A. Reading Assignment
- 1. Arthur, et al, Chapter 9, The Approach to an Obstetrical Case, pgs. 184-192; Chapter 12 - Manipulative Delivery per Vagina, pgs. 218-225; Chapter 13 - Dystocia due to Fetal Oversize, Treatment. pgs. 236-240.
B. Other References
- 1. Roberts Chapter VIII - Procedures Preliminary to the Handling of Dystocias, pgs. 287-297; Chapter IX - Obstetrical Operations for Relieving Dystocia, pgs. 298-324.
- 2. Current Therapy in Theriogenology, 1st Ed., 1980, Section V, Delivery by Forced Extraction and Other Aspects of Bovine Obstetrics, pgs. 247-257.
- 3. Sloss & Dufty, Chapter Eleven - Procedures on the Fetus, pgs. 162-179.
- 4. Fetotomy in Large Animals by Bierschwal & de Bois, pgs. 9-37.
- 5. Society for Theriogenology, Proceedings of the 1988 Annual Meeting, pgs. 1-12.
C. Other1. Syllabus
Given the above resource material and following a series of lectures, demonstrations and hands-on experiences, the student will be able to:
Each case of dystocia constitutes a clinical problem which may be solved if a correct procedure is followed. It is only after eliciting information from the owner or caretaker and after a methodical examination of the animal that one can make a diagnosis which is essential in correcting the abnormality to delivery.
As with all medical problems,it is essential that one obtain as much history as possible associated with the case. This can be obtained at the time the preliminary examination and preparations for handling the dystocia are being made. The history of the case as well as certain other information should be obtained from the owner as well as by observations. This information should include the dam's age, previous breeding record, (especially the number of pregnancies), and whether or not the animal has experienced previous dystocias or abortions. It is also important to determine whether parturition has started prematurely, is at full term, or is overdue. The progress of the birth can be assessed from the duration and intensity of labor contraction, time of rupture of the fetal membranes, and appearance of fetal parts at the vulva. In multipara, it is important to determine if any fetuses were expelled and if so, were they dead or alive. One should also try to determine if attempts were made to deliver the fetus(es) by the owner or others, and if so,the nature of the assistance should be determined. If the cow is recumbent, information should be sought regarding the duration of the recumbency.
It is important to diagnose any clinical conditions which may affect the dam and her offspring during delivery and the subsequent postpartum period. If urgent assistance is required to save the fetal and maternal life, a detailed examination should be done immediately after delivery of the fetus. The bodily condition, demeanor, and posture of the dam should be noted. Recumbent animals should be urged to rise, inability to do so may be a sign of obturator paralysis, parturient paresis, or other conditions causing paraplegia of pregnancy. Determination of the rectal temperature may be omitted since inaccurancies may arise through relaxation of the anus, or from the effects of labor. On the other hand, clinical examination of the mucous membranes, skin, heart, lungs and digestive system may provide vital information. Particular attention should be paid to the vulva. The nature of the discharge, whether it is watery, mucoid, bloody, or foul-smelling will often indicate the condition of the fetus. The character of the fetal membranes if hanging from the vulva are of further assistance in determining the condition of the fetus and the possible length of time the condition has existed. If a portion of the fetus protrudes from the vulva, its condition, position and posture should be observed as these may give valuable information regarding the fetus. The vulva itself should be noted to gain information on the amount of edema or trauma present as an indicator of the length of time the dystocia has existed and whether someone has already attempted to deliver the fetus.
In cases in which it is clear from the clinical signs that the fetus is dead and the uterus grossly infected, and there is an indication for inducing epidural anesthesia, this should be done before proceeding to a vaginal examination.
Proper restraint of the patient is necessary to avoid injury to the examiner and a detailed evaluation of the patient should not be undertaken until this is done.
The tail of the cow should be held out of the way, either by an assistant or tied with a tail rope. In the mare, the tail should be bandaged or covered with a plastic sleeve. The external genitalia should be thoroughly washed with warm water and an antiseptic to avoid carrying debris into the birth canal. The operator should then thoroughly wash and lubricate the hands and arms and proceed to make a vaginal examination.
