Introduction:
Uterine torsion is defined as a rotation of the uterus of more than 45 degrees on its long axis. It is an unusual complication of pregnancy and for most obstetricians it probably represents a ‘once in a lifetime’ diagnosis (1). Uterine torsion usually ranges from 45 degrees to 180 degrees but some cases of torsion of up to 720 degrees have also been reported (2). Uterine torsion is a rotation of the gravid horn around its long axis (Rakuljic-Zelov, 2002) which leads to narrowing of the birth canal causing dystocia.
Uterine torsion has been reported to occur in most domesticated species. The condition was first described in 1766 by Boutrolle (1). It is occasionally observed as a cause for dystocia in beef cows, bitches, queens, ewes, does, and mares, but rarely in sows (2).
Uterine torsion cases varied in its incidence in buffaloes from 53% to 83% of the dystocia presented at different referral centers (Vasishta, 1983, Malhotra 1990, Singh, 1991a, Prabhakar et al., 1994, Purohit and Mehta, 2006, Srinivas et al., 2007, Purohit et a., 2011a, Purohit et al., 2011b, Purohit et al., 2012). It appears that pregnancy stages affect the incidence of uterine torsion with a greater incidence during advanced pregnancy, immediately before parturition (Rakuljic-Zelov, 2002), and mostly during the second stage of labour (Arthur et al., 1989), although uterine torsion observed commonly in pluriparous animal at the time of parturition or during the last month of gestation and occasionally diagnosed at 5th–8th month of pregnancy (Roberts, 1986).
Uterine torsion is a very important maternal reason for dystocia as most cases occur during parturition. The post-cervical torsion (combined uterine and vaginal torsion, Torsio uteri and vaginae) is more commonly diagnosed than an intra-cervical or pre-cervical torsion. Torsions to the left occur more frequently than to the right
Majority As far as bovine species is concerned, torsion of uterus is of great importance due to its incidence. It is considered as one of the complicated cause of maternal dystocia in buffaloes culminating in death of both the fetus and the dam if not treated early. The present study evaluates retrospectively the type and extent of uterine torsion in affected buffaloes.
Predisposition factor of uterine torsion
Reassessment of various speculations made for justifying the higher incidence of uterine torsion in buffaloes in comparison to other species has produced some realistic explanations. Small quantity of fetal fluids and associated decrease in size of uterus at the end of pregnancy seems to be a realistic justification for the occurrence of uterine torsion. Destabilizing factors such as weak broad ligament musculature, lower tone of uterine muscles along with sudden movements of dam and fetus can further add up to probability of occurrence of torsion of uterus.
1. Maternal destabilizing factors
a) Attachment of broad ligaments:
Uterus is held in position by two folds of peritoneum called broad ligaments. Buffalo uterus is conducive to torsion during last trimester of pregnancy because of its relatively unstable anatomical arrangement. On one side, broad ligaments are attached at sub-ilial region and on the other side along the lesser (ventral) curvature of uterus which leaves greater (dorsal) curvature free. Also, uterine horns are not fixed by broad ligaments but are lying free. As pregnancy advances, there is a relatively small increase in the length of broad ligaments but the pregnant horn extends massively beyond the area of attachment. In addition, poor musculature of broad ligaments makes the pregnant uterus less stable in buffaloes.
b) Unfilled rumen:
Role of rumen in preventing torsion of uterus is evident from the fact that presence of rumen on left side increases the incidence of right side uterine torsion. If rumen is unfilled, space in the abdominal cavity is increased and relatively unstable pregnant uterus gets predisposed to torsion.
c) Body frame:
Capacious and pendulous abdomen of buffaloes facilitates easy rotation of pregnant uterus in buffaloes compared to cattle.
d) Age:
About 70-77% torsions occur in pluriparous and 23-30% in primiparous buffaloes due to larger abdominal cavity, stretching of pelvic ligaments, loose and long broad ligaments together with loosening of uterine tissue and decreased uterine tone in old age.
