Volvulus pathophysiology: Difference between revisions
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Regardless of cause, volvulus causes symptoms by two mechanisms. One is [[bowel obstruction]], manifested as [[abdominal distension]] and [[vomiting]]. The other is [[ischemia]] (loss of blood flow) to the affected portion of [[intestine]]. This causes severe [[pain]] and progressive injury to the [[intestinal wall]], with accumulation of gas and fluid in the portion of the bowel obstructed. Ultimately, this can result in [[necrosis]] of the affected [[intestinal wall]], [[acidosis]], and [[death]]. Acute volvulus therefore requires immediate surgical intervention to untwist the affected segment of bowel and possibly [[bowel resection|resect]] any unsalvageable portion. | Regardless of cause, volvulus causes symptoms by two mechanisms. One is [[bowel obstruction]], manifested as [[abdominal distension]] and [[vomiting]]. The other is [[ischemia]] (loss of blood flow) to the affected portion of [[intestine]]. This causes severe [[pain]] and progressive injury to the [[intestinal wall]], with accumulation of gas and fluid in the portion of the bowel obstructed. Ultimately, this can result in [[necrosis]] of the affected [[intestinal wall]], [[acidosis]], and [[death]]. Acute volvulus therefore requires immediate surgical intervention to untwist the affected segment of bowel and possibly [[bowel resection|resect]] any unsalvageable portion. | ||
==Pathophysiology== | ==Pathophysiology== | ||
*The twisting of a mobile loop of bowel can happen spontaneously and may be congenital or acquired. | |||
===Ileal and Sigmoid Volvulus=== | |||
*The mesentery anchors the ileum and sigmoid colon to the abdominal wall.<ref name="pmid5781046">{{cite journal |vauthors=Shepherd JJ |title=The epidemiology and clinical presentation of sigmoid volvulus |journal=Br J Surg |volume=56 |issue=5 |pages=353–9 |year=1969 |pmid=5781046 |doi= |url=}}</ref><ref name="pmid7387365">{{cite journal |vauthors=VerSteeg KR, Whitehead WA |title=Ileosigmoid knot |journal=Arch Surg |volume=115 |issue=6 |pages=761–3 |year=1980 |pmid=7387365 |doi= |url=}}</ref> | |||
*An air filled loop of the sigmoid colon or the ileum, sometimes, twists itself about the axis of the mesentery. | |||
*The incidence of volvulus occurring increases with a redundant or longer than normal mesentery. | |||
*If the degree of twisting is beyond 180 - 360 degress, then the bowel loop will become obstructed and ischemia will begin. | |||
*Ileosigmoid knotting is a variant of sigmoid volvulus where the ileum wraps around the sigmoid in a clockwise direction. | |||
===Gastric Volvulus=== | |||
*Normally, there are ligaments such as the gastrocolic, gastrohepatic, gastrosplenic and gastrophrenic ligaments that keeps the stomach in place by attaching it to other abdominal organs and the diaphragm.<ref name="pmid19900595">{{cite journal |vauthors=Rashid F, Thangarajah T, Mulvey D, Larvin M, Iftikhar SY |title=A review article on gastric volvulus: a challenge to diagnosis and management |journal=Int J Surg |volume=8 |issue=1 |pages=18–24 |year=2010 |pmid=19900595 |doi=10.1016/j.ijsu.2009.11.002 |url=}}</ref><ref name="pmid12823923">{{cite journal |vauthors=Shivanand G, Seema S, Srivastava DN, Pande GK, Sahni P, Prasad R, Ramachandra N |title=Gastric volvulus: acute and chronic presentation |journal=Clin Imaging |volume=27 |issue=4 |pages=265–8 |year=2003 |pmid=12823923 |doi= |url=}}</ref> | |||
*However, the stomach can twist around its horizontal or vertical axis. | |||
*Gastric outlet obstruction may occur as a result of abnormal rotation more than 180 degrees. | |||
*Chronic rotation can cause bleeding by decreasing venous return and increasing capillary pressure. | |||
===Cecal Volvulus=== | |||
There are three types of cecal volvulus, type I and II are the most common, type III account for the remaining 20% of cases: | |||
*Type I | |||
**The cecum twists in a clockwise manner along its axis. | |||
**The cecum fills with air and remains in right lower quadrant. | |||
*Type II | |||
**The cecum and a proximal part of the ileum twist in a counterclockwise direction. | |||
**The cecum becomes inverted and is relocated to the left lower quadrant. | |||
*Type III | |||
