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Abdominal Imaging


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Transmesenteric postoperative hernia, s/p liver transplant. Intraoperative photograph shows that most of the small intestine (SB) had herniated through the mesenteric defect and twisted 720°

Mesenteric defect.


CT shows the small bowel (SB) adjacent to the right abdominal wall, with no overlying omental fat, and displacement of the ascending colon (AC) medially. The mesenteric vessels are twisted and engorged, with a whirl pattern (arrow) characteristic of volvulus.


Transverse abdominal CT section obtained in a 69-year-old man with transmesenteric hernia and bowel ischemia after liver transplantation demonstrates a cluster of mildly dilated small-bowel loops (J) adjacent to the left abdominal wall, with no overlying omental fat. The mesenteric vessels (arrow) are engorged and crowded


A more caudal CT section obtained in the same patient demonstrates the engorged mesenteric vessels (arrow) and medial displacement of the descending colon (DC) with respect to the dilated small-bowel loops.
What are the signs of internal hernias, specifically of paraduodenal and transmesenteric hernias.

Groin components?
Inguinal canal

Femoral triangle
Where is inguinal canal
Within medial half of inguinal ligament, extending from a defect in it (deep inguinal ring) to its opening (superficial inguinal ring) which leads spermatic cord to testis.
What is inguinal canal formed by?
Thicked inferior free edge of the external oblique aponeurosis, which curls back on itself, forming a U-shaped canal on cross-section.
What is contained in this U-shaped gutter?
Spermatic cord in males

Round ligament of the uterus in females.
Where does round ligament of uterus insert?
Labia majora.
Where is femoral triangle.
inferior to inguinal ligament, lateral to pectineus, medial to sartorius.
What are contents of femoral triangle?
Femoral sheath (contains from lat to med, artery, vein, and femoral canal). Femoral nerve is lateral to femoral sheath. Also the greater saphenous vein, which drains into the common femoral vein.
What is the femoral sheath composed of?
An extension of the deep fascia of the thigh (fascia lata).
What is the femoral canal?
An empty space medial to the femoral vein which allows the vein to expand, and contains a lymph node (node of cloquet).
How are the superficial femoral lymph nodes arranged?
Like a "T"

The stem of the T is formed by vertically oriented nodes paralleling the greater saphenous vein. The top of the T is formed by nodes paralleling the inguinal ligament.
What are the 2 important inguinal region structures embryologically?
Gubernaculum and processus vaginalis.
What is the gubernaculum?
Fetal structure that attaches to the inferior aspect of the gonad superiorly, and the scrotum (labia majora) inferiorly.
What does it do in males?
As it does contain muscle, it pulls the testicle through the inguinal canal into the scrotum.
What does it become in the male?
Nothing. It involutes.
What does it do in females?
It attaches at its midpoint to the uterus. This has 2 effects: It prevents the ovary from descending into the perineum, and it puts anterior tension on the uterus, resulting in the normal position of the uterus in the adult (anteverted, anteflexed)
What does in become in the female?
The portion of the gubernaculum that extends from the lower pole of the ovary to the uterus becomes the ovarian ligament. The portion that extends from the uterus to the labia majus becomes the round ligament.
What is the processus vaginalis.
It is a peritoneal invagination which travels through the inguinal canal anterior to the gubernaculum and descending testicle, ending up in the scrotum.
What is the fate of the processus vaginalis in males?
It forms the tunica vaginalis surrounding the testicle. The rest of it normally involutes.
What is the processus vaginalis called in females?
Canal of Nuck.
What is the fate of the canal of Nuck?
It normally completely obliterates.
What are the 5 (6) primary classes of pathology affecting the groin.
Congenital abnormalities
Noncongenital hernias
Vascular abnormalities
Congenital hernias may contain what?
Bowel, fat, peritoneal fluid.
What is a cord/canal of Nuck hydrocele?
Peritoneal fluid that got loculated in a non-obliterated mid segment of the processus vaginalis.
What types of noncongenital hernias occur in the groin?
Inguinal (direct and indirect) and femoral.
Where does direct inginal hernia occur?
Through muscular weakening medial to inferior epigastric vessels.
Where does indirect inguinal hernia occur.
Through inguinal canal, originating at the deep inguinal ring.
Where does femoral hernia occur?
Through the femoral canal, the space medial to the femoral vein within the femoral sheath.