If the history of the case leads the examiner to know or suspect that others have been examining and attempting to relieve the dystocia, it is extremely important that the birth canal and caudal portions of the uterus be examined carefully for evidence of trauma.
The birth canal should be examined to determine if it is dilated, twisted, moist or slippery, inflamed, swollen, dry, necrotic, contains pathological bands, stenotic areas or tumors, or contains gummy mucus indicating that parturition has not yet begun or is in the early stages. The degree of dilation or relaxation of the cervix should be noted as well as whether there is any evidence of torsion. The size of the pelvic inlet, vulva, and vagina in relation to the size of the fetus should also be checked.
The fetus should be examined to determine if it is dead or alive as this will alter the prognosis and make a difference in the manner in which the case is managed. If the amnion is not ruptured, this should be done to facilitate proper palpation of the fetus. Signs of life in the fetus can be determined by pulling on the limb or pinching it, in the live fetus, this will cause movement of the limb. In the bovine fetus, a reliable sign is the presence of the interdigital reflex which can be illicted by firmly pinching between the claws in the region of the interdigital web. Other signs of life include the presence of a sucking reflex, response to the eyeball/eyelid reflex, palpation of the heartbeat (in the anterior presentation), and pulsations in the umbilical cord. Inserting a finger into the anus of a fetus in the breech presentation will cause contraction of the anal sphincter if the fetus is alive. If the fetus is dead, the degree of autolysis should be accurately assessed by the amount of subcutaneous edema or emphysema, whether or not the hair is sloughing and whether or not a putrid, fetid odor is present.
The fetus should be carefully examined to determine any possible abnormality of presentation, position or posture. In a breech presentation, the tail is often found hanging from the vulva or lying in the birth canal. If the head is not in the birth canal in anterior presentation, its location can be determined by finding the neck, the mane of the equine fetus, or the ears and head by swinging the arm and hand around the cephalic part of the body. If the feet are in the birth canal, it should be determined whether they are front or hind feet. These maybe differentiated on the following basis:
If the feet of the fetus are protruding from the vulva with the soles ventral, then the fetus is either in anterior longitudinal presentation, dorso-sacral position, or posterior longitudinal presentation, dorso-pubic position, the latter is rarely encountered. If the feet of the fetus are dorsal, then the fetus is either in a posterior longi- tudinal presentation, dorso-sacral position, or in anterior longitudinal presentation, dorso-pubic position. If no part of the fetus is in the birth canal, the condition is probably a transverse dorsal or rotated bicornual pregnancy. In the latter condition, the birth canal is very long and the fetus can be touched only at arm's length. If more than two limbs are in, entering, or are near the pelvis, the condition should be carefully evaluated to differentiate between twins, a schistosomus reflexus fetus, a double monster, an anterior longitudinal presentation with the rear limbs of the fetus extended over or under the body, or in the mare in a transverse ventral presentation.
The prognosis in a dystocia depends on a number of factors:
In general, it is very difficult to save the life of a mare if she has been in labor for more than 24 hours and the fetus is emphysematous. The same is true of other animals, but the prognosis is usually better as other species are more resistant to infection. The fetus in the cow and ewe usually dies after 6 to 12 hours of labor. In sows, the first fetus usually dies after 4 to 6 hours of labor. The other pigs may survive for 24 hours, however, after 24 to 36 hours of labor, all fetal pigs are invariably dead.
Williams has appropriately described that the handling of dystocia as resembling a salvage operation on a "ship on the rocks". If possible the following should be salvaged:
In the prognosis of a case, these should be weighted against the:
The major classification of obstetrical equipment is as follows:
Epidural anesthesia is widely utilized in the management of obstetrical problems in the mare and cow because:
The obstetrical operations may be divided into four major classifications: Mutation, forced extraction, fetotomy and caesarean section (hysterotomy)
Repulsion may be accomplished by the operator's arm or by the use of a crutch or repeller. In anterior presentation, the crutch or hand of the operation is usually placed on the fetus between the shoulder and chest or across the chest beneath the neck. In the posterior presentation, the hand or crutch is placed in the perineal region over the ischial arch.
Repulsion is difficult or impossible in the recumbent animal resting on its sternum as the abdominal viscera are pushing the fetus back toward the pelvis. If the animal is recumbent, it should be placed on its side with its four legs extended.
