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Why is colonoscopy more difficult in women?
0016-5107/96/4302-012455.00 + 0 GASTROINTESTINALENDOSCOPY Copyright 9 1996 by the American Societyfor Gastrointestinal Endoscopy
Why is colonoscopy more difficult in women? Brian P. Saunders, MRCP, Manabu Fukumoto, MD, Steve Halligan, MRCP, Craig Jobling, FRCS Mohammed E. Moussa, MD, Clive I. Bartram, FRCP, FRCR, Christopher B. Williams, BM, FRCP London, England
Background: In our experience colonoscopy in women is more difficult than in men. A retrospective review of 2194 colonoscopies performed by a single experienced endoscopist (CBW) showed that 31% of examinations in women were considered technically difficult compared with 16% in men. Methods: To investigate a possible anatomic basis for this finding, normal barium enema series from 183 female and 162 male patients were identified. From these barium enemas, measurements of colonic length and mobility were independently taken by two physicians who were unaware of each patient's gender. Results:Total colonic length was greater in women (median, 155 cm) compared to men (median, 145 cm), p= 0.005, despite women's smaller stature (p < 0.0001). Although there were no significant differences in rectum plus sigmoid, descending, or ascending plus cecum segmental lengths, women had longer transverse colons (female median length, 48 cm; male median length, 40 cm), p < 0.0001. There were no differences in mobility of the descending colon and transverse colon between the sexes, but the transverse colon reached the true pelvis more often in women (62%) than in men (26%), p < 0.001. Conclusions: Colonoscopy appears to be a technically more difficult procedure in women. The reason for this may be due in part to an inherently longer colon. (Gastrointest Endosc 1996;43:124-6.) It has been our experience, and also that of others, 1-6 that it is more difficult to perform colonoscopy in women than in men. At St. Mark's Hospital the endoscopist's subjective impression of the relative difficulty of each colonoscopic intubation is recorded immediately after the examination. The intubation is classified as being either "difficult" or "not difficult," according to the duration of the procedure, the final depth of insertion, and the degree of observed patient discomfort. With adequate bowel preparation and in the absence of colonic stricture, technical difficulty is usually recorded if cecal intubation has not been
achieved within the first 15 minutes of the procedure. Of a total 2194 colonoscopies performed by one experienced colonoscopist (CBW) between January 1988 and May 1993, 327 of 1067 procedures in women (31%) were considered technically difficult, in contrast to only 177 of 1127 procedures (16%) in men. The most common cause of difficulty at colonoscopy is recurrent looping of the colonoscope in a long or mobile colon. 7 We therefore wondered whether differences in colonic length and mobility could be demonstrated between male and female patients.
Received November 18, 1994. For revision December 27, 1994. Accepted June 6, 1995. From the Departments of Endoscopy, Surgery, and Radiology, St. Mark's Hospital, London, England. Reprint requests: Brian P. Saunders, MRCP, St. Mark's Hospital, City Road, London, ECIV 2PS England.
N o r m a l b a r i u m e n e m a s (without significant diverticular disease, colitis, megacolon, stricture, or resection) of 183 female a n d 162 male patients were identified from "in file," double-contrast, b a r i u m e n e m a x-ray films at St. M a r k ' s Hospital. All e n e m a series h a d been performed by a standardized technique (using large overhead films t a k e n with a fLxed film-tube distance in set radiographic positions).
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GASTROINTESTINAL ENDOSCOPY
PATIENTS AND METHODS
VOLUME 43, NO. 2, PART 1, 1996
',.
/
\
/'
Figure 1. Schematic showing method of measurement of the colonic segments.
