The first image is a longitudinal image taken of the pelvis. It shows some free fluid lying posterior to the bladder. In men free pelvic fluid is unusual and certainly indicated the likelihood of signifiant pathology.

The next images are focussed on the right iliac fossa.

• there is a blind ending tubular structure with bowel wall signature, it is non-peristalsing, non-compressible and typical of the appendix
• the appendix drapes medially across the iliac vessels with its tip lying in the pelvis
• at the junction of its proximal and middle third lies a solid, echogenic, shadow casting lesion characteristic of an appendicolith
• distal to this stone the appendix becomes markedly dilated reaching a maximum diameter of more than 15mm (normal < 6mm)
• the dilated portion of the appendix is filled with echogenic debris and several more appendicoliths
• at the tip the appendiceal wall becomes thin and the bowel wall signature is lost, suggesting imminent or recent perforation
• there is a small rim of echogenic periappendiceal fat and in several views adjacent free fluid was demonstrated
• findings are consistent with acute appendicitis with probable perforation

Ultrasound is a useful first line imaging investigation for appendicitis. It can be performed at the bedside, is well tolerated, involves no radiation and has acceptable sensitivity and specificity.

It can identify alternate diagnoses including:

Method for searching for the appendix:

Begin by looking where it hurts most – you will usually find the pathology there.

If you do not find pathology at the site of maximal tenderness search the right iliac fossa in an orderly manner, like you are “mowing the lawn” with your high frequency linear probe. I begin laterally and work my way medially “mowing” from a cranial to caudal direction. Firm gentle and persistent pressure will displace overlying bowel gas. Some describe using alternate patient positions such as the left lateral position to try to reveal a hidden appendix.

This is a 9 week gestation.

This can be calculated by measuring the crown-rump length (23mm in this case). The machine then references to standardised accepted reference ranges, or you can work it out yourself.

Tip 1: The following table is a nice way of remembering what an embryo looks like at various dates in early pregnancy.

Embryonic cardiac activity is clearly present and so the embryo is alive.

BUT it is not in the uterus. It is surrounded by a thickened haemorrhagic tube. This is an ectopic pregnancy.

Tip 2: When you see a pregnancy make sure it is in the uterus – by ensuring the mass containing the embryo that you are looking at connects to the cervix and that to the vaginal stripe. Only then can you be sure it is in the uterus.

As we scan across the pelvis you can see the uterus is anteverted and contains what could be interpreted as a sac. A heterotopic pregnancy where there are simultaneous intra end extra uterine pregnancies is very rare (quoted as 1 in 30000 in natural pregnancies – much higher with IVF).

Looking more closely shows that there isn’t a sac in the uterine fundus, but rather a fluid collection with a fluid level. There is a hypoechoic upper part and more echogenic dependent portion. There is no yolk sac nor embryo.  This is typical of settling blood in the endometrial cavity and is the characteristic pseudosac of an ectopic pregnancy.

Tip 3: To say you have confirmed an untrauterine pregnancy you must see a yolk sac or embryo in the gestation sac. Other wise it may simply be a cystic structure or any origin; or the pseudosac of an ectopic pregnancy.

Tip 4: Always explore the pelvis completely. This means fan across it in longitudinal section, from one iliac wing to the other. As you go note the internal iliac vessels, ovary and adnexa (particularly any masses), the uterus, any free fluid, the bladder, and then the same structures on the other side. Now scan through the pelvis from top to bottom with the probe placed transversely. Note bowel, uterine fundus, uterine content, ovaries, adnexal masses, internal iliac vessels, cervix, free fluid, bladder and urethra.

The views of the upper quadrants, both left and right confirm free intraabdominal fluid. There is echogenic clot in the Pouch of Douglas and more echo free free fluid in the upper quadrants.

Tip 5: Blood in the abdomen settles, with heterogenous grey clot often present dependently and at the site of bleeding, and hypoechoic more serous fluid in more distant part of the abdomen.

