Distal Rectum Research Articles

Imaging of the Inferior Mesenteric Vasculature.

The inferior mesenteric artery (IMA) and inferior mesenteric vein (IMV) supply and drain blood from the distal colon and rectum, respectively. Routinely imaged at cross-sectional imaging of the abdomen and pelvis, these vessels play a vital role in gastrointestinal tract health but may be neglected due to their diminutive caliber relative to other mesenteric vessels and potential lack of inclusion in routine search patterns. The authors describe and illustrate normal and abnormal appearances of the IMA and IMV and findings that are diagnostic of primary vascular abnormalities or can offer diagnostic clues. After the embryologic features, normal anatomy, and anatomic variants of the IMA and IMV are reviewed, various manifestations of IMA and IMV abnormalities, such as aneurysm and pseudoaneurysm, stenosis, occlusion, dissection, hemorrhage, arteriovenous malformations and fistulas, tumoral invasion, vasculitis, and perivascular lymphatic dilatation, are explored with use of case examples. The role of the IMA and IMV as collateral vasculature, including the clinical scenarios of superior mesenteric arterial occlusion, aortic endoleak, and portosystemic venous shunt, are discussed. Finally, diagnostic clues that the inferior mesenteric vessels and adjacent soft tissues can provide, including mesenteric venous gas, compression or displacement from bowel volvulus or internal hernias, lymphadenopathy, and venous flow artifacts, are highlighted. The authors provide a comprehensive reference for radiologists who evaluate the IMA and IMV on cross-sectional images and shine a spotlight on these neglected but important vessels. ©RSNA, 2024 Supplemental material is available for this article.

007. Distal Ileal Atresia and Total Colon Agenesis with Anorectal Malformation: A Case Report

Background: Atresia of the distal ileum and colon agenesis are rare conditions and can be the cause of obstructive symptoms. Case: A 1 day old baby girl complained of no anus since birth. The patient has no bowel movements or vomiting. The patient's stomach appears increasingly bloated. On physical examination of the abdomen revealed distension accompanied by difficult to hear bowel sounds. There was no anus or fistula in the patient but there is a dimple in the anus. Another abnormality found in the patient was the presence of CTEV on both of the patient's legs. The patient was planned for exploratory laparotomy and colostomy surgery. the length of the jejunum and ileum proximal to the ligament of Treitz was found to be 50 cm. The distal ileum, caecum, colon, rectum and anus were not found. An ileostomy was performed on this patient. The patient died 13 hours after surgery. Conclusion: Total colonic agenesis is a rare case and usually occurs with other congenital abnormalities. Early diagnosis and appropriate initial treatment are very important in this case. colonic agenesis causes congenital short bowel (CSB). CSB causes malabsorption due to inadequate intestinal length, which interferes with absorption. Staged surgery is a good option in the management of total colonic agenesis.

A rare case of acute colonic pseudo-obstruction leading to colonic perforation in a ventilated patient with cerebrovascular accident

Acute pseudo-colonic obstruction in a patient with a functioning ileocecal valve can be risky, resulting in closed-loop obstruction, significant distention of the colon, and increased chances of colon perforation and ischemia if diagnosis and timely non-operative treatments are delayed. We report a case of acute pseudo-colonic obstruction with closed-loop obstruction, resulting in colon perforation in a ventilated patient with a cerebrovascular incident. The situation was promptly identified during the first assessment with a surgical consultation and imaging study, resulting in timely surgical intervention which included removing the diseased section of the right colon, creating an end ileostomy, and colostomy. The postoperative contrast study of the remaining colon and colonoscopy confirmed the pseudo-obstruction without finding any blockages in the distal colon and rectum. After the operation, the patient recovered well and was sent home. In conclusion, early clinical suspicion, diagnosis, and prompt management of a complicated ACPO result in a good patient outcome.

