Chapter 66 - Bladder Flashcards
What is the bladder’s capacity in a 500-kg horse, and how does its position change when empty or full?
The bladder can hold** 4 L or more of urin**e in a 500-kg horse. When empty, it may lie entirely in the pelvic canal, and when full, it drops over the pelvic brim to extend to the level of the umbilicus.
What are the round ligaments of the bladder, and what is their origin?
The round ligaments of the bladder are the cranial free edges of the lateral ligaments, remnants of the umbilical arteries.
How is the bladder covered anatomically, both cranially and in the remainder of the retroperitoneal space?
Cranially at the apex, the bladder is covered with peritoneum, and in the remainder of the retroperitoneal space, it is covered with adventitial tissue.
What are the two muscle layers in the bladder wall, and how are they arranged anatomically?
Bladder wall contains an** outer layer of longitudinal** to obliquely arranged muscle fibers
**inner layer of transversely **or **circularly arranged **muscle fibers.
They are partly interwoven but become external to each other at the dorsal aspect.
Why is the dorsal wall of the bladder considered inherently weak, and what is the potential consequence of excessive bladder distention?
The** dorsal wall** is considered** weak** due to the anatomical arrangement of muscle fibers. Excessive bladder distention may lead to rupture, particularly at the dorsal wall.
What muscles form the urethral sphincter, and how are they arranged around the pelvic urethra?
The urethral sphincter is formed by an outer longitudinal and an inner circular layer of smooth muscle surrounding the pelvic urethra.
What is the lining of the bladder, and what allows the bladder to stretch considerably during filling?
the bladder is lined with transitional epithelium overlying a thick submucosa that allows considerable stretching.
How is sympathetic innervation provided to the bladder, and what receptors do the fibers supply in the bladder and proximal urethra?
Sympathetic innervation is provided via the hypogastric nerve, with fibers supplying the** bladder** (β2-adrenergic receptors) and proximal urethra (primarily α1- and some α2-adrenergic receptors).
What is the origin of parasympathetic innervation for the bladder, and how is somatic innervation primarily directed to the lower urinary tract?
Parasympathetic innervation originates in the sacral segments of the spinal cord, forming the pelvic nerve.
Somatic innervation is primarily directed to the lower urinary tract via a branch of the pudendal nerve.
What is the detrusor muscle, and how is it innervated in the bladder wall?
The detrusor muscle is the smooth muscle of the bladder wall. It is innervated by the parasympathetic pelvic nerve and β2-adrenergic postganglionic fibers.
Describe the filling/storage phase of the bladder, and what is the role of sympathetic nerve activity during this phase?
During filling/storage, there is an increase in tone of the urethral sphincter muscles. Sympathetic nerve activity is dominant, leading to relaxation of the detrusor muscle
What receptors mediate the relaxation of the detrusor muscle during the filling/storage phase?
Relaxation of the detrusor muscle during filling/storage is mediated by α-receptor–mediated inhibition of pelvic nerve afferents and stimulation of sympathetic β2 receptors in the smooth muscle of the bladder.
How is the detrusor muscle reflexively relaxed during bladder filling, and what triggers detrusor contraction during the elimination phase?
the detrusor muscle reflexively **relaxes during bladder filling due to sensory input from bladder stretch and pressure receptors**. Detrusor contraction is triggered by signals for voluntary micturition during the elimination phase.
What is the role of brainstem upper motor neurons in micturition, and what triggers the end of micturition?
Brainstem upper motor neurons transmit signals to trigger detrusor contraction during micturition. Micturition ends when detrusor stretch receptors cease firing, and pelvic nerve efferent activity stops.
How is sympathetic nerve and pudendal nerve activity involved in the post-micturition storage/filling phase?
Sympathetic nerve and pudendal nerve activity resumes for the next storage/filling phase after micturition.
What triggers the initiation of voluntary micturition signals, and what muscles are concurrently inhibited during this phase?
Voluntary micturition signals are initiated in the cerebrum, leading to the inhibition of pudendal nerve and hypogastric α- and β2-sympathetic activity, allowing relaxation of the urethral sphincter and facilitating detrusor muscle contraction.
How does sympathetic innervation contribute to the relaxation of the detrusor muscle during the filling/storage phase?
Sympathetic innervation leads to the relaxation of the detrusor muscle during the filling/storage phase by inhibiting pelvic nerve afferents and stimulating sympathetic β2 receptors in the smooth muscle of the bladder.
What are some disorders of the bladder that may necessitate surgery in horses?
Foals:
- uroperitoneum,
- patent urachus,
In adult horses,
- cystolithiasis/urolithiasis
- prolapse or eversion of bladder
- neoplasia
What is the most common surgical disorder of the bladder in adult horses?
Cystolithiasis
What can cause uroperitoneum in foals, and what is the prevalence of uroperitoneum after bladder rupture during parturition in colts?
Uroperitoneum in foals can result from bladder rupture during parturition in colts. The prevalence ranges from 0.5% to 2.5%.