From the prone film of each enema series the total length of the colon was measured using an opisometer (mapping wheel) passed along the long axis of the bowel. Of the 345 normal enema films identified, 204 (104 of women, 100 of men) were randomly selected for more detailed measurements of colonic anatomy and mobility. For this subset, segmental colonic lengths (rectum plus sigmoid, descending colon, transverse colon, ascending colon plus cecum) were measured from the prone film (Fig. 1). The upper border of the iliac crest was designated as the junction between the sigmoid and descending colon. The distance from the upper border of the twelfth thoracic vertebra (T12) to the lower border of the fourth lumbar vertebra (L4) was also measured from the prone film as an indicator of the stature of each patient. Mobility of the descending colon was assessed by measuring the distance from the midpoint of the third lumbar vertebra to the midpoint of the descending colon in the right and left lateral decubitus views and then subtracting for the difference. Mobility of the transverse colon was assessed by measuring the maximum perpendicular distance between the transverse colon and a line passing through both hepatic and splenic flexures (Fig. 2) on prone and erect films and then subtracting for the difference. The transverse colon was considered redundant when it sagged into the true pelvis on the erect film. All measurements and observations were
VOLUME 43, NO. 2, PART 1, 1996
Figure 2. Erect film showing method of measurement of transverse colon mobility. This measurement is repeated in the prone film; mobility of the transverse colon equals vertical distance in the prone film minus vertical distance in the erect film.
performed independently by two physicians blinded to the gender of the patient.
Statistical analysis The Mann-Whitney test was used to compare measurements of colonic length and mobility between male and female patients. Fisher's exact test was used to compare the finding of a redundant transverse colon between the sexes. A p value of less than 0.05 was considered significant.
RESULTS Male a n d f e m a l e p a t i e n t s w e r e s i m i l a r w i t h r e g a r d to age at the t i m e of e n e m a : m e a n f e m a l e age, 50.2 y e a r s (range, 19 to 85), m e a n m a l e age, 51.5 y e a r s (range, 15 to 86 years). T h e two p h y s i c i a n s ' m e a s u r e m e n t s w e r e a v e r a g e d for continuous d a t a a n d t h e r e w a s complete a g r e e m e n t over n o n c o n t i n u o u s d a t a (presence of a r e d u n d a n t t r a n s v e r s e colon). Total colonic l e n g t h w a s g r e a t e r in w o m e n (median, 155 cm; range, 108 to 206 cm) c o m p a r e d to m e n (median, 145 cm; range, 97 to 205 c m ) , p = 0.005, despite t h e s m a l l e r s t a t u r e of w o m e n (female T12 to L4 m e d i a n distance, 17 cm; m a l e T12 to L4 m e d i a n distance, 20 cm), p < 0.0001. A s s e s s m e n t of colonic s e g m e n t a l l e n g t h s (Table 1)
GASTROINTESTINAL ENDOSCOPY
125
Table 1. Segmental colonic lengths and degree of mobility of the descending and transverse colon Female (n = 104) Rectum plus sigmoid colon Median length (cm) 56 Range (cm) 22-100 Descending colon Median length (cm) 23 Range (cm) 11-43 Transverse colon Median length (cm) 48 Range (cm) 19-83 Ascending colon plus cecum Median length (cm) 23 Range (cm) 11-41 Descending medial mobility Median length (cm) 4 Range (cm) 0-12.5 Transverse mobility Median length (cm) 6 Range (cm) (-4)-(+15)
Male (n = 100)
Probability
59 31-103
NS
25 8-36
NS
40 20-67
<0.0001
23 15-38
NS
3.5 0-10.7 6 0.5-11
NS
NS
NS, Not significant.
showed that there was no significant difference in rectum plus sigmoid colon, descending colon, or ascending colon plus cecum lengths between the sexes. Transverse colon length was, however, greater in women (median length, 48 cm; range, 19 to 83 cm) than men (median, 40 cm; range, 20 to 67 cm), p < 0.0001. There was no significant difference between the sexes with regard to the degree of measured mobility of the descending colon or transverse colon (Table 1). However, redundancy of the transverse colon was a more frequent finding in female (62%) compared with male (26%) patients, p < 0.0001.