Understanding mechanotransduction in the distal colon and rectum via multiscale and multimodal computational modeling

Visceral pain in the large bowel is a defining symptom of irritable bowel syndrome (IBS) and the primary reason that patients visit gastroenterologists. This pain is reliably triggered by mechanical distension of the distal colon and rectum (colorectum). Consequently, the process of mechanotransduction by sensory afferents, responsible for translating mechanical colorectal stimuli into neural action potentials, plays a central role in IBS-related bowel pain. In this study, we aim to enhance our understanding of colorectal mechanotransduction by combining experimental findings in colorectal biomechanics and afferent neural encoding within a comprehensive computational simulation framework. To achieve this, we implemented a three-layered, fiber-reinforced finite element model that accurately replicates the nonlinear, heterogeneous, and anisotropic mechanical characteristics of the mouse colorectum. This model facilitates the computation of local mechanical stresses and strains around individual afferent endings, which have diameters on the micron-scale. We then integrated a neural membrane model to simulate the encoding of action potentials by afferent nerves in response to microscopic stresses and strains along the afferent endings. Our multiscale simulation framework enables the assessment of three hypotheses regarding the mechanical gating of action potential generation: (1) axial stress dominates mechanical gating of mechanosensitive channels, (2) both axial and circumferential stresses contribute, and (3) membrane shear stress dominates. Additionally, we explore how the orientation of afferent endings impacts neural encoding properties. This computational framework not only allows for the virtual investigation of colorectal mechanotransduction in the context of prolonged visceral hypersensitivity but can also guide the development of new experimental studies aimed at uncovering the neural and biomechanical mechanisms underlying IBS-related bowel pain.

Infracoccygeal/transperineal window: new method to prenatally diagnose and classify level of anal atresia.

To introduce a two-dimensional sonographic method to assess the fetal anus, and to evaluate the feasibility of this method to diagnose anal atresia prenatally and identify the presence or absence of anoperineal fistula (in males) and anovestibular fistula (in females). This was an observational study of suspected cases of anal atresia referred to a single center in Israel between August 2018 and October 2023. In addition to conventional evaluation of the perineum in the axial plane, fetuses referred to our center for suspected malformation were scanned with a new method termed the 'infracoccygeal/transperineal window'. This window consisted of a midsagittal view of the fetal pelvis, including the distal rectum and the anal canal. Normal anatomy was confirmed when the anal canal was continuous with the rectum and terminated at the expected location on the perineum. In female fetuses, the normal anal canal runs parallel to the vaginal canal and diverges posteriorly, terminating at the perineal skin, distant from the vestibule. In male fetuses, the normal anal canal diverges posteriorly in relation to the corpora cavernosa, terminating at the perineal skin, distant from the scrotum. High anal atresia was identified when a blind-ending rectal pouch was demonstrated in the pelvis without a fistula to the perineum or vestibule. Low anal atresia was determined when a rectal pouch was continuous with an anteriorly deflected fistula. In females, the fistula converges with the vaginal canal, terminating at the vestibule; in males, the fistula deflects anteriorly, terminating at the base of the scrotum. Postnatally, the diagnosis and type of anal atresia were confirmed through physical examination with direct visualization of the fistula, radiographic studies, surgical examination and/or postmortem autopsy. Of the 16 fetuses diagnosed prenatally with anal atresia, eight were suspected to have low anal atresia and eight were suspected to have high anal atresia. The median gestational age at diagnosis was 23 (range, 14-37) weeks. All cases showed additional structural malformation. Eleven patients opted for termination of pregnancy, of which four had low anal atresia and seven had high anal atresia. Postnatal confirmation was not available in four cases due to curettage-induced mutilation or in-utero degradation following selective termination of the affected twin, leaving 12 cases for analysis, of which seven were diagnosed with low anal atresia and five with high anal atresia. In these 12 cases, all prenatal diagnoses were confirmed as correct, rendering 100% sensitivity and 100% specificity in this high-risk fetal population. The infracoccygeal/transperineal window is an effective method to detect and classify the level of anal atresia prenatally. This may improve prediction of postnatal fetal continence and optimize prenatal counseling. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Minimally Invasive Surgery for Hirschsprung Disease: Current Practices and Future Directions.

