Resident's corner: low anterior resection syndrome: review

Document Type : Review Article


1 Royal Prince Alfred Hospital, Sydney, Australia

2 Prince of Wales Hospital, Sydney, Australia


Low anterior resection syndrome (LARS) is a common debilitating problem faced by patients who underwent low or ultralow anterior resection. The management of LARS is complicated by the fact that our understanding of the pathophysiology of this disease is as yet unclear. In fact, our limitation in understanding is highlighted by the fact that only in 2020 has there been an international consensus on the definition of LARS (LARS international collaborative group).
Evidence Acquisition:
A comprehensive review of the current literature on the pathophysiology, risk factors and management of LARS was performed.
In this review, we discuss the suspected pathophysiology of LARS, including damage to anatomy (sphincter, hiatal ligament, conjoint longitudinal ligamaent), loss of physiology (of rectum), and damage to nervous system (damage to hypogastric nerves, denervation of left colon, loss of recto-sigmoid brake). The risk factors for LARS are discussed, including neoadjuvant treatment, TME dissection, rectal stump height, anastomotic leak, as well as the protective role of a pouch formation in reducing the rate of LARS. Management of LARS involves management of symptoms, and management of underlying neurophysiology. The non operative measures include dietary restrictions, medications to reduce motility, pelvic floor exercises, colonic irrigations. Interventional approaches includes sacral nerve stimulation (SNS), and when bowel function becomes too debilitating a stoma may be created.
LARS is a significant and debilitating disorder. It has complex pathophysiology and there are some definite risk factors. Management involves non-operative and operative approaches, trans-anal irrigation and sacral nerve stimulation showing promise.