e) Sudden movements:
In case of sudden fall, sudden push from other animal and bumpy movements during transportation, the fetus in advanced pregnant uterus may respond with violent movements, and thereafter the heavy uterus may take time to return to its original position, while dam may change their position quickly to expose unstable pregnant uterus to torsion. In addition, while lying down, buffaloes go down on fore legs first and while getting up, the hindquarters are relevent first, tus each time, the pregnant uterus is temporarily suspended in the abdominal cavity and is prone to torsion. However, other contributory factors must be present in addition to instability that occurs during sudden movements of dam; otherwise uterine torsion would have been frequent in advanced pregnant buffaloes compared to during the first stage of parturition
2. Fetal contributory factors
a) Calf birth weight:
About 90% animals with uterine torsion deliver calves which have birth weight above breed average. During normal parturition, average size fetus is able to rotate and flex its limbs within the boundaries of uterine wall, however, when fetus is oversized, fetal limbs may get entangled in the uterine wall and the continued vigorous movements of fetus may lead to rotation of uterus.
b) Reduced amount of amniotic fluid:
About 90% animals with uterine torsion deliver calves which have birth weight above breed average. During normal parturition, average size fetus is able to rotate and flex its limbs within the boundaries of uterine wall, however, when fetus is oversized, fetal limbs may get entangled in the uterine wall and the continued vigorous movements of fetus may lead to rotation of uterus.
c) Fetal movements and uterine tone:
About 90% uterine torsions are encountered during the late first stage of parturition process. At this stage, conditions favorable for torsion are created because cervix has started to dilate and uterus has begun to contract and gets molded on fetus. The forces impulsive for the rotation of unstable uterus are strong intrauterine movements of fetus that are invoked by myometrial contractions, changes in intra-uterine pressure as well as changes in fetal blood flow. In addition, at this stage, uterine muscles are not in much tone, thus uterus is not able to restrict the movement of upper portion of fetus and the relaxed and unstable uterus may be a cause for torsion of uterus. In fact, uterine instability may induce torsion only up to 180º, whereas torsions of ≥360º require active fetal movements.
Aetiology and Pathogenesis
The exact mechanism and aetiology of torsion is not known. It has been noted to occur in the presence of intra-abdominal adhesions, ovarian tumors and fetal malpresentations. In most cases however, torsion is associated with uterine distortion and asymmetry caused by uterine myomas or uterine developmental anomalies.
Robinson & Duvall proposed that certain maternal irregular body movements or posture and positions may help trigger the rotation of a uterus with pre-existing structural pathology and intrinsic pelvic pathology is found in 66 percent of cases of uterine torsion (5).
More recently, cases have been reported with no associated pelvic factors although a common feature in these cases has been a previous caesarean section.
A study of magnetic resonance imaging evaluation of patients following low transverse caesarean section suggested that in rare instances poor isthmic healing may result in suboptimal restoration of normal cervical length in these cases (6). This results in an elongated cervix with structural weakness and angulation in the isthmic region leading to torsion. Uterine torsion resulting from abdominal trauma has also been reported (7). The occurrence is independent of maternal age, parity and gestation (1).
The etiology of the condition is not well understood. It generally occurs during late 1st stage or early 2nd-stage labor (8), but there are some reports of prepartum uterine torsions (9). The instability of the gravid uterus is certainly the most important predisposing factor in bovine uterine torsions. Each uterine horn is supported in a dorsolateral direction by the broad ligaments, which are attached to the ventral surface of the uterus. The greater curvature of the uterus is dorsal and, in advanced pregnancy, the uterus is positioned beyond the relatively stable area of attachment, resting on the abdominal floor and being supported by the rumen, viscera, and abdominal wall (10). In addition, the manner in which the cow lies down, with the forequarters going down first, and rises, by elevating the hindquarters first, implies that each time the cow lies down or rises, the gravid uterus is suspended in the abdominal cavity. Therefore, a sudden slip or fall could cause torsion of the unstable gravid uterus. However, there must be some contributory factors in addition to instability that occur during 1st-stage labor, otherwise uterine torsion would also be seen frequently in late gestation, which is not the case (8). Many authors suggest that the increased fetal movements that occur during 1st-stage labor in response to the contraction of the myometrium may be the precipitating parturient factor. Other factors that have been mentioned are a sudden push from another cow, decreased amounts of uterine fluid, a flaccid uterine wall, a small non-gravid horn, and excessive fetal weight (7,9,11). In the report of 1 study, pastured animals were more at risk (12), but in that of another study, uterine torsions were 3 times more frequent when animals were confined in stables for long periods (13). Twin pregnancy, on the other hand, tends to prevent torsion, because the bicornual nature of most cases of bovine twins stabilizes the gravid uterus (2).