Hirschsprung disease (HD) is a congenital disorder characterized by the absence of ganglion cells in the distal colon and rectum, leading to functional obstruction and severe constipation. Over the past decades, the surgical management of HD has significantly evolved, with minimally invasive surgery (MIS) techniques revolutionizing treatment approaches. This review explores recent innovations in MIS for HD, focusing on laparoscopic, transanal endorectal pull-through (TERPT), and robotic-assisted techniques. These approaches offer numerous advantages over traditional open procedures, including reduced surgical trauma, improved cosmesis, faster recovery times, and potentially lower complication rates. Laparoscopic surgery has become widely adopted, providing excellent visualization and precise dissection. TERPT has gained popularity for short-segment disease, offering a completely transanal approach with minimal scarring. Robotic-assisted surgery represents the cutting edge, enhancing surgical precision and dexterity. The review also examines emerging technologies and future directions, such as advanced imaging techniques, artificial intelligence applications, and potential developments in tissue engineering. While MIS techniques have shown promising outcomes, challenges remain in standardizing approaches, addressing long-segment disease, and optimizing long-term functional results. The future of HD surgery lies in personalized approaches that integrate genetic and molecular profiling with advanced surgical technologies. As the field continues to evolve, comprehensive long-term studies and efforts to improve access to specialized care will be crucial to further enhancing outcomes for patients with HD.

Impaired Epithelial CD200L Tolerance Signaling in Irritable Bowel Syndrome Cases With Diarrhea May Be Associated With Recurrent Miscarriages.

There is a higher incidence of irritable bowel syndrome with miscarriages, and recurrent miscarriages of otherwise normal embryos have been linked to subnormal expression of the immune checkpoint inhibitor CD200L. We sought to determine if alterations in the expression of the CD200 immune checkpoint inhibitor occur in colonic tissue in IBS-D patients. Quantitative immunohistochemical staining of biopsies from proximal and distal colon or rectum for the inhibitory CD200L and CD200S molecules was done. CD56 cells were also enumerated as they play a role in recurrent miscarriages and may express CD200S. CD200L was decreased and CD200S was unchanged in epithelium but not stroma of 3 IBS-D cases. One case had an increase in both CD200L and CD200S. CD56 cells were also stained for CD200S. Degranulation was assessed by the percentage of extracellular CD200S that was increased as epithelial CD200L decreased. This pilot study was promising and warrants a larger sample to determine if a correlation between uterine implantation site CD200L and CD200S expression in normal and failing implantation sites is needed. Colonic epithelial CD200L may then provide useful information about the pathogenesis of the spontaneous miscarriage in individual cases.

IRIS U kit usefulness in transanal total mesorectal excision for lower rectal cancer to avoid urethral injury

Transanal total mesorectal excision (taTME) has improved the laparoscopic dissection for rectal cancer in the narrow pelvis. Although taTME has more clinical benefits than laparoscopic surgery, such as a better view of the distal rectum and direct determination of distal resection margin, an intraoperative urethral injury could occur in excision ta-TME. This study aimed to determine the feasibility and efficacy of the ta-TME with IRIS U kit surgery. This retrospective study enrolled 10 rectal cancer patients who underwent a taTME with an IRIS U kit. The study endpoints were the safety of access (intra- or postoperative morbidity). The detectability of the IRIS U kit catheter was investigated by using a laparoscope-ICG fluorescence camera system. Their mean age was 71.4±6.4 (58–78) years; 80 were men, and 2 were women. The mean operative time was 534.6 ± 94.5 min. The coloanal anastomosis was performed in 80%, and 20% underwent abdominal peritoneal resection. Two patients encountered postoperative complications graded as Clavien–Dindo grade 2. The transanal approach with IRIS U kit assistance is feasible, safe for patients with lower rectal cancer, and may prevent intraoperative urethral injury.