  1. C. Keane, N. Fernhead, L. Bordeianou and P. Christensen, “International consensus definition of low anterior
    resection syndrome,” Colorectal Disease, vol. 22, pp. 331-341, 2020.
    2. C. Bryant, P. Lunniss, C. Knowles, M. Thaha and C. Chan, “Anterior resection syndrome,” Lancet Oncology, vol. 13, pp. 403-408, 2012.
    3. Croese, M. Lonie, A. Trollope, V. Vangaveti and Y. Ho, “A metaanalysis of the prevalence of low anterior resection syndrome and systematic review of risk factors,” International journal of surgery, vol. 56, pp. 234-241, 2018.
    4. Y. Ho, C. Tsang, C. Tang, D. Nyam, K. Eu and F. Seow-Choen, “. Anal sphincter injuries from stapling instruments introduced transanally: randomized, controlled study with endoanal ultrasound and anorectal manometry.,” Disease of colon and rectum, vol. 43, no. 2, pp. 169-173,
    5. R. Farouk, G. Duthie, P. Lee and J. Monson, “Endosonographic evidence of injury to the internal anal sphincter after low anterior resection: long-term follow-up,” Disease of colon and
    rectum, vol. 41, no. 7, pp. 888-891,1998.
    6. K. Koda, M. Yamazaki, K. Shuto, C. Kosugi and M. Mori, “Etiology and management of low anterior resection syndrome based on the normal defecation mechanism,” Surgery today, vol. 49, pp. 803-808, 2019.
    7. J. Remes-Troche, S. De-Ocampo, J. Valestin and S. Rao, “Rectoanal Reflexes and Sensorimotor Response in Rectal Hyposensitivity,” Disease of colon and rectum, vol. 53, no. 7, pp. 1047-1054, 2010.
    8. W. Lee, T. Takahashi, T. Pappas and C. Mantyh, “Surgical autonomic denervation results in altered colonic motilty: an explanation for low anterior resection syndrome?,”
    Surgery, vol. 143, pp. 778-783, 2008.
    9. K. Koda, N. Saito, K. Seike, K. Shimizu, C. Kosugi and M. Miyazaki, “Denervation of the neo-rectum as a potential cause of defecatory disorder following low anterior resection for
    rectal cancer,” Disease of colon and rectum, vol. 48, pp. 210-217, 2005.
    10. K. Emmertsen, S. Bregendahl, J. Fassov, K. Krogh and S. Laurberg, “A hyperactive postprandial response in the neorectum-- the clue to low anterior resection syndrome after
    total mesorectal excision surgery?,” Colorectal Disease, vol. 15, no. 10, pp. 599-606, 2013.
    11. Lin, P. Dinning, T. Milne, I. Bissett and G. O’Grady, “The “rectosigmoid brake”: Review of an emerging neuromodulation target for colorectal functional disorders,” Clinical and
    experimental pharmacology and physiology, vol. 44, pp. 719-728, 2016.
    12. R. Vather, G. O’Grady, J. Arkwright, D. Rowbotham, L. Cheng, P. Dinning and I. Bissett, “Restoration of Normal Colonic Motor Patterns and Meal Responses After Distal Colorectal
    Resection,” British Journal of Surgery, vol. 103, no. 4, pp. 451-461, 2016.
    13. D. Hughes, J. Cornish and C. Morris, “Functional outcome following rectal surgery—predisposing factors for low anterior resection syndrome,” International journal of colorectal
    disease, vol. 32, no. 5, pp. 691-697, 2017.
    14. P. Bondeven, K. Emmertsen, S. Laurberg and B. Pedersen, “Neoadjuvant therapy abolishes the functional benefits of a larger rectal remnant, as measured by magnetic resonance imaging after restorative rectal cancer surgery,” European Journal of surgical oncology, vol. 41, no. 11, pp. 1493-1499, 2015.
    15. L. Jimenez-Gomez, E. Espin-Basany, L. Trenti, M. Martí-Gallostra and J. Sánchez-García, “Factors Associated With Low Anterior Resection Syndrome After Surgical Treatment
    of Rectal Cancer,” Colorectal diseases, 2017.
    16. O. Hallbook and R. Sjodahl,“Anastomotic leakage and functional outcome after anterior resection of the rectum,” British Journal of Surgery, vol. 83, pp. 60-62, 1996.
    17. Nesbakken, K. Nygaard and C. Lunde, “Outcome and late functional results after anastomotic leakage following mesorectal excision for rectal cancer,” British Journal of Surgery, vol. 88, pp. 400-404, 2001.
    18. F. Hüttner, S. Tenckhoff, K. Jensen, L. Uhlmann, Y. Kulu and M. Büchler, “Meta-analysis of reconstruction techniques after low anterior resection for rectal cancer,” British Journal of
    surgery, vol. 102, no. 7, pp. 735-745, 2015 .
    19. Y. Parc, R. Ruppert, A. Fuerst, H. Golcher, M. Zutshi and T. Hull,
    “Better function with a colonic J-pouch or a side to end anastomosis? a randomized controlled trial to compare the complications, functional outcome, and quality of life in patients
    with low rectal cancer after a J-pouch or a side to end anastomosis,” Annals
    of surgery, vol. 269, no. 5, pp. 815- 826, 2019.
    20. W. Marti, G. Curti, H. Wehrli and F. Frieder, “Clinical Outcome After Rectal Replacement With Side-to- End, Colon-J-Pouch, or Straight Colorectal Anastomosis Following Total Mesorectal Excision: A Swiss Prospective, Randomized, Multicenter Trial (SAKK 40/04),”
