Anatomic Considerations

Since the first descriptions by Toldt (Fig. 8—106) in 1879,140 the fusion of contiguous peritonealized surfaces and blending of the connective layers of the apposed peritoneal sheets forming a fibrous layer strong enough to call a fascia has been widely accepted.139,141 The sheet of tissue behind the head of the pancreas and the duodenal loop has been called the retroduodenopancreatic fascia of Treitz, following his description in 1853.142 Its em-bryologic basis, however, of mesoduodenum fused to the posterior wall after bowel rotation was later clearly established by Toldt.140,143 Toldt also described the fusion fascia behind the body of the pancreas as a result of the fixation of the dorsal wall of the lesser sac, which subsequently has been named the retropancreatic fascia of Toldt (Fig. 8—107). In addition, he described the fusion fascia of the right and left mesocolon of the ascending and descending colon respectively, which since then are named right and left retrocolic fascia of Toldt (Fig. 8—107). In 1900, Fredet144 described thoroughly these processes of fusion with numerous cross-sectional drawings and coined the French term fascia d'accolement, which means joining or fusion fascia: a unique layer, more or less defined from surrounding tissue, with mobilization often remaining possible. Others have confirmed the ease of identification and surgical mobilization of these fusion fasciae.145,146 Yet, some have called this fascia a misuse of the term fascia,147 denied its existence,148 or hardly ever found a real fusion fascia at operation.149 Congdon et al.139 found these fusion fasciae to be very thin (0.1 to 0.6 mm) and sometimes bilaminar with a separable-looser stratum, ranging from similar thickness as the two lamina to several millimeters thick. They described the fused segments of the adult mesocolon as somewhat mobile, and not fixed, despite the fusions. According to Hureau et al.,32,33 the real anterior pararenal space is the potential space between the fusion fascia of mesoduo-denum and mesocolons and the perirenal fascia extending from diaphragm to pelvis.

Perirenal Hemorrhage

Fig. 8—104. Extension of pelvic hemorrhage into the anterior pararenal space and small bowel mesentery.

Following a left orchiectomy for seminoma, this 31-year-old man had a falling hematocrit.

(a) CT demonstrates extraperitoneal hemorrhage (H) with increased attenuation in the pelvis extending across the midline deep to the urinary bladder (B). Postoperative subcutaneous emphysema is evident on the left. (b and c) The blood rises into the anterior pararenal space within the abdomen. On the left, it extends within the two laminae of the posterior renal fascia (arrows). On the right, it continues into the lower small bowel mesentery (SBM). N = nodal metastasis.

The hemorrhage apparently originated from inadequate ligature of the testicular artery.

Fig. 8—104. Extension of pelvic hemorrhage into the anterior pararenal space and small bowel mesentery.

Following a left orchiectomy for seminoma, this 31-year-old man had a falling hematocrit.

(a) CT demonstrates extraperitoneal hemorrhage (H) with increased attenuation in the pelvis extending across the midline deep to the urinary bladder (B). Postoperative subcutaneous emphysema is evident on the left. (b and c) The blood rises into the anterior pararenal space within the abdomen. On the left, it extends within the two laminae of the posterior renal fascia (arrows). On the right, it continues into the lower small bowel mesentery (SBM). N = nodal metastasis.

The hemorrhage apparently originated from inadequate ligature of the testicular artery.

The effects of pancreatitis on small bowel and colon by spread along mesenteric planes were first noted by Meyers et al.84 In 1981, Strax et al.150 reported the correlation of barium enema and CT in acute pancreatitis. Later, Raptopoulos et al.20 reported the posterior exten sion of pancreatic effusions arising in the anterior pararenal space into the so-called retrorenal space, formed by dissection of the posterior renal fascia in two parts: the anterior part, continuous with the anterior renal fascia, and the posterior part, continuous with the latero-

Toldt Fascia

Carl Toldt was appointed to the Chair of Anatomy first in Prague and then in Vienna. His most important work is the widely accepted concept that during embryologic development, the secondary fusion of various mesenteries to the primitive parietal peritoneum is decisive for the definitive shape and location of mesenteries and different segments of the alimentary tract in adults. (Courtesy of the Institut für Geschichte der Medizin der Universität Wien.)

conal fascia.151 Recent injection studies29,34 of the pancreatic and peripancreatic tissues on the left further confirm extension from a retromesenteric plane, posterior to the fused mesocolon and anterior to the renal fascia, to the retrorenal plane. With volume and force, extension can occur across the midline, superiorly to the diaphragm and inferiorly to the pelvis.34,152 Fredet153 considered the posterior renal fascia embryologically as a result of a reinforcement by outcoming fibers of the

Fig. 8-105. Caudad extension of pancreatitis from the anterior pararenal space to the pelvis.