DISCUSSION Two recent abstracts have highlighted the difficulties encountered by female patients undergoing colonoscopy. Women were more likely to experience discomfort during the procedure2 and miss work the following day. s It has been suggested that colonoscopy may be more difficult in women because of previous pelvic surgery, particularly hysterectomyfi 5, 6 However, Waye et al.1 found that there was no higher incidence of previous hysterectomy in female patients with failed colonoscopies than in those who had undergone total colonoscopy. It has been our experience that recurrent looping of the colonoscope is the major cause of difficulty at colonoscopy 7 and our observation that this is a particular problem in female patients. This study has found that total colonic length is greater in women--despite their smaller staturc and that this difference is most prominent in the
126 GASTROINTESTINAL ENDOSCOPY
transverse colon. Our findings are in keeping with those of Sadahiro et al., 9 who studied the barium enemas of Japanese patients and also found a difference in total colonic length between men and women. Increased colonic length will tend to predispose to loop formation, difficulty in passing the colonoscope, and patient discomfort during intubation. Without continuous imaging of the colonoscope, 1~ 11 the exact frequency with which different loops occur is uncertain, and formation of transverse loops may be a more common cause of difficulty--particularly in female patients than was previously thought. In addition, the greater length and looping tendency in a long transverse colon, with consequent frictional resistance, may also result in looping of the sigmoid colon. It is possible that other gender-related anatomic factors have an influence over the relative difficulty of colonoscopy. The female pelvis is deeper and more rounded than its male counterpart, which may predispose to loop formation in the sigmoid colon. Also, women tend to be less muscular than men, whose abdominal walls may provide more resistance and thus prevent the colonoscope from looping, acting in the same way as nonspecific abdominal hand pressure during intubation. Although the endoscopist cannot change the anatomy of his or her patients, it is important to appreciate and to be able to explain to the patient why difficulties sometimes occur during colonoscope insertion. From our experience, colonoscopy in women is more frequently a technically difficult procedure, and this may be due in part to their inherently longer colons.
REFERENCES 1. Waye JD, Bashkoff MD. Total colonoscopy: is it always possible? Gastrointest Endosc 1991;37(2):152-4. 2. Hull TL, Church JM, Milsom JW, Oakley JR. Colonoscopy: How difficult? How painful? [Abstract] Dis Colon Rectum 1994;35(5): 43. 3. Nivatvongs S, Fryd DS, Fang D. How difficult is colonoscopy? [Abstract] Gastrointest Endosc 1982;28:140. 4. Schmitt CM, Schultz SM, Lee JG, Baillie J. The association between gender and difficult colonoscopy [Abstract]. Gastrointest Endosc 1994;40(2):46. 5. Ravi J, Brodmerkel GJ Jr, Agrawal RM, Gregory DH, Ashok PS. Does prior abdominal or pelvic surgery affect length of insertion of the colonoscope? [Abstract] Endoscopy 1988;20:43. 6. Church JM. Complete colonoscopy: How often? And if not, Why not? Am J Gastroenterol 1994;89:556-60. 7. Saunders BP, Macrae F, Williams CB. What makes colonoscopy difficult? [Abstract] Gut 1993;34(1). 8. Newcomer MK, Jowell PS, Williams DM, Prasad SM, Cotton PB. Determination of work time lost following outpatient colonoscopy [Abstract]. Gastrointest Endosc 1994;40(2):30. 9. Sadahiro S, Ohmura T, Yamada Y, et al. Analysis of length and surface area of each segment of the large intestine according to age, sex and physique. Surg Radiol Anat 1992;14:251-7. 10. Williams CB, Guy C, Gilles D, et al. Electronic three-dimensional imaging of intestinal endoscopy. Lancet 1993;341:724-5. 11. Bladen JS, Anderson AP, Bell GD, et al. Non-radiological technique for three-dimensional imaging of endoscopes. Lancet 1993;341:719-22.