Analysis of benzimidazole anthelmintic resistance in parasitic nematodes <i>Haemonchus contortus</i> using nested isothermal amplification (PCR)

The purpose of the research is to monitor farms located in the European part of the Russian Federation to identify resistance to effects of benzimidazole anthelmintics in populations of nematodes Haemonchus contortus dwelling in the gastrointestinal tract of small cattle.Materials and methods. The studies were conducted in slaughterhouses located in the Moscow Region in 2023–2024. At the first stage, taxonomic identification of parasitic nematodes and larvae (L3) was made, and Strongylata species was determined from sheep. The study material was the abomasum with duodenum fragments and a distal rectum fragment with feces. For molecular studies, we used mature nematodes and H. contortus L3 larvae isolated from the abomasum and feces of small cattle brought to slaughterhouses in the Moscow Region from 8 regions of the European part of the Russian Federation: Moscow, Astrakhan, Oryol, Lipetsk, Tula, Bryansk regions, Stavropol and Dagestan. The studies were conducted at the premises of the Laboratory of Molecular Biology, the VNIIP – FSC VIEV. Statistical processing of the obtained data was made, and mean infection rates of parasitic nematodes (infection intensity and prevalence) were determined. Fifty-six DNA samples of nematodes H. contortus were examined using nested isothermal amplification (PCR) to identify gene alleles that determine resistance to benzimidazole drugs.Results and discussion. Molecular genetic studies of H. contortus DNA sampled from sheep brought from different Regions only detected homozygous individuals (100%) resistant to benzimidazole in the parasitic nematode population from the Oryol Region. Other regions identified only homozygous and heterozygous individuals susceptible to benzimidazole.

Endoscopic assessment of the J pouch in ulcerative colitis: A narrative review.

Patients with ulcerative colitis sometimes need a total colectomy with ileal pouch-anal anastomosis due to medically refractory disease or colitis-associated neoplasia. Up to 50% of patients with ulcerative colitis postoperatively develop pouchitis and the rate of chronic inflammatory pouch conditions requiring pouch excision or diverting ileostomy is reported to be 10%. In order to diagnose and monitor pouchitis, pouchoscopy is essential to assess endoscopic inflammatory findings of the J pouch and to survey neoplasia development, particularly in the remnant distal rectum. However, endoscopic protocols for the evaluation of the pouch may not be standardized worldwide and the reliability of existing disease activity indices for pouchitis has been questioned due to the lack of validation. Recently, reliable endoscopic scoring systems based on an observation of the anatomical location of the J pouch were reported and a significant association between the distribution pattern of endoscopic inflammation (i.e., endoscopic phenotype) and pouch outcomes was also uncovered. In this review, we discuss how to survey the J pouch using pouchoscopy, endoscopic indices for pouchitis disease activity, endoscopic phenotypes and classification, and the pathological mechanisms of pouchitis phenotype in patients with ulcerative colitis.

Application value of laparoscopic double stapler firings and double stapling technique combined with rectal eversion and total extra-abdominal resection in the sphincter-preserving resection of low rectal cancer

