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M.D. Levin

Posterior sagittal anorectoplasty in the anorectal malformations. Myths and scientific facts. 

M.D. Levin, MD, PhD, DSc. 

Address: Amnon VeTamar, 1/2, Netanya, 42202, Israel.;


Objective: To evaluate the assumptions published in the articles of Dr. A. Peña concerning pathophysiology of anorectal malformations (ARM) from the point of view of modern science.


Methodology: Any supposition (hypothesis) is false if there is at least one indisputable scientific fact that contradicts it. The following assumptions were analyzed: 1) the puborectalis muscle does not play a significant role in fecal retention; 2) the vast majority of patients with ARM do not have the anal canal; 3) the posterior sagittal anorectoplasty (PSARP) is the gold standard in establishing anatomical shape of ARM; 4) PSARP provides excellent functional results; 5) poor results are associated with the absence of the anal canal and sacral spine abnormalities.


Results: Scientific evidence proving the fallacy of these assumptions is presented. A different concept of ARM pathophysiology is described proposing new tactics of surgical treatment that preserves all elements of the anal canal. Reasons for occurrence of false hypotheses that have been considered true for more than 30 years are analyzed.


Conclusions:  The generally accepted assumption of pediatric surgeons about the pathological physiology of anorectal malformations does not correspond to basic research (embryological, histological and functional). The anorectal malformations are in fact manifestations of an ectopic anus, mostly of a low type with intact normal functions of the internal anal sphincter, the puborectalis muscle and levator ani muscles. PSARP surgery damages all elements of the anal canal and has the poor functional outcomes.  The development of medicine is based on the victory of new ideas. Medical journals of different specialties should create theoretical columns for discussions of working hypotheses in order to ensure that false hypotheses are promptly rejected. Such a column would protect scientific facts from being overshadowed by the opinions of “luminaries” and “experts”. Researchers of fundamental sciences should be involved in reviewing articles and discussing working hypotheses. 


The posterior sagittal anorectoplasty (PSARP) proposed by Dr. A. Peña for correction of anorectal malformations (ARM), was first published in 1982 [1,2]. Despite the fact that more than 30 years have passed since the publication, this operation is still the most widely performed around the world, and Dr.Pena’s ideas first proposed in his article [2] are accepted as axioms.


Objective: To evaluate the assumptions published in the articles of Dr. A. Peña concerning pathophysiology of ARM from the point of view of modern science.


Until 1982 ARM was believed to be an ectopic anus. It can be of a high or a low type. In a low type a distal colon is located caudal to the pubococcygeal line. This part of a gut was considered to be the anal canal which needed to be saved during a surgery in order to maintain the functions of fecal retention and defecation. The following assumptions were first made in Peña’s article [2]: 1) the puborectalis muscle (PRM) does not play a significant role in fecal retention; 2) the vast majority of patients with ARM do not have the anal canal;  3) PSARP provides a good access and visualization of morphology of the abnormality (gold standard); 4) PSARP provides excellent functional results; 5) poor results are associated with the absence of the anal canal and sacral spine abnormalities

Anatomy and physiology of PRM.​

In his works A. Peña provides no scientific evidence proving that PRM does not play a significant role in the fecal retention. The rationale for this assumption is as follows: - "We do not deny the existence of the sling (PRM sling) but we have been unable to identify it.  Nor do we understand why it should be considered more important than the rest of the muscle structures we found" [2].  It is known that PRM is barely differentiated from the levator ani muscle (LAM) during an anatomical study. Obviously, tissue dissection during a surgery is less accurate than anatomical studies. Is it possible to draw conclusions about the role of PRM on the grounds that it is not differentiated during a surgery?


Numerous studies using various modern techniques have shown, "... that PRM contraction plays a major role in the anal canal, vagina and urethra closure mechanism " [3,4,5,6].


Thus, the assertion of Dr. A. Peña that PRM does not play an important role in fecal retention is false.


