A study in organogenesis: the arterial supply of the anorectal region in the human embryo and fetus. Anatomic and embryologic bases of anorectal malformations

The middle anorectal artery - a systematic review and meta-analysis of 880 patients / 1905 pelvic sides

INTRODUCTION

The middle anorectal artery (MAA) is considered to supply the middle and lower parts of the rectum however its prevalence and point of origin vary across the literature. Clinical importance of the MAA becomes evident in the total mesorectal excision during the colorectal surgery of rectal cancer in both sexes, as well as interventional radiology procedures utilizing the prostatic vasculature in males.

MATERIALS AND METHODS

Major electronic medical databases were investigated for terms pertaining to the MAA and its associated variations. Compatible data regarding the artery's prevalence, laterality, origin, and distribution in both sexes was acquired. The risk of bias within the studies was assessed utilizing the AQUA tool.

RESULTS

In total, 28 works (n=880 patients / 1905 pelvic sides) were included in this systematic review and meta-analysis, and their publication date ranged from 1897 until 2021. The overall pooled prevalence estimate for the MAA was 59.8% of the patients, and 55.2% of the pelvic sides studied. The vessel was identified more frequently in cadaveric pelvic sides evaluations (79.3%). The artery was found bilaterally more often (56.7%), and most commonly originated from the internal pudendal artery (50.3%). Anastomoses between the MAA and the other anorectal arteries were reported in 78.1%.

CONCLUSIONS

The MAA is predominantly a present vessel, with various point of origin. Its direct clinical significance is yet to be discovered in larger study samples, providing more detailed and unified reports of its anatomical features, especially regarding its branches.

Anal atresia as the diagnostic clue in VACTERL association: A first-trimester case report

Anal atresia is the most common malformation occurring in VACTERL association, but it is difficult to diagnose antenatally. We herein present a case of fetal anal atresia in VACTERL association diagnosed by ultrasonography and supported by autopsy. This case emphasizes the clues to ultrasonographic diagnosis of anal atresia at 11-13⁺⁶ weeks of gestation, promoting increased awareness of VACTERL association during first-trimester screening.

An exceptional type of anorectal malformation: anorectal atresia with posterior fistula in a newborn male

The authors report the case of a newborn male with an exceptional type of anorectal atresia with a fistula that passes posterior to the muscle complex and exits at a site just to the tip of the coccyx. This anorectal malformation was associated with other abnormalities including agenesis of the right kidney, pyelic dilatation of the left kidney, duplicity, and left megaureter. There was no defect in the spine. The anorectal malformation was managed successfully by a posterior sagittal approach according to the Pena procedure.

Single-stage management of all pouch colon (anorectal malformation) in newborns

BACKGROUND/PURPOSE

The standard procedure in the management of pouch colon is the staged procedure (SP), which has well-known disadvantages. We believe that staging is unnecessary and primary single-stage procedure (PSSP) can be done.

METHODS

Patients with pouch colon who underwent PSSP (102 cases from 1997 to 2003) and SP (98 cases from 1991 to 1997), 63 and 42 of whom, respectively, were in regular follow-up for more than 3 years, were evaluated.

RESULTS

In PSSP, male/female ratio was 94:8; in SP, 89:9. Mean age in PSSP was 4.6 days and in SP 26 months. The distribution of cases into types I, II, III, and IV was 10, 24, 14, and 15 in PSSP, and 8, 20, 10, and 4 in SP, respectively. The ratio of PSSP/SP for total pouch colon (I and II) was 34:28 and for partial pouch colon (III and IV) was 29:14. The ratio of PSSP/SP in terms of continence, mortality, and cost was 75:48, 11:47, and 1:4, respectively.

CONCLUSIONS

Primary single-stage procedure gives better continence and cosmesis, with low morbidity and mortality at a low cost, and hence is recommended.

Congenital pouch colon with prune belly syndrome and megalourethra

Congenital pouch colon (CPC), an unusual high anorectal malformation in which a varying length of colon is replaced by a dilated pouch, has appeared in a number of case reports and series published in the English literature. There is only one case report of its association with prune belly syndrome (also known as triad syndrome, Eagle-Barrett syndrome, and abdominal muscle deficiency syndrome). We report the description and management of this rare association in a male neonate with CPC, prune belly syndrome, and congenital megalourethra.

