Intra-abdominal abscess: Clinical sciences

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Introduction0:00–0:55

Intra-abdominal abscesses are a dangerous type of infection that, if left untreated, can progress to sepsis and death. They commonly arise from disruptions in the gastrointestinal or genitourinary tract, either from inflammation that causes microscopic leaks in the mucosal barrier or on a gross level from surgery or trauma.
Disruption allows intra-luminal bacteria to leak into the abdominal cavity and cause infection. Now, the immune system may try to contain the infected fluid by forming a discrete, walled-off pocket, called an intra-abdominal abscess.
If the infection doesn’t remain contained within the abscess, the free fluid containing the pathogen can lead to diffuse peritonitis.
Based on the location, localization, and contents of the abscess, they can be grouped as abscesses with and without complicating features.When a person presents with signs and symptoms suggestive of an intra-abdominal abscess, you should first perform an ABCDE assessment to determine whether they are stable or unstable.

Unstable patient0:55–1:21

If the individual is unstable, you need to stabilize their airway, breathing, and circulation, which usually involves intubation, establishing an IV access, or administering fluids.

History & physical examination1:21–1:59

Once you stabilize them, the next step is to obtain a focused history and physical examination, which might reveal signs and symptoms of diffuse peritonitis.
These patients often report severe, diffuse abdominal pain that worsens with movement. Additionally, the physical exam might reveal distention, rigidity, guarding, and rebound tenderness.
If this is the case, start empiric IV antibiotics and consult the surgical team immediately for further management, including imaging like CT scan, or bedside ultrasound if the patient is too unstable, followed by emergent laparotomy to explore and treat the infection.

Stable patient1:59–4:12

Alright, now let’s take a look at a stable patient that presents with signs and symptoms suggestive of intra-abdominal abscess.
Start with a thorough history and physical exam, and obtain labs like CBC, CMP, blood cultures, and urinalysis. Patients with an intra-abdominal abscess usually report abdominal pain, loss of appetite, constipation, diarrhea, nausea, vomiting, or bloating.
Next, ask about any recent surgeries, since many intra-abdominal abscesses occur after abdominal surgery. Another major risk factor is a history of recent gastrointestinal inflammatory conditions, such as appendicitis, diverticulitis, Crohn’s disease, as well as cholecystitis, pancreatitis, and pelvic inflammatory disease.
Finally, some patients will have a history of a perforated ulcer, penetrating abdominal trauma, or bowel infarction that eventually resulted in an intra-abdominal abscess.
On the other hand, the physical exam might reveal focal tenderness and a mass in the region of the abscess. Additionally, there might be signs of dehydration and infection or a systemic inflammatory response, like elevated temperature, tachycardia, and tachypnea.
Some high-yield facts to keep in mind! Depending on the abscess location, individuals might have specific symptoms caused by local inflammation in the area of the abscess.
A subphrenic abscess right below the diaphragm can cause shoulder pain or hiccups due to irritation of the diaphragm. On the flip side, a pelvic abscess can cause frequent urination or tenesmus.Now, when it comes to labs, the CBC usually reveals leukocytosis and the lactate level can be elevated.
In addition, labs may reveal abnormal results specific to the organ system or abdominal region involved, such as elevated amylase or lipase if there’s pancreatitis, elevated liver enzymes if there’s a liver source or septic shock causing organ failure, and abnormal urinalysis results like leukocyte esterase if there’s a genitourinary source.
Lastly, blood cultures might be positive for bacterial growth. Specifically, blood cultures positive for anaerobes should make you suspect an intra-abdominal abscess.
Alright, if you suspect an intra-abdominal abscess based on history and physical exam findings, you should initiate IV fluid resuscitation and empiric IV antibiotic therapy while you finish your diagnostic workup.

