A case of urachal abscess resection via colpotomy in a cow

Abstract

This study describes a novel surgical method to remove urinary bladder-related urachal abscesses in a cow. Traditional methods, such as the midline or paramedian approach in calves and the preinguinal approach, can be challenging in adult cattle, especially for lesions situated near the pelvic cavity. In this case, a 4-year-old cow had a urachal abscess attached to the bladder apex, making it difficult to approach via abdominal wall incision. Colpotomy and pulling the abscess through a vaginal wall incision allowed for complete exteriorization of the lesion and comfortable accessibility of the abscess and the resection site. This report suggests that colpotomy is an effective new route in adult cattle for accessing urachal abscesses not accessible via traditional surgical approaches.

The intraabdominal umbilical structures comprise one umbilical vein, carrying oxygenated blood, two umbilical arteries, carrying deoxygenated blood, and one urachus [14, 19]. The urachus is the continuation of the fetal urinary bladder to the allantoic sac [1]. At birth, the urachus is disrupted at the level of the abdominal wall and passively pulled dorsoventrally into the abdominal cavity by the actively retracting umbilical arteries [26]. Incomplete or abnormal involution can lead to urachal disease. Ascending infection of the urachal remnant may result in omphalourachitis; abscessation thereof may result in urachal abscess formation [2, 16].

Symptoms of a urachal abscess include fever, swelling, and pain on palpation of the umbilical region, drainage of pus from the umbilical region, and dysuria (frequent voiding of small amounts of urine). In young calves, the diagnosis may be made by bimanual deep abdominal palpation [1]. Ultrasonography is a reliable, noninvasive tool that can aid in accurately diagnosing deep abdominal conditions, such as the presence of intrabdominal umbilical remnants [3, 12, 24]. However, diagnosing abnormality of the urachus may be challenging in the absence of extra-abdominal umbilical abnormalities and dysuria [5, 6, 21, 25].

If the patient exhibits signs of urachal abscess formation, the urachus should be surgically removed via laparotomy. In most cases of urachal abscessation, the apex of the bladder is broadly attached to the wall of the abscess, necessitating surgical resection of a portion of the urinary bladder apex. Since the apex of the urinary bladder needs to be grasped, resected, and sutured under direct visual control, the ventral midline approach elongated from the umbilicus in the caudal direction is commonly used in calves.

A 50-month-old Japanese Black cow (six months pregnant), weighing 418 kg, showed no signs of disease, except dysuria (frequent voiding of small amounts of urine). Via rectal palpation, a mass, measuring approximately 10 cm in diameter, situated at the apex of the urinary bladder and appearing to adhere to the surrounding tissue, was identified.

Rectal ultrasonography, performed with a 5.0 MHz linear probe (HS-102V; Honda Electronics Co., Ltd., Toyohashi, Japan), confirmed the presence of a roundish structure (approximately 10 × 10 cm in size) located at the apex of the bladder. The contents were characterized as a mixture of high and medium echogenicity surrounded by a thick capsule, suggestive of an abscess. Based on the location of the mass and the ultrasonographic findings, the urachal abscess was diagnosed.

Surgery at this time was anticipated to be difficult due to the risk of miscarriage and difficulty in accessing the bladder apex due to the pregnant uterus. In addition, since the patient was in good general condition, surgery was postponed until after parturition.

The dysuria seemingly disappeared after normal parturition but was again evident for the farmer one month later. Two months after parturition, the cow was referred to the Miyazaki University Veterinary Teaching Hospital for diagnostic and prognostic evaluation and potential treatment.

Upon admission, her vital signs were as follows: heart rate, 64 beats/min; respiratory rate, 36 breaths/min; and rectal temperature, 39.1°C. The cow intermittently exhibited a hunchback posture and raised her tail when attempting to urinate, showing frequent voiding of small amounts of urine. Rectal examination revealed a contracted uterus and a mass approximately 10 cm in diameter, continuous with the apex of the urinary bladder and attached to the tissue covering the cranial aspect of the pubis bone (Fig. 1A).