Normal anatomic characteristics of the groin...inferior epigastric artery (short arrow) arises from the external iliac artery (long arrow). Fat surrounds the spermatic cord (arrowhead) where it enters the deep inguinal ring.

The inguinal ligament (short arrow), spermatic cord in the inguinal canal (long arrow), and normal superficial lymph node (arrowhead) are shown

The spermatic cord is at the superficial inguinal ring (short solid arrow). The inguinal ligament (long arrow) is shown. The femoral canal lies laterally and contains the common femoral vessels (arrowhead) and node of Cloquet (open arrow).

Undescended gonads in a 6-month-old male infant. Coronal T1-weighted magnetic resonance (MR) image shows the gubernaculum (open arrows) and undescended gonads (solid arrow).

Right groin pain and a small fluctuant groin mass in a middle-aged woman
see B

Longitudinal (a) and transverse (b) ultrasonographic (US) images show a cystic structure in the right inguinal canal (arrows in a, arrow in b) that lies superficial and medial to the pubic bone (bracket in each image) at the level of the superficial inguinal ring. No communication with the peritoneal cavity was seen, and no change occurred with the Valsalva maneuver. An encysted hydrocele of the canal of Nuck was diagnosed.

Right groin mass in a middle-aged woman with no recent history of trauma or instrumentation
See B

Color (a) and spectral (b) Doppler US scans are suggestive of venous flow (solid arrow in a) within a cystic right groin mass (* in a) apparently in continuity with the femoral vein (open arrow in a); a provisional diagnosis of venous pseudoaneurysm was made.
Color (a) and spectral (b) Doppler US scans are suggestive of venous flow (solid arrow in a) within a cystic right groin mass (* in a) apparently in continuity with the femoral vein (open arrow in a); a provisional diagnosis of venous pseudoaneurysm was made.
Traumatic diaphragmatic rupture: sidedness?
95% Left Side
Best method for evaluating traumatic diaphragmatic rupture?
1) MRI (but not useful in acute setting)
2) MDCT with multiplanar reformats.
Signs of TDR?
1) Visualization of discontinuity of hemidiaphragm.
2) Intrathoracic herniation of abdominal contents.
3) Collar sign
4) Dependent viscera sign
Collar sign on left?
Left: Focal waist-like constriction around typically herniating hollow viscus (stomach, splenic flexure)
Collar sign on right?
Posteriolateral indentation on liver.
Dependent viscera sign?
Right: upper 1/3 of liver, which normally is supported by diaphragmatic attachments flops so it is directly lying on posterior ribs.

Left: Stomach or spleen does same thing.
DDx of TDH?
1) Eventration
2) Diaphrag paralysis
3) Congenital hernias (Bochdalek, Morgagni)
Bochdalek hernias? What percent of non-hiatal diaphragmatic hernias?
Bochdalek: Location.
80% Left posterolateral

15% Right

5% Bilateral
Bochdalek: Incidence
Bochdalek: Organs herniated on Left?
Left lobe of liver
Bochdalek: Organs herniated on right?
Morgagnia location?
Antermedial parasternal location
Morgagni side?
Right more common
Morgagni percent of non-hiatal diaphragmatic hernias?
Morgagni incidence
What can obscure diagnosis?
Pleural effusion
Mesenteric cyst? Diagnosis?
Fluid filled mass in mesentery. Often with thin septatons.
MC location?
Anywhere in mesentery or omentum
Most common type of mesenteric cyst?
Cystic lymphangioma.
DDx of mesenteric cyst?
1) Loculated ascites
2) Duplication cyst
3) Pseudocyst
4) Cystic teratoma
5) Cystic mesothelioma (rare, benign!)
Eval of potential mesenteric cyst:
1) Exclude visceral origin of "cyst"
2) Histology needed to make diagnosis.
Desmoid tumors: where do they occur
In association with previous abdominal surgical scars.
Desmoid: Pathophysiology
Intermediate step between reparative process and malignancy. Tumors do not metastasize, but local invasion and recurrence is common.
Desmoid: Location
1) Mesentery (small bowel most common)

2) Musculature (rectus, obliques, psoas)

3) Retroperitoneum

4) Bladder, ribs, pelvic bones.
At what level does the SMA arise from aorta?
How else can the SMA orifice location be described in the CC plane?
1.5 cm below celiac orifice.

Just above renal arterial ostia.

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