    Annals of surgery, vol. 269, no. 5, pp. 827-835, 2019.
    21. K. Emmertsen and S. Laurberg, “Low anterior resection syndrome score: development and validation of a symptom based scoring system for bowel dysfunction after low anterior
    resection for rectal cancer,” Annals of surgery, vol. 255, no. 5, pp. 922-928, 2012.
    22. L. Temple, J. Bacik, S. Savatta, L. Gottesman and P. Paty, “The development of a validated instrument to evaluate bowel function after sphincter preserving surgery for rectal cancer,” Disease of colon and rectum, vol. 48, pp. 1353-1365, 2005.
    23. T. Chen, K. Emmertsen and S. Laurberg, “What are the best questionnaires to capture anorectal function after surgery in rectal cancer?,” Curr Colorectal Cancer Rep, vol. 11, pp. 37-43, 2015.
    24. J. Jorge and S. Wexner, “Etiology and management of fecal incontinence.,” Disease of colon and rectum, vol. 36, pp. 77-97, 1993.
    25. C. Vaizey, E. Carapeti and J. Cahill, “Prospective comparison of faecal incontinence grading systems,” Gut, vol. 44, pp. 77-80, 1999.
    26. T. Rockwood, J. Church and J. Fleshman, “Patient and surgeon ranking of the severity of symptoms associated with fecal incontinence,” Disease of colon and rectum, vol. 42, pp. 1525-1532, 1999.
    27. D. Bliss, K. Savik, H. Jung, R. Whitebird, A. Lowry and X. Sheng, “Dietary Fiber Supplementation for Fecal Incontinence: A Randomized Clinical Trial,” Res Nurs Health , vol.
    37, no. 5, pp. 367-378, 2014.
    28. R. Emblem, R. Stien and L. Mørkrid, “The Effect of Loperamide on Bowel Habits and Anal Sphincter Function in Patients with Ileoanal Anastomosis,,” Scandinavian Journal of Gastroenterology, vol. 24, no. 8, pp.1019-1024, 1989.
    29. R. Itagaki, K. Koda, M. Yamazaki, K. Shuto and C. Kosugi, “Serotonin (5-HT3) Receptor Antagonists for the Reduction of Symptoms of Low Anterior Resection Syndrome,”
    Clinical and experimental gastroenterology, vol. 7, pp. 47-52,2014.
    30. W. Visser, W. Te Riele, D. Boerma, B.van Ramshorst and H. van Westreenen,
    “Pelvic f loor rehabilitation to improve functional outcome after a low anterior resection: a systematic review.,” Annals of coloproctology, vol. 30, no. 3, pp. 109-114, 2014.
    31. J. Martellucci, A. Sturiale, C. Bergamini, L. Boni, F. Cianchi and A.
    Coratti, “Role of transanal irrigation in the treatment of anterior resection
    syndrome.,” Tech Coloproctol, vol. 22, no. 7, pp. 519-527, 2018.
    32. S. Koch, M. Rietveld, B. Govaert, W. van Gemert and C. Baeten, “Retrograde colonic irrigation for faecal incontinence after low anterior resection.,” Int J Colorectal Dis, vol.
    24, no. 9, pp. 1019-1022, 2009.
    33. G. McCutchan, D. Hughes, Z. Davies, J. Torkington, C. Morris and J. Cornish, “Acceptability and benefit of rectal irrigation in patients with Low Anterior Resection Syndrome: a qualitative study,” Colorectal Disease, vol. 20, pp. 76-84, 2017.
    34. H. Rosen, J. Robert-Yap, G. Tentschert, M. Lechner and B. Roche, “Transanal
    irrigation improves quality of life in patients with low anterior resection syndrome.,” Colorectal Diseases, vol.13, no. 10, pp. 335-338, 2011.
    35. E. Carrington, J. Evers, U. Grossi, P. Dinning, S. Scott, P. O’Connell, J. Jones and C. Knowles, “A Systematic Review of Sacral Nerve Stimulation Mechanisms in the Treatment of Fecal Incontinence and Constipation,” Neurogastroenterol Motil, vol. 26, pp. 1222-1237, 2014.
    36. Y. Huang and C. Koh, “Sacral nerve stimulation for bowel dysfunction following low anterior resection: a systematic review and meta-analysis,” Colorectal Disease, vol. 21, pp. 1240-
    1248, 2019.
    37. ClinicalTrials, “Clinical trials,” 2019. [Online]. Available: NCT04066894. [Accessed 22 June 2020].
    38. E. Rybakov, D. Pikunov, O. Fomenko, S. Chernyshov and Y. Shelygin, “Side to end vs straight strapled colorectal anastomosis after low anterior resection: results of randomized clinical trial,” International Journal of Surgery, vol. 31, pp. 1419-1426, 2016.
    39. N. Okkabaz, M. Haksal, A. Atici and Y. Altuntas, “J-pouch vs. Side-To-End Anastomosis After Hand-Assisted Laparoscopic Low Anterior Resection for Rectal Cancer: A Prospective
    Randomized Trial on Short and Long Term Outcomes Including Life Quality and Functional Results,” International journal of surgery, vol. 47, pp. 4-12, 2017.
    40. CancerAustralia, “National Cancer Council Indicators. Cancer Australia. Cancer Incidence,” 2019. [Online]. Available: https://ncci.canceraustralia. [Accessed 13 June 2020].
    41. T. Juul, H. Elfeki, P. Christensen, S. Laurberg, K. Emmertsen and P. Bager, “Normative Data for the Low Anterior Resection Syndrome Score (LARS Score),” Annals of surgery, vol. 269, no. 6, pp. 1124-1128, 2019.
    42. J. Marticelluci, “Low Anterior Resection Syndrome: A Treatment Algorithm,” Disease of colon and rectum, vol. 59, pp. 79-82, 2016.