Fig. 1.

Schematic representation of the intra-abdominal position of the urachal abscess and the surgical technique advocated for removal. (A) Abscess (asterisk) at the apex of the bladder. (B) Incision in the right vaginal wall (colpotomy; dotted line indicates the incision line). (C) The abscess and bladder are pulled through the incised right vaginal wall into the vagina. (D) The urachal abscess and urinary bladder are further withdrawn through the vulva for direct visualization and further manipulation. BL: urinary bladder.

Complete blood count results were within the normal ranges (white blood cell count, 6,810 cells/μL; red blood cell count, 807 × 10⁴ cells/μL; and thrombocytes, 38.1 × 10⁴ cells/μL) and serum examination revealed no abnormalities (total protein, 7.4 g/dL; blood urea nitrogen, 9.4 mg/dL; and creatine, 1.08 mg/dL).

Rectal ultrasonography, performed with a 13.0 MHz linear probe (MyLab One VET, Esaote Maastricht, Netherlands), confirmed the presence of a mass (approximately 10 × 9 × 6 cm) at the apex of the bladder. The mass had a capsule and hyperechogenic content, and was diagnosed as a urachal abscess formed at the apex of the bladder (Fig. 2). Communication of the lumen of the abscess with the lumen of the urinary bladder could not be confirmed.

Fig. 2.

Rectal ultrasonography image in the sagittal direction shows the presence of a mass (asterisk) attached to the apex of the urinary bladder. Cr: cranial; Cd: caudal; BL: urinary bladder.

The patient’s continued dysuria necessitated the surgical excision of the abscess. The cow was fastened for 36 hr before surgery. At one hour prior to the operation, a compound antibiotic containing 200,000 units of benzylpenicillin-procaine and 250 mg of dihydrostreptomycin sulfate (0.05 mL/kg; Mycillin Sol; Meiji-Seika Pharma, Tokyo, Japan) was administered intramuscularly to prevent perioperative infection, along with flunixin meglumine (2 mg/kg; Forvet50; MSD, Tokyo, Japan) intravenously for pain relief.

The patient was restrained in a standing position. Epidural anesthesia was administered between lumbar vertebrae 1 and L2, using 2.3 mL of 2% lidocaine (Xylocaine Injection 2%, Aspen Japan K.K., Tokyo, Japan). The tail was wrapped with a sterile stretch bandage, bent to the left, and secured with cephalad. The vagina was washed with several liters of diluted (1%) povidone-iodine solution and isopropanol (70%) for the final surgical preparation of the perineum. A vaginal speculum was inserted into the vagina through the vulva and then rotated 90° to further open the vagina dorsoventrally allowing for direct visualization of the left and right vaginal walls. Local anesthesia was performed by injecting procaine hydrochloride (2%; 15 mL; Adsan; Riken Vets Pharma, Saitama, Japan) at the 3 o’clock position into the right vaginal wall tissue.

As the abscess was located ventral to the midline of the uterus, closer to the than to the left side, and as it showed greater mobility to the right than to left, the decision was made to incise the right vaginal wall. An incision approximately 10 cm in length was made in the craniocaudal direction at the 3 o’clock position in the right vaginal wall (Fig. 1B). The mucosa and submucosa were spread with fingers until an opening was present that was large enough to accommodate the entire hand in the retroperitoneal space. The fascia and peritoneum were then bluntly torn with a finger, and bluntly elongated to create an opening into the abdominal cavity large enough to allow access of the surgeon’s hand to the pelvic and abdominal cavities. Close manual inspection of the area of interest revealed that the abscess at the apex of the bladder was tightly adhered to the surrounding tissues. A thin linear structure approximately 0.5 cm in diameter extended from the tip of the abscess towards the abdominal fundus. This structure was manually followed as far as possible, without revealing significant enlargement of diameter.