- 2. Rotation: Is turning of the fetus on its long axis to bring it into a dorso-sacral position.
In correcting dystocias in unipara by rotation of the body, the fetus should be repelled cranially out of the pelvic cavity. If this cannot be accomplished, as in cases of prolonged dystocia, proper lubrication of the fetus and birth canal is necessary to make rotation of the fetus possible.
In dorso-ilial position, repulsion is usually not necessary but may be helpful. Lubrication of the birth canal caudal and downward traction on the extremities, and rotation of the fetus with the operator's arm in the birth canal readily corrects this abnormal position.
If the fetus is in a dorso-pubic position it should be repelled out of the pelvis, leaving the limbs in the pelvic cavity, chains are fastened to the fetlock and cross traction is applied by two assistants. Depending upon which way the fetus is to be rotated, one leg is pulled at first upward, then horizontally to the left or right and then downwards, while the other leg is being pulled underneath the first leg downward and obliquely toward the right or left.
- 3. Version is the rotation of the fetus on its transverse axis into an interior or posterior presentation. This is done most often in the mare in transverse presentation of the fetus. The version is usually limited to 90 degrees and by repulsion on one end of the fetus and traction on the other, the transverse presentation is changed to a longitudinal presentation. If possible, the fetus should be turned into a posterior presentation; this prevents the head and neck from complicating the delivery.
- 4. Extension and adjustment of the extremities: This is the correction of abnormal postures, usually due to flexion of one or more of the extremities, thus causing dystocia. Abnormal postures are difficult and usually impossible to correct within the pelvis, as such, the fetus should be repelled out of the pelvis before these procedures are attempted. Although flexion of the limbs usually results in dystocia in uniparous animals, it is a rare cause of dystocia in multiparous animals.
Three basic mechanical principles are necessary to effect a prompt easy correction of a flexed extremity.
Traction is the most frequently applied obstetrical procedure intended for augmenting and occasionally replacing the dam's expulsive efforts. Normal fetal presentation, position and posture, and a reasonable normal birth canal to fetal size relationship areindispensable prerequisites for safe and effective delivery. As such, the indications for forced extractions are cases in which:
For safe and effective delivery, forced extraction must mimic natural expulsion as closely as possible. In addition to propelling the fetus, expulsive efforts simultaneously guide the fetus in a manner that reduces resistance. Thus, the general direction is adjusted to the arc formed by the greater curvature of the pregnant horn and the birth canal. In anterior presentation, one forelimb slightly precedes the other, thus reducing the width of the shoulders. The shoulders enters the pelvis with the fetus slightly tilted off the dorso-sacral position. The distance between the sacro-iliac and ilio-pubic junction is greater than the width of the pelvic inlet. Similarly passage of the hip is facilitated by rotation of the fetal body before entry into the pelvic inlet.
Myometrial contractions and synchronized tenesmus are intermittentallowing for expansion of the soft birth canal over the fetal parts. Along with this fetal fluids, particularly anmionic fluid, provides excellent lubrication of the birth canal, thus minimizing friction. Frequently, however, forced extraction has to be performed in protracted cases of dystocia with a dry birth canal.
Adherence to these basic principles calls for the following sequence of steps in forced extraction:
To avoid injury to the limb, a chain should be placed above the fetlock and a half hitch around the pastern. If a fetal extractor (calf puller) is used, the chains should be attached in such a manner that one leg precedes the other by a few inches. This will allow the shoulder to pass through the birth canal at an oblique angle which is extremely important with the delivery of a relatively large fetus.
Traction on the two feet is referred to as "2-point traction" and is adequate in many cases. In anterior presentation, however, it is common for the head to resist passage through the birth canal. When the head has entered the birth canal but does not proceed, a reversed telescoping of compressing effect occurs resulting in an increase in total fetal volume and as such, compounding the problem. To prevent this from occurring "3-point traction" should be considered which simply involves the use of a head snare, chain, or some other device used to apply traction to the head, neck and eventually the chest of the fetus. The end result is elongation of the head and neck with resulting decrease in fetal diameter.
Infusion of lubricant solution into the uterus provides continuous lubrication.