VOLUME 43, NO. 2, PART 1, 1996
Why is colonoscopy more difficult in women? Brian P. Saunders, MRCP, Manabu Fukumoto, MD, Steve Halligan, MRCP, Craig Jobling, FRCS Mohammed E. Moussa, MD, Clive I. Bartram, FRCP, FRCR, Christopher B. Williams, BM, FRCP London, England
Background: In our experience colonoscopy in women is more difficult than in men. A retrospective review of 2194 colonoscopies performed by a single experienced endoscopist (CBW) showed that 31% of examinations in women were considered technically difficult compared with 16% in men. Methods: To investigate a possible anatomic basis for this finding, normal barium enema series from 183 female and 162 male patients were identified. From these barium enemas, measurements of colonic length and mobility were independently taken by two physicians who were unaware of each patient's gender. Results:Total colonic length was greater in women (median, 155 cm) compared to men (median, 145 cm), p= 0.005, despite women's smaller stature (p < 0.0001). Although there were no significant differences in rectum plus sigmoid, descending, or ascending plus cecum segmental lengths, women had longer transverse colons (female median length, 48 cm; male median length, 40 cm), p < 0.0001. There were no differences in mobility of the descending colon and transverse colon between the sexes, but the transverse colon reached the true pelvis more often in women (62%) than in men (26%), p < 0.001. Conclusions: Colonoscopy appears to be a technically more difficult procedure in women. The reason for this may be due in part to an inherently longer colon. (Gastrointest Endosc 1996;43:124-6.) It has been our experience, and also that of others, 1-6 that it is more difficult to perform colonoscopy in women than in men. At St. Mark's Hospital the endoscopist's subjective impression of the relative difficulty of each colonoscopic intubation is recorded immediately after the examination. The intubation is classified as being either "difficult" or "not difficult," according to the duration of the procedure, the final depth of insertion, and the degree of observed patient discomfort. With adequate bowel preparation and in the absence of colonic stricture, technical difficulty is usually recorded if cecal intubation has not been
achieved within the first 15 minutes of the procedure. Of a total 2194 colonoscopies performed by one experienced colonoscopist (CBW) between January 1988 and May 1993, 327 of 1067 procedures in women (31%) were considered technically difficult, in contrast to only 177 of 1127 procedures (16%) in men. The most common cause of difficulty at colonoscopy is recurrent looping of the colonoscope in a long or mobile colon. 7 We therefore wondered whether differences in colonic length and mobility could be demonstrated between male and female patients.
Received November 18, 1994. For revision December 27, 1994. Accepted June 6, 1995. From the Departments of Endoscopy, Surgery, and Radiology, St. Mark's Hospital, London, England. Reprint requests: Brian P. Saunders, MRCP, St. Mark's Hospital, City Road, London, ECIV 2PS England.
N o r m a l b a r i u m e n e m a s (without significant diverticular disease, colitis, megacolon, stricture, or resection) of 183 female a n d 162 male patients were identified from "in file," double-contrast, b a r i u m e n e m a x-ray films at St. M a r k ' s Hospital. All e n e m a series h a d been performed by a standardized technique (using large overhead films t a k e n with a fLxed film-tube distance in set radiographic positions).
37/1/67026
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GASTROINTESTINAL ENDOSCOPY
PATIENTS AND METHODS
VOLUME 43, NO. 2, PART 1, 1996
',.
/
\
/'
Figure 1. Schematic showing method of measurement of the colonic segments.