This patient has a 9 week live ectopic.

The anteverted uterus contains some layered blood and demonstrates a typical pseudosac.

There is a considerable amount of free fluid in the abdomen, with clot in the pelvis.

This patient was haemodynamically stable, but had pain, a live 9 week ectopic and a considerable amount of free abdominal fluid (>500ml).

She is not a candidate for either conservative management (occassionaly used in already spontaneously resolving ectopics) or methotrexate (not appropriate in very large, live or actively bleeding ectopic pregnancies).

She requires urgent IV access, analgesia, cross matching, and expeditious preparation and delivery to the operating suite for laparoscopic salpingectomy (or salpingostomy).

This brief loop is the right upper quadrant view where one explores Morrison’s Pouch searching for fluid.

Getting the best view

• Begin with big bold moves of the transducer searching for the best acoustic window
• Start subcostally, ask the patient to take a deep breath and see if a clear view is attained
• If this cannot be achieved quickly move on to trying to get intercostal views
• Try at the anterior axillary line with the probe aligned with the interspace, looking back at the bed and kidney
• If this doesn’t work move further posteriorly
• Fan the probe exploring the whole of Morrison’sPouch – make sure you don’t miss a small amount of fluid.

Is it free fluid?

• Free fluid surrounds other abdominal organs
• It has corners and angles, no wall and no flow and doesn’t peristalse
• The IVC – tubular, behind the liver, medial to the kidney, colour Doppler demonstrates flow, may vary with respiration and the cardiac cycle
• The gall bladder – has a wall and rounded fundus
• Renal or adrenal cysts – have a wall, contained by the capsule of these organs (although may be exophytic)
• Fluid in bowel – usually contains some echogenic particles; hold the probe still and watch for peristalsis

If it is free fluid, what sort of free fluid is it?

• Think clinically – a young otherwise well trauma patient with hypotension and it’s probably blood.
• Ascites – if you think it could be ascites, using aseptic technique and ultrasound guidance use a 21 gauge needle to drain a bit – red is blood, straw coloured ascites.
• Bowel content with ruptured bowel – with contain echogenic debris
• Urine from a bladder rupture – hard to tell, unlikely if the bladder is nice and full and rounded and there is no blood in the urine
• Blood may clot – and have heterogenous echogenic areas, or may settle and have dependent echogenic elements – remember it is not always anechoic.

How do I quantify the amount of free fluid?

• It is not possible to give an accurate volume estimate, try to explain what you can see rather than quantify (eg fluid in all views with deepest pocket of 3cm vs fluid only in one view, with 2mm as the deepest pocket = large amount vs small amount)
• How many views can you see it in?
• More than one and there’s almost certainly a significant amount of free fluid
• What is the vertical depth in each pocket of fluid?
• If it’s 2mm or less – only a sliver of fluid – it probably reflects an injury, but if in one view only, is not generally enough to cause hypotension
• Fluid in more than one view, or more than 2mm of vertical depth and I start to worry; even more so when that vertical depth is over 10mm.

How do I integrate my findings into clinical practice?

Stable patient

• If there is significant suspicion of injury needs a CT free fluid or not
• If there is no free fluid and your suspicion is not very high, and you wish to avoid CT, serial examination and FAST scan is warranted. Some centres are dabbling with contrast enhanced ultrasound to assess for solid organ injury but this is not generally accepted or available practice at this stage.

