What type of computed tomography (CT) scan is recommended for a rectal abscess?

From the Guidelines

For a rectal abscess, a contrast-enhanced CT scan of the pelvis with intravenous (IV) contrast is the recommended imaging modality. This is based on the most recent and highest quality study available, which suggests that IV contrast is preferred to a noncontrast examination to help visualize and characterize fluid collections, abscesses, and fistulous tracts 1. The use of water-soluble rectal contrast is generally not necessary to diagnose a rectal abscess, but may be helpful in certain situations such as suspected perforation or leak 1.

The choice of imaging modality depends on various factors, including the patient's clinical presentation, past medical history, and local availability of resources and skills 1. However, CT scanning is generally preferred due to its widespread availability, short acquisition time, and ability to provide sufficient detail for diagnosis and management of rectal abscesses.

Some key points to consider when using CT scans for rectal abscesses include:

• The importance of IV contrast to delineate rim-enhancement of fluid collections and aid in the diagnosis of abscess 1
• The potential limitations of CT scans, including poor spatial resolution in the pelvis and difficulty differentiating between fistula tracts and inflammation 1
• The role of other imaging modalities, such as MRI and ultrasound, in the diagnosis and management of rectal abscesses 1

Overall, a contrast-enhanced CT scan of the pelvis with IV contrast is the recommended imaging modality for a rectal abscess, due to its ability to provide sufficient detail for diagnosis and management, while also being widely available and relatively quick to perform 1.

From the Research

Types of CT Scans for Rectal Abscess

• Computed Tomography (CT) scan-guided percutaneous drainage of intra-abdominal abscesses is an effective approach for managing rectal abscesses, as shown in a study published in 1994 2.
• CT-guided transrectal drainage is a viable option for draining pelvic abscesses, offering increased patient comfort and minimal risk of potential complications, according to a 1991 study 3.
• Contrast-enhanced CT is a useful tool for diagnosing anorectal sepsis, including rectal abscesses, and can guide clinical management in the emergency room setting, as discussed in a 2015 study 4.

Contrast Agents in CT Scans

• The use of contrast agents in CT scans for suspected acute abdominal processes, including rectal abscesses, may not be necessary for accurate diagnosis, as found in a 2010 study 5.
• Different combinations of intravenous, oral, and rectal contrast agents can be used in CT scans, but the choice of contrast agent may not significantly impact the accuracy of diagnosis, according to the same 2010 study 5.

Alternative Drainage Methods

• Endoscopic Ultrasound (EUS)-guided transrectal drainage is a minimally invasive alternative to conventional surgical and percutaneous drainage techniques for perirectal abscesses, as demonstrated in a 2021 case report 6.
• EUS-guided transrectal drainage may be a suitable option for patients with Crohn's disease-associated perirectal abscesses, as shown in the same 2021 case report 6.