The role of the anatomy of the sigmoid colon in developing sigmoid volvulus: a cross-sectional study

Purpose

The aim of this study was to determine the length of the sigmoid colon and sigmoid mesocolon in living subjects and fresh cadavers.

Methods

The subjects for the study were consecutive 50 living subjects undergoing abdominal surgeries via midline incision and 50 fresh cadavers undergoing a medicolegal postmortem at Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Osun State, Nigeria.

Results

The study showed that the mean length of the sigmoid colon in living subjects was 48.9 ± 1.3 cm (range 30.5–65 cm) while the mean length of the sigmoid colon in cadaver subjects was 50.1 ± 1.6 cm (range 34.5–67.8 cm) and this was not statistically significantly different. Two patterns of the shape of the sigmoid loop were identified: dolichomesocolic and brachymesocolic pattern. In about 80 % of subjects in both groups, dolichomesocolic-type was seen. The gender analysis showed that males had statistically significant longer sigmoid colon (P = 0.040). The dimension of sigmoid colon significantly increased with age of the patients in cadaver subjects and in both sexes (P = 0.001).

Conclusions

The study concluded that the lengths of sigmoid colon are not different in living and cadaver subjects but are relatively longer than measurement from western countries. The lengths of sigmoid colon and mesocolon also increases with age and this may possibly be the anatomical basis for the frequent occurrence of sigmoid volvulus and failed colonoscopy among the older population in our environment.     

Sigmoid colon morphology in the population groups of Durban, South Africa, with special reference to sigmoid volvulus

Sigmoid volvulus demonstrates geographical, racial, and gender variation. This autopsy study was undertaken to establish morphological differences of the sigmoid colon and its mesocolon in which the length and other characteristics were assessed. A total of 590 cadavers were examined (403 African, 91 Indian, and 96 White). Length and height of the sigmoid colon and mesocolon were significantly longer in Africans, and mesocolon root was significantly narrower in Africans. Mesocolic ratio for Africans, Indians, and Whites was 1.1 ± 0.8, 1.8 ± 0.7, and 1.9 ± 1.0, respectively. Africans had a significantly high incidence of redundant sigmoid colon with the long-narrow type and suprapelvic position predominating (P = 0.003); the opposite applied to the classic type. There was no difference in sigmoid colon length, mesocolon height, and width between males and females in all population groups. Among Africans, the long-narrow type was more common in males, and the classic and long-broad types were more common in females. Splaying of teniae coli and thickening of the mesentery were more common in Africans. Tethering of the sigmoid colon to the posterior abdominal wall was less common in Africans compared with other population groups. In conclusion, the sigmoid colon was longer, and the sigmoid mesocolon root was narrower in Africans compared with the other population groups, and the sigmoid colon had a suprapelvic disposition among Africans. In Africans, the sigmoid colon was longer in males with a long-narrow shape. These differences may explain geographical and racial differences in sigmoid volvulus.     

Anatomical variations in the level of origin of the sigmoid colon from the descending colon and the attachment of the sigmoid mesocolon

The origin of the sigmoid colon is considered constant as is the V‐shaped attachment of the sigmoid mesocolon attachment. This study was undertaken to establish anatomical variations in the level of origin of the sigmoid colon (590 autopsies; 403 Africans, 91 Indians, and 96 Whites), and the shape of the attachment of the sigmoid mesocolon (211 autopsies, 127 Africans, 47 Indians, and 37 Whites) in different population groups. The low‐level origin was significantly less common among Africans compared with the other population groups (P = 0.003) and the high‐level origin was significantly more common in Africans (P = 0.003). A midlevel origin was similar in all three groups. The shape of the mesocolon attachment was either straight (94), inverted U‐shaped (79), or inverted V‐shaped (38). The straight shape was more common in Whites (Whites vs. African and Indian P = 0.003), and the U‐shape more common in Africans (African vs. Whites P = 0.042). The distribution of the V‐shape was similar. There are anatomical variations in the level of origin of the sigmoid colon from the descending colon as well as in the shape of the attachment of its mesocolon. These variations are population based. Clin. Anat. 23:179–185, 2010. © 2009 Wiley‐Liss, Inc.     

