Surgical management of uterine torsion through ventral celiotomy in eleven mares

Uterine torsion is relatively an infrequent but an emergency condition of pregnant mare’s Frazer et al., (1997); Blanchard et al., (2010). Uterine torsion should be suspected in a mare having late pregnancy that is showing signs of low- grade abdominal pain Vasey, (1993). Variours surgical and non-surgical methods have been suggested to correct uterine torsion in the mares, non-surgical methods includes rolling the anaesthetised mare, attempting to fix the fetus per rectum or with the use of a wooden plank while rolling the mare manual repositioning of the foal through the cervix, and manual correction via laparotomy (Vasey, 1993; Doyle et al., 2002). Surgical methods like ventral midline, recumbent flank and standing flank approaches for laparotomy have also been used. Nonsurgical management of equine uterine torsion carries high risks for maternal death and fetal loss Embertson (2006: Jung et al., (2008). In India, equine abdominal surgery in not popular because of lack of infrastructure, manpower and expertise. There is lack of literature on long term outcome of cesarean section in Indian breeds of mare. Therefor there is a need to conduct clinical studies to document surgical outcomes of mares suffering for uterine torsion.  The present report describes presurgical evaluation, surgical management and postoperative outcome of surgical correction of uterine torsion through ventral midline celiotomy.

Eleven mares with signs of colic of varying duration were referred to the teaching veterinary hospital that formed a part of this study. At the time of presentation, signalment, gestation period, clinical signs, site, and degree of uterine torsion were recorded. In addition to this survival of fetus, postoperative recovery and reproductive health of the mares were also recorded. After confirmation of uterine torsion on per rectal and per vaginal examination, all the 11 mares were subjected to midline celiotomy and cesarean section. For surgical intervention, mares were premedicated with xylazine [1.1 mg/kg body weight (bwt), intravenously (IV)] followed by induction of anesthesia, after 10 minutes, with ketamine (2.2 mg/ kg bwt, IV) and midazolam (2mg/kg bwt IV).  After tracheal intubation, anesthesia was maintained on isoflurane. The mares were positioned in dorsal recumbency and ventral midline area was prepared for aseptic surgery. A 25-30-cm-long midline celiotomy incision was made on the skin, subcutaneous fascia, and the linea alba starting from umbilical to prepubic area. The uterus was examined for any adhesions and gross changes. The abdominal cavity was packed with sterile drapes, and the uterus was incised. To control uterine wall bleeding, incised ends of uterus were sutured using simple continuous pattern with No. 1 polyglactin 910. The foals were removed manually from the uterus and umbilicus was doubly ligated. Incision of the uterus was then closed using No. 1 polyglactin 910 in two layers with Lambert and Cushing pattern. The uterus was then detorted manually to its normal position. The normal position of the uterus was confirmed by per vaginal and intra-abdominal examination simultaneously. The abdominal incision was closed using No. 2 polyglactin 910 thread with simple interrupted sutures on linea alba and simple continuous sutures on subcutaneous tissue. Skin was closed using polyamide No. 2 in cross mattress fashion. Postoperatively, mares were given analgesic Inj Flunixin meglumine (1.1 mg/kg OD IV Virbac Animal Health India Pvt Ltd) for 3 days, a combination of Inj Piperacillin tazobactum (50mg /kg IV BID daily, Abbott Healthcare Pvt Ltd) for 7 days, Inj Amikacin (10 mg/kg IV once daily, Ranbaxy Laboratories Limited) for 5 days and metronidazole (10 mg/kg, bwt, IV, twice daily; Pfizer Animal Health Ltd., Haridwar, India) for 3 days. The wounds were dressed daily with povidone-iodine and the sutures were removed on the 14^th postoperative day. Uterine biopsy was done on all mares and subjected to histopathological examination using hematoxylin and eosin staining procedure. The surviving mares were periodically followed to record any complications and evaluate reproductive status. Various parameters were analyzed by t -test.