The absence of lateral fusion in cloacal partition

BACKGROUND/PURPOSE

The mechanism by which the cloaca becomes partitioned into a dorsal rectal part and a ventral genitourinary sinus has been the subject of speculation for more than a century. Despite repeated suggestions that partitioning of the cloaca by fusion of lateral folds does not occur, the concept continues to hold sway in many student and surgical texts. The authors reviewed the histologic and 3-dimensional appearance of the urorectal septum in human and rat embryos to see if there was any evidence of lateral fusion in its formation.

METHODS

Sprague-Dawley rat embryos (n = 143) were examined between 11 and 21 days' gestation and compared with human embryo sections (57 embryos) held in historical collections in Europe. Rat embryos were examined by microscopy, dissection, and serial histologic section. In addition, some specimens were sectioned in wax until the lumen of the cloaca was reached, after which they were dewaxed and the internal cavities imaged with scanning electronmicroscopy (n = 18 of 143).

RESULTS

Cloacal "partitioning" resulted from a combination of growth of the mesenchyme of the hindgut and genitourinary sinus, an alteration in the position of the cloaca in relation to surrounding structures secondary to growth in the ventral, infraumbilical abdominal wall and changes in the curvature of the developing spine, and apoptosis in the dorsal wall of the cloaca with shortening of the dorsal cloacal wall. There was no septum, as it is usually defined, between the developing bladder and hindgut. There was no evidence on either histologic section or scanning electronmicroscopy of any process of fusion occurring between the 2 lateral folds within the lumen of the cloaca.

CONCLUSIONS

Lateral fusion of the side walls of the cloaca does not play a role in cloacal "partition." Development of the bladder and hindgut occurs by a process that involves growth, differentiation, and remodeling.

[Development and clinical anatomy of the rectal adventitia. significance for radical operation of rectal carcinoma]

The development, topography and clinical anatomy of the adventitia recti were studied in 300- to 600-microns-thick sections through the pelves of human fetuses and newborn children and 5-mm sections through the pelves of adults. The adventitia recti constitutes a continuous compartment bordered laterally by the fascia recti. In the adult the adventitia recti consists mainly of adipose tissue. The extent of the adventitia recti differs in different parts of the rectal wall. The branches of the vasa rectalia superiora and the visceral lymph nodes of the rectum are situated within the adventitia recti. Our findings suggest that it is necessary to remove the adipose tissue of the adventitia recti and the adjoining lymph nodes individually during resection of the rectum in order to minimize the risk of tumor recurrence.

The embryology and management of congenital pouch colon associated with anorectal agenesis

Forty-one infants with a pouch colon malformation accompanied by a high anorectal anomaly were treated between January 1986 and December 1990. The 41 cases constituted 9% of all anorectal malformations and 15.2% of high defects managed during this period. There were 32 boys and nine girls; three of the girls had an associated cloaca. Many of the babies presented in poor condition, with gross abdominal distension caused by the distended colonic pouch. The typical radiological feature was an enormously distended colonic shadow occupying more than 50% of the width of the abdomen. At the time of surgery, the patients were classified into 4 subgroups based on the length of the normal colon. All but three infants had a high wide fistula, with the genitourinary tract consisting of a colovesical fistula in males and a colovaginal or colocloacal fistula in females. Frequent associated malformations included duplication of the appendix and vesicoureteric reflux. The operations performed initially were a window colostomy of the pouch with or without division-ligation of the fistula, end-colostomy after fistula ligation, or subtotal pouch excision with tubularization of the remaining colon and end-colostomy. Thirteen of the 41 patients have undergone a definitive pull-through operation using the posterior sagittal approach, including two children in whom one-stage reconstruction of a cloaca was performed. Standardized management of this complex anomaly is proposed for the initial operation and for definitive reconstruction.

Development of the anal canal muscles

The anal canal muscles development is studied in 18 human embryos. The external anal sphincter results to origin common with the urogenital sphincter from the cloacal sphincter. The muscle, after its appearance, is subdivided into two portions from a thin mesenchymal layer. Moreover, our embryologic study clearly confirms that the puborectalis muscle is a portion of the levator ani, its primordium being common with the ileo and the pubococcygeus muscles. The anal smooth musculature appears later than the striated one.