for PTA: Point-of-care ultrasound is an excellent tool for the ED. An endocavitary probe can be placed directly over the swollen area to quickly identify a hypoechoic fluid collection, confirming the abscess and guiding drainage. It's fast, radiation-free, and has good sensitivity and specificity.

• CT Scan with Contrast: This is the gold standard for differentiating cellulitis from a drainable abscess and is essential if you suspect the infection has spread into deeper neck spaces.

Management in the ED: Drainage and Medication

The Main Event: Drainage Procedures

The definitive treatment for a PTA is to drain the pus. The two main methods, needle aspiration and incision and drainage (I&D), are equally effective.

• Needle Aspiration: This is often the first choice in the ED. It's less invasive, less painful, and can be both diagnostic (confirming the presence of pus) and therapeutic.

• Incision and Drainage (I&D): This involves making a small incision over the abscess to allow for more complete drainage. This is typically performed by an ENT specialist.

Choosing the Right Antibiotics for PTA

Antibiotic therapy is essential for all patients. The goal is to cover both Group A Streptococcus and oral anaerobes.

First-Line Agents:

• Amoxicillin-clavulanate

• Penicillin VK + Metronidazole

• Clindamycin (an excellent choice for its anaerobic coverage and for patients with a penicillin allergy)

Clinical Pearl: Recent studies suggest that adding metronidazole to penicillin may not provide additional benefit, as penicillin alone often has sufficient anaerobic coverage for this type of infection.

The Power of Adjuncts: Dexamethasone Therapy for PTA

A single, one-time dose of a corticosteroid (e.g., dexamethasone 10 mg IV or IM) is recommended as adjunct therapy. Adjunct dexamethasone therapy for PTA has been shown to significantly reduce pain, decrease swelling, and speed up recovery, helping patients feel better, faster.

Disposition: To Admit or Not to Admit?

Most patients (~80%) can be safely managed as outpatients after successful drainage in the ED.

Indications for hospital admission include:

• Signs of sepsis or airway compromise

• Significant comorbidities (e.g., uncontrolled diabetes, an immunocompromised state)

• Inability to tolerate oral fluids or medications

• Suspicion of spread to a deep neck space

Patients discharged from the ED must have reliable follow-up arranged within 24– 48 hours to ensure clinical improvement . Most will not require a second drainage procedure.

High-Yield Takeaways for Your Next Shift

When you see a patient with a severe sore throat, remember these key points:

• Think PTA if you see the triad of unilateral throat pain, fever, and trismus.

• Look for the key sign: Palatal asymmetry with uvular deviation to the opposite side.

• Drainage is key: Needle aspiration is a simple, effective first-line method in the ED.

• Choose appropriate antibiotics : Amoxicillin-clavulanate or clindamycin are excellent choices.

• Don't forget the steroid: A single dose of dexamethasone can make a huge difference in your patient's pain and recovery.

• Most patients can go home: If they are stable, tolerating oral intake , and have good follow-up, outpatient management is appropriate.

Mastering the diagnosis and management of a peritonsillar abscess is a high-yield skill for any student or resident. By recognizing the classic signs and initiating the right treatment, you can prevent serious complications and provide rapid relief for your patient. You've got this!

References

• Galioto NJ. Peritonsillar Abscess. Am Fam Physician. 2017;95(8):501-506.

• Steyer TE. Peritonsillar Abscess: Diagnosis and Treatment. Am Fam Physician. 2002;65(1):93-96.

• Moen CM, Paramjothy K, Williamson A, et al. A Systematic Review of the Role of Penicillin Versus Penicillin Plus Metronidazole in the Management of Peritonsillar Abscess. J Laryngol Otol. 2023;137(7):696-702.

• Hur K, Zhou S, Kysh L. Adjunct Steroids in the Treatment of Peritonsillar Abscess: A Systematic Review. Laryngoscope. 2018;128(1):72-77.

• Chang BA, Thamboo A, Burton MJ, Diamond C, Nunez DA. Needle aspiration versus incision and drainage for the treatment of peritonsillar abscess. Cochrane Database Syst Rev. 2016;12(12):CD006287.

Forner D, Curry DE, Hancock K, et al. Medical Intervention Alone vs Surgical Drainage for Treatment of Peritonsillar Abscess: A Systematic Review and Meta-Analysis. Otolaryngol Head Neck Surg. 2020;163(4):645-653.