The age of mares suffering from uterine torsion ranged from 3 to 15 (9.18 ± 1.29) years (Table 1). In six of 11 mares, the gestation period was complete, and the remaining 5 mares were in last trimester of pregnancy of gestation (>260 days). 5 of 11 mares were in the fourth parity/foaling (Table 1). Per rectum and per vaginal examinations confirmed uterine torsion in all the mares. Mares had either right-sided (clockwise) 180° (n = 6) and 360° (n = 2) uterine torsion or left-sided (counter clockwise) 90° (n=1), 180° (n=1) and 270° (n = 1) uterine torsion. Mild recurrent signs of colic were observed in two mares with 360° of uterine torsion. Moderate colic in eight mares with 90- 180° of torsion and severe colic in one mare with 270° torsion. Uterine torsion should be suspected in a mare having late pregnancy that is showing signs of low grade abdominal pain Doyle et al., (2002). Diagnosis is straight forward because the twist can be palpated per rectal, cranial to the cervix and one or both broad ligaments can be felt following the direction of rotation The degree of rotation varies from 180º to 540º and can follow either direction Posche et al., (1981). In true uterine torsion, rotation of the uterus is classically >180°, but only occasionally >360° of uterus and the most common degree of torsion is 180-360 Chaney et al., (2007). While the causes of uterine torsion are not clear, sudden fetal and/or maternal movements are thought to play a significant role Immegart, (1997). In this study incidence of uterine torsion was more frequent in fourth and fifth parity mares and the majority was either in advanced stage of gestation or with completed gestation period, however, no age predilection was reported for uterine torsion in mares Vasey, (1993). Other workers also reported uterine torsion in the last trimester of pregnancy (Immegart, 1997), immediately before parturition Vandeplassche et al., (1972) and even up to 515 days of gestation Lopez and Carmona, (2010), it is also reported to occur in early pregnancy.
 

        
Heart rate and temperature at presentation ranged from 46 to 94 (71.09 ± 5.03) beats per minute and 100.1°F to 102.4°F (101.01 ± 0.26°f), respectively. Hemoglobin, total leukocyte count, neutrophil count and lactate levels ranged from 10.2 to 13.4 g% (11.97 ± 0.30), 8100 to 13,700/μL (9886 ± 540), 66% to 82% (77 ± 1.6) and 1.6-4.8 mmol/l (2.49±0.290) respectively (Table 1). Hematology was within the normal but the blood chemistry showed mild elevation of the serum lactate level). Higher level of serum lactate can be attributed  to increase in anaerobic glycolysis due to decrease in blood perfusion to the uterus and fetal tissues.
        
In the present study 10/11 (90.0%) mares survived after caesarian section a. The fetal survival rate was poor as only one foal was born alive but died within 15 minutes of surgery. The remaining foals were dead, of which three had severe umbilical cord torsion (Fig 1). In the present study, 90.0% (10/11) of the mares survived after caesarean section and detortion of the uterus. Grave prognosis has been indicated for foetus, particularly in later stages of gestation, as exposure of fetus to hypoxemia leads to neonatal complications like periparturient hypoxia syndrome Steel and Gibson, (2001). Survival for both mare and fetus is reported to be poor in cases where torsion occurs closer to term and the duration of torsion is longer Jones, (1976). Post-cesarean breeding chances of mares was usually encouraging, as 7/10 (70%) of the surviving mares in the present study were successfully bred, and one of them completed three foalings. Earlier workers had also reported successful breeding after surgical correction of uterine torsion (Chaneyet_al2007; Blanchard et al., 2010) and cesarean section Sainiet_al(2013). Grave prognosis was indicated for fetal survivability, particularly in later stages of gestation, as exposure of fetus to hypoxemia leads to neonatal complications like periparturient hypoxia syndrome. In the present study, survival of the mare was optimized by uterine torsion, under general anesthesia, through ventral midline celiotomy as reported by Taylor et al., (1989); Saini et al., (2013). Ventral midline cesarean section, under general anesthesia with animal in dorsal recumbency, provided ample vision and space for the removal of the fetus and detortion of the uterus Martens et al., (2008). Several other methods were indicated by various authors to detort the uterus. Manual rotation of uterus through cervix was advocated and it was opined that manual detortion of uterus containing dead fetus was difficult and involved more risk of uterine lesions Perkins and Frazer, (1994). Rolling the mare to detort uterus may be complicated by uterine rupture Wichtel et al., (1988). Previous reports also recommended that the if mare is in a surgical facility where many abdominal surgeries are performed, the ventral midline approach should be considered instead of the flank approach, because it is more versatile (Martens et al., 2008; Saini et al., 2015). Although a flank approach can be used in the mare under general anesthesia, it is not recommended because it provides very limited exposure and may cause severe muscle trauma Vasey, (1993).
 
Histopathological findings showed massive endometrial hyperplasia disoriented uterine muscle fibers Interfascicular haemorrhage and oedema(Fig 2, 3). Endometrial hyperplasia  affect fertility by reducing the uterine vasodilatory response to mating and delaying clearance of uterine fluid as a result of decreased uterine contractions England et. al., 2012.
 

 

On the basis of this study, it is concluded that uterine torsion is common in young mares in advanced stage of pregnancy with poor fetal survivablity. Cesarean section by ventral midline celiotomy under general anesthesia was a satisfactory technique to deliver the fetus and subsequently detort the uterus with high survival rate and successful breeding in mares. Fetal survivability, however, is poor in cases of uterine torsion.