INTERNAL HERNIAS. pptx internal herniass

internal hernias

1. INTERNAL HERNIAS MODERATOR- DR. MANASA MDRD PRESENTOR – DR. SWETHA

2. Hernias are of two types 1. External hernia 2. Internal hernias Internal hernias are protrusions of the viscera through the peritoneum or mesentery but remaining within the abdominal cavity Internal hernias have a low incidence of <1% The most common presentation is an acute obstruction of small bowel loops that develops through normal or abnormal apertures.

3. ETIOLOGY Physiologic defects such as foramina recesses, and fossae (e.g. fossa of Landzert ) Pathologic defects of the mesentery and visceral peritoneum, 1. congenital maldevelopment of the mesenteries 2. surgery also creates potential internal herniation orifices. 

4. TYPES Left and right  paraduodenal hernias. Lesser sac (foramen of Winslow) hernia Pericaecal hernia Sigmoid mesocolon hernias Small bowel mesentery internal hernia Supravesical hernia Broad ligament hernia

5. Fluoroscopy The appearances in barium studies vary depending on the type and site of the internal hernia. Clustering of small bowel loops Distended bowel proximal to the site of obstruction Abnormal site or displacement of normal parts of the gastrointestinal tract

6. CT The appearance depends on the particular internal hernia . Common features include: Distended bowel loops within an abnormal location Arrangement or crowding of small bowel loops within a hernial sac Evidence of obstruction with segmental dilatation and stasis Mesenteric vessel abnormalities Engorgement, crowding, twisting, stretching of mesenteric vessels

7. PARADUODENAL HERNIA Paraduodenal hernias occurs due to failure of the descending or ascending colonic mesentery to fuse with the posterior parietal peritoneum. Left paraduodenal hernia is more common and can cause closed-loop bowel obstruction and infarction

8. LEFT PARADUODENAL HERNIA There is congenital failure of fusion of the descending colon mesentery to the parietal peritoneum in the left upper quadrant Small bowel herniates through a single layer of distal colonic mesentery into a retroperitoneal fossa of Landzert

9. Cluster of small bowel loops in the left anterior pararenal space The inferior mesenteric vein (IMV) and ascending branch of the left colic artery are within the anterior neck of the hernial orifice.

10. RIGHT PARADUODENAL HERNIA There is congenital failure of fusion of the ascending colon mesentery to the parietal peritoneum in the right lower quadrant Small bowel herniates through a layer of the ascending colon mesentery into the associated retroperitoneal fossa of Waldeyer Associated with small bowel malrotation

11. Cluster of small bowel loops inferior to the third portion of the duodenum The superior mesenteric vein  (SMV), the superior mesenteric artery (SMA) , and the right colic vein are within the anterior neck of the hernial orifice

12. Lesser sac hernia Lesser sac hernias are a type of internal hernia, where abdominal contents protrude through the  foramen of Winslow, hence they are also known as foramen of Winslow hernia.  RISK FACTORS Long small bowel mesentery Large foramen of Winslow Elongated right liver

13. FORAMEN OF WINSLOW small vertical passage between the greater sac (peritoneal cavity proper) and the lesser sac (omental bursa), allowing communication between these two spaces.

14. Gas and/or fluid in the lesser sac. Mesenteric vessels passing into the lesser sac via the foramen of Winslow Mesenteric fat/vessels posterior to portal vein , common bile duct, hepatic artery , and anterior to the inferior vena cava Abnormal cecal position.

15. Pericaecal hernia It occurs due to a congenital defect in the caecal mesentery Herniations occur in the pericaecal fossa (located behind the cecum and ascending colon. Retrocecal hernia is the most common subtype caused by herniation of ileal loops through a defect in the cecal mesentery and the right paracolic gutter.

16. Cluster of bowel loops (usually ileal) located posteriorly and laterally to the normal cecum, occasionally extending into the right paracolic gutter. A beaking appearance at the entrance of the hernia, and a dilated afferent small bowel loop and collapsed efferent loop. 

17. Sigmoid mesocolon hernia Occur when small bowel loops protrude into a intersigmoid fossa formed between two adjacent sigmoid segments and their mesentery. TYPES intersigmoid hernia transmesosigmoid hernia intermesosigmoid hernia

18. Small bowel mesentery internal hernia Small bowel mesentery internal hernias  are a form of internal bowel herniation involving protrusions of viscera through defects in the peritoneum or bowel mesentery Defects are more common in the region of the ligament of trietz   or the ileocecal valve

19. There are two types ref transmesenteric small bowel internal hernia much more common occurs through a defect in the mesentery intramesenteric  ( mesenteric pouch hernia) occurs into the mesentery through a mesenteric defect predominantly in pediatric patients

20. Small bowel internal mesenteric hernias manifest as proximal small bowel dilatation and an abrupt change in caliber at the level of the mesenteric defect. Mesenterial stranding sign is often associated. The mesenteric vascular pedicle can be engorged or stretched ref. Transmesenteric small bowel internal hernias do not typically show a "sac-like" cluster of vessels (like a  paraduodenal internal hernia Intramesenteric small bowel internal hernias may appear "sac-like", with anterior and superior displacement of the superior mesenteric artery

21. Supravesical hernia Laxity with failure of the transversalis fascia and the transversus abdominis muscle are the main cause of supra vesical hernias  external supravesical hernia: the hernial sac remains above the pelvic floor protruding through the anterior abdominal wall internal supravesical hernia- the hernial sac goes downwards in the  paravesical space

22. INTERNAL SUPRAVESICAL HERNIA are a type of internal hernia in which viscera protrude into the  supravesical fossa, occupying the  paravesical space. CT is the modality of choice for diagnosis and typical features are:  dilatation of small bowel loops with a transition area in a “closed-loop” at the level of the  supravesical fossa displacement or compression of the lateral wall of the bladder

23. Broad ligament hernia Broad ligament hernia are a type of internal hernia in which small bowel passes through a congenital or acquired defect in the broad ligament

24. type I : defect through the entire broad ligament type II : defect through the mesovarium and mesosalpinx above the round ligament type III : defect through the mesoligamentum teres, between broad and round ligaments

25. CT Features are those of a pelvic small bowel closed-loop obstruction small bowel dilatation double transition point in pelvic location, lateral to the uterus. pelvic free fluid

26. Falciform ligament hernia Falciform ligament hernias  are a very rare type of internal hernia occurring through a defect in the falciform ligament. A falciform ligament hernia should be considered when a fluid-filled, curvilinear, dilated bowel loop is identified just anterior/inferior to the liver. The round ligament marks the inferior-most extent of the falciform ligament, and may be used as a landmark. The accompanying obliterated falciform artery and paraumbilical veins travel along this course as well, but are seldom visible.

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