Normal Radiologic Observations

The haustral recesses, bordered by the course of the taeniae, can be identified easily by routine barium enema examination, particularly with double contrast studies.1 Their distinctive organization into rows and the position and anatomic limits as well as the relationships of each row are clearly delineated.

In the supine position, barium gravitates to the dependent posterior row of sacculations in the middle third. This outlines the TM-TO row in the ascending colon (Fig. 15-8) and the TM-TL row in the transverse colon (Figs. 15-8 and 15-9). At the same time, air tends to outline the border-forming haustral rows.

In the prone position, the more ventral haustral groups are visualized more clearly. These include the TO-TL and TM-TL haustra of the ascending colon (Fig. 15-10) and the TO-TL and TM-TO haustra of the transverse colon (Fig. 15-11). Demarcation is provided by their shared taenia.

Precise correlation of the relative position of the haustral rows is further provided in lateral projections (Fig. 15-12).

The haustra are almost invariably demarcated clearly in the ascending and transverse colon and less often in the descending colon. The size of the haustra in each row is roughly equal, except in the lower descending colon. Here the TO and TL broaden and quickly approximate each other, reducing their intervening lateral haustral row. Sigmoid loops only rarely demonstrate haustral delineation. Because of their shape and the effects of gravity, the entire contour of a haustrum is not visualized in a single view. Yet, with the multiple views conventionally employed in a barium-contrast study, the complete contours of all of the haustral rows are usually seen. Decubitus and optimally obliqued or lateral projections adequately complement frontal views.

The appearance of the altered relations of the rows of haustra as they continue around the hepatic flexure from the ascending colon to the transverse colon is best ap-

Fig. 15-10. Prone projection.

The TO-TL and TM-TL rows in the ascending colon are delineated by the indentation of the taenia libera. (Reproduced from Meyers et al.1)

Fig. 15-10. Prone projection.

The TO-TL and TM-TL rows in the ascending colon are delineated by the indentation of the taenia libera. (Reproduced from Meyers et al.1)

Fig. 15-9. Double contrast barium enema.

In the supine position, barium fills the posterior TM-TL row of haustra in the internal third of the transverse colon, while air outlines the border-forming TM-TO row superiorly and the TO-TL row inferiorly. (Reproduced from Meyers et al.1)

Fig. 15-9. Double contrast barium enema.

In the supine position, barium fills the posterior TM-TL row of haustra in the internal third of the transverse colon, while air outlines the border-forming TM-TO row superiorly and the TO-TL row inferiorly. (Reproduced from Meyers et al.1)

Double Contrast Barium EnemaEnema Supine Position

Fig. 15—11. Prone projection.

The TM-TO and TO-TL rows in the transverse colon are delineated by the taenia omentalis. (Reproduced from Meyers et al.1)

Taenia Libera

Fig. 15—12. Ascending colon.

(b) Left lateral. Note that the three rows of haustra can be identified clearly in the lateral view. Multiple projections afford clearer visualization of their complete contour. (Reproduced from Meyers et al.1)

Fig. 15—12. Ascending colon.

(b) Left lateral. Note that the three rows of haustra can be identified clearly in the lateral view. Multiple projections afford clearer visualization of their complete contour. (Reproduced from Meyers et al.1)

preciated on oblique projections (Fig. 15-13). It can then be noted that the TM, for example, curves around the flexure from a posteromedial position on the ascending colon to assume a posterosuperior course on the transverse colon. Similarly, because of the rotation at the flexure, the other taeniae alter their course. In this way, continuity of the rows of haustra themselves can be traced.

Even with contractions of portions of the colon, the haustral rows may still be identified (Fig. 15-14). In a mass peristaltic movement, the wave of contraction may involve only one haustral row (Fig. 15-15). This may simulate a filling defect unless the haustral relationships are recognized.

Classically, interdigitation of haustral folds has been considered a plain film landmark for the identification of the large intestine and particularly in the differentiation from gas-distended small bowel loops. However, reliance on this feature, without an understanding of the

Haustral Folds The Colon

haustral anatomy, may be misleading. While it is true that the folds between two adjacent rows ofhaustra often interdigitate, it must be recognized that each row of sacculations may contract independently of the other two. In this way, the third row of haustra may not be appreciated on a single projection, either because it is in a state of contraction or obscured by superimposed shadows or densities (Figs. 15-16 and 15-17). The haustral folds visualized at the contours of the colon may then project in the same plane, rather than in an interdigi-tating manner, and be mistaken for the semicircular folds of a distended small bowel loop.

Appendices epiploicae, which appear as lobulated masses of subserosal fat, usually 2-5 cm long and 1-2 cm thick, are arranged in two separate longitudinal rows along the taenia libera and adjacent to the taenia omen-talis. They extend from the cecum to the rectosigmoid junction and are most prominent in size and number in the descending colon and sigmoid colon8-10 (Fig. 15-18).

Haustral Contraction

Fig. 15—13. The altered relationships of the taeniae and the haustral rows around the hepatic flexure are demonstrated.

(b) Left posterior oblique projection. (Reproduced from Meyers et al.1)

Radiographs The Haustra

Fig. 15—14. Contraction of haustra.

Each row remains identifiable. Note that in the transverse colon the rows are aligned transiently. (Reproduced from Meyers et al.1)

Fig. 15—14. Contraction of haustra.

Each row remains identifiable. Note that in the transverse colon the rows are aligned transiently. (Reproduced from Meyers et al.1)

Haustral Contractions
Fig. 15-15. Mass contraction limited to the TM-TO haustral row of the ascending colon mimics a filling defect due to a lesion.
Interdigitate

Fig. 15—16. In this instance, the interhaustral clefts of the border-forming TM-TO and TO-TL groups do not interdigitate.

Note, however, that the folds of each do interdigi-tate with those of the centrally projecting TM-TL group.

(Reproduced from Meyers et al.1)

Gastrocolic Ligament
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