What is the commonly accepted explanation for bladder rupture in colts during parturition?
high intravesicular pressure during passage through the pelvic canal and occlusion of the urethra.
what is the typical appearance of bladder tears in foals?
Bladder tears are typically** 2 to 5 cm in length** on the dorsal surface, with hemorrhagic and edematous margins.
What are the potential causes of bladder distention in stillborn and neonatal foals, and how can bladder distention be confused with uroabdomen?
Potential causes of bladder distention in stillborn and neonatal foals include excessively long umbilical cords and anomalies in bladder-urachus fusion. Bladder distention can be confused with uroabdomen, as seen in cases of enlarged, flaccid bladders.
what is the treatment of megavesica in foals
Surgical removal of a large portion of the bladder is the treatment for megavesica with uroabdomen in foals.
and what complications may arise after surgical correction?
Complications may include recurrent colic after weaning, as observed in some cases.
What electrolyte alterations are commonly found in foals with uroabdomen, and how is uroabdomen confirmed?
**Hyponatremia,
hypochloremia,
**
and moderate to marked hyperkalemia
Uroabdomen is confirmed by measuring a ratio of peritoneal fluid to serum creatinine greater than two.
How does bladder rupture in adult horses typically occur?
Bladder rupture in adult horses = less common than in foals
Causes:
- parturition
- urolithiasis
- penile hematoma and swelling
- blunt abdominal trauma
- falling during recovery from anesthesia, or after repair of bladder rupture or treatment of urachal sepsis.
What are the clinicopathologic findings in adult horses with bladder rupture, and how do they compare to neonates with uroabdomen?
Clinico pathologic findings in adult horses with bladder rupture include azotemia and alterations in serum electrolyte concentrations, which are similar to those found in neonates with uroabdomen.
Under what circumstances might foals with perinatal asphyxia syndrome (PAS) exhibit bladder distention
Foals with PAS, especially when recumbent, may exhibit bladder distention.
how is it managed to prevent rupture?
Temporary use of an indwelling bladder catheter is useful to keep the bladder empty and decrease the risk of rupture.
What is the potential complication associated with the temporary use of an indwelling bladder catheter in foals with PAS?
Ascending urinary tract infection
In adult horses, what has been observed as a complication following treatment of urachal sepsis as a neonate?
Uroabdomen has been observed as a complication following treatment of urachal sepsis as a neonate in adult horses.
What is the suggested cause of bladder tears in foals with smooth margins and no evidence of traumatic disruption?
ay be developmental anomalies rather than ruptures
What is the primary cause of lower urinary tract obstruction in male infants, and has it been recognized in horses?
he primary cause of lower urinary tract obstruction in male infants is posterior urethral valves. Although it has not been recognized in horses, bladder rupture, vesicoureteral reflux, and hydronephrosis can result from this condition.
Clinical signs of bladder rupture during parturition when does it manifest? what are the signs?
Foals with bladder rupture during parturition initially appear healthy and nurse well for the first 24 to 48 hours. Early signs include a decrease in nursing vigor, lethargy, and progressive abdominal distention, along with intermittent colic signs.
From what value must be corrected the hyperkalemia?
K>5.5 mEq/L mm tremors and cardiac arrythmias
What is the treatment dosage?
In sever hyperkalemia 50 kgs foal is** 25-50 mL of 23% calcium borogluconat**e added to **1L NaCl 0.9% **and infused 5-10 minutes
Administer more fluids supplemented with **50% dextrose 4-8 mg/kg/min
Drain abdomen go to surgery**
Bloqueio atrioventricular de terceiro grau demonstrando um intervalo R-R irregular sem qualquer relação com as ondas P e um complexo QRS largo (complexo de escape) (seta). O ECG apresenta ondas P regulares que não são seguidas por um QRS e os complexos QRS apresentam uma morfologia larga e bizarra,
Figure 66-1. Longitudinal bladder tear in the dorsal aspect of a 3-day-old colt (arrows). This is the typical surgical finding in a foal that develops uroabdomen consequent to bladder rupture sustained during parturition.
Figure 66-2. Transabdominal ultrasonographic images at the level of the umbilicus in foals. (A) A large amount of free peritoneal fluid is present in moderate to severe uroabdomen; (B) Only a modest amount of fluid is visible as would be imaged during the early stages of uroabdomen. BL, Bladder; F, free abdominal fluid [urine]; SI, small intestine; UA, umbilical artery.
Why do you drain the abdomen?
Essencial to remove large amount of potassium and decrease pressure on diaphragm
Urolithiasis
b
Figure 66-3. Equine cystic calculi. (A) The more common flattened, sphere-shape type of bladder calculus that is highly spiculated. (B) The less-common form of gray, smooth-surfaced calculi that can be more irregular in shape. (A, Courtesy Julie Rossetto, DVM, Alamo Pintado Equine Medical Center, Fenton, Michigan. B, Reproduced from DeBowes RM. Surgical management of urolithiasis. Vet Clin North Am Equine Pract. 1988;4:461, with permission.)