Our clinical impression was that the incidence of uterine torsion in dairy cows and heifers was higher than previously reported, and that uterine torsions were more common in the early summer months. In light of the conflicting reports in the literature, we also wanted to evaluate the effect of cow housing on the incidence of uterine torsions. The purpose of this study was to describe field cases of uterine torsion and their clinical management, and to compare them with other types of dystocia attended by field veterinarians.
Diagnosis
In early cases:
Typical history of a case of torsion of uterus will suggest that buffalo was about to calve (as exhibited by letdown of milk and relaxation of pelvic ligaments), but adequate time has passed and there is no appearance of water bags or fetus. On the contrary, dam has become restless (frequently gets up and down) with severe abdominal pain (due to stretching of the broad ligament) as manifested by kicking of the abdomen with her hind legs.
In delayed cases:
If the uterus is not detorted during this period, then the history will suggest that continuous straining initially exhibited by buffalo to deliver the fetus has ceased followed by tightening of pelvic ligaments and reabsorption of milk. If the condition remains undetected for several days, then appetite diminishes and rumination ceases. Based upon the symptoms of abdominal pain and discomfort of dam, farmers are usually misguided by the unqualified practitioners by treating the case of torsion of uterus as a simple case of digestive disorder and are usually treated for the same. Later on, when there is no improvement, animal is diagnosed with uterine torsion and is referred. In buffaloes with uterine torsion of <36 h and 36-72 h, pelvic ligament relaxation and mammary gland engorgement are usually evident in 90 and 37% cases, respectively. Beyond 72 h, milk usually gets reabsorbed and pelvic ligament are tightened in 80% torsions.
Treatment
Per-vaginal rotation of fetus:
Degree of torsion and the amount of cervical dilatation are critical factors for the success of this method. With rotations of ≤900, the fetus is easily rocked manually into a normal position. Success rate is high if dam is standing, cervix is sufficiently dilated to grasp the fetus and the fetus is live.
PICTURE INSERT GARNE
Rolling of dam:
The method used for detorsion of uterus in buffaloes is Sharma’s modified Schaffer’s method (Fig 1). This method was designed for buffaloes due to their thick skin which causes skidding of plank during detorsion of uterus and their pendulous abdomen which warrants greater pressure for fixation of pregnant uterus, Theory is to rotate the dam to the same degree and direction to which the uterus has rotated, keeping the fetus fixed by fixing uterus with a plank (length: 11.9 feet, width: 9 inch and thickness: 2 inch). In brief, after ascertaining the side of torsion, animal is casted carefully in lateral recumbency on the side of direction of torsion and the front and hind legs are secured separately. The plank is placed on the upper paralumbar fossa of dam in an inclined manner with lower end on ground. Next step is to quickly roll over the dam on to its back. For this, the front and hind legs are pulled up and over the recumbent dam. While rolling, plank is anchored by 1-2 medium weight assistants who stand still upon the lower end of plank and another assistant moves on the plank. An additional assistant modulates the pressure on the plank by pressing the upper end of plank (Fig 1). Sharma’s modified Schaffer’s method of detorsion was developed based upon the principle of lever (fulcrum, load and effort). In this, fulcrum is lower end of plank that does not move, load is the weight of assistants standing and moving on the plank and effort is the force used by the assistant on the upper end of plank (Fig 1). After each roll, effectiveness of roll is judged. If the roll is successful, disappearance of the vaginal spirals or rectal pouch can be immediately palpated. If the roll is not successful, then whole procedure needs to be repeated.
Caesarean:
Caesarean is usually attempted in 11-26% torsions, in which all other methods of detorsion had failed or there is failure of complete cervical dilatation subsequent to successful detorsion.