The role of the anatomy of the sigmoid colon in developing sigmoid volvulus: a case-control study

Sigmoid volvulus is a common condition throughout much of the world. To this date, there are no adequately controlled clinical trials examining the role of anatomy in sigmoid volvulus. Therefore, the objective of this study was to determine if the anatomic dimensions of the sigmoid colon differ in sigmoid volvulus compared to controls. This prospective case-control study was conducted at Kamuzu Central Hospital, Lilongwe, Malawi. Cases included individuals 18 years or older with surgically confirmed sigmoid volvulus, while controls included individuals undergoing surgery for reasons unrelated to the descending or sigmoid colon, or rectum. Intraoperative measurements of the sigmoid colon were taken, including mesosigmoid root width and mesosigmoid length. A total of 26 cases and 12 controls were enrolled. When compared to controls, the mesosigmoid of cases had a greater length and maximal width; however, mesosigmoid root width was similar between groups. These findings support the assertion that sigmoid volvulus is due to a long and wide mesosigmoid that rotates on a constant mesosigmoid root width. This is the first adequately controlled trial examining anatomy in sigmoid volvulus and provides strong evidence that refines prior hypotheses regarding the anatomic basis of sigmoid volvulus.     

Anatomy of the sigmoid colon, rectum, and the rectovaginal pouch in women with enterocele and anterior rectal wall procidentia

This study describes the anatomy of the rectovaginal pouch, the sigmoid colon, and rectum in women with posterior enterocele and anterior rectal wall procidentia. The anatomy of rectovaginal pouch, sigmoid colon, and rectum was described in 36 women with an enterocele (group A) and compared with those of 43 women (group B) without pelvic organ prolapse. Women with previous incontinence or prolapse surgery were excluded. The mean age in group A was 58 years (40-75) and in group B 35 years (19-64; P < 0.001). There were 15 nulliparas in group B. Nine women in group A had an internal anterior rectal wall procidentia, and one woman had an external anterior rectal wall procidentia. In group A, the rectovaginal pouch was significantly deeper, the sigmoid mesocolon at S1 shorter and showed more often a straight course (P < 0.05). These characteristics (termed "grande fosse pelvienne") were present in 23 women (64%) in group A and in 6 (14%) in group B, three of the latter were young nulliparas (P < 0.001). Age, parity, menopausal status, body mass index, constipation, and varicose veins were not associated with a grande fosse pelvienne. The typical anatomy in women with an enterocele and anterior rectal wall procidentia was a sigmoid colon with a straight course and a short mesentery at S1 and a rectovaginal pouch that covered more than half of the vaginal length. It may be a congenital condition and important in the development of an enterocele and rectal wall procidentia.     

Colosigmoid junction: Morphohistologic,morphometric, and endoscopic study with identification of colosigmoid canal with sphincter

To study the anatomical structure of the colosigmoid junction, 15 cadaveric specimens were studied morphologically, another 15 histologically, and a morphometric study was done in 10 specimens. Specimens consisted of the descending colon, sigmoid colon, and the colosigmoid junction. Histologic specimens were stained with hematoxylin and eosin and Masson's trichrome stain. Morphometric studies used an image analysis system. The colosigmoid junction was investigated endoscopically in 18 healthy volunteers. A narrow segment having a mean length of 5.2 ± 1.1 cm was identified both externally and internally between the descending and sigmoid colon. We called this segment the colosigmoid canal. Mucosal folds were found crowded in the colosigmoid canal, the lower end of which formed a nipple and was surrounded by a fornix. Histologically, the colosigmoid canal mucosa showed multiple folds. Its circular muscle was thicker than that of the descending or the sigmoid colon and confirmed morphometrically. The longitudinal muscle was thicker in only 4 of 10 specimens. Both the narrowing and the mucosal crowding were verified endoscopically. The colosigmoid junction is the narrow segment between the descending and the sigmoid colon. Histologic, morphometric and endoscopic studies indicated the presence of a sphincter in the colosigmoid canal. A colosigmoid sphincter is suggested to control the passage of colonic contents from the descending colon to the colosigmoid canal as well as to prevent reflux of sigmoid contents into the descending colon. Clin. Anat. 22:243–249, 2009. © 2008 Wiley‐Liss, Inc.     

