FUSIC Abdomen

FUSIC Abdomen Views

FUSIC Abdomen is a systematic 7-point ultrasound scan of the abdomen.
It is important to realise this is not a FAST scan, however, there is some overlap in terms of views obtained in both scans. A FAST scan is a Focused Assessment using Sonography for Trauma which uses point of care ultrasound to assess the trauma patient on presentation to hospital. The main aim of a FAST scan is to identify intra-peritoneal free fluid which is assumed to be secondary to bleeding in the context of trauma. It is important to be aware that a negative scan does not rule out bleeding. A CT scan is needed to rule out bleeding.

Abdominal scanning points

The 7 points which are assessed for FUSIC Abdomen are the right & left upper quadrant (RUQ & LUQ), the right and left kidney, the right & left iliac fossa (RIF & LIF), and the pelvis/bladder. In general the upper abdomen is assessed first before moving down into the lower abdomen and pelvis. Both sides should be compared as you go for any differences. The overall aim of the scan is to assess for intra-abdominal free fluid and for any evidence of urinary tract obstruction. These can both be assessed simultaneously as you work you way through the scanning points. 

Abdominal scanning points

7 abdominal scanning points labelled in general order of scanning

Normal abdominal structures on ultrasound

Each area of the abdominal ultrasound allows assessment of a different underlying structures. 

Scanning areas 1&2 assesses the RUQ of the abdomen and the liver, diaphragm, lung, and right kidney should be identified. 

Scanning areas 3&4 assess the LUQ of the abdomen and the spleen, diaphragm, lung, and left kidney should be identified.

Scanning point 5&6 assess the RIF&LIF of the abdomen for free fluid, but may just show bowel.

Scanning point 7 assess the suprapubic region of the abdomen and the bladder and prostate/cervix should be identified if possible.  

Abdominal structures

7 abdominal scanning points and the underlying anatomical structures

1. Intra-abdominal free fluid and paracentesis

Peritoneal free fluid accumulates in potential spaces in the abdomen, it has a low acoustic impedance so it is echo poor and appears dark on ultrasound. Due to it being a good transmitter of ultrasound underlying structures appear bright and well defined. 

It is important to be aware that ultrasound does not help identify the source of the free fluid which can be due to ascites or bleeding and the overall clinical picture needs to be taken into account.

The probe positions for assessment of intra-abdominal free fluid are:
If free fluid is present then ultrasound of the left and right iliac fossa is made to assess depth of fluid and to assess for potential paracentesis.

1. Right upper quadrant

The probe is placed in the RUQ of the abdomen in the coronal plane. In this view the liver is the main abdominal organ that can be identified. Superior to this is the diaphragm and below the liver and slightly posteriorly is the right kidney. 

Look for peri-hepatic fluid and fluid in the hepatorenal recess (also known as Morrison’s pouch). If fluid is seen above the liver it is important to identify the diaphragm to see if the fluid is pleural (above the diaphragm) or peritoneal (below the diaphragm).


RUQ coronal view showing the liver kidney and Morrison's pouch

Scanning through the RUQ coronal view showing the liver kidney and Morrison's pouch

Fluid shown on ultrasound around the inferior border of the liver and extending into Morrison's pouch

Sub-phrenic fluid shown on ultrasound in the RUQ above the liver. Basal lung collapse/consolidation can also be seen.

2. Left upper quadrant

In this view assess the spleen, left kidney and the diaphragm. The spleen is smaller than the liver and so can be hard to find. Once found assess for peri-splenic fluid or fluid in the splenorenal recess.

Similarly to the RUQ view if fluid is seen above the spleen it is important to assess whether the fluid is above the diaphragm and therefore pleural fluid or below the diaphragm and therefore peritoneal.


LUQ coronal view showing the spleen and kidney with the spleno-renal recess labelled

Scanning through the LUQ coronal view showing the spleen and kidney with the spleno-renal recess labelled

3. Suprapubic

The suprapubic view is assessed in both the sagittal and transverse view. The probe is placed superior to the pubic symphysis and angled down into the pelvis.  The main underlying structure is the bladder which appears thin walled and anechoic in the midline. The challenges of this view in critical care patients is that they are often catheterized and so have no bladder volume. In these cases the bladder may not be seen or the catheter balloon may be seen as a small circular structure with bright outline and anechoic centre.
The aim of the assessment is to identify the difference between intra-abdominal fluid and fluid in the bladder. This is done by looking for retro-vesicle fluid which is fluid behind the posterior bladder wall. In the sagittal view the fluid is seen behind the bladder and in front of the colon (in males), or behind the uterus  and in front of the colon (in females) also known as the pouch of Douglas. In the transverse view the free fluid can be seen around the bladder wall and also posterior to the uterus (in females).

Sagittal plane anatomy

Sagittal plane of the male lower abdomen - displaying the rectovesical pouch where free fluid can accumulate if present.

Sagittal plane of the female lower abdomen - displaying the pouch of Douglas where free fluid can accumulate if present.