Consequences of torsion of uterus
Uterine blood flow:
Rotation of uterus compresses middle uterine vein and increases carbon dioxide tension in the fetal blood. Consequently, uncomfortable fetus makes vigorous movements that further increase the degree of torsion. With the increase in degree of torsion, there is compression of middle uterine artery and oxygen going to fetus is decreased resulting in fetal death. With continued failure of blood supply, uterine wall becomes necrosed, brittle, fragile and prone to rupture. Inflammatory changes can cause adhesions of uterus with surrounding abdominal tissues. Ultimately, delay in correction of torsion of uterus causes death of dam due to generalized bacteremia, endotoxemia or cardiovascular failure.
Cervical damage:
The properties of cervix responsible for dilatation of cervix are disturbed following torsion of uterus. Depending upon degree and duration of torsion, there is variable amount of cervical ischemia followed by necrotic changes in cervical epithelium and musculature of cervix, which are responsible for its failure to dilate even after successful detorsion of uterus. When buffaloes are subjected to detorsion process within <36 h, 36-72 h and >72 h of occurrence of torsion, the possibility that cervix will dilate and there will be vaginal delivery is 83, 52 and 9%, respectively. Viability of fetus at the time of uterine detorsion has a major impact on the post-detorsion likelihood of complete cervical dilatation.
Survival of calf:
Both duration and degree of torsion influence the calf survival rate which varies between 4-56% at referral hospitals. Calf survival can be high if there is timely diagnosis and correction of torsion. Delay in diagnosis can cause fetal hypoxia due to placental separation even in the presence of intact water bags. Once uterine torsion is corrected, the delay in achieving complete cervical dilation may further compromise calf viability. Delay of even 2-3 h results in the death of calf.
Survival of dam:
Survival rate in torsion affected buffalo declines linearly (from 87 to 43%) with an increase in the duration of torsion. When buffaloes are subjected to detorsion within <36 h, 36-72 h and >72 h of exhibition of clinical signs of uterine torsion, there is a survival rate of 96, 61 and 35%, respectively. The duration of torsion and time taken for complete dilatation of cervix determine the severity of uterine necrosis, fetal putrefaction, maternal toxemia, dehydration, shock and peritonitis which is fatal to dam. Dam survival rate following delivery of calf through vagina or caesarean section is 88-100% and 25-95%, respectively. The survival rate of torsion affected buffaloes that are subjected to caesarean for delivery of fetus is also dependent upon the duration of torsion. When caesarean section is conducted within <36 h, 36-72 h and >72 h of occurrence of torsion, the dam survival rate is 100, 57 and 33%, respectively.
Prognosis
Stage of positive prognosis:
Buffaloes have variable degree (90º-360º) of uterine torsion of short duration (<12-36 h) and exhibit relaxation of pelvic ligaments and complete milk letdown. If the degree of torsion is less, fetal viability can be checked through partially dilated cervix. Rectal examination will reveal elastic uterine wall with easily palpable fetal reflexes. Torsion can be easily corrected by per-vaginal detorsion of fetus or by the rolling of dam. Chances of calf survival after correction of torsion are very high if degree is towards lesser side. Survival and subsequent fertility of bovines is >90 and 70%, respectively.
Stage of less positive prognosis:
Buffaloes have variable degree (180º-360º) of torsion of long duration (>36-72 h) and only half of them exhibit relaxation of pelvic ligaments and complete milk letdown. In the remaining, milk is reabsorbed and pelvic ligament are tightened. Rectal examination will reveal elasticity in the uterine wall. Subsequent to detorsion by rolling of dam, per-vaginal delivery of dead fetus is possible after cervical massage and manual dilatation of cervix. About 87% cases will survive when torsion is corrected around 36 h after the occurrence of torsion. Subsequent fertility of bovines is 40%.
Stage of poor prognosis:
Prognosis for survival is unfavorable as the presented case will have long standing (>72 h) torsion of >180º. In majority, milk is reabsorbed and pelvic ligament are tightened. Congestion resulting from long standing torsion of uterine vessels causes fetal death and subsequent autolytic and bacterial changes in fetus which lead to a bulged, tense, inelastic and fragile uterine wall with an immovable uterus. As the uterine wall is highly damaged, spontaneous uterine rupture can occur if rolling of dam is attempted by the plank method. Caesarean is advised for detorsion of uterus. During post-operative period, there is delayed involution due to inflammation, accumulation of toxins, and myometrial damage.