腹腔镜下左半结肠切除术相关筋膜平面的解剖观察

目的：探讨左半结肠切除术相关筋膜的解剖学特点和外科平面的鉴别方法。临床资料和方法：2003-2004年南方医院普通外科施行的腹腔镜左半结肠切除术15例，病例均为左半结肠癌。对腹腔镜下左半结肠后外侧、中线侧和直肠后外侧相关筋膜的解剖特点和镜下定位标志进行观察和描述。结果：在乙状结肠第一曲外侧缘肠壁与左侧腰大肌筋膜之间存在一个固定的粘连带，它是左侧Toldt’s线的尾侧端点。左半结肠系膜后外侧存在肾前筋膜；中线侧存在主动脉前筋膜；直肠系膜后外侧存在盆筋膜壁层。这三个部位的筋膜相互延续。结论：乙状结肠和左侧腰大肌筋膜之间的粘连带是左半结肠切除术外侧分离的起点。肾前筋膜是衬贴于左半结肠和直肠系膜后面的一层连续筋膜，在不同的解剖位置有不同的表现形式。左半结肠切除术的外科平面统一于结直肠系膜与连续的肾前筋膜之间。     

Multiple abdominal peritoneal and intestinal variations and their accompanying clinical implications

Accessory peritoneal sac and cystoduodenal ligament as peritoneal variations were observed in a cadaver in our laboratory. Slender stomach, thin transverse colon, redundant sigmoid colon, absent ascending colon and doubly distended gall bladder were also reported in the same cadaver. Relevant anatomical and clinical implications are discussed.     

乙状结肠位置和行程的研究

采用腹部九分区法加腹正中线,对 120 例成人尸体乙状结肠的位置和行程进行了分析研究,将其分为两大型八个亚型,又与 58 例活体 X 线片的乙状结肠进行分析对照,还与有关文献作了对比。     

Sigmoido-rectal junction reflex: Role in the defecation mechanism

The presence of a sphincter at the rectosigmoid junction (RSJ) is debated. This investigation studies the presence or absence of a sphincter and its possible role in sigmoid colon storage and rectal evacuation. Eighteen healthy volunteers (10 males, 8 females) with a mean age of 36.6 ± 14.8 years (range 21–53) were studied. The pressure response of the sigmoid colon, RSJ, and rectum to sigmoid and rectal distension, respectively, was determined before and after anesthetizing either the sigmoid colon or the rectum. The RSJ length was evaluated by the station pull-through technique. Sigmoid distension with balloon volumes of up to 80.6 ± 4.4 ml of H₂O effected no sigmoid, RSJ, or rectal pressure changes (P > 0.05). At a mean sigmoid distension of 88.6 ± 4.1 ml of H₂O, the sigmoid colon showed a significant pressure increase (P < 0.001), a RSJ pressure decrease (P < 0.05), and insignificant pressure changes in the rectum (P > 0.05); the balloon was dispelled into the rectum. Rectal distension of 94.6 ± 5.8 ml of H₂O produced rectal (P < 0.001) and RSJ (P < 0.05) pressure increases. Distension of the anesthetized sigmoid and rectum did not produce pressure changes in the RSJ (P > 0.05). This study demonstrated a high pressure zone at the RSJ of 3.8 ± 0.7 cm in length. This suggests that the RSJ might act as a functional sphincter. It opens reflexly upon sigmoid contraction, by a reflex we call “rectosigmoid inhibitory reflex,” and closes upon rectal contraction, a reflex we call “rectosigmoid excitatory reflex.” The former allows the stored feces in the sigmoid colon to pass to the rectum, and the latter reflex prevents stool reflux to the sigmoid upon rectal contraction. © 1996 Wiley-Liss, Inc.     