Objectives: To investigate the application value of laparoscopic double stapler firings and double stapling technique combined with rectal eversion and total extra-abdominal resection (LDER) in the anal preservation treatment of low rectal cancer. Methods: Inclusion criteria: (1) age was 18-70; (2) the distance of the lower tumor edge from the anal verge was 4-5 cm; (3) primary tumor with a diameter ≤3 cm; (4) preoperative staging of T1~2N1~2M0; (5) "difficult pelvis", defined as ischial tuberosity diameter<10 cm or body mass index>25 kg/m2; (6) patients with strong intention for sphincter preservation; (7) no preoperative treatment (e.g., chemotherapy, radiotherapy, molecular targeted therapy, or immunotherapy); (8) no lateral lymph node enlargement; (9) no previous anorectal surgery; (10) patients with good basic condition who could tolerate surgery. Exclusion criteria: (1) previously suffered from malignant tumors of the digestive tract or currently suffering from malignant tumors out of the digestive tract; (2) patients with preoperative anal dysfunction (Wexner score ≥ 10), or fecal incontinence. The specific surgical steps are as follows: the distal end of the rectum was dissected to the level of the interspace between internal and external sphincters of anal canal. Five centimeters proximal to the tumor, the mesorectum was ligated, and a liner stapler was used to transect the rectum. The distal rectum with the tumor were then everted and extracted through the anus. The rectum was transected 0.5-1.0 cm distal to the tumor with a linear stapler. Full thickness suture was used to reinforce the stump of the rectum, which was then brought back into the pelvic cavity. Finally, an end-to-end anastomosis between the colon and the rectum was performed. A retrospective descriptive study was performed of the clinical and pathological data of 12 patients with T1-T2 stage low rectal cancer treated with LDER at Henan Provincial People's Hospital from January 2020 to December 2022. Results: All 12 patients successfully completed LDER with sphincter preservation, without conversion to open surgery or changes in surgical approach. The median surgical time was 272 (155-320) minutes, with a median bleeding volume of 100 (50-200) mL. No protective stoma was performed, and all patients received R0 resection. The average hospital stay was 9 (7-15) days. There were no postoperative anastomotic leakage or perioperative deaths. All 12 patients received postoperative follow-up, with a median follow-up of 12 months (6-36 months) and a Wexner score of 8 (5-14) at 6 months postoperatively. There was no tumor recurrence or metastasis during the follow-up period. Conclusions: LDER is safe and effective for the treatment of low rectal cancer.

Abstract 2175: Multiple exposures to antibiotics and increased risk of colorectal cancer

Abstract Colorectal cancer (CRC) is the second leading cause of cancer related deaths in the United States and worldwide. In 2023, approximately 153,020 individuals will be diagnosed with CRC and 52,550 will die, including 19,550 cases and 3750 deaths in patients under 50 years of age. CRC in younger patients (less than 55 years) is known as early onset colorectal cancer (EOCRC). It is a growing global phenomenon whose incidence and mortality has incidence from 11% to 20% between 1995 to 2019 and is expected to increase by 140% by 2030. While it has been linked to known and established risks for CRC, the underlying causes and mechanisms are poorly understood. Based on our current knowledge of the disease, we propose that EOCRC results from exposure of children and young adults to exposome factors that have been increasing globally in the last four decades that may impact the microbiome causing dysbiosis and inflammation in the distal colon and rectum, the anatomical site of EOCRC. Among the likely factors is the use of antibiotics, particularly in infants and children. In this study we hypothesized that early life exposure to antibiotics causes dysbiosis and inflammation in the distal colon and rectum leading to increased mutations and epigenetic events that promote EOCRC development. Specifically, we examined the effect of the most commonly prescribed pediatric antibiotics on the gut microbiota and inflammatory environment in the colon, and their impact on tumor development upon exposure to a carcinogen. We treated A/J mice with multiples rounds of antibiotics and then exposed them to azoxymethane, a carcinogen to determine the effect on tumor development in the colon. The results showed that antibiotic exposure caused dysbiosis and inflammation in the colon of antibiotic treated mice as well as systemic inflammation in mice treated with antibiotics. Treatment with azoxymethane, a carcinogen in the presence of antibiotic-induced dysbiosis led to increased tumor burden in the distal colon. These results suggest a possible involvement of antibiotics on increased risk of EOCRC. Citation Format: Niti Jani, Maredith Richardson, Kristen Hogan, Maria M. Pena. Multiple exposures to antibiotics and increased risk of colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2175.