Manual blunt dissection and a vessel-sealing device (LigaSure Atlas^TM; Medtronic Plc, Dublin, Ireland) were used to detach the adhesions between the bladder, abscess, and surrounding tissues including the uterus, as well as the linear structure extending from the abscess in the cranio-ventral direction. Intraoperatively, the patient sat down several times and leaned towards the fixed belt.

The abscess, now detached from the surrounding tissue, was grasped and pulled in caudal direction through the vaginal wall and the vagina (Fig. 1C); it was then exteriorized through the vulva for direct visualization (Fig. 1D). Two bowel forceps were fixed to the urinary bladder approximately 1.5 cm from the apex (Fig. 3A). The abscess was removed by transection with a scalpel blade between the forceps and the bladder apex (Fig. 3B). The bladder was closed with a seromuscular simple continuous suture pattern oversewn with a seromuscular continuous-horizontal mattress pattern using synthetic absorbable suture material (PDS PLUS, USP 2–0; Johnson & Johnson K.K., Tokyo, Japan) (Fig. 3C). The urinary bladder was then released into the abdominal cavity to regain its physiological position.

Fig. 3.

Photographs taken during surgery. (A) The urachal abscess and apex of the urinary bladder exteriorized through the vulva with intestinal forceps positioned at the apex of the bladder. (B) The urachal abscess at the apex of the bladder was dissected. (C) The urinary bladder was double sutured. (D) A Foley catheter was placed in the urinary bladder. (E) The urinary bladder side of the excised intact urachal abscess. (F) Pus visible within the urachal abscess after incision of the abscess wall.

Since the vaginal incision was made at the 3 o’clock position, and the risk of urine entering the abdominal cavity and of external contamination were deemed low, the incision in the vaginal wall was not sutured. The surgical procedure lasted for a duration of 98 min. Postoperatively, a Foley catheter (NFA416, 16Fr Multi Eyes, Fujihira Industry Co., Ltd., Tokyo, Japan) was placed in the bladder for 5 days (Fig. 3D). Mycillin Sol (0.05 mL/kg) was also administered intramuscularly for 4 days.

No postoperative complications were observed and the vaginal incision was nearly restored to its preoperative state two months postoperatively (Fig. 4A, 4B). Estrus was confirmed three weeks postoperatively and pregnancy was successfully achieved by artificial insemination.

Fig. 4.

Photographs of the repair status of the incised vaginal wall at different time points. (A) Four days postoperatively. (B) Two months postoperatively. Arrows indicate the incision line.

The excised abscess measured 12 × 11 × 10 cm, weighed 678 g, and contained pus (Fig. 3E, 3F). Pus from the urachal abscess was aseptically collected and cultured on 5% sheep blood agar under both aerobic and anaerobic conditions at 37°C for 48 hr. The bacterial colonies that grew were subjected to mass spectrometric analysis using a matrix-assisted laser desorption/ionization biotyper (Bruker Daltonik Inc., Billerica, MA, USA) and the data were compared with the MBT Compass Library reference data to identify the bacterial species. Escherichia coli was detected. Drug susceptibility testing was performed according to the protocol described by the Clinical and Laboratory Standards Institute [4]. The isolated E. coli was found to be sensitive to cefazolin, kanamycin, and enrofloxacin, but resistant to penicillin and tetracycline.

Histopathological examination of the excised abscess wall showed that the mucosal epithelium had detached and the submucosal tissue was heavily infiltrated by inflammatory cells, including neutrophils, lymphocytes, and plasma cells. Additionally, small vessels proliferation with lymphocytic infiltration and calcification around them were observed.

Urachal abscesses are common during young age, and it is rare for a cow to develop symptoms around 50 months of age, as in this case. There are two possible causes for abscess formation at the apex of the bladder. The first is the presence of an urachal diverticulum, in which infection from the bladder reaches the diverticulum and forms an abscess, and the second is the establishment of infection of the urachus after birth and the gradual formation of an abscess. The presence of a thin linear structure at the apex of the abscess that appeared to be the urachal remnant suggests that the abscess was caused by infection of the urachus during after birth.