A case of a right-sided sigmoid colon]

During dissecting practice by students at Chiba University in 1991, a rare anomaly was found in a cadaver of a 50-year-old Japanese male. The distal part of the colon, including the sigmoid colon, was excessively long and formed a loop behind the ascending colon. This anomalous colon consisted of four parts. The first part began in the left iliac fossa and passed across the lower posterior abdominal wall into the right iliac fossa; the second turned upward and ascended along the posterior surface of the ascending colon to the inferior surface of the right lobe of the liver; the third turned backward and descended to the right iliac fossa and was in contact with the posterior abdominal wall; the fourth curved medially and downward and ended in the rectum at the median line. Only the anterior surface of the anomalous colon was covered with the peritoneum, and its mesocolon was not found. The inferior mesenteric artery gave off four branches toward the distal three-fourths of the excessively long colon and the superior rectal artery to the upper part of the rectum. Since it did not directly give off any branches toward the descending colon and the first part of the anomalous colon (these portions were supplied by a marginal artery), the branch supplying the second part was considered to be equivalent to the left colic artery. Thus, the proximal half of the long colon (parts 1 and 2) can be regarded as a part of the descending colon, and the distal half as the sigmoid colon.(ABSTRACT TRUNCATED AT 250 WORDS)     

A prospective radiological anatomical study of the variations of the position of the colon in the left pararenal space

Abstract: Percutaneous puncture of the kidney allows direct access to the pyelocalicial cavities. The posterior approach of this retroperitoneal organ can be complicated of transcolic punctures due to the postrenal position of the colon. A prospective radiological anatomical study of the relationship between the left kidney and the descending colon was undertaken. One hundred computed tomograms of adult subjects were obtained from which the anatomy of the left perirenal area was determined: the descending colon is more frequently behind the kidney in the young females. Two main factors determinants of this situation are: 1) colon ontogenesis in relation to the attachment of the primitive mesocolon, permitting a “fixed” left colon, or “moving” left colon at the end of a long mesocolon, allowing it to pass behind the kidney; 2) a mechanical factor whereby the accumulation of perirenal fat with increasing age may be a limiting factor in lateral displacement of the colon.     

乙状窦沟的应用解剖研究

目的：探讨乙状窦的发育差异,为临床上乙状窦前,后入路手术提供形态学依据和资料。方法：采用140侧颅骨,用分规和游标卡尺测量乙状窦沟的宽度,深度及乙状窦沟的前缘至外耳道后壁的距离。部分颅骨以外耳门为中心作水平锯切,直接测量乙状窦沟的前缘至外耳道后壁的距离,同时进行Law氏位X线摄片对照,结果：乙状窦前缘至外耳道后壁的距离在10mm以上者108例（77％）,距离在8－9mm者21侧（15％）,距离在6－7mm者7侧（5％）,距离在5mm以下者4侧（3％）,以10mm为正常值,右侧的乙状窦前移多于左侧（18：14）,但无统计学差异,结论：乙状窦前移在国人中的发生率为23％,进行乙状窦前,后手术入略时应引起注意。     