In practice, this means that a pediatric surgeon "... cutting through all muscle structures behind the rectum" [2] sometimes reaching the peritoneum inevitably dissects PRM. This is one of the causes of fecal incontinence.

The anal canal and ARM. 

In his “revolutionary” article, Dr. Peña claimed that in all cases of the ARM there was observed only the high type ectopy, which means that the end of the blind intestine was located cranial to the pubococcygeal line.  In numerous articles and textbooks he, together with his co-authors, states that "Except for patients with rectal atresia, most patients with anorectal malformations are born without an anal canal; therefore, sensation does not exist or is rudimentary" [7]. Contrary to known scientific data, they argue that:  "It seems that patients can perceive distention of the rectum but this requires a rectum that has been properly located within the muscle structures. This sensation seems to be a consequence of stretching of the voluntary muscle (proprioception)".  Firstly, it is known that there are no muscles around the rectum. Secondly, it was found that the sensors are located in the wall of the rectum and the anal canal [6].  The rectoanal inhibitory reflex can serve as a convincing example. Stretching the rectal wall causes reflex relaxation of the internal anal sphincter (IAS) and the contraction of PRM and the external anal sphincter (EAS) and PRM. This reflex is transmitted through the enteric nervous plexus [3-6].  In 1983, we’ve demonstrated that patients with visible fistulas had the rectoanal inhibitory reflex [8].  E.M. Ruttenstock and his colleagues found that prior to a surgery all patients with vestibular fistula had this reflex intact [9]. We had found during X-Ray examination that all patients with visible fistulas had normal functionality of  the IAS, PRM and  LAM. (Figure 1.2) [10]. These data prove that the terminal intestine in ARM with visible fistulas that Dr. Peña and his colleagues called a "fistula" or a "rectal pouch" is in fact a normally functioning anal canal. Its only difference from a normal anal canal is in the fact that its outlet opening  is shifted anterior to the normal anatomical location of the anal opening. Thus, what determines anomaly is not a fistula channel, but the orifice which often presents as a narrowed rigid ring. 




Figure 1. The radiographs of the anorectal area of the same girl made at different times 

А.   At the age of 3 months. The rectum is filled with barium through the catheter conducted through the fistula. The button is located near EAS.  The distal intestine with the length equal to the length of a normal anal canal contracted around the catheter preventing leakage of  barium.  

В.  At the age of 9 months. During a barium enema involuntary defecation occurred with a wide opening of the anal canal. The distance from the button near EAS to the distal wall of an open anal canal equals to 3-4 mm. There is no barium leaking-out because a fistulous opening is so narrow that the tip completely blocked its clearance.   



Figure 2.  X-ray image of the rectoanal inhibitory reflex. 

A. A child without ARM.  

B. A girl with vestibular fistula. A pellet is in the anal dimple.  Barium enema performed through an endotracheal tube to measure the anal pressure during the procedure. A contrast agent penetrates down in front of the enema tube as a result of  IAS relaxation. At the same time the posterior wall of the anal canal, as in normal (A), is pressed against the tube by the contracted PRM. IAS relaxation and PRM contraction prove the existence of the rectoanal inhibitory reflex. 

It is known that in ARM with perineal or vestibular fistulas and without stenosis of the ectopic anus, defect does not manifest itself and can be accidentally detected as a cosmetic defect. Normal functions of fecal retention and defecation in these patients prove the existence of a functioning anal canal. During X-ray examination if the child is anxious and tense, the location of rectum often can be observed as getting close to and “meeting” with the skin of the perineum. Dr. Peña explains this phenomenon by a "descending perineum", which occurs as a result of lowering of the pelvic floor in response to an increase in intra-abdominal pressure when a child is anxious. He believes that this is a misconception about a low type of ARM, since at rest the pelvic floor rises again to its original location.  Firstly, the "descending perineum" phenomenon was first described by Parks, as an opening of the anal canal during defecation [11]. Secondly, while intra-abdominal pressure is increasing, the pelvic floor is not lowered, but rises [12]. Thus, the "descending perineum" in patients with ARM is nothing but a disclosure of the anal canal during the defecation reflex, which takes place under the influence of the threshold pressure. At rest the anal canal is closed both in healthy patients and in patients with ARM. As we have shown earlier, the anal canal is present in not only in patients with perineal and vestibular fistulas, but also in many patients with urethral fistula [10]. These ideas are completely consistent with embryonic and histological studies. Gans and his co-workers have demonstrated that ARMs are the ectopic anus [13]. 