In a patient with fluid collection in the right anterior pararenal space secondary to severe acute pancreatitis, CT

scan of the pelvis demonstrates the inflammatory process has descended into the extraperitoneal prevesical space assuming a characteristic "molar-tooth" configuration (arrows) in relation to the urinary bladder (B). (Courtesy of Michiel Feldberg, M.D., University of Utrecht, The Netherlands.)

Fusion Fascia Space

peritoneal fascia, whereas Paturet154 viewed it as coming from fusion of the primitive retrorenal cul-de-sac to the posterior wall. Both concepts can explain the communication of the retromesenteric to the retrorenal plane through mobilization of these loose connections by fluid collections. Aizenstein et al.35 mention the so-called in-terfascial plane, indicating the potential space between the layers of renal and lateroconal fascia, to be the result of incomplete fusion of embryonic mesentery. The ease

Fascias Toldt

Fig. 8-107. Frontal diagram of the fusion fasciae of left and right colon and duodenal loop.

The fusion fascia of the left colon (1) fixes the meso of the descending colon to the posterior primitive parietal peritoneum. The superior limit, which covers part of the retroperitonealized pancreatic body and tail, is the line connecting the origin of the superior mesenteric artery to the left angle of the transverse mesocolon. The medial limit is in front of the aorta. The inferior limit begins a little left from the midline, in front of the promontory, and descends along the inner border of the psoas muscle, at the upper root of the sigmoid mesocolon. The retroduodenopancreatic fusion fascia of the duodenal loop (2) fixes the mesoduodenum and pancreatic head to the posterior primitive parietal peritoneum and to the fusion fascia of the left mesocolon, respectively, right and left from the midline. The superior limit above the root of the transverse mesocolon is the common hepatic artery. The medial limit is in front of the aorta. The left limit, below the radix of the transverse mesocolon, is short, starting below the superior mesenteric artery and extending to the duodenojejunal angle. The retropancreatic fusion fascia (3) fixes the dorsal mesogastrium, containing pancreatic body and part of the tail, to the posterior primitive parietal peritoneum. The fusion fascia of the right colon (4), located between cecum and transverse mesocolon, fixes the meso of the ascending colon to the posterior primitive parietal peritoneum and the duodenum and its fused meso, containing the caudal part of the pancreatic head. The superior limit is the line from the origin of the superior mesenteric artery across the second portion of the duodenum to the right angle of the transverse mesocolon. The inferior limit is the oblique line from the level of the aortic bifurcation to the ileocecal angle and the medial limit is close to the midline. (Adapted from Grégoire R, Oberlin S: Précis d'anatomie, 10th ed. J.B. Ballière, Paris, 1991.)

for surgeons to perform mobilization of the duodenum by blunt dissection, after incising the peritoneum lateral to the duodenal loop (Kocher maneuver), or mobilization of the colon after incising along the line of Toldt,140 laterally behind the ascending and descending colon where the fusion took place first,155 may simulate the manner rapidly accumulating fluid and gas collections may loosen the fusion fasciae. Anatomic cross-sections demonstrate these loose connections well (Fig. 8108).

Fig. 8-108. Anatomic sections of fusion fasciae.

(a) Section at the level of the pancreatic tail, with slight anterior traction on the left colonic fat. The mesenteric fat medial to the splenic flexure (SF) of the colon portrays the continuity between transverse mesocolon mediocranially and left colonic compartment laterocaudally. Note the loose areolar tissue (arrows) between this mesenteric fat and the pancreatic tail, representing the fusion fascia posterior to the transverse mesocolon medially and the cranial extension of the left retromesenteric plane, also called left fascia of Toldt, laterally. A space, also bridged by loose areolar tissue (arrowheads), appears between the pancreatic tail and perirenal space, representing the fusion fascia between the left pancreaticoduodenal compartment and primitive retroperitoneum. SP = spleen.

(This figure also appears in the color insert.)