Sonographic anatomy of the pubic symphysis in healthy nulliparous women

Pregnancy‐related symphyseal pain is a condition commonly encountered by clinicians but its pathogenesis is poorly understood. The pubic symphysis is readily visualized with ultrasound, yet the normal sonographic anatomy of the joint has not been accurately documented. This study aimed to describe the anatomy of the pubic symphysis in healthy, nulliparous women using ultrasound. An experienced and inexperienced sonographer scanned the joint in 30 female volunteers (mean age 26 years). Interobserver and intraobserver reliability of ultrasound measurements were examined and the accuracy of these measurements was validated by ultrasound and dissection of six female cadaver pelves (mean age 75 years). In healthy young women, pubic symphysis morphology varied, and six categories of anterosuperior joint shape were defined. Mean values of several anatomic parameters were obtained in supine and standing positions: joint width (widest 10.1 mm, narrowest 2.6 mm); superior pubic ligament (SPL) length and depth (41.4 and 3.4 mm, respectively); and pubic crest length (left 24.4 mm, right 24.4 mm). Statistically significant relationships between SPL width and depth and anthropometric variables (body mass index, pelvic width, and body fat percentage) were established. Larger ultrasonographic measurements, such as wide joint width and SPL length, could be measured more reliably than smaller measurements, such as narrow joint width and SPL depth, in both healthy volunteers and cadavers. Findings from this study provide normative reference data for examination of the pubic symphysis in pregnant women and may therefore be relevant to understand pregnancy‐related symphyseal pain. Clin. Anat. 27:1058–1067, 2014. © 2014 Wiley Periodicals, Inc.     

Radiological anatomy of the sigmoid colon

BACKGROUND: The variable incidence of sigmoid volvulus, which depends on the presence of an elongated sigmoid colon, suggests the possibility of variations in the length of the sigmoid colon. This study was undertaken among the three major population groups to prove this hypothesis. PATIENTS AND METHODS: Radiological films of patients of the three population groups (African, Indian and White) undergoing barium enema were reviewed. The stature was measured by the distance from T12 to L4. The collective length of the rectum and sigmoid colon as well as the entire colon was measured on the barium enema film using an opisometer. Measurement was from the upper border of the symphysis pubis to the upper border of the left iliac crest. The level of the apex of the sigmoid colon loop and its redundancy were also assessed. RESULTS: There were 109 patients (61 females) undergoing barium enema (39 Africans, 49 Indians, and 21 Whites). For the entire group the T12-L4 distance was 16.6 +/- 2.2 cm and the entire colon length was 133 cm (range 88-262 cm) and was significantly longer among African patients (P = 0.003). The combined length of the rectum and sigmoid colon was 48.8 +/- 15.7 cm (Africans 60.9 +/- 14.4 cm, Indians 41.3 +/- 12.2 cm and Whites 44 +/- 11.6 cm). The sigmoid colon was significantly more redundant in Africans (90%), compared to Indians (25%) and Whites (24%) (P = 0.003 for Indians and P = 0.048 for whites). The apex of the sigmoid colon reached L1-L3 in 54% among Africans, 6% among Indians and in 10% among Whites (10%). CONCLUSION: African patients had the longest combined length of the rectum and sigmoid colon translating into a long sigmoid colon. They also had the highest number of redundant sigmoid colon. This may explain the high incidence of sigmoid volvulus in African patients.     

An anatomical,histopathological, and molecular biological function study of the fascias posterior to the interperitoneal colon and its associated mesocolon: their relevance to colonic surgery

The study aim was to explore the anatomy, histopathology, and molecular biological function of the fascias posterior to the interperitoneal colon and its mesocolon to provide information for improving complete mesocolic excision. To accomplish this aim, we performed intraoperative observations in 60 interperitoneal colon‐cancer patients accepted for complete mesocolic excision and conducted local anatomy observations for five embalmed cadavers. An additional two embalmed child cadaver specimens were studied with large slices and paraffin sections. Ten of the 60 patients were examined with a lymph node tracer technique in vivo, while fresh specimens from these patients were assessed by histopathological examination and transwell cell migration assays in vitro. The anatomical and histopathological findings showed that the fascias posterior to the interperitoneal colon and its associated mesocolon were composed of two independent layers: the visceral and parietal fascias. These two fascias were primarily composed of collagen fibers, with the parietal fascia containing a small amount of muscle fiber. The in vivo test showed that the visceral fascia surrounded the colon and its associated mesocolon, including vessels and lymphatics, and that it had no lymphatic flow through it into the rear tissues. Moreover, the in vitro assays showed the visceral fascia was able to block tumor cell migration. Although many surgical scholars have known of the existence of fascia tissue posterior to the intraperitoneal colon, the detailed structure has been ignored and been unclear. As shown by our findings, the visceral and parietal fascias are truly formed structures that have not been previously reported. A thorough understanding of fascial structures and the function of the visceral fascia barrier in blocking tumor cells will facilitate surgeons when performing high‐quality complete mesocolic excision procedures.     

