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SBA Answers and Explanations
Published in Vivian A. Elwell, Jonathan M. Fishman, Rajat Chowdhury, SBAs for the MRCS Part A, 2018
Vivian A. Elwell, Jonathan M. Fishman, Rajat Chowdhury
A Meckel’s diverticulum is the anatomical remnant of the vitello-intestinal duct. In the developing fetus the vitello-intestinal duct connects the primitive midgut vto the yolk sac and also plays a part in intestinal rotation. The urachus (a derivative of the allantois) is different and connects the bladder to the umbilicus in the fetus. After birth the urachus becomes known as the median umbilical ligament.
Urologic procedures
Published in J. Richard Smith, Giuseppe Del Priore, Robert L. Coleman, John M. Monaghan, An Atlas of Gynecologic Oncology, 2018
Padraic O’Malley, Peter N. Schlegel
The Boari flap was first described in 1899 as a bladder flap substitution for the distal ureter (Boari 1899). The Boari flap provides an excellent substitute for the psoas hitch technique when ureteric defects of longer than 6 to 8 cm exist (Stein et al. 2013). It is important to mobilize the bladder with division and ligation of the median umbilical ligament (urachus) and both medial umbilical ligaments. If greater mobilization is required, the contralateral superior vesicle pedicle can be divided and ligated. Caution must be used in patients who have had previous radiation, and thought given to the functional capacity of their bladder. A rhomboid flap is raised from the dome of the bladder, keeping the base of the flap at least 1 to 2 cm wider than the tip of the flap, and the length-to-width ratio not more than 3:1 in order to ensure good vascular supply (Figure 30.3). The ipsilateral vesical pedicle supplies the flap. The spatulated ureter may be implanted using a tunneled intravesical anastomosis or an extravesical mucosa-to-mucosa anastomosis and closure of the remaining flap vertically. The Boari flap can provide between 10 and 15 cm in length and can even reach the proximal ureter in certain cases on the right-hand side.
Clinical anatomy of the newborn
Published in Prem Puri, Newborn Surgery, 2017
Mark D. Stringer, S. Ali Mirjalili
At birth, the umbilical vessels constrict rapidly in response to a fall in umbilical cord temperature and hemodynamic changes. Occlusion of the umbilical artery is facilitated by the “folds of Hoboken,” constriction rings along the length of the umbilical artery produced by oblique or transverse bundles of myofibroblasts.19 Numerous mediators of umbilical vessel vasoconstriction have been proposed, including bradykinin and endothelin-1, some of which are produced locally within the umbilical cord. After birth, the obliterated umbilical arteries become the paired medial umbilical ligaments usually visible under the peritoneum of the anterior abdominal wall below the umbilicus; the proximal parts of each umbilical artery remain patent as the superior vesical artery. The intra-abdominal segment of the umbilical vein becomes the ligamentum teres. The urachus has normally involuted before birth leaving the fibrous median umbilical ligament.
The Allantois and Urachus: Histological Study Using Human Embryo and Fetuses
Published in Fetal and Pediatric Pathology, 2022
Xuelai Liu, Xianghui Xie, Zhe-Wu Jin, Huan Wang, Yanbiao Song, Peng Zhao, Long Li
During development, the urogenital sinus is divided into three parts: a cranial part that is continuous with the allantois, a middle pelvic part that becomes the urethra in the bladder neck and the prostatic portion of the urethra in males or the entire urethra in females, and a caudal part that grows toward the genital tubercle [2]. The urinary bladder develops mainly from the cranial part of the urogenital sinus, which is called the allantois. The allantois soon becomes a thick fibrous cord known as the urachus and extends from the apex of the bladder to the umbilicus. The urinary bladder enters the pelvic cavity at about GA 6 weeks, subsequently extending posteriorly along the posterior surface of the anterior abdominal wall and becoming the fibrous remnant of the urachus. In adults, the urachus is represented by a median umbilical ligament, the fibrous remnant of the umbilical arteries [3–5]. In the clinical setting, about 50% of urachal anomalies in infants are present in the inferior part of the urachus, and its lumen is continuous with the cavity of the urinary bladder. This may give rise to urachal sinuses, urachal cysts in children with umbilical recurrent infection and moisture, and patent urachus in children with urine leakage from the urinary bladder to the umbilical orifice. However, the exact anatomical location of allantois/urachus and its correlation with the abdominal wall remain unknown, as is histological information about the allantois/urachus during early phases of normal human development.
Is excision necessary in the management of adult urachal remnants?: a 12-year experience at a single institution
Published in Scandinavian Journal of Urology, 2018
Daanesh H. Hassanbhai, Foo Cheong Ng, Li-Tsa Koh
In the 4th–5th month of gestation as the bladder descends, a 3-layered structure connecting the allantois to the foetal bladder, known as the urachus, is stretched, resulting in luminal obliteration and formation of the median umbilical ligament [1]. Figures 1a and b illustrate the embryology of the urachus. Failure of this process results in an epithelialized urachal canal with a potential for various urachal anomalies, including cysts, sinus tracts, diverticula and malignancies [2–4]. Urachal anomalies in children are well documented in the current literature. These are traditionally removed to alleviate symptoms or to prevent future complications [5]. If they persist into adulthood, they have malignant potential, especially if precipitating factors, such as chronic urinary retention with resultant infection and inflammation, are present [5]. The literature is inconclusive on how to manage urachal anomalies that are discovered incidentally in adulthood. Divergent views on management clearly highlight a lack of consensus, thus creating uncertainty of the value of prophylactic surgical resection. We hypothesized that the value of surgical intervention for urachal remnants is limited and unwarranted in the adult population.