(b) Section at the level of pancreatic head (P) and neck, with traction on the left colonic compartment. The left colonic compartment is demarcated from the primitive retroperitoneum by loose areolar tissue representing the left retromesenteric plane (black arrows). Anteriorly, the transverse mesocolon (black asterisks) attaches to the pancreatic neck, posterior to the stomach, and anterior to the duodenojejunal junction (white asterisk) in the left paraduodenal fossa. White arrow = inferior mesenteric vein; DC = descending colon; TC = transverse colon.

(This figure also appears in the color insert.)

Fig. 8-108. Anatomic sections of fusion fasciae.

(a) Section at the level of the pancreatic tail, with slight anterior traction on the left colonic fat. The mesenteric fat medial to the splenic flexure (SF) of the colon portrays the continuity between transverse mesocolon mediocranially and left colonic compartment laterocaudally. Note the loose areolar tissue (arrows) between this mesenteric fat and the pancreatic tail, representing the fusion fascia posterior to the transverse mesocolon medially and the cranial extension of the left retromesenteric plane, also called left fascia of Toldt, laterally. A space, also bridged by loose areolar tissue (arrowheads), appears between the pancreatic tail and perirenal space, representing the fusion fascia between the left pancreaticoduodenal compartment and primitive retroperitoneum. SP = spleen.

(This figure also appears in the color insert.)

(b) Section at the level of pancreatic head (P) and neck, with traction on the left colonic compartment. The left colonic compartment is demarcated from the primitive retroperitoneum by loose areolar tissue representing the left retromesenteric plane (black arrows). Anteriorly, the transverse mesocolon (black asterisks) attaches to the pancreatic neck, posterior to the stomach, and anterior to the duodenojejunal junction (white asterisk) in the left paraduodenal fossa. White arrow = inferior mesenteric vein; DC = descending colon; TC = transverse colon.

(This figure also appears in the color insert.)

Continued on opposite page

Anterior Extension Pancreas

Fig. 8-108. (Continued) (c) Section at the level of the pancreatic head (P). The right pancreaticoduodenal compartment is demarcated posteriorly by the loose areolar tissue of the retropancreaticoduodenal fusion fascia (arrowheads), also called fascia of Treitz, and anteriorly by the loose areolar tissue of the cranial extension of the right retromesenteric plane, also called right fascia of Toldt (arrows). Note the continuity of the transverse mesocolon (asterisks) with the right colonic compartment, located anterior to the right perirenal space. White arrow = inferior mesenteric vein; HF = hepatic flexure. (This figure also appears in the color insert.)

(d) Section below the level of the pancreatic head, demonstrating the slender right and left colonic compartments at this level (black arrows). Note how the right colonic compartment covers the right side of the pancreaticoduodenal compartment (white asterisk), while the medial extension of the left colonic compartment (black-and-white arrow) Lies posterior to the left extension of the horizontal part of the duodenum (D). The retropancreaticoduodenal fusion fascia is located posterior to the duodenum and anterior to the primitive retroperitoneum, aorta, and inferior caval vein. AC = ascending colon; DC = descending colon.

(This figure also appears in the color insert.)

Fig. 8-108. (Continued) (c) Section at the level of the pancreatic head (P). The right pancreaticoduodenal compartment is demarcated posteriorly by the loose areolar tissue of the retropancreaticoduodenal fusion fascia (arrowheads), also called fascia of Treitz, and anteriorly by the loose areolar tissue of the cranial extension of the right retromesenteric plane, also called right fascia of Toldt (arrows). Note the continuity of the transverse mesocolon (asterisks) with the right colonic compartment, located anterior to the right perirenal space. White arrow = inferior mesenteric vein; HF = hepatic flexure. (This figure also appears in the color insert.)

(d) Section below the level of the pancreatic head, demonstrating the slender right and left colonic compartments at this level (black arrows). Note how the right colonic compartment covers the right side of the pancreaticoduodenal compartment (white asterisk), while the medial extension of the left colonic compartment (black-and-white arrow) Lies posterior to the left extension of the horizontal part of the duodenum (D). The retropancreaticoduodenal fusion fascia is located posterior to the duodenum and anterior to the primitive retroperitoneum, aorta, and inferior caval vein. AC = ascending colon; DC = descending colon.

(This figure also appears in the color insert.)

Essentials of Human Physiology

Essentials of Human Physiology

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