Acute management and intra-abdominal abscess4:12–6:03

Now, to confirm the diagnosis of an intra-abdominal abscess, order a CT scan with oral and IV contrast and call the surgery team while you wait for imaging results.
However, if the patient is too unstable to transport to CT, a bedside ultrasound can provide diagnostic information, but it’s less sensitive.
An intra-abdominal abscess on CT looks like a fluid collection outside of the bowel lumen, usually surrounded by a contrast-enhancing rim.
To spot this fluid, look for bubbles and air-fluid levels, which are sharp lines caused by gravity-dependent layering at the air-fluid interface.
Once you determine the location of the abscess, determine whether the abscess is percutaneously accessible. This technique might not be possible for a deep abscess, or if there are any vital structures between the skin and the abscess pocket.
Second, determine whether the abscess is localized and contained, or if it’s multifocal. Third, look at the fluid density measured in Hounsfield Units, since a high-density fluid like a hematoma is hard to drain through a small tube.
Next, assess whether the abscess is uniloculated or multi-loculated. Multi-loculated means that there are multiple cavities within the abscess, divided by internal septations.
Even if a drain penetrates one of these cavities, infected fluid can stay trapped within the other loculated pockets. Finally, assess for other surgical issues like an anastomotic leak or hollow organ perforation.Now, what about complicating features?

Abscess without complicating features6:03–7:50

If the abscess is percutaneously accessible, well-localized, made up of low to medium-density fluid, and uniloculated, the patient has an intra-abdominal abscess without complicating features.
Rarely, if the abscess is smaller than 3 centimeters, you can treat it with just IV antibiotics and close follow-up. However, this is pretty uncommon, and most cases will require some procedure.So for larger abscesses, you should call Interventional Radiology for image-guided percutaneous drain placement.
This procedure uses real-time CT or ultrasound images to guide drain placement through the skin and into the abscess. Once the drain is placed, you should send the fluid to pathology for analysis to verify the source and determine the presence of blood, bile, pus, pancreatic enzymes, ascites, and cytology, as well as obtaining gram stain and bacterial and fungal cultures in order to tailor antibiotic therapy appropriately.
Then, reassess the patient’s status after 48 to 72 hours. If there’s clinical improvement, this means that the drain is working well, so keep it in place until the output is minimal and clinical signs of infection are resolved.
On the other hand, if there’s no evidence of clinical improvement, repeat CT scan to evaluate the drain location, look for any interval changes in the abscess, and see whether additional abscesses are present.
If the drain tip is in the wrong spot, call Interventional Radiology to reposition the existing drain. But, if the drain isn’t functioning or if there are additional abscess pockets, they might place another one.
If all of these interventions are unsuccessful and the patient is still not improving, consult the surgical team for surgical drainage.
Alright, let’s go over complicating features. Based on CT findings, some abscesses are likely too difficult to percutaneously drain.

Abscess with complicating features7:50–8:28

This means that an abscess might be percutaneously inaccessible, poorly localized, contain high-density fluid, appear multi-loculated; or there’s another surgical issue present.
If you see any of these findings on CT, consult the surgical team for open or laparoscopic abscess washout and drainage in the operating room.
However, if the patient is a poor surgical candidate, you should call interventional radiology to place a percutaneous drain instead.Alright, as a recap… Intra-abdominal abscesses can be categorized into two broad treatment groups, based on whether or not there are complicating features that prevent percutaneous drainage.

Review8:28–9:16

If the intra-abdominal abscess has no complicating features, you can treat it with percutaneous drain placement and wait 48-72 hours to assess for improvement.
If the patient improves, keep the drain in place. However, if they don’t improve, you need to repeat the CT scan to determine if there is something wrong with the drain.
If the drain isn’t placed correctly, call interventional radiology to reposition it, but if it isn’t working, they should reposition it, or you can proceed with surgical drainage.
On the other hand, if the intra-abdominal abscess has complicating features on imaging, like being percutaneously inaccessible or poorly localized, it should be treated with surgical drainage.