**The cecum folds upwards and back on itself rather than rotating along its axis. | |||
●Congenital mobile cecum is hypothesized to result from failed fusion of the ascending colon mesentery to the posterior parietal peritoneum [15]. Based upon autopsy studies, approximately 10 to 25 percent of the population have a cecum and ascending colon with sufficient mobility to develop a volvulus [16]. A congenital mobile cecum can also cause mobile cecum syndrome [17]. (See 'Differential diagnosis' below.) | |||
●Acquired anatomic abnormalities, such as adhesions from abdominal surgery, can also contribute to the development of a cecal volvulus. Other clinical settings that have been associated with cecal volvulus include pregnancy [18], colonic atony, colonoscopy [19], and Hirschsprung's disease [20]. | |||
===Intestinal Malrotation in Neonates and Infants === | |||
EMBRYOLOGY AND PATHOGENESIS — Intestinal malrotation occurs as a result of an arrest of normal rotation of the embryonic gut. (See "Overview of the development of the gastrointestinal tract".) | |||
●Embryology – During the fourth to eighth week of embryonic development, the embryonic coelom, or cavity, cannot accommodate the rapidly expanding gastrointestinal (GI) tract. As a result, the primary intestinal loop buckles into the area of the yolk stalk, which will be the future umbilicus. The axis of this loop is the developing superior mesenteric artery (SMA). As the primary intestinal loop buckles out of the abdomen, it begins the normal rotation of the bowel by twisting 90 degrees counterclockwise (figure 1 and figure 2). This initial rotation is driven by two factors [1]: | |||
•The proximal bowel (the "prearterial" or duodenojejunal loop) grows faster than the distal bowel (the "postarterial" or cecocolic loop), and | |||
•The rapid growth of the liver. | |||
The primary loop continues to grow, and then returns to the abdomen during the 8th to 10th week of gestation. With the return to the abdomen, there is an additional 180 degrees counterclockwise rotation. The overall effect is that the bowel rotates 270 degrees counterclockwise from the original primary loop (figure 1 and figure 2). | |||
Once the bowel has rotated into its final position, fixation to the posterior abdomen occurs. The proximal portion of the bowel is fixed to the retroperitoneum early in gestation (at the ligament of Treitz), whereas fixation of the colon is gradual and usually completed near term [15]. | |||
●Normal gut development – Normal rotation and fixation result in a wide-based mesentery that extends from the ligament of Treitz in the left upper quadrant to the ileocecal valve in the right lower quadrant (figure 3). Most anomalies of rotation result in an abnormally narrow mesenteric base (figure 4). Because the midgut is suspended on this narrow vascular pedicle rather than on the wide base of the mesentery, there is a risk of volvulus (torsion of the intestines). | |||
●Abnormal gut development – The most common abnormalities of rotation are nonrotation or malrotation (incomplete rotation) abnormalities: | |||
•If both limbs of the primary loop return to the abdomen with no further rotation, nonrotation occurs. In this condition, the small bowel is located on the right of the abdomen and the colon on the left (image 1). Nonrotation is not as dangerous for the patient as malrotation because, in general, the base of the mesentery is wider than in malrotation, and the risk of volvulus is less. However, nonrotation can be a difficult diagnosis radiologically; symptomatic patients may warrant laparoscopic or open exploration to confirm the diagnosis [8,16]. Asymptomatic patients with radiologic findings suggesting nonrotation can be observed. | |||
•In malrotation, the duodenojejunal limb remains in a position of nonrotation, and the cecocolic limb has partial rotation (usually approximately 90 degrees instead of 180 degrees). The end result is that the cecum ends up in the mid-upper abdomen and the abnormally positioned cecum is fixated to the right lateral abdominal wall by bands of peritoneum. These bands of peritoneum, called Ladd bands, cross the duodenum and can cause extrinsic compression and obstruction of the duodenum (picture 1). | |||