Thus, the assertion of Dr. A. Peña that patients with perineal and vestibular fistulas do not have the anal canal is false. 

In practice this means that during an operation, when the rectal pressure is low, the anal canal closes, and then it may be mistaken for a fistula. Therefore, the recommendation to remove distal 1-2 cm of the fistula channel actually leads to the removal of a part of IAS and weakening of the fecal retention function. Misunderstanding pathophysiology of ARM can cause damage to all elements of the anal canal. For example, L. Lombardi and his co-workers recommend removing 3 cm of the distal intestine in order to prevent chronic constipation [14].  A complete removal of IAS dramatically weakens the anal canal, resulting in fecal incontinence instead of chronic constipation.

Is surgical dissection the gold standard to determine an anatomic type of ARM? 

Among pediatric surgeons there is a belief that surgical dissection determines the exact final diagnosis, i.e. it is the gold standard. For example, MG. Thomeer and colleagues found that compared to surgery, MRI or colostography/fistulography correctly predicted anatomy in 88 % (29/33) and 61%  (20/33) of cases, respectively (p=0.012). The distal end of the rectal pouch was correctly predicted in 88 % (29/33) and 67 % (22/33) of cases, respectively   [15].   

This belief is false.   In spite of the extensive experience of surgical interventions, Dr. A. Peña wrongly considers that: a) PRM does not play a significant role in fecal retention; b) many patients with ARM do not have the anal canal; c)  the  anal canal is a fistula and should be removed. On the contrary, MRI fistulography and colostografiya with introduction of contrast agents under pressure may cause disclosure of the existing anal canal and accurately determines the level of ARM and location of the fistula orifice. 

Functional results after PSARP application.

Numerous articles, which are all nothing but statistical reports about Dr. Pena’s operations, resounded like a mantra the thesis about the "wonderful" functional results following PSARP. After multiple repetitions this statement started to be perceived as a scientific fact. Now Peña’s "doctrine" has become a bible for pediatric surgeons. When it became obvious that in reality functional results post PSARP were not so wonderful after all, the author and his followers blamed poor results on a) bad qualification of the surgeons, b) presence of sacral spine pathology, and c) a congenital absence of the anal canal. 

According to a systematic review (1994-2015) including 455 patients older than 10 years with a history of anorectal malformation repair (patients with cloaca were excluded) "…the range of reported prevalence of long-term active problems was as follows: fecal incontinence, 16.7% to 76.7%; chronic constipation, 22.2% to 86.7%; urinary incontinence, 1.7% to 30.5%; ejaculatory dysfunction, 15.6% to 41.2%; and erectile dysfunction, 5.6% to 11.8% " [16]. Some of these patients underwent a surgery performed through the anterior approach and the results of this surgery were no worse than that after PSARP. I dare to call these results very poor because most of the patients had had a functioning anal canal before the surgery. Large fluctuations in numbers in fecal incontinence and chronic constipation depend on tactics followed by surgeons. If they use a part of the anal canal, the patients mostly suffered from chronic constipation. Patients of those surgeons who removed IAS and damaged PRM do not have chronic constipation, but they suffer from fecal incontinence.  There are no healthy patients after PSARP [17]. 