Initial presentation of the post-partum mare with aneverted bladder. EVE 2020 Segmental ischaemic necrosis of the jejunum in a post-partummare due to two mesenteric avulsionsL. Vilaregut
Figure 66-5. (A) An enlarged bladder filled with a sphere of inspissated sabulous urine sediment at postmortem examination. The mass of urine sediment weighed 5 kg. (B) The sphere of urine sediment could be cut rather easily with a knife. (Reproduced from Schott HC. Urinary incontinence and sabulous urolithiasis: Chicken or egg? Equine Vet Educ. 2006;8:17, with permission.)
Figure 66-6. Everted bladder in a postpartum 4-year-old Standardbred mare.
Figure 66-7. (A) In male horses or foals, the caudal aspect of the cutaneous midline incision and subcutaneous dissection is directed abaxially to avoid the prepuce and penis. (B) Then the penis and prepuce are retracted laterally so the body wall can be incised on midline.
Figure 66-8. After completing the midline incision and mobilizing the umbilicus and urachal remnant from the abdominal wall, the bladder is exposed by careful traction on the umbilicus. When the bladder is exposed, the tissues are retracted caudad.
The external umbilicus should be oversewn if present of the abdomen.
Fusiform incision is made around the external umbilicus.
The umbilicus and urachus are dissected free from the bodywall.
Umbilical vein is double ligated and resected as farcraniad as necessary to remove any portion of abnormal umbilicalvein.
Sterile moistened laparotomy sponges to pack the intestines.
Ligate umbilical arteries
Exposure of the bladder is achieved by traction on the urachus.
Stay sutures
Isolate urachus in the apex of the bladder
Transverse incision to remove urachus
describe surgery
Figure 66-16. The urolith can be grasped with sponge forceps for expedient removal.
When the bladder is exposed, moistened laparotomy sponges are used to pack off the bowel and elevate the bladder in the surgical field. Large-diameter stay sutures can be positioned at the ventrolateral aspects of the bladder to facilitate control of the cystotomy incision and to reduce urine spillage.
A** transverse incision** is made across the ventral bladder to expose the urolith. Frequently, the urolith is closely adherent to the bladder mucosa, particularly in the case of a type I urolith. The mucosal layer of the bladder must be peeled back from the urolith to permit removal of the calculus (Figure 66-16). The bladder can be** lavaged in an effort to remove small fragments of calcular material and blood clots. Irrigation of the bladder by retrograde introduction of sterile saline through the urinary catheter flushes small fragments of the urolith from the neck of the bladder toward the incision, where they can be evacuated by suction.
The cystotomy is sutured with a two-layer closure of monofilament synthetic absorbable suture material. Continuous inverting suture patterns such as the Cushing and Lembert patterns **are preferred. The sutures should not penetrate the mucosa of the bladder. After closure of the cystotomy, the bladder may be carefully distended with sterile saline to evaluate the closure for leakage. The abdomen is lavaged with sterile balanced saline solution, which is subsequently suctioned off. The **midline incision is closed with USP size 2 or 3 synthetic absorbable** suture material in continuous or interrupted fashion. In very large horses, a suture size of USP size 6 can be used if available. If the caudal limit of the incision was made in a **paramedian location, **the fascial closure is completed in two layers by suturing the internal and external layers of the rectus abdominis sheath separately. Of the two layers, the external rectus sheath is the more critical to the security of the abdominal closure.The subcutaneous tissues and skin are closed in routine fashion.
Bernardis et al 2017 Components of the pneumatic lithotripsy equipment. a)Gas regulator, b) Gas line, c) Pneumatic scaler, d) laparoscopicretrieval bags, e) stainless steel lithotrite.
Hall and Rodgerson EVE 2020 describe a transurethral intraluminal closure of a caudally located bladder neck tear in standing mare
Hall 2020 Endoscopic view of the bladder tear, located caudally inthe region of the neck of the bladder.
Figure 66-9. The bladder is retroflexed to examine a tear on the dorsocranial wall of the bladder.
Figure 66-11. Tissues surrounding a tear in the bladder should be excised before primary repair.
Figure 66-12. A two-layer inverting continuous closure is appropriate for repair of a bladder rupture.
Figure 66-10. A rupture of the urachus (located at the tip of the hemostatic forceps) is readily apparent on inspection of the cranial bladder.
Figure 66-13. After mobilizing and retracting of an umbilical or urachal abscess, the abdomen should be explored for adhesions or additional foci of abscessation.
Figure 66-14. Before urachal-umbilical resection, a clamp is applied to prevent spilling urachal contents into the peritoneal cavity. Here, the bladder has been stabilized by stay sutures transfixed as ligatures around the umbilical arteries. The urachus and umbilical tissues are removed by sharp dissection. The bladder is closed by the two-layer inverting continuous suture pattern.