The fetal extractor, or so-called "calf puller", is one of the most common obstetrical instrument used to remove the fetus from the birth canal. When properly used, the fetal extractor is effective and relatively safe. On the other hand the injudicious use of the fetal extractor may produce severe, irreversible trauma to the dam and fetus. The traction force generated by the fetal extractor exceeds the maternal force by nearly six times. As such, it is imperative that this fact be considered when this instrument is being used.
Forced Traction Force (in lbs.)
The General rule is that no more force should be applied with the fetal extractor than could be applied by two to three strong individuals.
Fetotomy can be defined as the sectioning or dismemberment of a fetus to facilitate its delivery through the birth canal. This procedure is usually performed only on dead fetuses; if the fetus is alive and cannot be safely delivered by mutation and forced extraction, then a caesarean section is indicated.
Indications for the use of fetotomy include:
Some of the terminologies used in fetotomy include:
Prior to the introduction of the wire-saw fetatome, the subcutaneous method was utilized by some veterinarians to alleviate dystocias, however, because this method was both exhaustive and time consuming, it was never widely accepted. The introduction of newer, improved models of wire-saw fetatomes resulted in a renewed interest in fetotomy. In general, total fetotomies are not generally performed because even with the percutaneous method, it has been found to be time consuming. As such, most authorities recommend a ceasarean section in place of a total fetotomy. Partial fetotomy has, however, retained its usefulness.
Before one embarks on performing a fetotomy, there are certain factors which should be considered. In general, fetotomy should not be attempted unless.
Another clearly definite contraindication is the presence of injuries in the birth canal of the dam.
Basic guidelines for total or partial fetotomy include:
Another important feature which should always be borne in mind is that adequate lubrication of the birth canal is essential to the success of the procedure.
Technique for percutaneous fetotomy includes:
Always remember that the position of the head of the fetatome determines the direction of the cut. Progress of the cut has to be monitored and the position of the head of the fetatome and/or wire adjusted if and when necessary.
Fetotomy of the fetus in anterior presentation begins with removal of the head at the occiput. This is the only indirect cut made in the entire procedure that does not require counterforce to hold the head of the fetatome in position against the forces generated by the pull of the fetatome wire during the cutting process. The constricted nature of the neck behind the occiput holds the wire in place adequately without counterforce.
The second procedure is removal of the forelimbs. The foot is chained above the fetlock. The fetatome is fully threaded. The foot-chain is passed through the loop of obstetrical wire and the wire is placed between the claws of the hoof of the fetus. The chain is looped on the lateral side of the leg. The wire saw will eventually be released and passed up the medial side of the leg once the head of thefetatome is positioned dorsal and caudal to the scapular cartilage. The fetatome head is placed in position and the chain, which provides counterforce, is attached to the butt-plate of the fetatome. The wire is released from between the claws of the calf and worked up the leg into the axiliary space, making certain that the wire passes beneath the scapulo-humeral joint on the anterior and behind the elbow on the posterior side of the leg and the cut is made.
The second leg is removed in the same way. If the manipulation is difficult on the down leg, the cow can be rolled to her opposite side to make the cut easier. It is preferable to keep the cow standing if possible; a light epidural will help make this possible.
At this point, the Krey's hook is attached to the severed spinal column of the neck and its chain passed through the looped fetatome wire. The looped wire is passed up the chain and over the torso of the fetus. The head of the fetatome is positioned along the side of the fetus or near its back and Krey's hook chain is attached to its butt plate for counterforce. A right angle cut is made through the midsternal plane. After the cut is made, thoracic viscera is removed.
The next cut involves a similar procedure but the section that is left to be removed will be the largest one. If it will not pass through the birth canal, it can be further reduced in size by an additional cut. The fetatome is partially unthreaded, the fetatome wire guide is attached to the wire of the head of the fetatome and the wire passed through the diaphragm and back around the ribs near the vertebral column. The wire is pulled to the outside of the birth canal and re-threaded through the fetatome. The Krey's hook is left attached to the fetal spinal column and the head of the fetatome is held together with the Krey's hook so that the cut will be made as close to the costo-vertebral attachments as possible. Once the cut is made, the rib cage can be rolled into a small unit and removed.