Thus, the assertion of Dr. A. Peña and his followers that functional results after PSARP are wonderful, is false. 

From the point of view of elementary logic it seems totally unjustified to isolate IAS from surrounding tissues, to remove it and to place an extended rectum in its place.   During isolation of IAS its separates from LAM.   after surgery do not disclose the anal canal during a bowel movement. Therefore after surgery LAM do not disclose the anal canal during a bowel movement [10.18]. This causes a sharp increase in frictional resistance for the fecal movement through the anal canal, which in its turn leads to the development of chronic constipation and megarectum. Constipation is not observed in patients with a  high type of ARM after PSARP because in such cases it is necessary to allocate the rectum at a much greater length, which leads to damage of PRM and complete removal of IAS. 


To save all elements of the anal canal and  surrounding it muscle, it can be necessary to create an opening in the wall of the opened anal canal through a lumen in subcutaneous portions of EAS (Fig. 3A). After bougienage of a created anus, the ectopic anus needs to be closed (Fig. 3, B) [10, 19]. 

Figure 3. Scheme of a surgery in the girl with vestibular ectopic anus using the radiograph from figure 1.B. 

Stage 1: Creation of a channel between the distal wall of the anal canal and the skin on the perineum through the hole in the subcutaneous portion of EAS with the length of 2 to 4 mm (A). 

Stage 2: Closure of ectopic anus (B). 

The role of the spine pathology in ARM pathophysiology. ​

ARMs are often combined with malformations of other systems that although can aggravate the general condition of a child, do not affect the severity of the anorectal defect. It is known that spinal abnormality sometimes occurs in children without pathology of the anorectal area and with favorable or unfavorable cases of ARM. There is no scientific evidence suggesting that this pathology affects the results of treatment.   In our practice, when all elements of the anal canal were used before development of a secondary megacolon with damage to PRM, continence and defecation do not differ from the norm regardless of the state of the spine [10, 20].




How is it possible that the world community of pediatric surgery for over 30 years has being using ideas that had no scientific foundation, contradicted facts about human anatomy and physiology and were not supported by medical research (anatomical, histological, embryological, manometric, radiologic, etc)?  In recent years the volume of medical information has been growing exponentially. Medical specialty became fragmented, surgery split into many branches: pediatric, adults, vascular, cardiac, abdominal, orthopedic, etc. Moreover, surgery has further become specialized in the separate anatomical parts of the body too. The amount of knowledge and practical skills in each of the specialties is so great that a doctor can work at the present level only after multiple specialization. The way of a doctor to independent work is long and hard. As a rule, a good doctor becomes independent practitioner after he/she masters the protocols of diagnostics and therapeutic procedures and completes the studies in the adjacent specialties and of course acquires basic knowledge of human anatomy and physiology.  If he does not know something, he turns to the textbooks and journals in his field. He cannot go beyond the protocol in fear of legal issues in case of a failed treatment.  Thus, a certain psychology is born, in which the idea about knowledge perfection prevails. Consequently, the majority of practitioners have no skills of scientific analysis, and they have no need to search for new solutions. 

Practical medicine in western countries, where the health of an individual plays an important role, has a high social status and considerable resources, modern expensive equipment, laboratory instrumentation, etc. Numerous manufacturers offer more and more new devices, funding their approbation in order to expand their sales. Fundamental medical science receives a limited budget. The social status of its employees is low. Moreover, practical and fundamental sciences, as a rule, have their own prints which impede timely acquaintance of practitioners with theoretical studies. Since practical surgeons do not have sufficient skills and appropriate material basis in the field, their theoretical conclusions often have low scientific value.  Most of the articles written by practitioners are the exchange of experiences on the use of standard protocols, in which scientific novelty represents a little significant statistical change. Sometimes novelty of an article involves the application of a new or better equipment, often imposed by equipment manufacturers.   New scientific ideas which cause a breakthrough in diagnosis or treatment of patients do not reach practitioners soon enough. Why? 