Carbohydrate quality, not quantity, linked to reduced colorectal cancer incidence and mortality in US populations: evidence from a prospective study

BackgroundCarbohydrates have been implicated in colorectal cancer (CRC) risk, but the specific impact of carbohydrate quality and quantity on CRC susceptibility in US populations remains unclear.MethodsWe followed 101,694 participants from Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. The carbohydrate quality index (CQI) and low-carbohydrate diet score (LCDs) were used to evaluate the daily carbohydrate quality and quantity separately, where higher scores indicated greater adherence. Cox proportional hazards regression was used to compute HRs and 95% CIs for incident CRC and related death. Subgroup analyses were conducted to identify potential effect modifiers.ResultsDuring follow-up, we documented 1085 incident cases of CRC, of whom 311 died from CRC. Individuals in the highest compared with the lowest quartiles of CQI had a lower CRC incidence (Q4 vs Q1: HR 0.80, 95% CI 0.67–0.96, Ptrend = 0.012) and mortality (Q4 vs Q1: HR 0.61, 95% CI 0.44–0.86, Ptrend = 0.004). The inverse association between CQI and CRC risk was observed for distal colon and rectum but not for proximal colon cancer. Regarding mortality, this association was only significant for rectum cancer. Subgroup analyses indicated this inverse association of CQI with CRC risk was only observed in participants with lower LCDs. No significant associations were found between LCDs and CRC incidence or mortality.ConclusionsOur findings suggest focusing on higher quality, rather than restricting the quantity, of carbohydrate consumption may be an effective approach to reduce the risk of CRC in the US population, particularly for distal colon and rectal cancers.

Vegetating Lesions that Appear in the Scar after Neoadjuvant Therapy for Rectal Tumors: Tumor Regrowth or Benign Neoplasm?

Abstract Introduction After the diagnosis of neoplasm of the middle and distal rectum, patients are often submitted to oncological treatment by neoadjuvant therapy. At the end of this treatment, those patients who show complete clinical response can choose, together with their physician, to adopt the watch-and-wait strategy; although it implies lower morbidity for the patient, this strategy is dependent on strict adherence to treatment follow-up for the early identification of any future local injury. Materials and Methods Survey of data from medical records and description, and discussion of case reports with a literature review in books and databases. Results We report the case of a 73-year-old patient diagnosed with moderately differentiated adenocarcinoma of the middle rectum, Stage II (cT3bN0M0), who presented complete clinical response after undergoing treatment with neoadjuvant therapy.Together with the assistant team, the watch-and-wait strategy was chosen. During the follow-up, an endoscopic examination showed a vegetating at the proximal limit of the tumor scar. We chose to perform submucosal endoscopic dissection. The report of the anatomopathological examination evidenced a serrated adenoma with narrow margins free of neoplasia. Conclusion Patient adherence to cancer treatment using the watch-and-wait strategy is essential for the early identification of new local lesions. After resection of the lesion identified in the tumor scar site as a neoplasm-free lesion, it is consistent to think that this lesion would be the origin of the neoplasm, given the adenomatous origin.

Successful surgical correction of caudal duplication syndrome in a dog.

To describe a case of caudal duplication successfully operated with long-term follow-up. A 12-week-old female Chihuahua mix. The dog of this report presented for evaluation of duplicate external organs, including 2 anuses, 2 vulvas, and 2 tails. The dog was clinically normal except for signs of cystitis. Contrast CT identified complete urogenital and anorectal duplication, characterized by duplication of the cecum, descending colon/rectum, urinary bladder, urethra, uterus, and ovaries, with left-sided rectovestibular fistula. Exploratory laparotomy was performed to remove the left cecum and colon, the left ureter was transected and implanted into the right urinary bladder, the left bladder and urethra were removed, and bilateral ovariohysterectomy removed 4 ovaries and 2 uteruses. Following abdominal closure, the left anus and vulva with remaining portions of distal rectum and urethra, respectively, were removed en bloc with both tails. Long-term follow-up at 5 years showed the dog to be clinically normal. Caudal duplication is extremely rare in veterinary medicine, and this report details successful surgical correction with good long-term follow-up.