Unstable patient

• Lots of free fluid
• Depends a bit on the degree of instability and the amount of free fluid – if at all possible get them to the CT scanner but make it slick and quick!
• If there is lots of free fluid, the patient is very unstable, and this is likely isolated abdominal injury go straight to laparotomy
• If there is lots of free fluid and there is multiple trauma with probable mediastinal and/or pelvic injuries a CT will be extraordinarily useful. Otherwise your surgeons may be doing a laparotomy whilst the patient bleeds out from another injury. CT if you can.
• If CT is not immediately available, laparotomy with damage control surgery and packing the pelvis is indicated.
• Dont forget the “E” bit of the EFAST examination looking for pneumothorax, haemothorax and tamponade
• Manage other injuries you discover concurrently

• No or minimal free fluid (one view and <2mm vertical depth)
• Free intraabdominal bleeding is unlikely to be the cause of hypotension (assuming you are and experienced scanner)
• Search for other causes of hypotension
• Get the patient to the CT scanner as expeditiously as possible
• Perform serial FAST scans – trauma is dynamic and you may find fluid accumulating

Practice and practice your EFAST examination

If at all possible get the multiple trauma patient with significant injuries through the CT scanner immediately

Carefully consider the clinical situation and integrate the ultrasound findings appropriately

These brief loops are all subcostal views of the heart. In the critically ill patient with suspected tamponade this is often the best view.

Each shows the distended pericardium compressing the right sided cardiac chambers, typifying tamponade.

The point to note is that the pericardial fluid is not always black. Blood that is not flowing doesn’t look black, and certainly clotted blood is grey.

Blood can clot within the pericardium, when it appears as a solid grey mass within the pericardium; or if it remains liquid is often grey made up of homogenous fine particulate appearing material.

Acute haemorrhagic tamponade (pure blood) may be the result of:

• trauma – penetrating or blunt
• rupture of one of the free myocardial walls (usually post infarct)
• aortic dissection advancing proximally and rupturing into the pericardial sac
• malignancy eroding into the heart , great vessels, pericardium…
• post cardiac surgery

Causes of haemorrhagic tamponade which develop more slowly are not usually pure blood, but rather blood mixed with serous fluid, transudate or exudate, or fibrinous debris, as may occur with haemorrhagic pericarditis (of many causes, usually infectious)

Ultrasound is incredibly useful when considering the diagnosis of pericardial tamponade.

The subcostal view is usually the best initial view to attempt.

Whist pericardial fluid is often anechoic, in acute haemorrhagic tamponade it is usually grey.

Clot will appear solid, and is unlikely to be amenable to aspiration.

Fibrinous exudate and pus may also appear grey.

This is a brief loop taken in the right iliac fossa. It shows the absolutely typical features of diverticulitis.

• thickened bowel wall muscular layer (muscularis propria); a common finding with diverticular disease
• a diverticulum (out pouching); there are often more than one
• this one contains air, with posterior dirty acoustic shadowing, which again is very common
• the diverticulum protrudes through the muscularis propria and into the surrounding mesenteric fat
• the mesenteric fat surrounding the diverticulum is echogenic when compared to the non-inflamed mesenteric fat nearby
• with colour Doppler there is some increase in flow
• no other complications are seen in this case
• diverticular disease usually affects the sigmoid colon – and as in this case, that may go to the right of midline mimicking appendicitis.
• diverticular disease is not only localised to the sigmoid and we have certainly seen right sided diverticulitis particularly in the Asian population where for some reason it often effects men of a younger age than the typical diverticular disease we see in the Western population with Western diet.

Ultrasound is incredibly useful when searching for bowel pathology.

Begin by looking where it hurts most – you will usually find the pathology there.

Press gently, and firmly, gradually moving bowel gas away from the probe.

Try to determine which bit of bowel you are looking at? With a little practice it is easy to determine these areas.

1. Stomach
2. Pylorus
3. Duodenum – and which part
4. Other small bowel
5. Terminal ileum
6. Caecum
7. Appendix
8. Ascending, transverse, descending or sigmoid

Look for the typical bowel wall signature (from inside to outside)

1. The lumen – the appearance depends on what is in the lumen (gas, solid or liquid)
2. The mucosal layer               =       echogenic
3. The muscularis mucosa     =     thin and hypoechoic
4. The submucosa                     =     thicker and echogenic
5. The muscularis propria      =     hypoechoic
6. The serosa                              =     echogenic
7. Surrounding mesenteric and omental fat, usually a mid level echogenic structure that becomes much brighter when inflamed

Then look for abnormalities of the layers

1. Are the layers thickened – and if so which layers?
2. Are they poorly defined?
3. Is the abnormality focal or diffuse?
4. Is there increased blood flow?
5. Are there complications – perforation, fistula or sinus formation?