Other rare anomalies of rotation can occur [1]. These include: | |||
•Reverse rotation of the duodenojejunal limb resulting in a duodenum that rests anterior to the superior mesenteric artery. | |||
•Reverse rotation of the cecocolic limb resulting in a transverse colon that is posterior to the superior mesenteric artery. | |||
•Reverse rotation of the duodenojejunal limb with normal rotation of the cecocolic limb resulting in a paraduodenal hernia. In this anomaly, the duodenum is located anterior to the superior mesenteric artery. Anterior to the duodenum, the cecocolic limb rotates normally, and the mesentery of the right colon creates a pouch into which the small bowel can herniate. | |||
==References== | ==References== | ||
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: ; Hadeel Maksoud M.D.[2]
Overview
Regardless of cause, volvulus causes symptoms by two mechanisms. One is bowel obstruction, manifested as abdominal distension and vomiting. The other is ischemia (loss of blood flow) to the affected portion of intestine. This causes severe pain and progressive injury to the intestinal wall, with accumulation of gas and fluid in the portion of the bowel obstructed. Ultimately, this can result in necrosis of the affected intestinal wall, acidosis, and death. Acute volvulus therefore requires immediate surgical intervention to untwist the affected segment of bowel and possibly resect any unsalvageable portion.
Pathophysiology
- The twisting of a mobile loop of bowel can happen spontaneously and may be congenital or acquired.
Ileal and Sigmoid Volvulus
- The mesentery anchors the ileum and sigmoid colon to the abdominal wall.[1][2]
- An air filled loop of the sigmoid colon or the ileum, sometimes, twists itself about the axis of the mesentery.
- The incidence of volvulus occurring increases with a redundant or longer than normal mesentery.
- If the degree of twisting is beyond 180 - 360 degress, then the bowel loop will become obstructed and ischemia will begin.
- Ileosigmoid knotting is a variant of sigmoid volvulus where the ileum wraps around the sigmoid in a clockwise direction.
Gastric Volvulus
- Normally, there are ligaments such as the gastrocolic, gastrohepatic, gastrosplenic and gastrophrenic ligaments that keeps the stomach in place by attaching it to other abdominal organs and the diaphragm.[3][4]
- However, the stomach can twist around its horizontal or vertical axis.
- Gastric outlet obstruction may occur as a result of abnormal rotation more than 180 degrees.
- Chronic rotation can cause bleeding by decreasing venous return and increasing capillary pressure.
Cecal Volvulus
There are three types of cecal volvulus, type I and II are the most common, type III account for the remaining 20% of cases:
- Type I
- The cecum twists in a clockwise manner along its axis.
- The cecum fills with air and remains in right lower quadrant.
- Type II
- The cecum and a proximal part of the ileum twist in a counterclockwise direction.
- The cecum becomes inverted and is relocated to the left lower quadrant.
- Type III
- The cecum folds upwards and back on itself rather than rotating along its axis.
●Congenital mobile cecum is hypothesized to result from failed fusion of the ascending colon mesentery to the posterior parietal peritoneum [15]. Based upon autopsy studies, approximately 10 to 25 percent of the population have a cecum and ascending colon with sufficient mobility to develop a volvulus [16]. A congenital mobile cecum can also cause mobile cecum syndrome [17]. (See 'Differential diagnosis' below.)
●Acquired anatomic abnormalities, such as adhesions from abdominal surgery, can also contribute to the development of a cecal volvulus. Other clinical settings that have been associated with cecal volvulus include pregnancy [18], colonic atony, colonoscopy [19], and Hirschsprung's disease [20].
Intestinal Malrotation in Neonates and Infants
EMBRYOLOGY AND PATHOGENESIS — Intestinal malrotation occurs as a result of an arrest of normal rotation of the embryonic gut. (See "Overview of the development of the gastrointestinal tract".)