The abdominal viscera are removed. The Krey's hook is attached to the pelvic spine. The fetatome is partially unthreaded. The fetatome wire guide is attached to the wire and passed between the legs of the calf. This is usually easier to accomplish by going dorsally, passing the wire guide handle between the legs and then procuring it ventrally from between the legs. The wire is positioned between the ischial arch. The tail is included so it will be left attached to the leg not affixed by the Krey's hook. Positioning of the wire in this manner is not absolutely essential, but will make it less likely that the wire will slip so that the cut is made through the femur rather than the pelvis. The two legs can then be easily removed.
Fetotomy of the fetus in posterior presentation follows a pattern similar to that in anterior presentation. If legs are retained, the wire guide is attached to the wire at the head end of the half-threaded fetatome and passed around one retained leg. It is important that the wire be positioned medial to the stifle joint. The head of the fetatome is held on the side of the base of the tail opposite to the leg to be removed and the cut is made. The second leg, if retained, can be removed in the same manner if it cannot be repositioned by the flexed hock manipulation.
If legs are presented, an indirect cut must be made. The procedure is analogous to that of the removal of a forelimb. The head of the fetatome is positioned just cranial to the tuber coxa on the side of the leg to be
removed. The looped wire is seated in the ischial arch and the tail is included with the leg to be first removed.
The second leg is removed together with the abdominal region behind the rib cage by indirect fetotomy. The fetus is eviscerated and the thoracic section behind a plane caudal to the scapula removed next. This piece is the largest one and may require division of the ribs in a manner similar to that described in anterior presentation fetotomy.
To complete the fetotomy, a direct cut can be made removing either one forelimb or a forelimb and most of the remaining thoracic part. To accomplish this, the fetatome is half unthreaded and the wire attached to the wire guide. The Krey's hook is attached to the spinal column of the fetus and the fetus retracted to the pelvic inlet. The fetatome wire is passed between the front leg and the neck, around the leg, and rethreaded through the fetatome. The location of the final cut will be dependent on placement of the fetatome head. If it is placed behind the leg to be severed, the cut will be made between the scapula and rib cage. If the head of the fetatome is placed on the opposite side of the Krey's hook, the cut will include part of the rib cage and spinal column and, this will reduce the size somewhat more. The latter section is preferred by most theriogenologists.
Incise the skin on each side of the head from the occipital bone, carrying the incision in front of the ear to the anterior angle of the mandible. Reflect the skin back to the occipital - atlanto joint. Severe the ligaments and muscles, disarticulate the head; reflect the skin from the mandible, make a transverse incision through the trachea, esophagus and muscles of the throat. The head is now free, and the remaining skin-flaps can be used to supply traction.
Indications - When the fetal head becomes firmly impacted within the maternal pelvic, and it is impractical either to repel or extract it, or when the head because of hydrocephalus or other cranial deformity is too large to enter or pass through the pelvis.
Cephalotomy is accomplished by fixing the head with a snare around the lower jaw. The cranium may be broken down with an obstetrical chisel or fetatome. In cases ofhydrocephalus, sometimes simply incising the distended cranium may cause sufficient reduction in size to permit delivery. In most cases, however, the fetatome is necessary to separate the enlarged cranium from the rest of the head by passing a loop of obstetrical wire around the base of the enlargement and fixing the head of the fetatome in the frontal region.
Amputation of the head and neck may be performed by the wire saw or fetatome. The fetatome is preferred because if the operation is properly performed, the neck is amputated close enough to the body so that traction on the forelimbs will pull the scapular and shoulder joints over the exposed stump of the cervical vertebra. Occasionally in large mares, it may be necessary to remove the forelimb opposite the side to which the head and neck are flexed, and to apply traction to the fetus in order to enable the operator to reach the neck and pass the fetatome wire around it. The fetatome wire saw is attached to a wire saw director or obstetrical chain and passed over the base of the neck and drawn around it. The head of the fetatome is held forcibly between the shoulder joint and neck of the fetus and the neck is severed as close to the body as possible. The head and neck are then removed with the hands, snare or Krey's hooks, and the fetus delivered by traction.