From the prone film of each enema series the total length of the colon was measured using an opisometer (mapping wheel) passed along the long axis of the bowel. Of the 345 normal enema films identified, 204 (104 of women, 100 of men) were randomly selected for more detailed measurements of colonic anatomy and mobility. For this subset, segmental colonic lengths (rectum plus sigmoid, descending colon, transverse colon, ascending colon plus cecum) were measured from the prone film (Fig. 1). The upper border of the iliac crest was designated as the junction between the sigmoid and descending colon. The distance from the upper border of the twelfth thoracic vertebra (T12) to the lower border of the fourth lumbar vertebra (L4) was also measured from the prone film as an indicator of the stature of each patient. Mobility of the descending colon was assessed by measuring the distance from the midpoint of the third lumbar vertebra to the midpoint of the descending colon in the right and left lateral decubitus views and then subtracting for the difference. Mobility of the transverse colon was assessed by measuring the maximum perpendicular distance between the transverse colon and a line passing through both hepatic and splenic flexures (Fig. 2) on prone and erect films and then subtracting for the difference. The transverse colon was considered redundant when it sagged into the true pelvis on the erect film. All measurements and observations were
VOLUME 43, NO. 2, PART 1, 1996
Figure 2. Erect film showing method of measurement of transverse colon mobility. This measurement is repeated in the prone film; mobility of the transverse colon equals vertical distance in the prone film minus vertical distance in the erect film.
performed independently by two physicians blinded to the gender of the patient.
Statistical analysis The Mann-Whitney test was used to compare measurements of colonic length and mobility between male and female patients. Fisher's exact test was used to compare the finding of a redundant transverse colon between the sexes. A p value of less than 0.05 was considered significant.
RESULTS Male a n d f e m a l e p a t i e n t s w e r e s i m i l a r w i t h r e g a r d to age at the t i m e of e n e m a : m e a n f e m a l e age, 50.2 y e a r s (range, 19 to 85), m e a n m a l e age, 51.5 y e a r s (range, 15 to 86 years). T h e two p h y s i c i a n s ' m e a s u r e m e n t s w e r e a v e r a g e d for continuous d a t a a n d t h e r e w a s complete a g r e e m e n t over n o n c o n t i n u o u s d a t a (presence of a r e d u n d a n t t r a n s v e r s e colon). Total colonic l e n g t h w a s g r e a t e r in w o m e n (median, 155 cm; range, 108 to 206 cm) c o m p a r e d to m e n (median, 145 cm; range, 97 to 205 c m ) , p = 0.005, despite t h e s m a l l e r s t a t u r e of w o m e n (female T12 to L4 m e d i a n distance, 17 cm; m a l e T12 to L4 m e d i a n distance, 20 cm), p < 0.0001. A s s e s s m e n t of colonic s e g m e n t a l l e n g t h s (Table 1)
GASTROINTESTINAL ENDOSCOPY
125
Table 1. Segmental colonic lengths and degree of mobility of the descending and transverse colon Female (n = 104) Rectum plus sigmoid colon Median length (cm) 56 Range (cm) 22-100 Descending colon Median length (cm) 23 Range (cm) 11-43 Transverse colon Median length (cm) 48 Range (cm) 19-83 Ascending colon plus cecum Median length (cm) 23 Range (cm) 11-41 Descending medial mobility Median length (cm) 4 Range (cm) 0-12.5 Transverse mobility Median length (cm) 6 Range (cm) (-4)-(+15)
Male (n = 100)
Probability
59 31-103
NS
25 8-36
NS
40 20-67
<0.0001
23 15-38
NS
3.5 0-10.7 6 0.5-11
NS
NS
NS, Not significant.
showed that there was no significant difference in rectum plus sigmoid colon, descending colon, or ascending colon plus cecum lengths between the sexes. Transverse colon length was, however, greater in women (median length, 48 cm; range, 19 to 83 cm) than men (median, 40 cm; range, 20 to 67 cm), p < 0.0001. There was no significant difference between the sexes with regard to the degree of measured mobility of the descending colon or transverse colon (Table 1). However, redundancy of the transverse colon was a more frequent finding in female (62%) compared with male (26%) patients, p < 0.0001.