●Embryology – During the fourth to eighth week of embryonic development, the embryonic coelom, or cavity, cannot accommodate the rapidly expanding gastrointestinal (GI) tract. As a result, the primary intestinal loop buckles into the area of the yolk stalk, which will be the future umbilicus. The axis of this loop is the developing superior mesenteric artery (SMA). As the primary intestinal loop buckles out of the abdomen, it begins the normal rotation of the bowel by twisting 90 degrees counterclockwise (figure 1 and figure 2). This initial rotation is driven by two factors [1]:
•The proximal bowel (the "prearterial" or duodenojejunal loop) grows faster than the distal bowel (the "postarterial" or cecocolic loop), and
•The rapid growth of the liver.
The primary loop continues to grow, and then returns to the abdomen during the 8th to 10th week of gestation. With the return to the abdomen, there is an additional 180 degrees counterclockwise rotation. The overall effect is that the bowel rotates 270 degrees counterclockwise from the original primary loop (figure 1 and figure 2).
Once the bowel has rotated into its final position, fixation to the posterior abdomen occurs. The proximal portion of the bowel is fixed to the retroperitoneum early in gestation (at the ligament of Treitz), whereas fixation of the colon is gradual and usually completed near term [15].
●Normal gut development – Normal rotation and fixation result in a wide-based mesentery that extends from the ligament of Treitz in the left upper quadrant to the ileocecal valve in the right lower quadrant (figure 3). Most anomalies of rotation result in an abnormally narrow mesenteric base (figure 4). Because the midgut is suspended on this narrow vascular pedicle rather than on the wide base of the mesentery, there is a risk of volvulus (torsion of the intestines).
●Abnormal gut development – The most common abnormalities of rotation are nonrotation or malrotation (incomplete rotation) abnormalities:
•If both limbs of the primary loop return to the abdomen with no further rotation, nonrotation occurs. In this condition, the small bowel is located on the right of the abdomen and the colon on the left (image 1). Nonrotation is not as dangerous for the patient as malrotation because, in general, the base of the mesentery is wider than in malrotation, and the risk of volvulus is less. However, nonrotation can be a difficult diagnosis radiologically; symptomatic patients may warrant laparoscopic or open exploration to confirm the diagnosis [8,16]. Asymptomatic patients with radiologic findings suggesting nonrotation can be observed.
•In malrotation, the duodenojejunal limb remains in a position of nonrotation, and the cecocolic limb has partial rotation (usually approximately 90 degrees instead of 180 degrees). The end result is that the cecum ends up in the mid-upper abdomen and the abnormally positioned cecum is fixated to the right lateral abdominal wall by bands of peritoneum. These bands of peritoneum, called Ladd bands, cross the duodenum and can cause extrinsic compression and obstruction of the duodenum (picture 1).
Other rare anomalies of rotation can occur [1]. These include:
•Reverse rotation of the duodenojejunal limb resulting in a duodenum that rests anterior to the superior mesenteric artery.
•Reverse rotation of the cecocolic limb resulting in a transverse colon that is posterior to the superior mesenteric artery.
•Reverse rotation of the duodenojejunal limb with normal rotation of the cecocolic limb resulting in a paraduodenal hernia. In this anomaly, the duodenum is located anterior to the superior mesenteric artery. Anterior to the duodenum, the cecocolic limb rotates normally, and the mesentery of the right colon creates a pouch into which the small bowel can herniate.
References
- ↑ Shepherd JJ (1969). "The epidemiology and clinical presentation of sigmoid volvulus". Br J Surg. 56 (5): 353–9. PMID 5781046.
- ↑ VerSteeg KR, Whitehead WA (1980). "Ileosigmoid knot". Arch Surg. 115 (6): 761–3. PMID 7387365.
- ↑ Rashid F, Thangarajah T, Mulvey D, Larvin M, Iftikhar SY (2010). "A review article on gastric volvulus: a challenge to diagnosis and management". Int J Surg. 8 (1): 18–24. doi:10.1016/j.ijsu.2009.11.002. PMID 19900595.
- ↑ Shivanand G, Seema S, Srivastava DN, Pande GK, Sahni P, Prasad R, Ramachandra N (2003). "Gastric volvulus: acute and chronic presentation". Clin Imaging. 27 (4): 265–8. PMID 12823923.