Ultrasound of bladder
- Sagittal & transverse plane


Sagittal plane ultrasound of the bladder in a male - showing the rectum and recto-vesicle pouch. Superior is to the left of the image.


Transverse plane ultrasound of the bladder in a male - showing the recto-vesicle pouch.

Assessment of bladder volume

Bladder volume can be estimated using the formula [½ x width (cm) x height (cm) x depth (cm)]. In the transverse plane measure the width at the largest point, then obtain the sagittal view and measure the height and depth of the bladder at the largest point.

Transverse plane of the bladder with colour flow doppler demonstrating ureteric jets (the normal physiological efflux of urine from the distal ureter into the bladder)

Assessment for paracentesis

If free fluid is present and paracentesis needs to be performed, then the right or left iliac fossa is generally the best area to perform the procedure. This is due to the lack of underlying major organs such as liver, spleen, kidney or bladder, however, there is usually underlying bowel. This is why assessment with ultrasound can help increase success rate for paracentesis and reduce complications.

RIF ultrasound demonstrating the presence of ascites. The fluid is seen surrounding the bowel.


  • Suspicion of spontaneous bacterial peritonitis (SBP) in patients with decompensated liver disease
  • Assessment of ascitic fluid for new onset ascites – considering malignancy
  • Large volume ascites may need draining to help with symptomatic relief in patients



  • Disseminated intra-vascular coagulation
  • Infection at local puncture site


  • Bowel obstruction
  • Organomegaly
  • Pregnancy
  • Coagulopathy

    [Note that whilst coagulopathy may increase tendency to bleed following the procedure it is not a contraindication in patients with decompensated liver disease because the necessity to confirm and treat SBP if present far outweighs the risks.]

Procedural tips

Assess both the right and left iliac fossa with the ultrasound and find the deepest pocket. Measure it with calipers and mark the area, making sure to assess in 2 planes. A depth of 3cm is enough to perform the procedure. With the ultrasound any large abdominal wall vessels can be seen and avoided.

2. Urinary tract obstruction

Identification of the bladder has been covered above when also assessing for intra-abdominal free fluid. 

It is important to identify whether the bladder is full or empty. On intensive care the majority of patients are catheterised so the bladder should be empty. If a patient is catheterised with evidence of residual volume then the catheter may be blocked. 

It is also important to identify the kidneys and assess for any hydronephrosis and whether it is unilateral or bilateral. This will help determine the area causing the obstruction. 

The kidneys

The kidneys are found on ultrasound bilaterally beneath the spleen and liver in normal patients. The scanning window is often found postero-laterally in the coronal view. The kidneys cortex appears dark with echo bright fat in the renal sinuses. The medullary pyramids appear triangular, are echo poor and are seen between the renal cortex and renal pelvis.

Labelled ultrasound of the kidney from the RUQ coronal view in longitudinal section

Kidney Anatomy

Illustrated anatomy of the kidney


Hydronephrosis is when urinary flow from the kidney is blocked the renal pelvis starts to dilate. The severity of hydronephrosis depends on the extent of the dilatation. 

If only the renal pelvis is dilated this is mild hydronephrosis, if the renal pelvis and calyces are dilated this is most likely moderate hydronephrosis. If there is gross renal pelvis and calyces dilatation and there is evidence of this impacting renal architecture/causing cortical atrophy then this is severe hydronephrosis. 

If hydronephrosis is found on ultrasound both kidneys should be examined for hydronephrosis and the bladder should be assessed as to whether it is full or empty. This can help determine the level of the obstruction. 

If there is unilateral hydroneprosis with an empty bladder the level obstruction is likely in the ureter. If there is bilateral hydronephrosis with a full/distended bladder then the obstruction is likely below the level of the bladder. 

The absence of hydronephrosis and an empty bladder make urinary tract obstruction unlikely. 

Grading of hydronephrosis

(Grade 1)

(Grade 2)

(Grade 3)

Renal pelvis dilatation

Moderate renal pelvis dilatation

Gross renal pelvis dilatation

No calyceal dilatation

Moderate calyceal dilatation

Gross calyceal dilatation

No parenchymal atrophy

Early parenchymal atrophy may be present

Loss of normal architecture

Cortical atrophy

Ultrasound appearance hydronephrosis

Renal pelvis dilatation is a key feature of all grades of hydronephrosis. This appears as an echo poor area (the dilated renal pelvis) surrounded by echo bright fat from the renal sinuses.

As the hydronephrosis progresses this echo poor area extends into the calyces and becomes larger and in severe cases starts causes loss of normal architecture of the kidney and  cortical atrophy. 

Moderate Hydronephrosis:
Ultrasound view of the right kidney in the longitudinal section. The renal pelvis is dilated and this can be extending up into the calyces. There is no obvious cortical atrophy.

Moderate Hydronephrosis:
Scanning through the right kidney in the longitudinal section. This further demonstrates the dilated renal pelvis extending up into the calyces.

Content created by Ben Stoney
Design by Max Broadbent

The ultrasound images and clips used on this website have be reproduced following the local clinical governance guidance.