The role of radiologist in abdominal wall lesions

45 Pages·2012·3.26 MB·English

The role of radiologist in abdominal wall lesions
Poster No.: C-2378
Congress: ECR 2012
Type: Educational Exhibit
Authors: 1 2 2
R. Sanchez Oro , R. Pastor Toledo , L. Ariño Montaner , J.
2 2 2 2
Joudanin Seijo , A. Llanes Rivada , J. Uchiyamada , M. Rausell ,
2 2 1 2
J. Palmero , M. J. Moreno Gomez ; valencia/ES, Valencia/ES
Keywords: Abdominal wall, CT, MR, Ultrasound, Normal variants, Surgery,
Complications, Hernia, Neoplasia, Pathology
DOI: 10.1594/ecr2012/C-2378
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Learning objectives
• Describe the anatomy and the most common congenital abnormalities of the
abdominal wall.
• Recognize the different types of abdominal wall hernias and their
complications before and after surgery.
• Review other abdominal wall pathologies such as infections, hematomas, and
tumors.
Background
The abdominal wall extends from the bottom edge of the ribs to the top of the bony pelvis.
The layers of the abdominal wall are: skin, subcutaneous fat, muscle and their fascais,
transverse fascia , extraperitoneal fat and in the anterior lateral wall, the peritoneum.
The rectus muscles originate from the front of the xiphoid apophasis and in the fifth
to seventh costal cartilages, inserted into the pubic symphysis. Each rectus fascia is
surrounded by the terminals of the external oblique, internal oblique and transverse
muscles, forming a fibrous sheath, the rectus sheath.
The anterolateral abdominal wall consists of 3 pairs of muscles. From outside to inside:
external oblique, internal oblique and transversus. The internal oblique aponeurosis
in its lower part forms the inguinal ligament. An asymmetry in size of the abdominal
wall muscles is common. In most cases these are normal variants or postsurgical or
postinflammatory changes.
The inguinal canal is the main structure that passes through the lateral abdominal wall.
In men, this leads the spermatic cord and in women to the round ligament.
The main muscles of the posterior abdominal wall are medially, the elevator muscles of
the back and the quadratus lumborum and laterally, the latissimus dorsi. The relationship
of the posterior wall in depth is with the retroperitoneum and the thoracolumbar spine.
Congenital anomalies of the abdominal wall are rare. Many of them presented as major
malformations in the newborn and the diagnosis is clinical. However, some congenital
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anomalies of the urachus and the inguinal canal can be detected in the older child or
adult as an incidental finding or complication.
Hernias are the most common pathology of the abdominal wall. Most are
diagnosed clinically but radiologic studies may be necessary in doubtful cases,
preoperative assessment for certain types of hernias, and suspected complications after
herniorrhaphy.
Infections can be spontaneous or secondary to trauma, Most are bacterial infections.
Rare causes of infection are tuberculosis, actinomycosis, parasites and fungi.
Hematomas can be caused by vascular injury or a torn muscle fibers of the wall.
Causative or predisposing factors are trauma, anticoagulation, bleeding diathesis, or
severe persistent cough, previous surgery, pregnancy, puerperium and obesity. The
clinical significance of these hematomas is that they can be confused with other causes
of acute abdomen in cases of large hematomas in anticoagulated patients can be deadly
for hypovolemic shock. The most common are the rectus hematomas followed by the
anterolateral wall.
Rectus hematomas supraumbilical location may be limited by its sheath. The
infraumbilical location where there is no posterior rectus sheath can be extended to
extraperitoneal supravesical space, and from there seep into the peritoneal cavity,
causing hemoperitoneum.
.
Imaging findings OR Procedure details
CONGENITAL ANOMALIES OF THE URACHUS
The urachus is a remnant of fetal allantoic duct. It extends from the bladder dome to the
umbilicus. As a consequence of failure in the process of obliteration of the urachal light
produced different types of urachal anomalies: congenital and acquired. The congenital
patent urachus is the persistence of fetal communication between the bladder dome and
the navel, demonstrating the output of urine through the umbilicus at birth.
Acquired urachal anomalies are characterized by the partial reopening of the urachal
light:
• Urachal fistula: cyst connected with the navel.
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• Uracovesical diverticulum: cystic structure connected to the bladder(Figures
1 and 2).
• Urachal cyst: not communicated with either the bladder or the umbilicus
(Figure 3).