REFRACTORY VULVODYNEA AND THE PROMISING RESULTS WITH ODD GANGLION BLOCKAGE

Vulvodynia is a chronic gynecological disease with no clear cause, lasting at least three months, presenting a history of intense pain with a neuropathic component, starting before diagnosis, refractory treatment with steroids, hormonal therapy, anticonvulsants, antidepressants, psychotherapy, physiotherapy , acupuncture and even vulvectomy. The odd ganglion is the most caudal of the sympathetic ganglion chain. Visceral afferent fibers originating from the perineum, distal rectum, anus, distal section of the urethra, vulva, and vagina are found in the distal third of this ganglion. Its blockade has been effectively used to control pain in patients with vulvodynia. Women with chronic gynecological diseases who received multimodal pain therapy and underwent infiltration with local anesthetics in the impar ganglion demonstrated successful therapy in the majority of them. Blockade is a good treatment option for patients suffering from chronic pain and discomfort caused by vulvodynia.

Morphological, molecular, and functional characterization of mouse glutamatergic myenteric neurons.

The enteric nervous system (ENS) functions largely independently of the central nervous system (CNS). Glutamate, the dominant neurotransmitter in the CNS and sensory afferents, is not a primary neurotransmitter in the ENS. Only a fraction (∼2%) of myenteric neurons in the mouse distal colon and rectum (colorectum) are positive for vesicular glutamate transporter type 2 (VGLUT2), the structure and function of which remain undetermined. Here, we systematically characterized VGLUT2-positive enteric neurons (VGLUT2-ENs) through sparse labeling with adeno-associated virus, single-cell mRNA sequencing (scRNA-seq), and GCaMP6f calcium imaging. Our results reveal that the majority of VGLUT2-ENs (29 of 31, 93.5%) exhibited Dogiel type I morphology with a single aborally projecting axon; most axons (26 of 29, 89.7%) are between 4 and 10 mm long, each traversing 19 to 34 myenteric ganglia. These anatomical features exclude the VGLUT2-ENs from being intrinsic primary afferent or motor neurons. The scRNA-seq conducted on 52 VGLUT2-ENs suggests different expression profiles from conventional descending interneurons. Ex vivo GCaMP6f recordings from flattened colorectum indicate that almost all VGLUT2-EN (181 of 215, 84.2%) are indirectly activated by colorectal stretch via nicotinic cholinergic neural transmission. In conclusion, VGLUT2-ENs are a functionally unique group of enteric neurons with single aborally projecting long axons that traverse multiple myenteric ganglia and are activated indirectly by colorectal mechanical stretch. This knowledge will provide a solid foundation for subsequent studies on the potential interactions of VGLUT2-EN with extrinsic colorectal afferents via glutamatergic neurotransmission.NEW & NOTEWORTHY We reveal that VGLUT2-positive enteric neurons (EN), although constituting a small fraction of total EN, are homogeneously expressed in the myenteric ganglia, with a slight concentration at the intermediate region between the colon and rectum. Through anatomic, molecular, and functional analyses, we demonstrated that VGLUT2-ENs are activated indirectly by noxious circumferential colorectal stretch via nicotinic cholinergic transmission, suggesting their participation in mechanical visceral nociception.