Watch for normal bowel function

1. Is the bowel peristalsing normally?
2. Is it fluid filled, distended and poorly functioning as commonly occurs with obstruction?

Are there any other abnormalities?

This is a brief loop taken from the subcostal window. There is no myocardial contraction, but the heart is not still. The cardiac muscle is shimmering and wriggling – this is ventricular fibrillation. Fine VF, which can be missed on the ECG trace, is shown in the second clip (another patient). Again the fine shimmering appearance of the myocardium is noted. Compare this with the final brief clip where there is asystole and absolutely no cardiac motion.

Echo is increasingly available and being used in the cardiac arrest scenario.

It is essential not to interrupt the resuscitation process – good, essentially non-interrupted CPR & timely defibrillation remain the cornerstones

Echo can be used to help in excluding reversible causes

1. Use the echo probe in the subcostal position
2. Use a deep preset and prepare whilst CPR is going, ensuring your position, orientation, depth and gain are optimal
3. During the rhythm and pulse check take a 5 second loop and then stand back so CPR recommences as soon as possible.
4. Review the clip
5. Is there a large pericardial effusion – could this be tamponade?
6. It there an empty left ventricle and full right ventricle – could this be a massive pulmonary embolus?
7. Is the heart empty (and hyperdynamic in the peri-arrest siutation) – could this be hypovolaemia?
8. Is there any ventricular motion – lack of ventricular motion in the presence of an electrical complex (true electro-mechanical dissociation) is a particularly poor prognostic indicator
9. Complete lack of cardiac motion and lack of electrical activity whilst usually reflecting death, has occassionally been reported with ROSC and even more rarely survival to hospital discharge. Correlate your findings clinically, is the patient hypothermic, are there other features that suggest you should persist with resuscitation (young patient, toxicological cause, other reversible cause, short down time, good quality CPR throughout…). Use your experience (and not ultrasound alone) to make appropriate clincal judgements.
10. Is anything else obvious happening – like ventricular fibrillation or ruptured abdominal aortic aneurysm (often seen whilst you are preparing the probe during CPR)

Do one of the many accredited echo in the periarrest situation courses to give yourself a firmer foundation in this area of echocardiography.

• In this case the inflamed appendix lies in the right adnexa between the right ovary and uterus. It is not surprising there was cervical excitation.
• BHCG was negative for those of you concerned this adnexal mass was an ectopic.

• Appendicitis is sometimes found on transvaginal ultrasound when transbdominal scanning has been unsuccessful.
• This case demonstrates the classic features of acute appendicitis listed below, but also shows incongruity of the appendiceal wall and a small walled off periappendiceal abscess.
• In acute appendicitis the appendix typically develops the following characteristics:
  • Distended to more than 6mm in diameter
  • Non compressible
  • Tender to probe palpation
  • Echogenic mesentry surrounding it
  • Small amount of free fluid
  • Hyperaemia
  • An appendicolith may be present
  • Complications such as perforation and abscess formation may be present

• In this case the appendix can be seen arising from the caecum in the right iliac fossa, and traversing medially across the psoas muscle and iliac vessels, to lie within the pelvis.
• Its tip lies between the bladder and uterus, and there is a little free fluid seen in the Pouch of Douglas.
• The appendix is distended to 12 mm, is surrounded by echogenic mesentry and was the site of maximal tenderness.