• Alternating fistula: a urachal cyst intermittently draining the bladder or the
umbilicus.
Fig. 1: Figure 1. Hipoecocia structure located in midline of lower abdomen, connected
to the bladder dome corresponding to uracovesical diverticulum.
References: R. Sanchez Oro; radiodiagnostico, valencia, SPAIN
Fig. 1 on page 28
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Fig. 2: Figure 2. Same image as in Figure 1 obtained by a linear transducer
References: R. Sanchez Oro; radiodiagnostico, valencia, SPAIN
Fig. 2 on page 29
Fig. 3: Figure 3. T2. Cystic structure adjacent to the anterior abdominal wall without
communication neither with bladder nor with the umbilicus in relation to urachal cyst.
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References: R. Sanchez Oro; radiodiagnostico, valencia, SPAIN
Fig. 3 on page 29
ABDOMINAL WALL HERNIAS
Ultrasound allows dynamic studies (Valsalva maneuver, coughing, postural changes,
compression) that facilitate the diagnosis of small hernias, assess whether or not the
hernia is reducible and is especially suitable for pediatric patients.
MDCT may be necessary for the evaluation of large hernias, intestinal obstruction cases
in lumbar hernias in very obese patients or when you need an overall assessment of the
abdomen. It is convenient to perform the scan during a Valsalva maneuver.
MRI more accurately shows anatomical details. The fast sequences allow a dynamic
study during provocation maneuvers.
Types of Hernias
Inguinal hernia: 80% of all hernias. They are more common in men than in women (7:1).
The key to differentiate the type of inguinal hernia is the relationship of the hernia sac
to the inferior epigastric artery.
INDIRECT INGUINAL HERNIA: lateral to the epigastric artery (figures 4 and 5). The
hernia sac lies anterior to the spermatic cord in man. It is the most common hernia. It can
reach the scrotum in males and the labia majora in women.
DIRECT INGUINAL HERNIA: medial to the inferior epigastric vessels, and posterior and
medial to the spermatic cord. Rarely reaches the scrotum. Becasuse of their extensive
ring are less prone to complication. Predominate in the elderly.
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Fig. 4: Figures 4 and 5. Left indirect inguinal hernia (black arrow) lateral to the
epigastric artery (white arrow) containing ascitic fluid and reach the scrotum.
References: R. Sanchez Oro; radiodiagnostico, valencia, SPAIN
Fig. 4 on page 30
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Fig. 5: Figures 4 and 5. Left indirect inguinal hernia (black arrow) lateral to the
epigastric artery (white arrow) that reaches the scrotum and contains ascitic fluid.
References: R. Sanchez Oro; radiodiagnostico, valencia, SPAIN
Fig. 5 on page 31
Femoral hernia. They originate in the crural ring and travel down the femoral canal.
In ultrasound or CT are medial to the common femoral vein and lateral to the pubic
tubercle. 40% of femoral hernias present with incarceration or strangulation. They are
more common on the right side. To differentiate inguinal hernia by CT, one can trace an
imaginary line one anterosuperior iliac spine to the symphysis pubis: femoral hernia is
following this line, medial to the femoral vein and lateral to the symphysis pubis, while
that inguinal hernias are available prior to this imaginary line.
Umbilical hernia. Through the umbilical ring. They are more common in women. They
are very superficial (figure 6).
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Fig. 6: Figure 6. Umbilical hernia contains small bowel loops.
References: R. Sanchez Oro; radiodiagnostico, valencia, SPAIN
Fig. 6 on page 31
Linea alba hernia. They are caused by a defect in the linea alba, fascia located
in the midline between the rectus muscles. Above the navel is called epigastric
hernias, below, hypogastric (figure 7) and adjacent to it, periumbilical. They are usually
small hernia containing fat content extraperitoneal than intraperitoneal. Diastasis recti
produces a weakness with bulging anterior wall and can be distinguished from a hernia
demonstrating the integrity of the white line in the test image.
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Fig. 7: Figure 7. Linea alba hernia contains small bowel loops.
References: R. Sanchez Oro; radiodiagnostico, valencia, SPAIN
Fig. 7 on page 32
Spigelian hernia. The semilunar or Spigelian fascia is between rectus and lateral
muscles. The wider area and weaker its infraumbilical portion, where there are most of
these hernias (figure 8). Spigelian hernias are often intraparietal, being contained by the
external oblique muscle fascia, making the clinical diagnosis more difficult and more likely
to be incarcerated.
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