Anorectal developmental anomalies

Anorectal malformations include a wide range of conditions that can affect both sexes and involve the distal anus and rectum, as well as the urinary and genital tracts. An imperforate anus is a common birth defect that results from defects or delays in the development of the hindgut. The diagnosis of nonperforation of the anus is usually made shortly after birth through a routine medical examination. Patients have the best chance for a good functional outcome if the disease is diagnosed early and effective anatomic repair is started immediately. Most malformations in girls can only be correctly diagnosed on physical examination. An anus visible in the perineum with a normal vagina and urethra suggests a perineal fistula. A rectovestibular fistula occurs when the opening is in the posterior vestibule and beyond the hymen. If only one opening is visible between the labia, it is very likely a cloaca. Rectovaginal fistulae may initially appear as a non-perforating anus without a fistula (a normal-looking vagina and urethra, but no visible anus). Close examination usually reveals the presence of an opening in the back wall of the vagina or inside the hymenal ring. Radiological evaluation of a newborn with non-perforated anus should include abdominal ultrasound, using it to detect urological abnormalities. Sepsis, aspiration, abdominal distention, colonic perforation, respiratory distress, electrolyte imbalance are complications that can result from delayed diagnostic and therapeutic treatment of anorectal malforations. Accurate preoperative identification of an internal fistula between the distal part of the genitourinary tract is very important for optimal surgical treatment and prevention of possible damage to the genitourinary tract. Staged surgery, the most common approach for treating anorectal malformations, consists of three operations: a colostomy at birth, a definitive operation at 2–3 months of age, and closure of the colostomy at approximately 6 months of age.

Rectal biopsy: is it really necessary in anorectal malformations?

The coexistence of Hirschsprung's disease (HD) with anorectal malformation (ARM) is rare but many surgeons still ask pathologists to look for ganglia in the terminal rectum or fistula. In this study, we aimed to highlight the rarity of this association and question the necessity of histological evaluation. After obtaining board review approval, rectal specimens of ARM patients who underwent corrective surgery in the last 8 years were re-analyzed by two blinded pathologists for the presence and structure of ganglia. Clinical and radiological data of patients retrieved from center records and correlated with histopathologic findings. 67 patients with ARM were identified, distal rectal specimen was obtained in 47. The median age at the time of surgery was 11 months (2days-59months). A normal pattern of ganglia was present in 51.1% (24/47), 29.7% (14/47) had aganglionosis and 19.1% (9/47) were inconclusive due to insufficient material. None of the aganglionic specimens showed other histological findings of HD. Patients were followed up regularly in the outpatient colorectal clinic for a median of 87 months (42-117m). Only 6 experienced severe constipation (3 ganglionic, 2 no biopsy, 1 aganglionic), all of whom responded to a bowel management program, and none developed other manifestations of HD (abdominal distension, failure to thrive or enterocolitis) or required additional surgery. Our results strongly suggest that the association of ARM and HD is extremely rare and the practice of searching for ganglia in the distal rectum or fistula of ARM patients should be discouraged to avoid potential misdiagnosis and overtreatment.

Comparing three-dimensional endorectal ultrasound and magnification chromoendoscopy for early rectal neoplasia invasion depth assessment.

Accurate assessment of invasion depth of early rectal neoplasms is essential for optimal therapy. We aimed to compare three-dimensional endorectal ultrasound (3D-ERUS) with magnification chromoendoscopy (MCE) regarding their accuracy in assessing parietal invasion depth (T). Patients with middle and distal rectum neoplasms were prospectively included. Two providers blinded to each other's assessment performed 3D-ERUS and MCE, respectively. The T stage assessed through ERUS was compared to the MCE evaluation. The results were compared to the surgical specimen anatomopathological report. Sensitivity, specificity, accuracy, positive (PPV), and negative (NPV) predictive values were calculated for the T stage and for the final therapy (local excision or radical surgery). In 8years, 70 patients were enrolled, and all underwent both exams. MCE and ERUS showed an accuracy of 94.3% and 85.7%, sensitivity of 83.7 and 93.3%, specificity of 96.4 and 83.6%, PPV of 86.7 and 60.9%, and NPV of 96.4 and 97.9%, respectively. Kappa for T stage assessed through ERUS was 0.64 and 0.83 for MCE. MCE and 3D-ERUS had good diagnostic performance, but the endoscopic method had higher accuracy. Both methods reliably assessed lesion extension, circumferential involvement, and distance from the anal verge.