Bone mass in normal children and young adults

The growth of bone mass in the radius of children from age 6 on was studied in Indiana and Wisconsin. Growth curves describing change in bone mass, bone width, body height and weight were fitted separately to the data of males and females in the two states. Statistically significant differences between states were found in almost all growth measurements in both sexes. Refined growth curves with standard deviations were generated separately for the two states. When adjusted for age and bone width, Wisconsin subjects always had higher mean bone mass than Indiana subjects. Thus researchers should exercise caution when using published normative values established elsewhere.     

Intramesocolic diverticular perforation of the sigmoid colon diagnosed by detecting air collection in anterior pararenal space on computed tomography: report of a case

A 64-year-old woman was admitted to our hospital with lower abdominal pain. Routine laboratory values were unremarkable except for the white blood cell count (15,000/micro litter) and the C-reactive protein (CRP) value (22.5 mg/dl). A Computed tomography (CT) scan revealed air collection in the middle of the anterior pararenal space. One day later, CT revealed air collection in the anterior pararenal space spread to the right side and abscess in the sigmoid mesentery. Because an intramesocolic perforation of the sigmoid colon was suspected, an emergency operation was performed. Abscess formation was recognized in the sigmoid mesentery, and sigmoidectomy including the contaminated mesentery and Hartmann.s procedure were performed. The perforation was 3 cm in diameter, and some diverticula were present in the vicinity of the perforated site. The specimen microscopically revealed perforation at the edge of the diverticulum in association with sudden disruption of the proper muscle layer. Based on pathological findings, intramesocolic diverticular perforation of the sigmoid colon was diagnosed. The present case is a very rare condition. However, it was possible to make a diagnosis preoperatively by detecting air collection in the anterior pararenal space on CT scan. If a sigmoid perforation occurs between the leaves of the mesocolon, air extends into the root of the sigmoid mesocolon and within the anterior pararenal space.     

颅底后外侧立体应用显微解剖学研究

目的探讨颅底后外侧区各解剖结构之间的对应关系及立体结构框架,为颅底侧方入路提供相应的解剖学数据及资料。方法10例(20侧)成人带颈头颅标本,按颅底后外侧区解剖层次进行解剖和观测,同时对相应区域进行测量,并做统计学分析。结果乳突、茎突、星点、横窦、乙状窦、寰椎横突外侧端在颅底后外侧入路中是重要的解剖学标志,椎动脉V2段寰枢椎间段、V3段及围绕椎动脉的静脉丛在该手术中应注意保护,本实验进一步确定了各重要骨性标志的定位及相关重要结构之间的距离。结论该区域中以乳突为圆点、以星点为中心各解剖结构的测量、椎动脉重要区段的观测可有效而安全地保护重要结构,避免损伤重要的血管及神经。     

Microsurgical anatomy of the pituitary gland (hypophysis cerebri) and the sellar region. Part IV: The optic nerves and optic chiasma

The anatomical relationships of the optic nerve and optic chiasma to the different structures of the sellar region were studied in 100 cadaver sphenoidal blocks and in patients during transfrontal surgery to the sellar region. This study includes the relationships with the bony structures (tuberculum sellae, dorsum sellae, sella turcica, optic canal), with the meninges (arachnoidal cisterns, tentorium of the optic nerve), with the vessels (carotid and ophthalmic arteries), and finally with the neural structures (hypophysis cerebri, cranial nerves third ventricle). Relevant clinical or surgical aspects in relation to normal anatomy and anatomical variations of the optic nerves and optic chiasma are discussed. The varieties of the chiasma (normal, prefixed, postfixed) and the measurements of the optic nerves and optic chiasma (width, length, height, distance, and angle between optic nerves) were studied in the cadaver only. Different transfrontal approaches to the sellar region are discussed according to the morphology of the chiasma.