Spleen, Adrenals, and Lymph Nodes
These disparate organs are artificially collected in a single chapter.
Spleen
Ultrasound can diagnose splenomegaly. The probe must be applied rather posteriorly at the last inter- costal spaces. In a supine patient, the distal part of the probe should in practice sink into the bed. A normal spleen can be difficult to see, since it can be surrounded by lung air and bowel gas. Conversely, an enlarged spleen is easily diagnosed. What is more, the homogeneous or heterogeneous pattern of the parenchyma can be appraised (Fig. 11.1). In an obese patient, for instance, ultrasound will be of precious help, even if some think the diagnosis of splenomegaly remains clinical.
Splenomegaly can also create an acoustic win- dow making the analysis of the following organs accessible: adrenals, kidney, tail of the pancreas, stomach, and aorta.
Splenic abscess in the critically ill is often occult, with a paucity of clinical signs. In the mini- mal cases, ultrasound can be normal, showing only an apparently homogeneous enlarged spleen, whereas CT shows the abscess perfectly (Fig. 11.2).
In intermediate cases, the abscess is isoechoic to the spleen, but is separated from the normal parenchyma by a thin dark border that clearly outlines the pathological mass (Fig. 11.3). Usually, abscesses yield hypoechoic heterogeneous images (Fig. 11.4). Hemorrhagic splenic suppuration ac- companying stercoral peritonitis can yield hy- poechoic enlarged spleen with liquid-like areas and hyperechoic elements caused by microbial gas (Fig. 11.5). Last, the spleen can be discretely het- erogeneous, not to say normal, in genuine fulmi- nant tuberculous miliaries (Fig. 11.6).
Perisplenic effusion (see Fig. 5.3), a traumatic rupture of the spleen (irregular intraparenchy- matous image, with capsular hematoma), and a CHAPTER 11
Fig. 11.1. Splenomegaly (S) covering the entire left kid- ney. This homogeneous spleen is 16 cm long. Longitudi- nal scan of the left hypochondrium
Fig. 11.2. This spleen was considered homogeneous using ultrasound, whereas CT revealed an abscess. In these cases, especially in plethoric, poorly echoic pa- tients, the poor echogenicity of the image should be re- cognized, in order to request other imaging modalities
splenic infarct (regular pyramidal hypoechoic image) can also be diagnosed (Fig. 11.7). Splenic infarct can become superinfected. Homogeneous splenomegaly is common in portal hypertension.
On occasion, splenic artery aneurysm can be rec- ognized. More relevant in daily practice is the possibility of locating the spleen before any left thoracentesis (see Fig. 15.7, p 99).
Interventional Ultrasonography of the Spleen
The spleen, a peripheral organ, is a possible tar- get for interventional procedures. Percutaneous drainage of splenic abscesses is an alternative to surgery [1–3]. Described complications are hem- orrhage or infections, but, although spontaneous mortality of splenic abscess is 100% and 7.8% if surgically treated [4], it is only 2.4% after percuta- neous procedures [3].
Interventional Ultrasonography of the Spleen 67
Fig. 11.3. Splenic abscess isoechoic to the spleen. How- ever, a thin stripe is noted. Septic shock in a 68-year-old female who had had cold abdominal surgery 1 month before, and without focal clinical signs at the time of the examination
Fig. 11.4. Hypoechoic images (M) within an enlarged spleen. The tap revealed pus with staphylococcus.
Splenic abscesses complicating endocarditis in a 48-year- old male
Fig. 11.5. Hypoechoic and heterogeneous splenomegaly in a septic patient. Surgery revealed stercoral peritonitis with hemorrhagic suppuration of the spleen
Fig. 11.6. This spleen has normal dimensions and quasi- normal echostructure, except for some mildly hypoech- oic areas (M). Autopsy of this young man with septic shock revealed diffuse tuberculous miliary, including the spleen. The mildly granulose pattern of the spleen was slightly questionable when subsequently reading the examination. Longitudinal scan. K, left kidney
Some authors propose a simple therapeutic aspiration with a 18- to 19.5-gauge needle as a first line of treatment. Antibiotics can possibly be in- jected in situ [3]. With a 21-gauge needle, we have diagnosed staphylococcus abscess (see Fig. 11.4) and subsequently aspirated it (Fig. 11.8), without hemorrhagic or infectious complications.
Adrenals
Imaging the adrenals in emergency situations is without doubt of limited value. However, the potential impact of corticotherapy in septic shock can be a reason for new interest in this exploration if it is accepted that accurate detection of adrenal necrosis will alter management. It is assumed that CT will be more accurate than ultrasound, but this requires transportation of a very unstable patient.
The adrenals are usually not visible. They are surrounded by fat covering the kidney (Fig. 11.9).
Ultrasound signs of the acute adrenals have been described insufficiently in the literature. In the case of bilateral hemorrhagic necrosis, an echoic mass over the kidney has been described [5, 6].
Pheochromocytoma can sometimes yield a volu- minous mass. Other conceivable applications, although of limited clinical value, will be the search for an adrenal tumor in a patient admitted for severe arterial hypertension, for adrenal metas- tases, and last, assessment of acute adrenal failure.
Enlarged Lymph Nodes
Voluminous lymph nodes can create obstructions, for instance of the bile ducts. The diagnosis is based on one or several masses, round or egg- shaped, tissular, and above all located along the vascular axes (see Fig. 12.8, p 73). Detection of lymph node enlargement allows making certain diagnoses but, without exception, the definitive exploration will be made after the critical period.
References
1. Berkman WA, Harris SA Jr, Bernardino ME (1983) Non-surgical drainage of splenic abscess. Am J Roentgenol 141:395–397
2. Lerner RM, Spataro RF (1984) Splenic abscess: per- cutaneous drainage. Radiology 153:643–647
68 Chapter 11 Spleen, Adrenals, and Lymph Nodes
Fig. 11.7. Splenic infarction. Roughly pyramidal hypo- echoic image with peripheral base
Fig. 11.8. This figure is the sequel to Fig. 11.4, after eva- cuation of the abscess. The target is significantly reduced
Fig. 11.9. If not detecting the adrenal itself, ultrasound can expose the adrenal space perfectly, here between liver and right kidney. This area is currently being in- vestigated in our septic patients
3. Schwerk WB, Görg C, Görg K, Restrepo I (1994) Ultra- sound-guided percutaneous drainage of pyogenic splenic abscesses. J Clin Ultrasound 22:161–166 4. Nelken N, Ignatius J, Skinner M, Christensen N
(1987) Changing clinical spectrum of splenic abs- cess: a multicenter study and review of the literature.
Am J Surg 154:27–34
5. Enriquez G, Lucaya J, Dominguez P, Aso C (1990) Sonographic diagnosis of adrenal hemorrhage in patients with fulminant meningococcal septicemia.
Acta Paediatr Scand 79:1255–1258
6. Mittelstaedt CA, Volberg FM, Merten DF, Brill PW (1979) The sonographic diagnosis of neonatal adre- nal hemorrhage. Radiology 131:453–457
References 69