Traction should be applied to the limb. A loop of fetatome wire is passed up the leg, over the olecranon and tightened. The head of the fetatome is placed firmly in the pectoral region and held or strapped securely to extended leg in the metacarpal region to avoid slipping and the humerus amputated through its distal end.
A loop fetatome wire is passed around the body of the fetus and the head of the fetatome is inserted into the birth canal and positioned over the lumbar region of the fetus. After the wire is manipulated back of the last ribs, detruncation is rapidly accomplished. On occasions, two cuts through the trunk of a large fetus may be necessary using Kery's hooks on the exposed vertebrae for traction, further reduction on the fetal body is facilitated. In cases where the fetus is large or emphysematous, or if the birth canal is swollen, small or dry evisceration along with adequate lubrication tend to make this operation easier and safer. Following detruncation, the forequarters are removed following which the hindquarters are turned to a posterior longitudinal dorso sacral position and delivered.
The presence of the head usually prevents access to the flexed carpi. Thus the head is amputated first. Following removal of the head the fetatome wire is passed through the flexed carpus brought to the exterior and threaded into the fetatome. The head of the fetatome is positioned as close as possible to the distal carpus and the lower forelimb amputated.
A transverse incision is made through the skin and muscle just cranial to the wing of the ilium. A loop of fetatome wire is carried upon one hindleg and placed in this incision. The head of the fetatome is placed between the hindlimbs and one hindleg and a portion of the pelvis are removed.
Modus Operandi - The head of the fetatome is placed on the lower row of tarsal bones or the head of the metatarsal bone and the limb is amputated in this area.
Caesarean section is indicated in those cases when mutation, forced extraction or fetotomy are deemed inadequate or too difficult to be employed to relieve the impending or present dystocia, and when it is desired that the fetus be delivered alive. Indications for caesarean section include fetal oversize, feto-pelvic disproportion, incomplete dilation of the cervix, irreducible torsion of the uterus, hydrops of the fetus, hydrops allantois or abnormalities of presentation, position or posture, ventral hernias and prolonged cases of dystocia.
Many newborn animals that have been delivered following dystocia die without breathing despite a strong heart beat and normal or depressed reflexes. Many of these can be saved if immediate steps are taken to provide resuscitation.
If spontaneous respiration is not initiated within a few seconds after the newborn is delivered or if the newborn is making gasping sounds, resuscitation should be promptly instituted.
Check the heart rate, respiratory rate and effort, reflexes, and mucous membranes (color and CRT). Any new- born with a weak or slow heart rate, pale m.m. with delayed CRT, and lacking ventilatory effort should be resuscitated.
In the absence of an IPPV apparatus inserting a rubber tube, attached to an oxygen source, into the upper nostril and allowing gas to flow at a rate of 5 liters/min or by applying mouth-to-nose resuscitation at the rate of 25/min until a spontaneous rhythm is established.
An increased heart rate is the best indication of adequate resuscitation, and as long as a heart beat is present, there is hope for survival.
Aftercare and Examination of the DamAfter Mutation, Forced Extraction or Fetotomy
Following a dystocia operation, the genital tract of the dam should always be examined for the presence of another fetus which may be in the uterus or abdominal cavity. In the sow, the farrowing of the last fetus is usually followed by the sow becoming quiet and content, nursing her pigs, urinating, eating and drinking. If the sow remains restless, uneasy, shows anorexia and intermittent straining, she should be examined for the presence of another fetus. In these cases radiographic examination of the abdomen is very beneficial.
After every Dystocia operation, the uterus and soft birth canal should be examined for lacerations and ruptures. Small superficial lacerations of the cervix, vagina or vulva are of little importance or significance unless retention of the placenta favors infection. If the fetal membranes are retained, attempts to remove them at this areaseldom successful and vigorous traction may result in eversion of the uterine horn.
Contamination of the birth canal and uterus is inevi- table. As such, the use of local antibicrobral agents in the uterus is clearly indicated.
Following fetotomy, the uterus should be lavaged with warm water to remove hair and other debris following which it should be medicated with a broad spectrum antimicrobial.
If the animal is unable to rise, the operator should try to determine the cause of the paraplegia or paralysis.
The udder should be examined to make sure that no pathology is present, and that teat wounds and lacerations did not occur if they have occurred, then they should be treated.