1. New ideas, methods of research and treatment published in the leading western peer reviewed medical journals are considered to have passed approbation and are formally permitted to be recognized with the right to be included in the protocol. This implies a great responsibility of reviewers. Conservatism of a reviewer is important in preventing publication of poor quality works.  

 2. Nevertheless, there are several non-scientific factors that influence reviewers’ decision: а) Editors of specialized medical journals and reviewers are high-level practical doctors who think that in their field of knowledge almost everything is known. b) Specialists of these subdivisions are members of the corporation. They meet each other at congresses, discussing issues of their specialty, and freely publish their researches in print publications in this specialty. с) Among them, there is always a specialist, who is considered to be the head of the corporation, “the expert” i.e. the coryphaeus. His concepts, techniques, and decisions are perceived as the protocol. As a rule, luminaries stand guard over their own concepts. The observation of the great German physicist Max Planck referred to this psychological phenomenon when he said: “A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.”  Max Planck, Scientific Autobiography and Other Papers

d) All members of the corporation hold dear to their status. The most difficult test for them is to not displease the coryphaeus and fall out of peers’ respect. Therefore, they cherish their status quo. 

3. There are editions that specialize on hypotheses publication. However, firstly, reviewers are also practical doctors. Secondly, members of the corporation ignore new ideas published in journals not controlled by them. 

4. The struggle happens behind closed doors. An author receives anonymous reviews more often with non-motivated refusal and author’s attempts to explain or object are ignored. He does not have an equal rights to debate. Discussion in medical journals is extremely rare. Only real scientists who are interested in the truth and not in protection of their former achievements are open to discussion.  

I have to remind the basics of scientific approach. Even one irrefutable scientific fact that contradicts a working hypothesis, converts this hypothesis into a false suggestion.  



The generally accepted assumption of pediatric surgeons about the pathological physiology of ARM does not correspond to basic medical research (embryological, histological and functional). Anorectal malformations are in fact an ectopic anus, mostly of a low type with a normal functioning internal anal sphincter, puborectalis muscle and levator ani muscles. During a PSARP surgery all elements of the anal canal are damaged which causes the poor functional results. 

The development of medicine is a result of the victory of new ideas. Medical journals of different specialties should create theoretical columns to discuss working hypotheses in order to ensure that false hypotheses are rejected as fast as possible. A theoretical section where opinions of luminaries are not allowed to overshadow scientific facts should be open for discussion. Researchers of fundamental sciences should be involved in reviewing articles and discussing working hypotheses. 


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  15. Thomeer MG1, Devos A2, Lequin M2, et al.  High resolution MRI for preoperative work-up of neonates with ananorectal malformation: a direct comparison with distal pressure colostography/fistulography. Eur Radiol. 2015 Dec;25(12):3472-9. doi: 10.1007/s00330-015-3786-0. Epub 2015 May 23.

  16. Rigueros Springford L1, Connor MJJones KKapetanakis VVGiuliani S. Prevalence of Active Long-term Problems in Patients With AnorectalMalformations: A Systematic Review. Dis Colon Rectum. 2016 Jun;59(6):570-80. doi: 10.1097/DCR.0000000000000576.

  17. Levitt MA1, Kant APeña A. The morbidity of constipation  in patients with  anorectal malformations. J Pediatr Surg. 2010 Jun;45(6):1228-33. doi: 10.1016/j.jpedsurg.2010.02.096.

  18. Petros P, Swash M, Bush M, Fernandez M, at al. Defecation 1: Testing a hypothesis for pelvic striated muscle action to open the anorectum. Tech Coloproctol. 2012 Dec;16(6):437-43.


  20. Nikiforov ANLevin MDAbu-Varda IF. Diagnosis and treatment of ectopy of the anal canal. Vestn Khir Im I I Grek. 1990 Aug;145(8):78-82. [Article in Russian]

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