Dysuria seemingly disappeared after parturition and were again observed at about 1 month thereafter. It might be possible that the sudden reduction of the pressure from the uterus on the urinary bladder after parturition made the symptoms of dysuria temporarily less evident for the farmer.

Colpotomy is a useful surgical technique that allows the patient to remain standing, avoids general anesthesia, and reduces operative and postoperative recovery times [8, 13]. In horses, colpotomy is used for ovariectomy to control estrus behavior in mares, create riding mares for semen collection [18], and prevent chronic colic during estrus [13]. Further, colpotomy in mares has been reported as an approach to the bladder for laceration repair [20], the removal of bladder stones [22], and as an approach to the uterus to facilitate the reduction of a twin fetus via transuterine cranio-cervical dislocation [8, 11, 23]. In cattle, colpotomy has been performed for ovariectomy [9] and for the removal of mummified fetuses [15]; however, this is the first time, it has been applied for the removal of an urachal abscess in an adult cow.

Urachal abscesses that form at the apex of the bladder usually show a broad attachment to the urinary bladder; therefore, they are excised along with part of the bladder apex. Grasping, resection, and suturing of the bladder during excision must be performed under direct vision; in calves, this approach is commonly performed via midline or paramedian access.

Sato et al. reported that the preinguinal approach was effective for urachal abscesses formed at the apex of the bladder in cattle aged >18 months, which are difficult to access via the midline or paramedian [21]. However, even the preinguinal approach may not allow access to the lesion in large individuals, such as adult cows, or when the lesion is located in or near the pelvic cavity. In the present case, the abscess was located close to the pelvic cavity. During the preoperative examination, we considered manipulating the abscess to pull it towards the preinguinal area, but this proved impossible.

When approaching the abdominal cavity via colpotomy, the 2 or 10 o’clock positions of the vaginal fornix are recommended to avoid injury to the rectum (12 o’clock), bladder (6 o’clock), and iliac arteries (3 o’clock and 9 o’clock). Incisions at these positions reduce the risk of visceral prolapse and prevent urine from entering the abdominal cavity. Postoperatively, the incision site shrinks rapidly (to a diameter of one finger within 3 days) and heals completely, usually within 3 weeks [17]. This is the main reason why colpotomy incisions are usually not sutured. Moreover, in mares, suturing may lead to vaginitis and straining [18].

Theoretically, the ideal incision site for colpotomy is the 2 o’clock or 10 o’clock position of the vaginal wall. However, in this case, the incision was made at the 3 o’clock position because manipulations to release the severe adhesions between the abscess and the surrounding tissues were judged to profit from a more ventral approach. The adhesions were carefully manipulated to avoid damaging the iliac artery. The 3 o’clock incision site did not result in any postoperative complications.

Colpotomy is often a blind procedure. Possible complications in mares include laceration of the vaginal artery during incision, bleeding from the omental pedicle after oophorectomy, accidental incision into the rectum or bladder, peritonitis, abscess or hematoma formation at the site of surgery, and vaginal adhesion formation [7, 8, 10]. When adhesions between the abscess and surrounding area are severe, as in this case, the risk of complications is high. Although no complications occurred in this case, the surgical procedure can be performed more safely if a laparoscope that allows visual confirmation of the degree of adhesion is used.

The operative time may vary considerably, depending on the degree of adhesion between the abscess and the surrounding area. However, the advantages of shorter postoperative recovery time, the avoidance of general anesthesia, and a good cosmetic appearance may make colpotomy a viable option for addressing urothelial abscesses in or near the pelvic cavity that cannot be approached from the abdominal floor or preinguinal region. To reduce the risk of complications, thorough preoperative examination, careful intraoperative manipulation, and appropriate postoperative management are essential to confirm the anatomical location of the lesion and to accurately determine the degree of surrounding tissue involvement. In addition, pain management and general health checks are necessary to prevent contamination during intraoperative sitting.

CONFLICT OF INTEREST

The authors declare no conflict of interest.