• Ultrasound examination of the patient presenting with pelvic pain should include a search of the right iliac fossa for appendicitis.
• The appendix comes in many shapes and sizes and lies in highly varied positions.
• Correspondingly the presentations and complications of appendicitis are very diverse.
• The appendix
  • Is a blind ending tube with bowel wall signature, originating from the caecum
  • In the non-inflamed state it is less than 6mm across, is compressible with the probe but non-peristalsing, and is non tender.
• In acute appendicitis the appendix typically develops the following characteristics:
  • Distended to more than 6mm in diameter
  • Non compressible
  • Tender to probe palpation
  • Echogenic mesentry surrounding it
  • Small amount of free fluid
  • Hyperaemia
  • An appendicolith may be present
  • Complications such as perforation and abscess formation may be present

https://gmep.org/media/11237

• This is a case of acute appendicitis where an appendicolith obstructs the lumen of the appendix causing distention and inflammation of the distal appendix.
• The appendix is typically described as a non-peristalsing, blind ending tube with bowel wall signature, originating from the caecum.
• It usually measures less than 6mm across but in this case where it is distended it measures 14mm across.
• It maintains the normal sonographically differentiable layers indicating no frank necrosis or perforation.
• An echogenic shadow casting faecolith obstructs the proximal appendix
• The base can also bee seen and has a more typical appearance of an inflamed appendix as it enters the caecum.
• There is no associated free fluid, nor particularly echogenic mesenteric fat.

• The appendix lies in highly variable locations.
• Ensure you explore throughout the right side of the abdomen in your search for the appendix, but particularly at the site of maximal pain.
• An appendicolith is often but not invariably seen in appendicitis.
• Steps in diagnosis are:
  • Find the appendix – a grid search of the abdomen using a high frequency linear transducer
  • Confirm it is the appendix
  • Assess for features of appendicitis – distended to >6mm across, tender, appendicolith, surrounding free fluid, surrounding echogenic mesenteric fat, hyperaemia
  • Assess for complications – perforation, abscess formation
  • Assess for alternate causes of the pain

• This is the typical appearance of a retinal detachment.
• The echogenic retinal membrane normally attached to the back of the globe has separated.
• Attachment at the disc confirms this is a retinal detachment (retinal neurons run into the disc and separation cannot occur).
• Fine echogenic debris is seen in the vitreous and is consistent with earlier vitreous detachment which often precedes and contributed to retinal detachment. Vitreous haemorrhage can apear similar.

• Ocular ultrasound is relatively easily performed without patient discomfort.
• Confirming a retinal detachment is easy; ruling out a small detachment or tear is much more difficult.
• It is important to avoid confusion with other pathology including vitreous detachment. Compared to retinal detachment, vitreous detachment does separate from the disc (the Weiss ring seen on fundoscopy), is much finer requiring increased gain settings to visualise well, and is usually seen as much more delicate linear structure with associated particulate debris that swirls within the vitreous with eye movement.

Ultrasound Findings

• The biliary system appears normal, as does the liver.
• Just inferior to the liver in the region of interest is a trace of free fluid.
• Deep to this there is echogenic mesenteric and retroperitoneal fat with some hypoechoic oedematous stranding.
• Small amounts of retroperitoneal fluid track toward the right kidney.
• Several highly echogenic focci with dirty posterior acoustic shadowing are seen directly adjacent to a poorly defined loop of bowel.

In this case an elongated appendix passing retrocaecally, then up to the right upper quadrant, had become necrotic and perforated. The appendix is shown to contain a faecolith seen on CT scan.

Take home messages

• Inflamed fat is generally echogenic on ultrasound. This can be seen with mesenteric fat surrounding an inflamed appendix, or the fat around an inflamed diverticulum. In more superficial tissues it can be seen in cellulitis and lymphangitis.
• The stranding around inflammatory masses seen on CT often correlates with fluid tracking through the tissues that can be seen on ultrasound. Examples include the stranding around the kidney with renal colic, or around the pancreas with pancreatitis, or in this case.
• Small foci of free gas appear as highly echogenic areas with dirty posterior acoustic shadowing. Gas within bowel tends to move with peristalsis and have a thin layer of hypoechoic bowel wall around it. These findings of free gas are typical of what occurs with a ruptured hollow viscus.