DISCUSSION Two recent abstracts have highlighted the difficulties encountered by female patients undergoing colonoscopy. Women were more likely to experience discomfort during the procedure2 and miss work the following day. s It has been suggested that colonoscopy may be more difficult in women because of previous pelvic surgery, particularly hysterectomyfi 5, 6 However, Waye et al.1 found that there was no higher incidence of previous hysterectomy in female patients with failed colonoscopies than in those who had undergone total colonoscopy. It has been our experience that recurrent looping of the colonoscope is the major cause of difficulty at colonoscopy 7 and our observation that this is a particular problem in female patients. This study has found that total colonic length is greater in women--despite their smaller staturc and that this difference is most prominent in the
126 GASTROINTESTINAL ENDOSCOPY
transverse colon. Our findings are in keeping with those of Sadahiro et al., 9 who studied the barium enemas of Japanese patients and also found a difference in total colonic length between men and women. Increased colonic length will tend to predispose to loop formation, difficulty in passing the colonoscope, and patient discomfort during intubation. Without continuous imaging of the colonoscope, 1~ 11 the exact frequency with which different loops occur is uncertain, and formation of transverse loops may be a more common cause of difficulty--particularly in female patients than was previously thought. In addition, the greater length and looping tendency in a long transverse colon, with consequent frictional resistance, may also result in looping of the sigmoid colon. It is possible that other gender-related anatomic factors have an influence over the relative difficulty of colonoscopy. The female pelvis is deeper and more rounded than its male counterpart, which may predispose to loop formation in the sigmoid colon. Also, women tend to be less muscular than men, whose abdominal walls may provide more resistance and thus prevent the colonoscope from looping, acting in the same way as nonspecific abdominal hand pressure during intubation. Although the endoscopist cannot change the anatomy of his or her patients, it is important to appreciate and to be able to explain to the patient why difficulties sometimes occur during colonoscope insertion. From our experience, colonoscopy in women is more frequently a technically difficult procedure, and this may be due in part to their inherently longer colons.
REFERENCES 1. Waye JD, Bashkoff MD. Total colonoscopy: is it always possible? Gastrointest Endosc 1991;37(2):152-4. 2. Hull TL, Church JM, Milsom JW, Oakley JR. Colonoscopy: How difficult? How painful? [Abstract] Dis Colon Rectum 1994;35(5): 43. 3. Nivatvongs S, Fryd DS, Fang D. How difficult is colonoscopy? [Abstract] Gastrointest Endosc 1982;28:140. 4. Schmitt CM, Schultz SM, Lee JG, Baillie J. The association between gender and difficult colonoscopy [Abstract]. Gastrointest Endosc 1994;40(2):46. 5. Ravi J, Brodmerkel GJ Jr, Agrawal RM, Gregory DH, Ashok PS. Does prior abdominal or pelvic surgery affect length of insertion of the colonoscope? [Abstract] Endoscopy 1988;20:43. 6. Church JM. Complete colonoscopy: How often? And if not, Why not? Am J Gastroenterol 1994;89:556-60. 7. Saunders BP, Macrae F, Williams CB. What makes colonoscopy difficult? [Abstract] Gut 1993;34(1). 8. Newcomer MK, Jowell PS, Williams DM, Prasad SM, Cotton PB. Determination of work time lost following outpatient colonoscopy [Abstract]. Gastrointest Endosc 1994;40(2):30. 9. Sadahiro S, Ohmura T, Yamada Y, et al. Analysis of length and surface area of each segment of the large intestine according to age, sex and physique. Surg Radiol Anat 1992;14:251-7. 10. Williams CB, Guy C, Gilles D, et al. Electronic three-dimensional imaging of intestinal endoscopy. Lancet 1993;341:724-5. 11. Bladen JS, Anderson AP, Bell GD, et al. Non-radiological technique for three-dimensional imaging of endoscopes. Lancet 1993;341:719-22.
VOLUME 43, NO. 2, PART 1, 1996